essay helping a stranger

A Belief in Helping Strangers

The collision of the two vehicles startled me. I swerved to the side of the road to ensure that I did not become a victim. My husband jumped out of the car before it had even stopped and rushed towards one of the cars that had been involved in the accident. Instinctively, I rushed towards the other car in an attempt to try and save the victim. From inside it, I heard the voice of a woman, calling faintly for assistance, “someone help me… my back! My hips! I can’t breathe, please help me!” carefully, I pulled at the door. Immediately, it flung open. The woman was trapped between the driver’s seat and the steering wheel. She was trying to pull herself from the entrapment but her attempts were all in vain because she did not move an inch. Slowly, I tagged at the seat and unfastened the seat belt. Luckily, there were no more complications and to our great relief, she was finally free! Pulling her from the smashed car, I carefully stretched her on a blanket offered to me by my husband, from my memory of first aid that I received in senior school, I covered her hastily to prevent the incidence of shock and waited for the arrival of the ambulance. This incident was stamped in my memory and it has never faded in my mind. It could be as a result of how much I received than I got. The assistance I gave this stranger gave me peace, inner satisfaction, and calm. Above all, it gave me one of life’s greatest lessons; giving unconditionally is a virtue that should be put to use because all kind of giving without other intentions helps to elevate human suffering and makes life more bearable.

One of the benefits of being helpful to people is the fact that all manner of kindness has the tendency to spread. This means that it may just start with you helping a couple of people that you don’t even know and probably they will never get the opportunity to know you and soon, the number grows and you realize that a dozen more people have joined in to help, the number continues to increase to up to a hundred and even thousands. These people do not know each other but kindness still has a positive influence on the receivers and just like ripples of water in a lake, there will be a whole sea of people with happy faces across the country who are just gaining happiness from a mere action of help. This just serves to show that helping makes life bearable to both the sufferers and the helping parties (Lowe, par. 20; L’Armand & Pepitone 193)

Good deeds rarely go unrewarded. There are three ways in which helping can be rewarding, one of them being that the probability of one receiving help later on in the future is high when they help other people. Another reward that can be obtained from helping is the fact that the person who is helped is relieved from the personal distress they were going through before they received help and finally, the last reward that can be obtained from helping others is that people can be able to gain approval from the society and thus increasing their self-worth (Burnstein 775).

Another good thing about helping is that help emanates purely from people’s hearts. Pure altruism comes by when someone experiences empathy towards an individual who is in need. This means that pure giving comes in when one is able to put themselves into the shoes of the people who are suffering and personally feel the emotional torment that the person is undergoing. When we are empathetic with someone’s troubling situation then we are willing to go through any options to attempt for purely altruistic reasons and this is done irrespective of what rewards one is likely to acquire through the help accorded (Darley 105)

Works Cited

Burnstein, Eric, Crandall, Earnest, & Kitayama, Evans. “Some Neo-Darwinian decision rules for altruism: Weighing cues for inclusive fitness as a function of the biological importance of the decision.” Journal of Personal Social Psychology74.6 (1994) : 773-789.

Darley, Johnson & Batson, Cole. “From Jerusalem to Jericho: A study of situational and dispositional variables in helping behavior.” Journal of Personality and Social  Psychology 27.3 (1973) : 100-108.

L’Armand, Katrina, & Pepitone, Arwin. “Helping to reward another person: A cross-cultural analysis.” Journal of Personality and Social Psychology 31 .7(1975): 189-198.

Lowe, Richard. “Being helpful.” Online mind , 2009. Web.

Cite this paper

• Chicago (N-B)
• Chicago (A-D)

StudyCorgi. (2021, November 25). A Belief in Helping Strangers. https://studycorgi.com/a-belief-in-helping-strangers/

"A Belief in Helping Strangers." StudyCorgi , 25 Nov. 2021, studycorgi.com/a-belief-in-helping-strangers/.

StudyCorgi . (2021) 'A Belief in Helping Strangers'. 25 November.

1. StudyCorgi . "A Belief in Helping Strangers." November 25, 2021. https://studycorgi.com/a-belief-in-helping-strangers/.

Bibliography

StudyCorgi . "A Belief in Helping Strangers." November 25, 2021. https://studycorgi.com/a-belief-in-helping-strangers/.

StudyCorgi . 2021. "A Belief in Helping Strangers." November 25, 2021. https://studycorgi.com/a-belief-in-helping-strangers/.

This paper, “A Belief in Helping Strangers”, was written and voluntary submitted to our free essay database by a straight-A student. Please ensure you properly reference the paper if you're using it to write your assignment.

Before publication, the StudyCorgi editorial team proofread and checked the paper to make sure it meets the highest standards in terms of grammar, punctuation, style, fact accuracy, copyright issues, and inclusive language. Last updated: November 25, 2021 .

If you are the author of this paper and no longer wish to have it published on StudyCorgi, request the removal . Please use the “ Donate your paper ” form to submit an essay.

Pure altruism – the connection that explains why we help strangers

Senior Lecturer in Psychology, Leeds Beckett University

Disclosure statement

Steve Taylor does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Leeds Beckett University provides funding as a member of The Conversation UK.

View all partners

• Bahasa Indonesia

Just over two years ago, my home city of Manchester suffered a terrorist attack . Waiting in the arena foyer after an Ariana Grande concert, a young man detonated a bomb strapped to his chest, killing 22 people and injuring several hundred. But in the midst of the senseless savagery of the attack, there were many stories of heroism and selflessness .

An off-duty doctor who was walking away from the venue ran back into the foyer to help the victims. A woman who saw crowds of confused and frightened teenagers guided around 50 of them to the safety of a nearby hotel where she shared her phone number on social media so that parents could come and pick their children up.

Taxi drivers across the city switched off their meters and took concert-goers and other members of the public home. As one paramedic at the scene commented : “There was an unbelievable amount of people doing what they could to help … I saw people pulling together in a way I have never seen before.”

He added: “The thing I will remember more than any other is the humanity that was on display. People were catching each other’s eye, asking if they were okay, touching shoulders, looking out for one another.”

Such acts of altruism are almost always a feature of emergency situations. In a London street in 2015, a cyclist was trapped under the wheel of a double decker bus. A crowd of around 100 people gathered together, and in an amazing act of coordinated altruism, lifted the bus so that the man could be freed.

The question of why human beings are sometimes prepared to risk their own lives to save others has puzzled philosophers and scientists for centuries. According to the modern Neo-Darwinian view , human beings are basically selfish, the “carriers” of thousands of genes, whose only aim is to survive and replicate themselves.

Under this view, it makes sense to help people who are closely related to us genetically, such as family members or distant cousins, because what may seem like self-sacrifice actually benefits our gene pool. But what about when we help people to whom we are not closely genetically related, or even animals?

A variety of different explanations to account for this have been put forward. One suggests that perhaps there is no such thing as “pure” altruism at all . When we help strangers (or animals), there must always be some level of benefit to ourselves, such as making us feel good about ourselves, or gaining the respect of others.

Or perhaps altruism is an investment strategy: we do good deeds to others in the hope that they will return the favour (known as [ reciprocal altruism ]. It could even be a way of demonstrating our resources, showing how wealthy or able we are, so that we become more attractive and enhance our reproductive possibilities.

Rooted in empathy

I don’t doubt that these reasons apply sometimes. Many acts of kindness may be primarily (or just partially) motivated by self-interest. But is it naive to suggest that “pure” altruism can exist as well? That in the very moment when an altruistic act takes place, our motivation is purely to alleviate another person’s suffering?

In my view, pure altruism is rooted in empathy. Empathy is sometimes described as the ability to see things from another person’s perspective. But in its deepest sense, empathy is the ability to feel, not just to imagine, what others are experiencing. It is the ability to actually enter the mind space of another person (or being) so that you can sense their feelings and emotions. In this way, empathy can be seen as the source of compassion and altruism.

Empathy creates a connection that enables us to feel compassion. We can sense the suffering of others and this gives rise to to an impulse to alleviate their suffering, which in turn gives rise to altruistic acts. Because we can feel with other people, we are motivated to help them when they are in need.

As I suggest in my book, Spiritual Science , it is wrong to think of human beings as completely separate entities, made up of selfish genes that are only concerned with their own survival and replication. The capacity for empathy suggests a deep interconnection between us.

There is a sense in which we are part of a shared network of consciousness . It is this which makes it possible for us to identify with other people, to sense their suffering and respond to it with altruistic acts. We can sense other people’s suffering because, in a sense, we are them. So we feel the urge to alleviate other people’s suffering – and to protect and promote their well-being – just as we would our own.

In the words of the German philosopher Arthur Schopenhauer :

My own true inner being actually exists in every living creature …[This] is the ground of compassion … and whose expression is in every good deed.

In other words, there is no need to make excuses for altruism. Instead, we should celebrate it as a transcendence of seeming separateness. Rather than being unnatural, altruism is an expression of our most fundamental nature – connection.

Read more: Spiritual science: how a new perspective on consciousness could help us understand ourselves

• Selfishness
• the selfish gene

Want to write?

Write an article and join a growing community of more than 183,800 academics and researchers from 4,959 institutions.

Register now

8 Feel-Good Stories Of Strangers Helping Someone They Didn't Know

Senior Life Editor, HuffPost

Sometimes the person you need most in a trying moment isn’t a person you know at all.

A few months ago, we asked readers to share experiences in which a complete stranger went out of their way to help. The ongoing project, called The Good Kind , seeks to highlight the unexpected kindness that people have received from someone they didn’t know. These stories range from simple acts that brightened a person’s day to grand gestures that changed a person’s life.

Below is just a selection of the hundreds of submissions we’ve received so far. Read on about the good kind of strangers in this world.

“I shared with her that I was a cancer survivor and the two of us ― complete strangers ― shared a hug and some tears.”

A few years ago, I was circling the block to find a parking space so I could get a cup of coffee. A woman walking by flagged me down and said she would go in and get me the coffee if I gave her my order. While she was inside, a spot opened up and I was waiting by my car when she exited. I thanked her when she came out and went to hand her money. She said the coffee was on her. She went on to explain that she had metastatic cancer and with the time she had left, she wanted to do as many good deeds as possible. I shared with her that I was a cancer survivor and the two of us ― complete strangers ― shared a hug and some tears. She asked me to pay it forward as often as possible, and ever since that day I make sure to do random acts of kindness for others as often as I can. ―Sara Marsi, Providence, Rhode Island

“When they headed to pay their bill, they were told that a guest had already paid and wanted to be anonymous.”

It was in a restaurant in downtown Chicago in the mid-sixties. I was sitting across from a table of ten or twelve soldiers. When they headed to pay their bill, they were told that a guest had already paid and wanted to be anonymous. The soldiers look around the restaurant searching for the benefactor and said, “Whoever you are, thank you.” They were the ones who deserved the thanks. I’ve never forgotten that moment of grace. Made me aware of the impact of acts of kindness with no need for recognition. ―Mike Grunsten, Chicago

“He drove out of the way for me, dropped me off, made sure I got into my car at the station safely and refused gas money.”

About 20 years ago, a man named John drove me home from the train station in the middle of the night. I had fallen asleep and missed my stop and landed up two towns down the line. This was before Uber and there were no taxis available. My husband was asleep so he didn’t pick up. I was all alone, shivering in the cold, and John asked me if I needed a ride. Naturally, I was hesitant but I surmised quickly that if he were a serial killer, stumbling onto me, his next victim, was an unusual stroke of luck. He drove out of the way for me, dropped me off, made sure I got into my car at the station safely and refused gas money. I will always be grateful to him and think of him every now and again. ―Peggy Buck, Wheaton, Illinois

“I had so much fun ice skating for the first time and have never forgotten that kind man.”

We were very poor growing up and couldn’t afford very many special outings. We were out somewhere when I was about 7 or so and there was a makeshift ice skating rink there. Growing up in New Zealand, we don’t get ice and snow so this was the first time I’d ever seen anything like that. I thought it was amazing. I knew there was no point in asking my parents if I could go skating as we just wouldn’t be able to afford it, so I just watched longingly from the side at people having fun. The man running the rink must of felt sorry for me or something and asked if I wanted a go. I said I couldn’t as I didn’t have any money, but he said it was OK. I had so much fun ice skating for the first time and have never forgotten that kind man or the chance to experience something new and exciting. ―Shelene Crane, Auckland, New Zealand

“I looked up to see a fellow commuter not only shoveling my car out, but offering me his snow brush to clear off my windows.”

I had recently moved to Boston from Florida. I take the commuter rail into the city, and one stormy winter’s day the train was delayed for hours. People were cold, wet, tired and grumpy. When I finally made it to my car, well after dark, I found it covered with snow and blocked by a two-and-a-half-foot wall of snow from a plow. Without a shovel and feeling frustrated and teary-eyed, I searched my car for a makeshift tool. I had to resort to using my hands to clear the snow. We New Englanders have a reputation of being “cold” and I dreaded asking someone to lend me something, further delaying their journey home. After making a couple of passes with my arms and hands to clear the snow off my car, I looked up to see a fellow commuter not only shoveling my car out, but offering me his snow brush to clear off my windows. I couldn’t thank that man enough! We made fairly quick work of digging my car out and we both went our separate ways. On my way home, I cried like a baby from happiness and the unexpected kindness bestowed upon me. ―L. Lou Dan, Boston

“I received an anonymous check for $200 to help with groceries. I don’t know her name but that woman saved us.”

I was pregnant at my job, a high-volume, low-cost vet clinic. I worked in surgery, eventually couldn’t do the physical labor, and my job’s HR department refused to help find me placement or help accommodate me. They effectively let me go, and not having protection or means (my husband stayed home to care for our special needs daughter), I applied for unemployment. They actually FOUGHT me on it and I was so fortunate to have a compassionate case worker to help with my claim. The second time around, my assessor listened to me bawling, pregnant and scared trying to figure stuff out. A week after I spoke to that woman, I received an anonymous check for $200 to help with groceries. I don’t know her name but that woman saved us. If you’re reading this, know you fed my family, helped take some bills off our plate and made a lasting impression for life. ―Teresa Banks, Chicago

“She took us to her own home and we were welcomed as precious guests by her large family. They insisted that we stay the night with them.”

After hiking to an obscure waterfall for a few hours of our weeklong backpacking vacation, we returned to our car to find that it had been broken into, belongings gone. We had our plane tickets, ID, and the keys to the car. No cash, no clothes, no wallets. We drove to the nearest town and asked if there was a police station where we could report the theft. The officer on duty was a native Hawaiian woman who was very sympathetic, took our information and then invited us to have dinner with her. At the end of her shift, she took us to her own home and we were welcomed as precious guests by her large family. They insisted that we stay the night with them. The next morning, our angel police officer took us to the office of a local lawyer who managed an emergency fund for locals fallen on hard times. He suggested we borrow some money from this fund to get us home and pay it back when we could. After filling out some paperwork, we had enough cash to survive and an invitation to have lunch with the lawyer. This experience, which could have been a disaster for us, ended up being the highlight of the trip, and I will never forget the kindness and generosity of this small community. ―Carolyn Reynolds, Maui, Hawaii

“I was the recipient of a kidney from an altruistic donor, an event that significantly changed my life.”

I was the recipient of a kidney from an altruistic donor, an event that significantly changed my life. Because of my age at 74, I had not considered that a transplant would be an option for me. Candy, my altruistic donor, and I met in pre-op on the morning of the surgery, and only then did we discover that we are both educators. She was a third grade teacher and former teacher of the year, and I was a teacher in North Carolina. My daughter, Jennifer, had not hesitated to offer one of her kidneys, but we were not a match. Jennifer was determined to “pay it forward,” and just four-and-a-half weeks after my transplant, she had her surgery. The recipient of her kidney was a 35-year-old man in Columbus, Ohio, who had been waiting for a kidney for five years. ―Sharon Dole, Augusta, Georgia

Responses have been lightly edited for length and clarity.

Want to contribute an encounter of your own? Fill out the form here to share your personal story . You can also hit us up at [email protected] to share your experience, with details on what happened, where it occurred and how it made you feel or the particular mark it left on your life. We want to hear your experiences with kind strangers ― no matter how big or small they may be.

From Our Partner

Huffpost shopping’s best finds, more in life.

.

, , , , , , .

Why talking to strangers is good for you, them and all of us

Share this idea.

• Click to share on Facebook (Opens in new window)
• Click to share on Twitter (Opens in new window)
• Click to share on LinkedIn (Opens in new window)
• Click to share on Reddit (Opens in new window)
• Click to share on Pocket (Opens in new window)
• Click to share on WhatsApp (Opens in new window)

Want to live a more meaningful life? TED Courses are here to help. Taught by some of your favorite TED speakers, each course will educate you, inspire you and illuminate new ways of being and thinking. Plus, it will  connect you with a global community of fellow learners. Go here to find out more. Below, a piece of life advice from author Julie Lythcott-Haims, who teaches the TED Course on how you can become your best self.   

In childhood, we’re told: “Don’t talk to strangers.”

But this is short-sighted advice because after we finish high school and move out into the world, everyone we encounter is a stranger. And we’re a social species, which means we need each other.

So instead of avoiding strangers, we need to get good at interacting with them, both to get help when we need it and to be of use to them. 

When you give someone eye contact and a smile, it demonstrates “You exist, fellow human,”  and it makes them feel good.

Let’s start with actual strangers — like the p eople you pass on the street or in a store. You may not think you’re in a relationship with them, but you essentially are .

Research shows that when you look right through someone as if they aren’t there, they feel a small sting.

The reverse is also true. When you give someone eye contact and a smile, it demonstrates “You exist, fellow human, I see you ,” and it makes them feel good. And you feel good too when they do it back to you.

I appreciate that not everyone can make eye contact or smile for reasons including cultural norms, social anxiety or neurodivergence. But if you can, do. 

What about the humans you interact with regularly yet don’t really know, like the baristas at your coffee shop, the clerks at your grocery store, the person at the front desk in your building, your postal carrier and so on?

Researchers call these folks “consequential strangers,” because having them in your life is of consequence to you.

Show them that they matter by saying “How’s your day going?” Learn their name so next time you can say, “Hey, Breonna, how’s your day going?” If you want to really make someone’s day, offer them some gratitude with the simple sentence: “Thank you for being here, George. I appreciate you.”

When you’re kind to someone, you, they and everyone who observes your interaction will get a lift from your act of kindness. 

Part of you might think it’s a bit weird to thank them, but keep in mind that they came to work today and their work makes your life easier, right?

And if they’re grumpy, don’t be offended — it’s not about you.

Instead, double down on kindness. Say: “Hey, thanks so much, Michael, I hope you have a good day.” Or kindly say: “Looks like it’s a tough day, Sandra. Hope it gets better.” You, they and everyone who observes this interaction will get a lift from your act of kindness. 

Then there are those in your loose network, like neighbors and colleagues. For years, although it’s hard for me to admit this, I’d drive into my driveway after work each day and realize that I didn’t even know my neighbors .

So I formed a monthly writing group with some of them in order to experience the real connections that form from hearing each others’ stories. After doing this, we’ve been more able to do what neighbors do, like borrow sugar or collect mail when someone’s away. What might you do on your street or in your building?

When you see a neighbor, try stopping to ask them how their day’s going.

You have the power to make your community stronger through exchanges like this.

Or if you’re going to the store, ask if you can pick something up for them. Or, you can throw a barbecue or potluck and put out name tags to remove any guilt that people feel for not remembering each others’ names. 

Finally, at work, listen for the small things people reveal about their lives.

Whether it’s something good or bad, they’re sharing it for a reason, so I want you to remember it. Within the next couple of days, you don’t have to pry but show them you noticed. Say, “Did you say you’re an uncle now? Congratulations!”; “Sounds like that trip you took was amazing”; “I’m so sorry to hear your family member has been really sick.” If someone went out of their way to do something thoughtful, drop a quick note to say “I saw what you did and it was really kind of you.” 

You have the power to make your community stronger through exchanges like this. It’s good for you, it’s good for them, and it’s good for all of us. 

Sign up now for Julie Lythcott-Haims’s TED Course called “How to become your best adult self,” which will also tell you how you can build healthy relationships, speak up and show up for the issues you care about. And while you’re at it, c heck out our other TED Courses. Podcast host Manoush Zomorodi can show you how to make your career more meaningful; neuroscientist Lisa Genova will help you sharpen your memory and keep your brain in shape; and world traveler Pico Iyer will share the secrets to making the most out of your travels (even if it’s just to the next town!). 

Watch Julie Lythcott-Haims’s TED Talk here: 

About the author

Julie Lythcott-Haims is an author, speaker and activist focused on helping humans find their true north. At its core, her work is about the obstacles that prevent us from being our most authentic selves and how to overcome them. She offers us all an invitation to grow deeper — to continuously return to and strengthen our voice, values, meaning and joy. She holds degrees from Stanford, Harvard Law and California College of the Arts. She started off as a corporate lawyer, a career pathway she admits she originally sought out to gain approval from others. She quickly realized that work was not for her and began working with students in higher education, becoming the Dean of Freshmen at Stanford University. Later, she added “writer” to her list of accomplishments. She is the New York Times bestselling author of parenting guide How to Raise an Adult. Her second book is the critically-acclaimed and award-winning prose poetry memoir Real American, which describes her experience as a Black and biracial person in white spaces. Her third book, Your Turn: How to Be an Adult, has been called a “groundbreakingly frank” guide to adulthood. To learn more about her work, visit julielythcotthaims.com

• julie lythcott-haims
• relationships
• society and culture
• ted courses

TED Talk of the Day

How to make radical climate action the new normal

6 ways to give that aren't about money

A smart way to handle anxiety -- courtesy of soccer great Lionel Messi

How do top athletes get into the zone? By getting uncomfortable

6 things people do around the world to slow down

Creating a contract -- yes, a contract! -- could help you get what you want from your relationship

Could your life story use an update? Here’s how to do it 

6 tips to help you be a better human now

How to have better conversations on social media (really!)

Let’s stop calling them “soft skills” -- and call them “real skills” instead

3 strategies for effective leadership, from a former astronaut

There’s a know-it-all at every job — here’s how to deal

How to raise successful kids without overparenting

3 types of normal forgetting -- and 1 that isn’t

Have you quietly quit? Your next step: Go to the neutral zone

clock This article was published more than  4 years ago

Would you help a stranger? UCLA to study why people are kind or not.

On Father’s Day 2017, a woman paying for her meal at a McDonald’s drive-up window in Scottsburg, Ind., told the cashier that she’d also like to buy the meals of the man with four children in the van behind her. “Tell him ‘Happy Father’s Day,’ ” she told the salesclerk .

Her small act of kindness was soon regenerated 167 times, with each customer offering to pay for the subsequent person's order. The story made national headlines, but Daniel Fessler wasn't surprised.

The University of California anthropology professor has spent the past several years studying the positive effects of kindness, and he is now the inaugural director of an academy devoted to the subject.

“The very fact that we can live cheek and jowl next to each other is remarkable in itself,” he said. “With the world more connected than ever before, kindness has never been more important."

This church gave its parishioners $60,000 and told them to pay it forward. Here’s what happened.

The Bedari Kindness Institute opened last month in a UCLA social sciences building with a $20 million gift from the Bedari Foundation to fund research on what provokes kindness and how that can empower everyday people. It will also offer classes and workshops on the topic.

Research has already been done at UCLA about how kindness can reduce heart disease, depression and a person’s risk for developing cancer, said Darnell Hunt, dean of the university’s social sciences division and administrator of the new program. Researchers have begun to study the effects of kindness on depressed students.

Another project underway is studying why some people choose to risk their lives to save others during genocide while their friends and neighbors do not.

“What are the mechanisms that determine whether somebody is going to be kind or not?” Hunt asked. “Who are these people, and what motivated them to take action?”

He added that “kindness is at the core of humans’ ability to cooperate with one another.”

How a town came together to rescue a missing 6-year-old — and used a thermal camera on a drone to find him

The institute is being funded by Manhattan philanthropists Matthew C. Harris and his wife, Jennifer, who named the research facility Bedari after the first syllables of the names of their children: Beckett, Dakota and Riley.

Matthew Harris said he was inspired to help start the institute after awakening one morning in his New York City home and realizing that negative thoughts he was having about himself were beginning to affect his relationships with family and friends, he said.

“Whether it’s being judgmental, holding yourself to a higher standard or insisting on perfection — all the ways I lived my life — it became my experience that if you’re not kind and compassionate to yourself, it’s hard to do the same for others,” said Harris. “I simply didn’t want to live my life like that anymore,” he said.

Harris, who is a founder of Manhattan’s Global Infrastructure Partners, an equity firm that focuses on areas such as energy and waste, conferred with his wife and several educators at UCLA (his 1984 alma mater) and came up with a plan for the kindness academy.

Fessler, the academy’s director, is one of several professors working with the institute. He recently finished a study on whether kindness can evoke an emotional response that becomes contagious. Answer: yes.

The anthropology professor and his research volunteers randomly selected about 8,000 people in Los Angeles to earn $5 by watching a light video of a person doing backflips or an emotional video of a young man performing kind acts for strangers.

At the end of each viewing (the video each person watched was decided by a coin toss), people were given the option of donating their $5 or any other amount they desired to a local children's hospital, said Fessler.

“They put whatever they wanted in a padded envelope while the researcher turned her back, and then the envelope was given to another researcher who recorded it and forwarded it to the hospital,” he said.

Participants who were shown the video featuring kind acts were more generous with their donations, Fessler observed.

This Miami bus driver performed CPR on a passenger. It was the third time she helped save someone.

“So when people are exposed to an emotional experience of kindness, they're more likely to respond in kind,” he said. “Can we predict who will have this or not? Yes, we can. But it depends on what kind of expectations they have about other people.”

A cynical person who watches the kindness video and thinks the do-gooder is either a sucker or is out to exploit people, isn't as likely to pay it forward than a person who comes away thinking that their community is full of good people, said Fessler.

“When people get this emotional boost, they become more pro-social,” he said. “The people we studied used words like ‘uplifted,’ ‘moved’ and ‘tears in my eyes’ to describe how they felt internally. One person told me, ‘I feel like hugging a puppy.’ ”

Fessler likes to compare his experiment to the real-life story of those 167 people who paid for each other's meals at McDonald's.

“Each individual's act spurred somebody else to engage in pro-social behavior,” he said. “If people are interacting with each other again and again, then theoretically, that can lift the community to the point where people are more cooperative with one another.”

At a time when people trade political barbs with strangers online and some choose to spend hours each day in isolation with their phones, kindness has never been more needed, he said. Fessler said he spent years working in Indonesia and learned a saying: “There is no ivory which is not cracked.”

“It’s a metaphor for ‘we are all imperfect,’ " he said. “For any of us to say, ‘My way is the right way and I have the only right values’ is to fail to recognize that all of us can be kinder and more tolerant. We’re all in the same lifeboat together.”

‘I had to buy it and finish it’: Why 1,000 people offered to crowd-stitch the quilt of a dead woman none of them knew

Having trouble sleeping? Try forgiving someone.

Firefighters let terrified toddler paint their fingernails at an accident scene

• lol Badge Feed
• win Badge Feed
• trending Badge Feed

Browse links

• © 2024 BuzzFeed, Inc
• Consent Preferences
• Accessibility Statement

These 26 Stories About Strangers Helping People In Need Will Remind You That Humanity Is Not Doomed

Take comfort in these stories of the best of humanity.

BuzzFeed Staff Writer

We asked the BuzzFeed community to share their favorite stories of a time they received an act of kindness from a stranger . The results were overwhelmingly heartfelt and moving.

1. a nurse that went above and beyond:.

"One time I had an ovarian cyst and had to go to the hospital. I had no one to watch my 1-year-old son so I had to bring him with me. I was crying really hard because I couldn’t get my son to sit still with me and he kept trying to pull on my tubes. I just broke down. My phone was dead so I couldn’t call anyone. One of the nurses came up to me in my room and asked me if it was alright if she tried to calm my son down and give me a break. She brought some toys and a blanket back for him, and she held him in her arms and played with him so that I could calm down until my mother-in-law showed up. I didn’t even get her name, but it was so meaningful that she would show enough compassion to help us. Angels are REAL."

— pattiecolvin23

2. A guardian angel at the gas station:

"I was 40 miles from home in a high-crime area for a work obligation and I had driven with my empty gas tank light on for the entire trip there. I had $1.67 on my debit card and as I asked the clerk at the sketchy gas station I stopped at to put $1.00 on my pump, a man walked in. My card was declined so I sat in my car trying to find any change or singles I might have stashed. The man came up to my car and told me he put $5.00 on my pump. I don't know if this man has any idea how much he helped me but it got me home safe even though I cried tears of appreciation for most of my drive."

— oliviaf41947d6af

3. A good samaritan on a bicycle:

"I had just moved to a new country with my husband and 6-month-old baby. I had nothing to do and knew no one, so I went for a walk with the baby in the stroller and was about three miles from our apartment when the stroller tire got a puncture and went flat. I knew my son was going to start crying if we took too long and I was getting anxious about embarrassing myself in a foreign country. A very nice man was riding his bike and hopped off and said he had a tire repair kit and patched up my tire, inflated it, and even topped up the air in the rest of the tires. It only took him about five minutes and then he just hopped back on his bike and left, but it saved me so much time and stress and I am so grateful still."

— luvalatte

4. Generosity at the grocery store:

"I was grocery shopping when I received a call that my grandpa had died. My grandpa and I were close my whole life, everybody called me his little shadow. We knew it was coming, but to hear it over the phone put me into a shock. I just stood there and went white and numb. An older couple happened to be standing near me and sensed something was wrong. They asked but I couldn’t make words come out. They sat with me for a while, got ahold of my best friend to come pick me up, AND bought the groceries in my cart. Then, not too long after, they sent flowers to my house! Apparently they had my friend’s phone number from when they called her and they paid her to send a bouquet to me. That was one of the worst days of my life and I miss my grandpa every single day, but that kindness and humanity makes me cry in a good way."

— susieunderpants

5. A gentlemanly gesture:

"It was raining really hard one afternoon and I was walking back to my car with my groceries for the week and an old man offered to share his umbrella with me and walked me all the way to my car."

6. A quiet gesture of comfort and care:

"I'm a burn survivor. I was injured when someone neglectfully tossed chemicals on a bonfire. I spent a month in the hospital, had to have surgery, etc. When I got home I was severely depressed and struggled with PTSD. My mom decided to get me out of the house and took me to get my nails done and a pedicure. My usual nail girl was aware of the incident and was quietly asking me questions while I got my pedicure. When it was time to pay, they told me the woman seated next to me paid for my entire treatment and tip. It was a small gesture, but it made me burst into tears. I was so grateful. I never got to thank her."

— taylorb461b6566d

7. A grateful tribute for a veteran:

"We went to have all-you-can-eat steamed crabs at a local seafood joint here in Maryland. It was a nice break from our grandchildren that we raise. A friendly gent next to us asked my husband if he was in the Marines — he was wearing a T-shirt with USMC — and he said that he was. They chatted on and off while I enjoyed my steamed crab. He and his family got up and thanked my hubby for his service. After they left, the waitress came over and said that the man and his family paid for our meal. I will forever remain grateful and humbled by this experience. We have paid uniformed military tabs a time or two, paid for the car behind us in toll booths or a fast food joint but have never had it happen to us. Amazing feeling. We should all do things like this when we can."

— tangeemckenrickw

8. A kind word in the middle of a toddler meltdown:

"One time while I was out shopping, my toddler was in the cart having an absolute meltdown over a toy. I was mortified. My kid was literally screaming like she was being stabbed and people were giving me all sorts of disapproving looks. I felt like a total failure as a mom and I am sure that my face was as red as a tomato. A random man was walking by me with his cart and put his hand on my shoulder and said, 'Been there, done that. It happens to the best of us,' and walked away. His tiny little comment made me feel so much better about myself. Thank you sir for calming me in my time of need. I appreciated it."

— jesskelleherf

9. A server who went beyond the call of duty:

"I was a kid on vacation in France . Being a teenager, I was starving and asked the waitress for a French classic, a croque monsieur. Sadly, the kitchen at that place had been closed for the day. However this wonderful waitress ran all the way to the restaurant across the street to find me a sandwich. It was such a big deal to me because I was starving and this woman who didn’t even speak much English, went out of her way to do something kind for a random tourist."

— michelleg45101cb41

10. A warm meal for a tired worker:

"When I was working at Hobby Lobby during the Christmas season, I was sick and had almost lost my voice, but kept my attitude very upbeat. It was almost at the end of the night when this elderly couple came through my line. We started joking about them going to Cracker Barrel and the man asked me what I wanted. I joked about meatloaf and green beans with a sweet tea. About 20 minutes later, the elderly couple came back into the store with a bag from Cracker Barrel with my exact order, down to the sweet tea. The lady whispered, 'Merry Christmas' to me and I literally cried right there in the store."

— hollye4bc461713

11. A Bubbie to the rescue:

"I took my then 3-year-old to Florida to see my grandma. While waiting to board the plane my son fell asleep. I had him in my arms, his stroller, my diaper bag, and our carry-on luggage. Out of nowhere a little old lady came up to me and said, 'My darling there you are! Let Bubbie help you with the baby!' There I was with my blue hair, tattoos and piercings, and a sleeping child and this Jewish grandma came to save the day. I hugged her and thanked her and handed her my sleeping son so we could board together. When we finally got to my seat, she asked the man next to me if she could sit next to us and he very quickly gave up his seat. I looked at her and said, 'This was Bashert,' which means 'meant to be' in Yiddish. She smiled and said, 'Yes it was.' And there we sat on our flight to the motherland, Florida. Two very different Jewish mothers and a little boy who slept through the whole thing. I'd love to find my mystery Bubbie and thank her again but I'm sure she knows."

— lisar4b4c8cc6c

12. A Christmas miracle:

"My parents got divorced when I was 10. My mom and I struggled financially after that and our first few holidays were hard. My first Christmas after the divorce was difficult and emotional for both of us. On our first Christmas Eve without my dad our doorbell rang, and when I opened the door no one was there, but someone had left an envelope. In the envelope was a card from 'Santa' with a few hundred dollar bills. Someone had anonymously tried to give us a great Christmas, and to this day we still have no idea who it was! I’ll remember that forever."

13. A celebration of life:

"When I was 23, I was going through chemo and the day I found out it was working and I would survive, my friend and I went to lunch and an anonymous person covered the bill. That was the most important day of my life and the person who covered the bill will never know just how much it meant to me. I wish I could say thank you but since I cannot I try and pay it forward."

— rebeccanealonr

14. A single mom's new hero:

"I was a single mom, working at a well-known Italian restaurant, pulling doubles whilst putting myself through school. After picking my son up from my dad's house, I took him for an ice cream . I left my server book, with all my cash, at the ice cream shop downtown. About $180 in all. By the time I realized it and went back it was gone. I got to work the next day, and found out that a gentleman had brought my server book back to the restaurant, every dollar accounted for. He guessed which location to bring it to and they knew it was mine because I had a picture of my son taped inside. It still makes me tear up."

— smurakami86

15. Two habitual do-gooders:

"My husband and I went to the San Diego Zoo on our honeymoon. Before we could pay the $50 per person entry fee, two older ladies approached us and offered to take us in on their membership passes. Turns out they had both purchased memberships that allow you a guest entry every visit, and went walking at the zoo often. Every time they went, they take a couple of strangers in for free with them. Not necessarily life changing, but wonderful for a couple of newlyweds on a budget."

— scarfmonster

16. A life-saving love story:

"I moved to California last month completely on my own. Two weeks after I got here, I was in a huge car accident. Not only had I just arrived but I had absolutely no one to call in an emergency. Going through such a major trauma with no one by your side was the worst feeling in the world. However, that day a ton of strangers banded together to make sure I didn't feel alone. The paramedics and firefighters not only saved me at the scene, but ended up falling in love with my dog who was in the accident with me, so they brought him back to their fire station and kept him while I was in the hospital recovering. And my nurses were out of this world. When they heard I didn't have anyone to come get me and no way to get home and had pretty much lost everything in the crash, they banded together and raised hundreds of dollars of their own money to pay for me to get home and have something in my pocket to start rebuilding. They were my literal angels and I don't even have the words to express adequate thanks.

I'm now dating one of the paramedics who saved my life and took care of my dog. So maybe everything happens for a reason." — frodofreaklotr

17. A generous lift:

"A woman drove me 30 miles to work when my car broke down at the gas station." — courtiepaigee

18. A hug and a braid to remember:

"When I was in high school, I struggled really badly with depression and anxiety. One day I left class because I started having a panic attack. I was crying in the bathroom alone when a girl came in. I didn't know her, but she hugged me hard and let me cry, and then she re-braided my hair for me, which had come undone while I was crying. It was such an act of kindness when I was at a low point, and even though this was six years ago now, I still remember it."

— mairesequin

19. A life-saving donation:

"A young man passed away and donated his kidney to me. I don't know anything more about him, not even his name, but he saved my life and the lives of many other people. Thanks to his generosity and the kindness of his family during an impossible time I wake up healthy everyday." — damnitno

20. A concerned stranger:

"After my family and I lost our home in the Tubbs fire last year, I found myself sobbing in a McDonald's parking lot a day or two later. I didn't think anybody could hear or see me but a woman came over to my car, gave me a huge hug, and pulled out her wallet to give me a fifty dollar bill. I kept trying to give it back to her, but she insisted. I felt like I could do nothing but cry more and tell her thank you, while the only thing she told me was, to keep it and help my family. I never even got her name." — lionesserin91

21. A hand-picked bridal bouquet:

"On my wedding day, my husband and I were taking pictures after our courthouse wedding, and a woman from afar saw us taking pictures by the river walk. She noticed that I didn't have a bouquet of flowers so she cut some flowers from her garden and brought them over to us. She said it was just what I needed to be a perfect bride. To this day, I'm always grateful that this wonderful and kind woman exits." — i487aca532

22. Some much-needed shelter during a house fire:

"My house had caught on fire from the backyard, resulting in the whole house up in flames. I had been running around outside barefoot panicking, and had an asthma attack from the smoke in the air while people filmed me and my home. A woman living on the same street quickly opened her home to me and my three younger siblings, lending me a pair of shoes when we found out a firefighter had rescued one of our cats so I could take her to a vet. I am still so shocked and thankful for her kindness and generosity to people who were sobbing on the street, knowing nothing about us, giving my family a safe space in a moment of despair." — calliam

23. An unexpected pizza delivery:

"I used to work the front desk at the YMCA. There was a dad who used to come in pretty regularly with his little girl, who I always made sure to greet with a big smile and ask how she was. One night, as they were leaving he was talking to her about getting pizza, and I jokingly said that I could really go for a pizza too. He asked me what kind, and I told him, thinking he was just playing along. Twenty minutes later, he comes back in and hands me an entire pizza. Easily my favorite memory from working there." — ljvincent

24. An impressive display of respect from some young kids:

"I live in South Carolina, so our southern roots tend to melt like butter on a hot day when we witness or receive kindness. My Grandma had died and as we were driving from the church to the cemetery, three little boys, roughly aged 6-9, who had been riding their bicycles got off of their bikes, took their tiny little baseball caps off, and put them over their hearts and stayed in that position until I could no longer see them. That’s the only thing from that day 20 years ago that I remember. Even my black, nasty teenage heart melted over that small gesture." — tracyp10

25. An angel who opened her home to a complete stranger:

"I was in grad school and 70 miles from home when my car blew a gasket in a snowstorm. On a Sunday. No mechanic shops open, and no one would tow my car back to my place until the snowstorm lifted because of the dangerous roads. I was crying in a coffee shop on the phone, and a woman approached me and offered me a place to stay for the night. She did not know me at all, and she took me back to her house where I ate dinner with her, her mom, and her kids and slept in borrowed pajamas in her office. The next day she drove me back to my car and I got towed home. I will never forget what extreme kindness it must have taken to bring a stranger into your home with your kids like that." — raphaelahops

26. Ladies helping ladies:

"I was at a football game tailgating and unexpectedly got my period. I have a wallet-style phone case so all I had with me was my phone, ID, and credit card. The game was starting in about an hour so everyone was trickling into the stands. I found the closest bathroom, ran in, and it was packed. There was a line of about 25 girls waiting for stalls. I screamed, 'Ladies!! Please help me! It’s an emergency, does anyone have a tampon??' And I kid you not almost every damn one of them held one up and there were hands with tampons coming out from under stalls and if that’s not enough to make a girl on her period cry, they then all let me skip the line to take care of business. I love girls' girls."

— dutchtritan

Want to be featured in similar BuzzFeed posts? Make sure to follow the BuzzFeed Community on Facebook and Twitter !

Submissions have been edited for length and clarity.

Share This Article

• Reference Manager
• Simple TEXT file

People also looked at

Review article, why humans might help strangers.

• 1 Department of Genetics Evolution and Environment, University College London, London, UK
• 2 Institut de Biologie, Université de Neuchâtel, Neuchatel, Switzerland

Humans regularly help strangers, even when interactions are apparently unobserved and unlikely to be repeated. Such situations have been simulated in the laboratory using anonymous one-shot games (e.g., prisoner’s dilemma) where the payoff matrices used make helping biologically altruistic. As in real-life, participants often cooperate in the lab in these one-shot games with non-relatives, despite that fact that helping is under negative selection under these circumstances. Two broad explanations for such behavior prevail. The “big mistake” or “mismatch” theorists argue that behavior is constrained by psychological mechanisms that evolved predominantly in the context of repeated interactions with known individuals. In contrast, the cultural group selection theorists posit that humans have been selected to cooperate in anonymous one-shot interactions due to strong between-group competition, which creates interdependence among in-group members. We present these two hypotheses before discussing alternative routes by which humans could increase their direct fitness by cooperating with strangers under natural conditions. In doing so, we explain why the standard lab games do not capture real-life in various important aspects. First, asymmetries in the cost of perceptual errors regarding the context of the interaction (one-shot vs. repeated; anonymous vs. public) might have selected for strategies that minimize the chance of making costly behavioral errors. Second, helping strangers might be a successful strategy for identifying other cooperative individuals in the population, where partner choice can turn strangers into interaction partners. Third, in contrast to the assumptions of the prisoner’s dilemma model, it is possible that benefits of cooperation follow a non-linear function of investment. Non-linear benefits result in negative frequency dependence even in one-shot games. Finally, in many real-world situations individuals are able to parcel investments such that a one-shot interaction is turned into a repeated game of many decisions.

Human Helpfulness

One doesn’t have to observe humans in their natural habitat for long to witness many and varied examples of prosocial behavior, often directed towards complete strangers. People might vacate a seat on a crowded bus or train to let an elderly person sit down; hold open a door for others; or help a struggling parent to carry their pram down a flight of stairs. Humans also willingly donate resources, such as money or food, to others for example by giving to charity (e.g., Frey and Meier, 2004 ; Soetevent, 2005 ). These charitable donations are typically directed at recipients the helpful individual does not know or will expect to meet in the future. This propensity to help unrelated others who reside outside our regular social circle is striking when one considers that these helpful acts are seemingly unobserved and many of the interactions are unlikely to persist beyond the current round. To explain why humans are so helpful under conditions that seem to predict selfishness, researchers have attempted to bring this behavior into the laboratory by creating stylized games where subjects can cooperate with or help one another, but where payoffs are structured such that self-interested behaviors yield greater rewards. One of the most widely-used paradigms is the anonymous one-shot prisoner’s dilemma game ( Luce and Raiffa, 1957 ). In this game, two interacting players simultaneously choose between cooperating or defecting. Payoffs are structured such that mutual cooperation yields higher payoffs for both than mutual defection, but defecting yields a higher individual payoff than cooperating regardless of how the partner behaves. Hence there is a temptation to defect even if the partner cooperates (see Figure 1 ). This game can be modeled with more than two players with similar incentives, yielding a temptation to defect when others cooperate: this is an n-player prisoner’s dilemma game (also commonly referred to as a public goods game, Ledyard, 1995 ). Regardless of whether the game is played with two or more than two players, in a one-shot prisoner’s dilemma the evolutionarily stable strategy ( Maynard-Smith, 1982 ) is to defect. Another game that has been widely used is the dictator game ( Kahneman et al., 1986 ). This is a two-player game where one player (the “dictator”) is endowed with a sum of money and can choose to give none, some or all of the endowment to the partner. The “receiver” in the game has no power and must accept any division of the endowment offered by the dictator. As in the prisoner’s dilemma game, individuals can maximize their earnings in the game by behaving selfishly and keeping the entire endowment.

Figure 1. Payoffs accruing to (Player 1, Player 2) according to each player’s decision to cooperate (C) or defect (D) in a social dilemma are shown. R is the reward for mutual cooperation, T is the temptation to defect, S is the sucker’s payoff and P is the punishment for mutual defection . A game satisfies the assumptions of the prisoner’s dilemma where T > R > P > S . The snowdrift game is captured wherever T > R > S > P . Thus, the prisoner’s dilemma and the snowdrift game differ only in the best possible response to a partner’s defection: in the prisoner’s dilemma, the best response is to defect whereas in the snowdrift game, the best response is to cooperate.

Empirical studies have shown that humans often cooperate in anonymous one-shot prisoner’s dilemma games (or give money in dictator games) despite the fact that not contributing is the optimal solution ( Camerer, 2003 ; Henrich et al., 2005 ; Engel, 2011 ). It has been suggested that helping in the absence of obvious rewards emerges from proximate psychological mechanisms that make helping others subjectively rewarding for the actor ( Andreoni, 1990 ; Fehr and Camerer, 2007 ; Harbaugh et al., 2007 ). To explain why these psychological mechanisms exist, one has to ask under which conditions they are likely to have been favored by Natural Selection. The two dominant current explanations—the “big mistake hypothesis” (also known as the “mismatch hypothesis”) and the “cultural group selection hypothesis”—mainly disagree on the question of whether anonymous one-shot interactions were absent in human evolutionary history until very recently, and hence whether helping strangers is based on a psychological constraint or is instead adaptive under certain circumstances (specifically, when interaction partners belong to the same cultural group) ( Rand and Nowak, 2013 ). Here, we first present these two hypotheses in more detail. We then move on to discuss how the laboratory game settings may differ from real-life interactions with strangers not only with respect to population structure but also in other fundamental ways. Based on this assessment, we will argue that there are several plausible routes by which cooperative behavior towards strangers could increase an individual’s direct fitness (Table 1 ). We hope that this evaluation will stimulate researchers to use or develop new experimental paradigms, such that our knowledge of the proximate mechanisms that underpin cooperation can be complemented with a better understanding of the adaptive significance of such strategies.

Table 1. The key features of different theories to explain why humans cooperate in ostensibly anonymous, one-shot encounters.

Cooperation—A Big Mistake?

Some researchers have argued that the expression of prosocial behaviors in laboratory anonymous, one-shot encounters can be explained by mis-firing of psychological mechanisms in a context we are not evolutionarily adapted to (e.g., Cosmides and Tooby, 1989 ; Hoffman et al., 1998 ; Ben-Ner and Putterman, 2000 ; Johnson et al., 2003 ; Tooby et al., 2006 ). The line of reasoning is that the proximate mechanisms underpinning human social behavior evolved in close-knit, small groups comprised of kin and stable interaction partners, where no interaction was ever truly one-shot or anonymous. In such an environment, an individual that was predisposed to help group members would likely have been compensated for their investment, either via indirect benefits to kin ( Hamilton, 1964a , b ) or via personal benefits arising from future interactions with the recipient ( Trivers, 1971 ) or observers ( Nowak and Sigmund, 1998 ; Roberts, 1998 ). It is clear that these putative ancestral environments were fundamentally different to the modern day environment of most humans and especially to the artificial setup of most laboratory games. It is argued, therefore, that subjects in laboratory settings rely on psychological mechanisms that evolved in the context of repeated, non-anonymous interactions and that our predisposition to cooperate in the lab (or with strangers in the real world) might, therefore, be an evolutionary relic of times gone by. In support of the so-called ( Boyd and Richerson, 2002 ; Fehr and Henrich, 2003 ) mismatch or big mistake hypothesis, there are several instances where imperfect human behavior can be attributed to the mismatch between our evolved psychology and our current environment. For example, the common tendency to be phobic of ancestrally dangerous stimuli (e.g., snakes, spiders) relative to more pressing modern-day threats (e.g., cars, guns); and the proclivity to ingest excessive quantities of foods that are high in sugar, fat and salt based on their relative abundance nowadays as compared with ancestral environments ( Irons, 1998 ) can both be explained as psychological mechanisms that on average produced fitness enhancing outcomes in ancestral environments but that no longer deliver such benefits—and can even be harmful—in the modern world ( Hagen and Hammerstein, 2006 ; Tooby et al., 2006 ).

Nevertheless, critics of the big mistake hypothesis have questioned the validity of assumption that ancestral social environments were devoid of anonymous one-shot encounters. Instead, it seems probable that even ancestral hunter-gatherers probably had some encounters with strangers with no obvious future follow-up, for example in the context of interactions outside their immediate social group (e.g., trading, feuds and so on, Lee, 1972 ; Wiessner, 1982 ; Keeley, 1996 ; Fehr and Henrich, 2003 ; Hill et al., 2011 ). It can be shown that, despite our evolutionary heritage, humans are able to identify interactions where helping is likely to yield a return benefit (e.g., by identifying kin, by predicting when behavior is likely to be observed or not, or when interactions are likely to be repeated)—and adjust behavior accordingly ( Fehr and Henrich, 2003 ). For example, various studies have shown that people recognize and preferentially help kin over non-kin ( Barber, 1994 ; Gurven, 2004 ); that we cooperate more when investments are public rather than anonymous (e.g., Milinski et al., 2002 ; Andreoni and Petrie, 2004 ; Soetevent, 2005 ; Lamba and Mace, 2010 ); and that we cooperate less when interactions will not be repeated or will end soon (e.g., Gächter and Falk, 2002 ; Gächter et al., 2008 ). Moreover, recent work has suggested that while people may use heuristics from daily life to guide cooperative decision making, these heuristics can be rapidly updated to reflect the conditions imposed in the artificial lab setting ( Rand et al., 2012 , 2014 ). In fact even fish are apparently able to adjust levels of cooperation to the likelihood of repeated interactions ( Oates et al., 2010 ). Thus, critics of the big mistake hypothesis have good arguments that humans do have the cognitive machinery to detect when an interaction is likely to yield direct return benefits, and to adjust behavior accordingly.

If, as seems likely, interactions with strangers probably did exist in our evolutionary history, why do humans have a psychology that seems geared towards cooperating in these contexts, given that the short-term, payoff-maximizing approach is apparently to defect under such conditions? For cooperative investments to come under positive selection, the behavior must form part of a strategy that on average increases the fitness of the bearer. In other words, cooperative actors must somehow ultimately be repaid for their investments. Broadly, it has been suggested that the ultimate benefits associated with making costly investments could arise either with or without assortative population structure (often referred to as group-level (or multi-level) and individual-level selection in the literature). We consider these two arguments in turn.

Between-Group Competition

Whenever populations are structured into groups of relatively stable composition, there is potential for competition between groups. The stronger such competition between groups is the more individual and group interests are closely aligned, and selection may favor strategies that prioritize unconditional contributions towards group success. The tendency for such “multi-level selection” to promote cooperation is seen at all levels of life and several of the major evolutionary transitions identified by Szathmáry and Smith (1995) rely on the repression of lower order conflict to bring about a higher-level advantage. According to accounts of helping based on between-group competition in humans (e.g., Gintis, 2000 ; Henrich, 2004 ; Boyd and Richerson, 2009 ), group-level benefits favor individual costly investments (even in the absence of obvious mechanisms to be directly compensated) because within-group helping generally predicts group success in the face of extinction threats (e.g., due to competition with other groups, environmental catastrophes etc., Gintis, 2000 ). Similar arguments emphasizing the importance of group-level benefits have been proposed by biologists for the evolution of helping behavior among non-relatives in cooperatively breeding groups (e.g., Kokko et al., 2001 ) and have been formulated with the notion of interdependence replacing the relatedness term in Hamilton’s rule ( Roberts, 2005 ). Although group-level benefits could theoretically arise via genetic group selection, the high levels of between-group genetic variance that would be necessary to facilitate selection are thought to be unrealistic given the genetic evidence for (female) migration among groups ( Seielstad et al., 1998 ; Bell et al., 2009 ). Moreover, since genetic between-group selection is thought to be a small force in large groups, it is unlikely to account for large-scale cooperation seen in modern day human societies. Thus, colleagues have focussed instead on the concept of cultural group selection, whereby immigrating individuals are expected to adopt the cultures of the new group, thereby reducing the behavioral variance that migrating individuals would otherwise have ( Boyd and Richerson, 1982 ; Henrich, 2004 ; Bell et al., 2009 ). Cultural group selection of cooperative traits is thought to be facilitated by a general predisposition to learn socially from others, which would be adaptive where the cost of information acquisition was sufficiently high ( Boyd and Richerson, 1982 , 2009 ; Henrich and Boyd, 2001 ; Guzmán et al., 2007 ; Richerson and Boyd, 2008 ; but see Eriksson and Coultas, 2009 ; André and Morin, 2011 ). Selection for social learning outside the cooperative domain could then facilitate the evolution of cooperative cultural norms within populations. If populations varied in these norms and if the outcomes of competition between populations varied according to within-group levels of cooperation, then cultural group selection could favor cooperative strategies. The benefits of within-group cooperation could, in turn, select for psychological predispositions to cooperate with in-group members while punishing defectors (i.e., “strong reciprocity”, Gintis, 2000 ; Fehr et al., 2002 ; Fehr and Henrich, 2003 ; Boyd and Richerson, 2009 ), even in anonymous, one-shot encounters. Evidence for cross-cultural variation in cooperative tendency across societies ( Henrich et al., 2001 , 2005 , 2006 , 2010 ; Gächter and Herrmann, 2009 ; Gächter et al., 2010 ; House et al., 2013 ) has been touted as key evidence for the existence of between-group variation in cooperative norms that could be the basis for such selection ( Henrich, 2004 ; Henrich et al., 2005 ).

Nevertheless, the assumptions underpinning the cultural group selection account of human cooperation have been subject to debate ( Burnham and Johnson, 2005 ; Hagen and Hammerstein, 2006 ; West et al., 2011 ). For instance, while it is often assumed that the predisposition for conformity necessary to catalyze the emergence of within-group cooperation is an adaptive trait, it has been demonstrated that non-conformist transmission dominates conformist strategies in evolutionary models ( Eriksson and Coultas, 2009 ). Moreover, analytical models have shown that a tendency for conformist transmission can undermine the evolution of helping behaviors ( Feldman et al., 1985 ; Lehmann et al., 2008 ), not catalyze them as was originally predicted. Thus, in contrast to the predictions of the cultural group selection models, it is apparently easier for costly helping strategies to evolve under genetic systems of inheritance rather than via culture. Another central assumption of cultural group selection models is that individuals are constrained by a predisposition for conformity to blindly adopt the behaviors of others, even when strategic non-conformity would increase biological fitness (e.g., Gintis, 2003 ; Boyd and Richerson, 2009 ). The validity of this assumption is contested ( Hagen and Hammerstein, 2006 ; André and Morin, 2011 ; El Mouden et al., 2014 ; Morin, 2014 ). Instead, it has been argued that the conditions under which cultural group selection would be expected to produce a maladaptive tendency to copy altruistic behavior are prohibitively restrictive ( El Mouden et al., 2014 ; Morin, 2014 ) and, moreover, that antagonistic co-evolution should act to curb psychological predispositions to copy maladaptive actions ( El Mouden et al., 2014 ). Indeed, strong empirical evidence suggests that people are sensitive to the benefits of imitation and do not copy blindly as supposed ( Rendell et al., 2011 ; Morgan et al., 2012 ; Morin, 2014 ). More recently, it has also been suggested that asymmetries among individuals within groups can facilitate within-group cooperation when there is between-group competition, without having to resort to cultural transmission, reciprocity or punishment ( Gavrilets and Fortunato, 2014 ). Specifically, when some individuals are able to benefit more than others from the production of a (within-group) public good (e.g., if they are dominant to others in the group), it pays for these individuals to invest more in the production of the public good, and this effect is particularly pronounced when groups are in competition with one another. Thus, population structure and between-group competition can facilitate within-group cooperation even in the absence of culturally transmitted tendencies to copy cooperative and punitive behaviors.

Empirical evidence for cultural group selection has also been called into question. While the existence of inter-cultural variation in cooperative norms (e.g., Henrich et al., 2001 , 2005 ) seemed initially supportive of the predictions of the cultural group selection models, more recent empirical work has shown that substantial within-culture variation in cooperation exists that can be explained by local demography and ecology rather than culture ( Lamba and Mace, 2011 ; Nettle et al., 2011 ; Schroeder et al., 2014 ). The extent of within-culture variation has been demonstrated to be comparable to that previously observed between cultures ( Lamba and Mace, 2011 ) and, since many of the former studies sampled only one or a few populations per culture, it is argued that much of the measured variation that has been attributed to cultural differences may not in fact exceed within-group variation in these traits. Furthermore, cultural group selection models do not predict unconditional help towards any recipient but instead only towards members of the relevant in-group. Out-group members should not receive help and may in fact be harmed (“parochial altruism”, Bernhard et al., 2006 ). There is no a-priori reason for human subjects in laboratory one-shot games to assume that the co-players are members of the in-group, and so deserving of help. One might just as easily expect that subjects assume that co-players are out-group members, which would not predict costly cooperative behavior. Finally, it appears biologically questionable that in-group members are indeed unfamiliar with each other and that they can be reasonably certain that there will not be any future interactions; such a scenario would be much more likely with out-group members. Thus, even with a cultural group selection account of cooperation, human behavior in stylized laboratory games still remains a puzzle because we have to understand why co-players are apparently treated as in-group rather than out-group members ( Burnham and Johnson, 2005 ).

Direct Benefits Without Between-Group Competition

The cultural group selection approach makes assumptions about population structure (grouping) and competition between these units without specifying whether a tendency to help strangers increases indirect fitness (through relatedness) or direct fitness (through interdependence). An alternative approach is to investigate conditions under which helping strangers may yield direct benefits in the absence of any specific population structure. One plausible suggestion is that human cooperation in one-shot games can be thought of as a strategy that minimizes costly error types ( Burnham and Johnson, 2005 ; Yamagishi et al., 2007 ; Delton et al., 2011 ; Morin, 2014 ). Error management theory assumes that where there is uncertainty over the perceptual accuracy of the environment (such that all is not necessarily as it seems) and there are asymmetries in the costs of false-positive and false-negative error types, then evolution should favor strategies that minimize the costlier of the two error types ( Johnson et al., 2013 ). It is important to bear in mind that Natural Selection is expected to favor strategies that on average increase the fitness of the bearer rather than to produce perfect behavior in every context. In other words, assessment errors mean that adaptive strategies will sometimes produce behavioral mistakes ( West et al., 2011 ; Morin, 2014 ). For example, consider a meerkat who hears an alarm call indicating the likely, but only probabilistic, presence of a predator. In such a scenario there are likely to be asymmetric costs associated with erroneous behavioral responses. Responding to a false alarm call by fleeing incurs energetic and opportunity costs, while failing to flee when the threat is real incurs a far higher possible cost of being caught by a predator. Based on these asymmetric costs of behavioral errors, a strategy of “if hear alarm call, then flee” might be on average adaptive even if it produces several behavioral errors (i.e., fleeing in response to false alarms). In the context of interactions with strangers, it may well be the case that humans experience perceptual uncertainty over several features of the interaction, any or all of which may favor strategies that err on the side of caution by cooperating even when there is little ostensible benefit to doing so. The uncertainty could stem from inaccuracies in perceiving the likely duration of the interaction, whether the interaction is truly anonymous, or the payoff matrix of the interaction. We discuss how perceptual uncertainty in any of these features might select for broadly cooperative strategies below.

Misperceiving Interaction Duration or Anonymity

It has been argued that cooperation can be favored by evolution if there is even a small possibility that the interaction will be repeated and if this possibility is fundamentally unpredictable ( Delton et al., 2011 ). Such a strategy could be adaptive even if it produces several behavioral errors (i.e., cooperating when no return benefits are possible). In a laboratory setting, an experimenter can exogenously impose the one-shot structure on the game (such that subjects can be certain that the interaction is not repeated) but this is unlike real life interactions with strangers, where we might often experience a degree of uncertainty about whether we might meet again. Using agent-based simulations, Delton et al. (2011) showed, using a mix of agents playing either always-defect (ALLD) or the conditionally cooperative strategy tit-for-tat (TFT), that cooperation can indeed be favored so long as there is a non-zero probability that the interaction might be repeated (and the partner is TFT rather than ALLD). In this setting, uncertainty over the number of interactions favors cooperation also in interactions that turn out to be one-shot. Cooperation is favored because mistaking a repeated interaction for one-shot (and therefore defecting in the first round of the game) incurred a greater cost than mistaking a one-shot interaction for repeated (and therefore erroneously cooperating). This is due to the unforgiving nature of TFT, whereby defecting in the first round of the game prompts the partner to defect in the next round and thus establishes mutual defection for the duration of the interaction. Strategies that take a chance on the interaction being repeated (and the partner playing TFT) by cooperating in the first round could instead establish mutually productive, cooperative relationships with TFT partners. In support of the idea, it has additionally been argued that due to autocorrelation of individual locations over time, interacting with an individual once leads to an increased probability of interacting with the same individual again in the future ( Krasnow et al., 2013 ). Thus, by definition, meeting a partner once implies that the interaction will be repeated and that conditionally cooperative strategies will prevail.

Nevertheless, the generality of these findings have been challenged on the grounds that only interactions with unrepentant (ALLD) and unforgiving (TFT) strategies were explored ( McNally and Tanner, 2011 ; Zefferman, 2014a , b ). ALLD is unrepentant in the sense that it is committed to play defect in all rounds; it cannot change its behavior if the interaction turns out to be repeated. TFT is unforgiving in the sense that any defection by the partner will be immediately reciprocated with defection. By contrast, it was verbally argued that the importance of uncertainty for catalyzing one-shot cooperation might be substantially reduced if agents employed strategies that allowed for flexible responses, either an increased propensity to cooperate once the interaction extended beyond round one or a non-zero probability to forgive cheating partners in a repeated interaction ( McNally and Tanner, 2011 ). This is because, with flexible strategies, the importance of cooperating in the first round would be reduced substantially since cooperation could still be established (or re-established) beyond round one ( McNally and Tanner, 2011 ). Thus, the question of why individuals cooperate in ostensible one-shot interactions would remain unresolved. Indeed, the inclusion of repentant and forgiving strategies under the same conditions of uncertainty has subsequently been shown to vastly diminish the advantage to cooperating in (ostensible) one-shot interactions; in some cases actually reversing the direction of selection ( Zefferman, 2014a ). Zefferman (2014a) proposes that the failure of the model to predict one-shot cooperation when an arguably more realistic strategy set is considered emphasizes the importance of social learning of local cooperative norms (i.e., the cultural group selection approach) for explaining one-shot cooperation. Ultimately, empirical studies are likely to be important for understanding whether defection in an ostensible one-shot encounter precludes cooperation from being established (as predicted by Delton et al., 2011 ; Delton and Krasnow, 2014 ) or, instead, whether humans are more likely to forgive an interaction partner who starts by defecting but then switches to cooperation if the interaction continues.

While the Delton et al. (2011) model assumed that psychological responses to cooperate evolved in the context of directly reciprocal interactions, one also has to consider that under real world scenarios, actions might also be observed by uninvolved bystanders, who adjust their behavior towards the actor accordingly. For example, under indirect reciprocity models, helpful acts are reciprocated by third-parties rather than by recipients. Misperceiving that an interaction is unobserved by bystanders might carry similar costs to misperceiving the likely duration, in that erroneous defection incurs greater costs than erroneous cooperation in both scenarios. Thus, error-management might still play a role in sustaining cooperation but because individuals can never be certain that their actions are unobserved, rather than because they misperceive interaction duration. If there is even a slight possibility that actions will be observed—and if being seen as unhelpful carries greater costs than helping when no one is watching (as has been proposed in models of judgment bias, Rankin and Eggimann, 2009 )—then selection might favor psychological mechanisms that make us behave as though we are observed most of the time. Empirical evidence suggests that reputation concerns have an important influence on prosocial tendency: people are typically more cooperative in public rather than anonymous laboratory games (e.g., Andreoni and Petrie, 2004 ; Lamba and Mace, 2010 ) and even exposing people to subtle cues of being watched (in the form of eye images) increases prosocial behavior under some circumstances (e.g., Haley and Fessler, 2005 ; Bateson et al., 2006 ; but see Fehr and Schneider, 2010 ; Raihani and Bshary, 2012 for failed replications). The presence of potential observers is made even more important when one considers that, via gossip, one’s positive or negative actions could be broadcast to several “observers”, who need not even have been present at the time of the event (e.g., Sommerfeld et al., 2007 , 2008 ; Feinberg et al., 2014 ). Thus, an error-managing strategy might often cooperate—even when interactions seem to be anonymous—to minimize the reputation costs of not cooperating if the interaction turns out to be observed.

Partner Choice Via Exploration

Many of the games used to explore cooperation under laboratory settings impose a forced-play structure on subjects: players cannot choose who they want to interact with or to leave unproductive relationships ( Axelrod and Hamilton, 1981 ). While cooperation can evolve under such circumstances in artificial simulations (e.g., via clustering or assortment of cooperators, Nowak and May, 1992 ; Fletcher and Doebeli, 2009 ; but see Hauert and Doebeli, 2004 ), network reciprocity based on spatial structure does not seem to support cooperation in empirical studies ( Grujić et al., 2014 ). Indeed, assuming that players are constrained to use pure strategies and are forced to interact with one another is unlikely to reflect the conditions under which real-word relationships operate. Instead, individuals are typically able to choose interaction partners, and can choose to continue interactions with cooperative partners while terminating relationships that prove unproductive (e.g., Noë and Hammerstein, 1994 ; Baumard et al., 2013 ).

The possibility for partner choice might therefore favor unconditionally helpful strategies if being observed as helpful increases the chance of being chosen for future interactions. Importantly, the chooser need not make costly investments to reimburse the helper for their actions. Instead, simply being chosen for a mutually productive interaction (e.g., producing offspring, cohabiting) could compensate the helper for their initial investment (e.g., Bshary and Grutter, 2006 ; McNamara et al., 2008 ). According to the “competitive altruism” theory, competition for interaction partners occurs within a biological market ( Noë and Hammerstein, 1994 ); and individuals who produce the strongest signals of quality (via helping) will be preferred as partners ( Roberts, 1998 ; Lotem et al., 2003 ; Barclay, 2011 ). Empirical evidence suggests that competitive altruism might be an important mechanism underpinning human helping behavior: people choose interaction partners based on cooperative reputation (e.g., Barclay and Willer, 2007 ; Sylwester and Roberts, 2010 , 2013 ) and avoid defectors ( Rockenbach and Milinski, 2011 ), hence individuals compete with one another to advertise helpful actions ( Raihani and Smith, in press ).

The possibility for partner choice could also promote cooperation, even with unknown individuals in an anonymous setting, because individuals can use cooperative first moves to test the response of the partner and then decide whether to continue the interaction or not. Error-management might still play a role but, unlike the Delton et al. (2011) model, the cost of not cooperating would be that one misses out on the chance to have a mutually productive relationship with the partner, rather than that one is stuck in a mutually destructive relationship. It has been demonstrated that where there is extrinsically maintained variation in cooperative tendency within a population (maintained by differences in quality or ability to invest in the partner, McNamara and Leimar, 2010 , or by mutation, immigration, recombination or epistasis, McNamara et al., 2004 ), then this variation could select for cooperative strategies because this is a way to identify whether the partner is also cooperative ( McNamara et al., 2004 ). In such scenarios cooperation can evolve whenever the benefit of interacting with a cooperator outweighs the benefit of occasional exploitation. Variability in cooperativeness, together with a long lifespan during which to reap the benefits of a productive partnership, can then pave the way for the evolution of choosiness because, given sufficient variation in partner quality it can pay to leave a less cooperative partner in hope of finding a more cooperative individual next time ( Sherratt and Roberts, 1998 ; McNamara et al., 2008 ). In many real-world scenarios, initial cooperative acts might often be low cost (in comparison to the potential benefits of establishing a mutually productive relationship) but investments could increase as the relationship becomes more established (e.g., Roberts and Sherratt, 1998 ). For example, while we do not routinely see people handing out $100 bills to strangers, low cost helpful acts, such as holding a door open or assisting with heavy bags, are relatively commonplace. These low cost investments are consistent with the idea that cooperation could be used as an exploratory strategy to strike up mutually productive relationships with other individuals in the population. Nowadays, modern technology may even allow us to develop long-distance relationships as a consequence of chance encounters where we help or are helped by others.

Alternative Payoff Matrices

Most theoretical and laboratory studies of cooperation in humans have assumed a prisoner’s dilemma type payoff-matrix, where benefits scale linearly with investments. In such scenarios, the payoff-maximizing strategy in a one-shot game is to defect regardless of how the partner(s) behave. As a consequence, explanations based on assortment, repeated interactions or relatedness are typically invoked to account for the emergence and stability of cooperative behavior. The assumption that all social dilemmas have the structure of an n-player prisoner’s dilemma is, however, flawed ( Kollock, 1998 ; Archetti and Scheuring, 2011 ). Alternative social dilemmas with different payoff matrices can yield evolutionarily stable cooperative strategies without having to invoke assortment, relatedness or repeated interactions (e.g., Doebeli and Hauert, 2005 ; Archetti, 2009a , b ; Archetti and Scheuring, 2011 ). For example, consider the 2-player snowdrift game. This game describes two drivers traveling in opposite directions when they come across a snowdrift blocking the road. Neither driver can get home unless the road is cleared. Although each driver prefers the other to do the clearing, each would also rather clear the snowdrift himself than for the snowdrift to not be cleared at all. As a consequence, in the two-player snowdrift game, the best response to a cooperative partner is to defect, while the best response to a defecting partner is to cooperate. Thus, the strategic payoffs differ markedly from those in more frequently used prisoner’s dilemma, where defecting always yields the highest payoff ( Doebeli and Hauert, 2005 ; Figure 1 ). An n-player snowdrift game is often referred to as a volunteer’s dilemma ( Diekmann, 1985 ). In its simplest form, this game assumes that a public good will be produced if one player cooperates and that additional investments do not increase the magnitude of the public good. Thus, unlike the traditional n-player prisoner’s dilemma, benefits are a non-linear function of investment and cooperation is therefore expected to be under negatively frequency dependent selection. As in the snowdrift game, the benefit of the public good being produced is larger than the cost associated with producing it, such that all players would do best to invest to produce the public good if no one else does so.

Relaxing the assumption of linearity has far-reaching consequences for the emergence and stability of cooperative strategies in n-player games. Specifically, when individuals are unsure about how others are likely to behave in a non-linear public goods game, then the best strategy is to cooperate probabilistically (where the probability depends on the cost to benefit ratio of cooperating and group size, Archetti, 2009a , b ; Archetti and Scheuring, 2011 , 2012 ). Such probabilistic strategies will emerge even in non-repeated games without spatial assortment or interactions among relatives. Where players differ in their ability to invest, or in the benefit that they can extract from the public good being produced, then this can also offer a potential solution to a non-linear public goods game, with those players who will reap the largest benefit from investing being more likely to contribute to the public good (e.g., see Gavrilets and Fortunato, 2014 ; Szolnoki and Perc, 2014 ). With respect to the assumption of linearity in benefits, n-player prisoner’s dilemma games lie at one end of a spectrum with threshold Public Goods Games (i.e., volunteer’s dilemmas) at the other end. All intermediate cases (where benefits are a sigmoidal function of investment in the public good) resemble the volunteer’s dilemma more than the traditional n-player prisoner’s dilemma in that they also yield a stable mixed equilibrium of cooperators and defectors in the population, even in the absence of other incentives to cooperate ( Archetti and Scheuring, 2011 ). Thus, it has been argued that many biological examples of cooperation in social dilemmas are more likely to yield non-linear rather than linear benefits, which has profound implications for our understanding of how cooperation evolves and is maintained in these scenarios ( Kummerli et al., 2007 ; Archetti, 2009a ; Sherratt et al., 2009 ; Archetti et al., 2011 ; Archetti and Scheuring, 2012 ). For example, the costly production of invertase in yeast, alarm calling in animal groups and the formation of fruiting bodies in social amoebas are all examples that can be described as non-linear public goods games where cooperation is under negative frequency dependent selection ( Gore et al., 2009 ; Archetti and Scheuring, 2011 ; Archetti et al., 2011 ). Yeast growth requires the costly production of the enzyme invertase to hydrolyze sucrose into smaller glucose molecules which can be imported into the cell ( Gore et al., 2009 ). Although invertase production is costly and can be parasitized by non-producing cells, a complete lack of invertase can be lethal, meaning that producer cells outperform non-producers when rare. Conversely, at high densities of producers, non-producing cells have an advantage because they can parasitize the invertase being produced by the other cells ( Gore et al., 2009 ).

For humans, it is less clear whether the majority of the social dilemmas that have shaped our social behavior ought to be described with linear or with non-linear payoff functions. In the case of punishment, which has been modeled as a second-order public good (and often therefore explained in terms of cultural group selection, e.g., Boyd et al., 2003 ), it has been argued that the payoffs of investing in punishment (in terms of increased within-group cooperation) are likely to scale non-linearly with number of punishers, thereby providing a direct individual-level solution for its existence ( Raihani and Bshary, 2011 ). Other social dilemmas that have been explained in terms of cultural group selection, for example contributions to group defense during war, might also be more likely to have non-linear than linear payoffs. Group survival, which is the typical currency for payoffs associated with cooperating in warfare, is likely to be a non-linear function of contributions to defense, meaning that the payoffs associated with increasing within-group cooperation are by definition non-linear. It may turn out to be the case that linear public goods problems exist mainly in artificial laboratory settings and that subjects use strategies and psychology that evolved predominantly in the context of non-linear games when they participate. Specifically, if most real-world public goods problems are non-linear in nature and if there is always a certain degree of uncertainty about whether others will contribute to produce the public good (thereby obviating the need for the subject’s own investment), selection may have favored strategies that either probabilistically cooperate (when cooperation is binary) or that invest intermediate amounts (when cooperation is a continuous variable) (c.f. Kummerli et al., 2010 ), even in one-shot games.

Parceled Investments

Finally, we would like to highlight an additional discrepancy with the way laboratory prisoner’s dilemma experiments are set up compared with how interactions typically occur in the real-world. In many experimental games, the act to cooperate or to defect is an all-or-nothing action where players press a button, and typically learn about each other’s choices post hoc . On the other hand, interactions with strangers in our evolutionary past (e.g., in the context of trades) are highly unlikely to have involved exchange of closed boxes where players only found out after separating what the other put in the box. Instead, real-world interactions with strangers might often have involved simultaneous or parceled exchanges, where individuals could monitor the behavior of one another, make behavioral adjustments in real time and—importantly—terminate unproductive exchanges prematurely (e.g., Connor, 1992 ; Hart and Hart, 1992 ). For example, most female lions approach intruders simulated by playbacks more slowly if they teamed up with laggard female group members, apparently looking back regularly to check the spatial configuration of self vs. partners ( Heinsohn and Packer, 1995 ). Theoretical models have shown that where cooperation is not an all-or-nothing event but investments can instead can be parceled and adjusted in real time, then prisoner’s dilemma type situations can be solved cooperatively, even in one-shot anonymous games ( Friedman and Hammerstein, 1991 ; Connor, 1995 ; Johnstone and Bshary, 2002 ). The key issue is that stable cooperation does not rely on repeated interactions but on repeated decisions. The question of whether encounters between strangers (either currently, or in our evolutionary past) are more likely to involve single vs. multiple decisions remains open for empirical exploration.

We have discussed potential explanations for the observation that humans help complete strangers under natural conditions and often cooperate in laboratory anonymous one-shot games. While the extent to which humans encountered such situations in our evolutionary past necessarily remains an open debate, it is clear that such encounters happen today. Moreover, it appears that we are at least partly adapted to adjust behavior to such situations. Our aim was to identify functional explanations for why humans regularly help strangers under natural conditions. The main take-home message is that the laboratory settings deviate from natural encounters in various important ways that make helping in real-world encounters potentially under positive selection while it is clearly not in the lab setting. Error-management arguments suggest that during natural encounters it is very hard to assess whether an interaction will be one-off and/or whether the interaction will remain truly anonymous. Furthermore, while lab games typically impose a forced-play scenario on subjects, in real-life individuals can choose to pursue productive relationships and abandon unproductive partners. This possibility for partner choice might select for helping behavior even with unknown strangers. Another issue is that in real-world interactions, the payoffs might often be a non-linear function of total investment, causing helping to be under negative frequency dependent selection rather than being altruistic. Finally, as soon as interactions involve multiple decisions, stable cooperation may be achieved even between strangers without any future perspective. We note that these different explanations are not mutually exclusive and that different explanations are likely to apply to different real-world scenarios. One way to explore the importance of the different explanations we proposed would be to use a wider variety of laboratory games, that replicate conditions that are likely to prevail in real-world interactions with strangers.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

André, J.-B., and Morin, O. (2011). Questioning the cultural evolution of altruism. J. Evol. Biol. 24, 2531–2542. doi: 10.1111/j.1420-9101.2011.02398.x

Pubmed Abstract | Pubmed Full Text | CrossRef Full Text | Google Scholar

Andreoni, J. R. (1990). Impure altruism and donations to public goods: a theory of warm-glow giving. Econ. J. 100, 464–477. doi: 10.2307/2234133

CrossRef Full Text | Google Scholar

Andreoni, J., and Petrie, R. (2004). Public goods experiments without confidentiality: a glimpse into fund-raising. J. Pub. Econ. 88, 1605–1623. doi: 10.1016/s0047-2727(03)00040-9

Archetti, M. (2009a). Cooperation as a volunteer’s dilemma and the strategy of conflict in public goods games. J. Evol. Biol. 22, 2192–2200. doi: 10.1111/j.1420-9101.2009.01835.x

Archetti, M. (2009b). The volunteer’s dilemma and the optimal size of a social group. J. Theor. Biol. 261, 475–480. doi: 10.1016/j.jtbi.2009.08.018

Archetti, M., and Scheuring, I. (2011). Coexistence of cooperation and defection in public goods games. Evolution 65, 1140–1148. doi: 10.1111/j.1558-5646.2010.01185.x

Archetti, M., and Scheuring, I. (2012). Game theory of public goods in one-shot social dilemmas without assortment. J. Theor. Biol. 299, 9–20. doi: 10.1016/j.jtbi.2011.06.018

Archetti, M., Scheuring, I., Hoffman, M., Frederickson, M. E., Pierce, N. E., and Yu, D. W. (2011). Economic game theory for mutualism and cooperation. Ecol. Lett. 14, 1300–1312. doi: 10.1111/j.1461-0248.2011.01697.x

Axelrod, R., and Hamilton, W. (1981). The evolution of cooperation. Science 211, 1390–1396. doi: 10.1126/science.7466396

Barber, N. (1994). Machiavellianism and altruism: effect of relatedness of target person on Machiavellian and helping attitudes. Psychol. Rep. 75, 403–422. doi: 10.2466/pr0.1994.75.1.403

Barclay, P. (2011). Competitive helping increases with the size of biological markets and invades defection. J. Theor. Biol. 281, 47–55. doi: 10.1016/j.jtbi.2011.04.023

Barclay, P., and Willer, R. (2007). Partner choice creates competitive altruism in humans. Proc. Biol. Sci. 274, 749–753. doi: 10.1098/rspb.2006.0209

Bateson, M., Nettle, D., and Roberts, G. (2006). Cues of being watched enhance cooperation in a real-world setting. Biol. Lett. 2, 412–414. doi: 10.1098/rsbl.2006.0509

Baumard, N., André, J.-B., and Sperber, D. (2013). A mutualistic approach to morality: the evolution of fairness by partner choice. Behav. Brain Sci. 36, 59–78. doi: 10.1017/S0140525x11002202

Bell, A. V., Richerson, P. J., and McElreath, R. (2009). Culture rather than genes provides greater scope for the evolution of large-scale human prosociality. Proc. Natl. Acad. Sci. U S A 106, 17671–17674. doi: 10.1073/pnas.0903232106

Ben-Ner, A., and Putterman, L. (2000). On some implications of evolutionary psychology for the study of preferences and institutions. J. Econ. Behav. Organ. 43, 91–99. doi: 10.1016/s0167-2681(00)00110-4

Bernhard, H., Fischbacher, U., and Fehr, E. (2006). Parochial altruism in humans. Nature 442, 912–915. doi: 10.1038/nature04981

Boyd, R., Gintis, H. M., Bowles, S., and Richerson, P. J. (2003). The evolution of altruistic punishment. Proc. Natl. Acad. Sci. U S A 100, 3531–3535. doi: 10.1073/pnas.0630443100

Boyd, R., and Richerson, P. J. (1982). Cultural transmission and the evolution of cooperative behavior. Hum. Ecol. 3, 325–351. doi: 10.1007/bf01531189

Boyd, R., and Richerson, P. J. (2002). Group beneficial norms can spread rapidly in a structured population. J. Theor. Biol. 215, 287–296. doi: 10.1006/jtbi.2001.2515

Boyd, R., and Richerson, P. (2009). Culture and the evolution of human cooperation. Philos. Trans. R. Soc. Lond. B Biol. Sci. 364, 3281–3288. doi: 10.1098/rstb.2009.0134

Bshary, R., and Grutter, A. S. (2006). Image scoring and cooperation in a cleaner fish mutualism. Nature 441, 975–978. doi: 10.1038/nature04755

Burnham, T. C., and Johnson, D. D. P. (2005). The biological and evolutionary logic of human cooperation. Anal. Kritik 27, 113–135.

Google Scholar

Camerer, C. (2003). Behavioral Game Theory: Experiments in Strategic Interaction. Princeton, New Jersey: Princeton University Press.

Connor, R. C. (1992). Egg-trading in simultaneous hermaphrodites: an alternative to Tit-for-Tat. J. Evol. Biol. 5, 523–528. doi: 10.1046/j.1420-9101.1992.5030523.x

Connor, R. C. (1995). Impala allogrooming and the parcelling model of reciprocity. Anim. Behav. 49, 528–530. doi: 10.1006/anbe.1995.0070

CrossRef Full Text

Cosmides, L., and Tooby, J. L. (1989). Evolutionary psychology and the generation of culture, part II: case study: a computational theory of social exchange. Ethol. Sociobiol. 10, 51–97. doi: 10.1016/0162-3095(89)90013-7

Delton, A. W., and Krasnow, M. M. (2014). An independent replication that the evolution of direct reciprocity under uncertainty explains one-shot cooperation: commentary on Zeffermann. Evol. Hum. Behav. 35, 547–548. doi: 10.1016/j.evolhumbehav.2014.07.004

Delton, A. W., Krasnow, M., Cosmides, L., and Tooby, J. (2011). Evolution of direct reciprocity under uncertainty can explain human generosity in one-shot encounters. Proc. Natl. Acad. Sci. U S A 108, 13335–13340. doi: 10.1073/pnas.1102131108

Diekmann, A. (1985). Volunteer’s dilemma. J. Confl. Resol. 29, 605–610. doi: 10.1177/0022002785029004003

Doebeli, M., and Hauert, C. (2005). Models of cooperation based on the prisoner’s dilemma and the snowdrift game. Ecol. Lett. 8, 748–766. doi: 10.1111/j.1461-0248.2005.00773.x

El Mouden, C., André, J.-B., Morin, O., and Nettle, D. (2014). Cultural transmission and the evolution of human behaviour: a general approach based on the Price equation. J. Evol. Biol. 27, 231–241. doi: 10.1111/jeb.12296

Engel, C. (2011). Dictator games: a meta-study. Exp. Econ. 14, 583–610. doi: 10.1007/s10683-011-9283-7

Eriksson, K., and Coultas, J. C. (2009). Are people really conformist-biased? an empirical test and a new mathematical model. J. Evol. Psych. 7, 5–21. doi: 10.1556/jep.7.2009.1.3

Fehr, E., and Camerer, C. F. (2007). Social neuroeconomics: the neural circuitry of social preferences. Trends Cogn. Sci. 11, 419–427. doi: 10.1016/j.tics.2007.09.002

Fehr, E., Fischbacher, U., and Gächter, S. (2002). Strong reciprocity, human cooperation and the enforcement of social norms. Hum. Nat. 13, 1–25. doi: 10.1007/s12110-002-1012-7

Fehr, E., and Henrich, J. (2003). “Is strong reciprocity a maladaptation?,” in Genetic and Cultural Evolution of Cooperation , ed P. Hammerstein (Cambridge, MA: MIT Press), 55–82.

Fehr, E., and Schneider, F. (2010). Eyes are on us, but nobody care: are eye cues relevant for strong reciprocity? Proc. Biol. Sci. 277, 1315–1323. doi: 10.1098/rspb.2009.1900

Feinberg, M., Willer, R., and Schultz, M. (2014). Gossip and ostracism promote cooperation in groups. Psychol. Sci. 25, 656–664. doi: 10.1177/0956797613510184

Feldman, M. W., Cavalli-Sforza, L., and Peck, J. L. (1985). Gene-culture coevolution: models for the evolution of altruism with cultural transmission. Proc. Natl. Acad. Sci. U S A 82, 5814–5818. doi: 10.1073/pnas.82.17.5814

Fletcher, J. A., and Doebeli, M. (2009). A simple and general explanation for the evolution of altruism. Proc. Biol. Sci. 276, 13–19. doi: 10.1098/rspb.2008.0829

Frey, B. S., and Meier, S. (2004). Pro-social behavior in a natural setting. J. Econ. Behav. Organ. 54, 65–88. doi: 10.1016/j.jebo.2003.10.001

Friedman, J. W., and Hammerstein, P. (1991). “To trade, or not to trade; that is the question,” in Game Equilibrium Models I: Evolution and Game Dynamics , ed R. Selten (Berlin, Heidelberg: Springer), 257–275.

Gächter, S., and Falk, A. (2002). Reputation and reciprocity: consequences for the labor relation. Scand. J. Econ. 104, 1–26. doi: 10.1111/1467-9442.00269

Gächter, S., and Herrmann, B. (2009). Reciprocity, culture and human cooperation: previous insights and a new cross-cultural experiment. Philos. Trans. R. Soc. Lond. B Biol. Sci. 364, 791–806. doi: 10.1098/rstb.2008.0275

Gächter, S., Herrmann, B., and Thöni, C. (2010). Culture and cooperation. Philos. Trans. R. Soc. Lond. B Biol. Sci. 365, 2651–2661. doi: 10.1098/rstb.2010.0135

Gächter, S., Renner, E., and Sefton, M. (2008). The long-run benefits of punishment. Science 322:1510. doi: 10.1126/science.1164744

Gavrilets, S., and Fortunato, L. (2014). A solution to the collective action problem in between-group conflict with within-group inequality. Nat. Commun. 5:3526. doi: 10.1038/ncomms4526

Gintis, H. (2000). Strong reciprocity and human sociality. J. Theor. Biol. 206, 169–179. doi: 10.1006/jtbi.2000.2111

Gintis, H. (2003). The hitchhiker’s guide to altruism: gene-culture coevolution and the internalization of norms. J. Theor. Biol. 220, 407–418. doi: 10.1006/jtbi.2003.3104

Gore, J., Youk, H., and can Oudenaarden, A. (2009). Snowdrift game dynamics and facultative cheating in yeast. Nature 459, 253–256. doi: 10.1038/nature07921

Grujić, J., Gracia-Lázaro, C., Milinski, M., Semmann, D., Traulsen, A., Cuesta, J. A., et al. (2014). A comparative analysis of spatial Prisoner’s Dilemma experiments: conditional cooperation and payoff irrelevance. Sci. Rep. 4:4615. doi: 10.1038/srep04615

Gurven, M. (2004). To give and to give not: the behavioral ecology of human food transfers. Behav. Brain Sci. 27, 543–559. doi: 10.1017/s0140525x04000123

Guzmán, R. A., Rodríguez-Sickert, C., and Rowthorn, R. (2007). When in Rome, do as the Romans do: the coevolution of altruistic punishment, conformist learning and cooperation. Evol. Hum. Behav. 28, 112–117. doi: 10.1016/j.evolhumbehav.2006.08.002

Hagen, E. H., and Hammerstein, P. (2006). Game theory and human evolution: a critique of some recent interpretations of experimental games. Theor. Popul. Biol. 69, 339–348. doi: 10.1016/j.tpb.2005.09.005

Haley, K. J., and Fessler, D. M. T. (2005). Nobody’s watching? Subtle cues affect generosity in a one-shot game. Evol. Hum. Behav. 26, 245–256. doi: 10.1016/j.evolhumbehav.2005.01.002

Hamilton, W. (1964a). The genetical evolution of social behaviour I. J. Theor. Biol. 7, 1–16. doi: 10.1016/0022-5193(64)90038-4

Hamilton, W. (1964b). The genetical evolution of social behaviour II. J. Theor. Biol. 7, 17–52. doi: 10.1016/0022-5193(64)90039-6

Harbaugh, W. T. W., Mayr, U. U., and Burghart, D. R. D. (2007). Neural responses to taxation and voluntary giving reveal motives for charitable donations. Science 316, 1622–1625. doi: 10.1126/science.1140738

Hart, B. L., and Hart, L. A. (1992). Reciprocal allogrooming in impala, Aepyceros melampus . Anim. Behav. 44, 1073–1083. doi: 10.1016/S0003-3472(05)80319-7

Hauert, C., and Doebeli, M. (2004). Spatial structure often inhibits the evolution of cooperation in the snowdrift game. Nature 428, 643–646. doi: 10.1038/nature02360

Heinsohn, R., and Packer, C. (1995). Complex cooperative strategies in group-territorial African lions. Science 269, 1260–1262. doi: 10.1126/science.7652573

Henrich, J. (2004). Cultural group selection, coevolutionary processes and large-scale cooperation. J. Econ. Behav. Organ. 53, 3–35. doi: 10.1016/s0167-2681(03)00094-5

Henrich, J., and Boyd, R. (2001). Why people punish defectors: weak conformist cransmission can stabilize costly enforcement of norms in cooperative dilemmas. J. Theor. Biol. 208, 79–89. doi: 10.1006/jtbi.2000.2202

Henrich, J., Boyd, R., Bowles, S., Camerer, C. F., Fehr, E., Gintis, H. M., et al. (2001). In search of homo economicus: behavioral experiments in 15 small-scale societies. Am. Econ. Rev. 91, 73–78. doi: 10.1257/aer.91.2.73

Henrich, J., Boyd, R., Bowles, S., Camerer, C. F., Fehr, E., Gintis, H. M., et al. (2005). “Economic man” in cross-cultural perspective: behavioral experiments in 15 small-scale societies. Behav. Brain Sci. 28, 795–855. doi: 10.1017/s0140525x05000142

Henrich, J., McElreath, R., Barr, A., Barrett, C., Bolyanatz, A., Cardenas, J. C., et al. (2010). Markets, religion, community size and the evolution of fairness and punishment. Science 327, 1480–1484. doi: 10.1126/science.1182238

Henrich, J., McElreath, R., Barr, A., Ensminger, J., Barrett, H. C., Bolyanatz, A., et al. (2006). Costly punishment across human societies. Science 312, 1767–1770. doi: 10.1126/science.1127333

Hill, K. R., Walker, R. S., Bozicevic, M., Eder, J., Headland, T., Hewlett, B., et al. (2011). Co-residence patterns in hunter-gatherer societies show unique human social structure. Science 331, 1286–1289. doi: 10.1126/science.1199071

Hoffman, E., McCabe, K., and Smith, V. (1998). Behavioral foundations of reciprocity: experimental economics and evolutionary psychology. Econ. Inq. 36, 335–352. doi: 10.1111/j.1465-7295.1998.tb01719.x

House, B. R., Silk, J. B., Henrich, J., Barrett, H. C., Scelza, B. A., Boyette, A. H., et al. (2013). Ontogeny of prosocial behavior across diverse societies. Proc. Natl. Acad. Sci. U S A 110, 14586–14591. doi: 10.1073/pnas.1221217110

Irons, W. (1998). Adaptively relevant environments versus the environment of evolutionary adaptedness. Evol. Anthropol. 6, 194–204. doi: 10.1002/(sici)1520-6505(1998)6:6<194::aid-evan2>3.0.co;2-b

Johnson, D. D. P., Blumstein, D. T., Fowler, J. H., and Haselton, M. G. (2013). The evolution of error: error management, cognitive constraints and adaptive decision-making biases. Trends Ecol. Evol. 28, 474–481. doi: 10.1016/j.tree.2013.05.014

Johnson, D. D. P., Stopka, P., and Knights, S. (2003). Sociology: the puzzle of human cooperation. Nature 421, 911–912. doi: 10.1038/421911b

Pubmed Abstract | Pubmed Full Text | CrossRef Full Text

Johnstone, R. A., and Bshary, R. (2002). From parasitism to mutualism: partner control in asymmetric interactions. Ecol. Lett. 5, 634–639. doi: 10.1046/j.1461-0248.2002.00358.x

Kahneman, D., Knetsch, J. L., and Thaler, R. (1986). Fairness as a constraint on profit seeking: entitlements in the market. Am. Econ. Rev. 76, 728–741.

Keeley, L. H. (1996). War before Civilisation: The Myth of the Peaceful Savage. Oxford, UK: Oxford University Press.

Kokko, H., Johnstone, R. A., and Clutton-Brock, T. H. (2001). The evolution of cooperative breeding through group augmentation. Proc. Biol. Sci. 268, 187–196. doi: 10.1098/rspb.2000.1349

Kollock, P. (1998). Social dilemmas: the anatomy of cooperation. Annu. Rev. Sociol. 24, 183–214. doi: 10.1146/annurev.soc.24.1.183

Krasnow, M. M., Delton, A. W., Tooby, J., and Cosmides, L. (2013). Meeting now suggests we will meet again: implications for debates on the evolution of cooperation. Sci. Rep. 3:1747. doi: 10.1038/srep01747

Kummerli, R., Burton-Chellew, M. N., Ross-Gillespie, A., and West, S. A. (2010). Resistance to extreme strategies, rather than prosocial preferences, can explain human cooperation in public goods games. Proc. Natl. Acad. Sci. U S A 107, 10125–10130. doi: 10.1073/pnas.1000829107

Kummerli, R., Colliard, C., Fiechter, N., Petitpierre, B., Russier, F., and Keller, L. (2007). Human cooperation in social dilemmas: comparing the snowdrift game with the prisoner’s dilemma. Proc. Biol. Sci. 274, 2965–2970. doi: 10.1098/rspb.2007.0793

Lamba, S., and Mace, R. (2010). People recognize when they are really anonymous in an economic game. Evol. Hum. Behav. 31, 271–278. doi: 10.1016/j.evolhumbehav.2010.02.002

Lamba, S., and Mace, R. (2011). Demography and ecology drive variation in cooperation across human populations. Proc. Natl. Acad. Sci. U S A 108, 14426–14430. doi: 10.1073/pnas.1105186108

Ledyard, J. (1995). “Public goods: a survey of experimental research,” in Handbook of Experimental Economics , eds J. Kagel and A. Roth (Princeton: Princeton University Press).

Lee, R. B. (1972). !Kung spatial organization: an ecological and historical perspective. Hum. Ecol. 1, 125–147. doi: 10.1007/bf01531351

Lehmann, L., Feldman, M. W., and Foster, K. R. (2008). Cultural transmission can inhibit the evolution of altruistic helping. Am. Nat. 172, 12–24. doi: 10.1086/587851

Lotem, A., Fishman, M., and Stone, L. (2003). From reciprocity to unconditional altruism through signalling benefits. Proc. Biol. Sci. 270, 199–205. doi: 10.1098/rspb.2002.2225

Luce, R. D., and Raiffa, H. (1957). Games and Decisions. New York: Wiley.

Maynard-Smith, M. (1982). Evolution and the Theory of Games. Cambridge, UK: Cambridge University Press.

McNally, L., and Tanner, C. J. (2011). Flexible strategies, forgiveness and the evolution of generosity in one-shot encounters. Proc. Natl. Acad. Sci. U S A 108:E971. doi: 10.1073/pnas.1115225108

McNamara, J. M., Barta, Z., Fromhage, L., and Houston, A. I. (2008). The coevolution of choosiness and cooperation. Nature 451, 189–192. doi: 10.1038/nature06455

McNamara, J. M., Barta, Z., and Houston, A. I. (2004). Variation in behaviour promotes cooperation in the Prisoner’s Dilemma game. Nature 428, 745–748. doi: 10.1038/nature02432

McNamara, J. M., and Leimar, O. (2010). Variation and the response to variation as a basis for successful cooperation. Philos. Trans. R. Soc. Lond. B Biol. Sci. 365, 2627–2633. doi: 10.1098/rstb.2010.0159

Milinski, M., Semmann, D., and Krambeck, H. (2002). Reputation helps solve the ‘tragedy of the commons’. Nature 415, 424–426. doi: 10.1038/415424a

Morgan, T. J. H., Rendell, L. E., Ehn, M., Hoppitt, W., and Laland, K. N. (2012). The evolutionary basis of human social learning. Proc. Biol. Sci. 279, 653–662. doi: 10.1098/rspb.2011.1172

Morin, O. (2014). Is cooperation a maladaptive by-product of social learning? The docility hypothesis reconsidered. Biol. Theor. 9, 286–295. doi: 10.1007/s13752-014-0181-z

Nettle, D. D., Colléony, A. A., and Cockerill, M. M. (2011). Variation in cooperative behaviour within a single city. PLoS One 6:e26922. doi: 10.1371/journal.pone.0026922

Noë, R., and Hammerstein, P. (1994). Biological markets: supply and demand determine the effect of partner choice in cooperation, mutualism and mating. Behav. Ecol. Sociobiol. 35, 1–11. doi: 10.1007/bf00167053

Nowak, M. A., and May, R. M. (1992). Evolutionary games and spatial chaos. Nature 359, 826–829. doi: 10.1038/359826a0

Nowak, M. A., and Sigmund, K. (1998). Evolution of indirect reciprocity by image scoring. Nature 393, 573–577. doi: 10.1038/31225

Oates, J., Manica, A., and Bshary, R. (2010). The shadow of the future affects cooperation in a cleaner fish. Curr. Biol. 20, R472–R473. doi: 10.1016/j.cub.2010.04.022

Raihani, N. J., and Bshary, R. (2011). The evolution of punishment in n-player public goods games: a volunteer’s dilemma. Evolution 65, 2725–2728. doi: 10.1111/j.1558-5646.2011.01383.x

Raihani, N. J., and Bshary, R. (2012). A positive effect of flowers rather than eye images in a large-scale, cross-cultural dictator game. Proc. Biol. Sci. 279, 3556–3564. doi: 10.1098/rspb.2012.0758

Raihani, N. J., and Smith, S. (in press). Competitive helping in the real world. Curr. Biol.

Rand, D. G., Greene, J. D., and Nowak, M. A. (2012). Spontaneous giving and calculated greed. Nature 489, 427–430. doi: 10.1038/nature11467

Rand, D. G., and Nowak, M. A. (2013). Human cooperation. Trends Cogn. Sci. 17, 413–425. doi: 10.1016/j.tics.2013.06.003

Rand, D. G., Peysakhovich, A., Kraft-Todd, G. T., Newman, G. E., Wurzbacher, O., Nowak, M. A., et al. (2014). Social heuristics shape intuitive cooperation. Nat. Commun. 5:3677. doi: 10.1038/ncomms4677

Rankin, D. J., and Eggimann, F. (2009). The evolution of judgement bias in indirect reciprocity. Proc. Biol. Sci. 276, 1339–1345. doi: 10.1098/rspb.2008.1715

Rendell, L., Fogarty, L., Hoppitt, W. J. E., Morgan, T. J. H., Webster, M. M., and Laland, K. N. (2011). Cognitive culture: theoretical and empirical insights into social learning strategies. Trends Cogn. Sci. 15, 68–76. doi: 10.1016/j.tics.2010.12.002

Richerson, P. J., and Boyd, R. (2008). Not by Genes Alone: How Culture Transformed Human Evolution. Chicago, IL: University of Chicago Press.

Roberts, G. (1998). Competitive altruism: from reciprocity to the handicap principle. Proc. Biol. Sci. 265, 427–431. doi: 10.1098/rspb.1998.0312

Roberts, G. (2005). Cooperation through interdependence. Anim. Behav. 70, 901–908. doi: 10.1016/j.anbehav.2005.02.006

Roberts, G., and Sherratt, T. (1998). Development of cooperative relationships through increasing investment. Nature 394, 175–179. doi: 10.1038/28160

Rockenbach, B., and Milinski, M. (2011). To qualify as a social partner, humans hide severe punishment, although their observed cooperativeness is decisive. Proc. Natl. Acad. Sci. U S A 108, 18307–18312. doi: 10.1073/pnas.1108996108

Schroeder, K. B., Pepper, G. V., and Nettle, D. (2014). Local norms of cheating and the cultural evolution of crime and punishment: a study of two urban neighborhoods. PeerJ 2:e450. doi: 10.7717/peerj.450

Seielstad, M. T., Minch, E., and Cavalli-Sforza, L. L. (1998). Genetic evidence for a higher female migration rate in humans. Nat. Genet. 20, 278–280. doi: 10.1038/3088

Sherratt, T. N., and Roberts, G. (1998). The evolution of generosity and choosiness in cooperative exchanges. J. Theor. Biol. 193, 167–177. doi: 10.1006/jtbi.1998.0703

Sherratt, T. N., Roberts, G., and Kassen, R. (2009). Evolutionary stable investment in products that confer both an individual benefit and a public good. Front. Biosci. (Landmark Ed.) 14, 4557–4564. doi: 10.2741/3548

Soetevent, A. R. (2005). Anonymity in giving in a natural context-a field experiment in 30 churches. J. Pub. Econ. 89, 2301–2323. doi: 10.1016/j.jpubeco.2004.11.002

Sommerfeld, R., Krambeck, H., and Milinski, M. (2008). Multiple gossip statements and their effect on reputation and trustworthiness. Proc. Biol. Sci. 275, 2529–2536. doi: 10.1098/rspb.2008.0762

Sommerfeld, R. D., Krambeck, H.-J., Semmann, D., and Milinski, M. (2007). Gossip as an alternative for direct observation in games of indirect reciprocity. Proc. Natl. Acad. Sci. U S A 104, 17435–17440. doi: 10.1073/pnas.0704598104

Sylwester, K., and Roberts, G. (2010). Cooperators benefit through reputation-based partner choice in economic games. Biol. Lett. 6, 659–662. doi: 10.1098/rsbl.2010.0209

Sylwester, K., and Roberts, G. (2013). Reputation-based partner choice is an effective alternative to indirect reciprocity in solving social dilemmas. Evol. Hum. Behav. 34, 201–206. doi: 10.1016/j.evolhumbehav.2012.11.009

Szathmáry, E., and Smith, J. M. (1995). The major evolutionary transitions. Nature 374, 227–232. doi: 10.1038/374227a0

Szolnoki, A., and Perc, M. (2014). Coevolutionary success-driven multigames. EPL 108:28004. doi: 10.1209/0295-5075/108/28004

Tooby, J., Cosmides, L., and Price, M. E. (2006). Cognitive adaptations for n-person exchange: the evolutionary roots of organizational behavior. MDE Manage. Decis. Econ. 27, 103–129. doi: 10.1002/mde.1287

Trivers, R. L. (1971). The evolution of reciprocal altruism. Q. Rev. Biol. 46, 35–57. doi: 10.1086/406755

West, S. A., El Mouden, C., and Gardner, A. (2011). Sixteen common misconceptions about the evolution of cooperation in humans. Evol. Hum. Behav. 32, 231–262. doi: 10.1016/j.evolhumbehav.2010.08.001

Wiessner, P. (1982). “Risk, reciprocity and social influences on !Kung-San economics,” in Politics and History in Band Societies , eds E. Leacock and R. Lee (Cambridge, UK: Cambridge University Press), 61–84.

Yamagishi, T., Terai, S., Kiyonari, T., Mifune, N., and Kanazawa, S. (2007). The social exchange heuristic: managing errors in social exchange. Ration. Soc. 19, 259–291. doi: 10.1177/1043463107080449

Zefferman, M. R. (2014a). Direct reciprocity under uncertainty does not explain one-shot cooperation, but demonstrates the benefits of a norm psychology. Evol. Hum. Behav. 35, 358–367. doi: 10.1016/j.evolhumbehav.2014.04.003

Zefferman, M. R. (2014b). When repentance and forgiveness are possible, direct reciprocity does not explain one-shot generosity, even under arbitrarily high levels of uncertainty. Evol. Hum. Behav. 35, 548–549. doi: 10.1016/j.evolhumbehav.2014.07.003

Keywords: human cooperation, one-shot games, prisoner’s dilemma, error-management, cultural group selection, strong reciprocity

Citation: Raihani NJ and Bshary R (2015) Why humans might help strangers. Front. Behav. Neurosci. 9 :39. doi: 10.3389/fnbeh.2015.00039

Received: 03 December 2014; Accepted: 04 February 2015; Published online: 20 February 2015.

Reviewed by:

Copyright © 2015 Raihani and Bshary. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution and reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Nichola J. Raihani, Department of Genetics Evolution and Environment, University College London, Darwin Building, London WC1E 6BT, UK e-mail: [email protected]

This article is part of the Research Topic

Prosocial and antisocial behavior in economic games

Student Essays

11 Best Written Essays on Helping Others in Life-Need & Importance

Helping others refers to an act whereby human beings help the fellow human in one way or the other. The concept of helping others has strong basis upon respecting, identifying and accepting the needs and issues of others and taking practical steps to resolve others issues. The following Essay on helping others talks on why helping others is important in our life, why we need to mutually support and cooperate other people in life.

1. Essay on Helping Others in Life |Need, and Importance of Helping others in Life

Helping others in the times of need is the basic instinct of human nature. It is the feeling of happiness and satisfaction that comes with being able to help someone in need that drives us towards doing good deeds. It is not only restricted to lending a helping hand during difficult times but also extends to small, everyday gestures that make a big difference in the lives of others.

>>>> Read Also : ” Essay on My Idea of Happy Life “

There are many benefits of helping others in life. The most obvious one is that it makes us feel good about ourselves. When we help someone in need, our brain releases serotonin, which is a hormone that makes us feel happy and satisfied. It also gives us a sense of purpose and meaning in life. Helping others allows us to connect with people on a deeper level and form meaningful relationships. It also gives us a sense of belonging and strengthens our bond with the community.

Apart from the personal satisfaction that comes with helping others, there are also many practical benefits. Helping others can boost our career prospects and open up new networking opportunities. It can also lead to positive changes in our society. When we help others, we set an example for others to follow and inspire them to do good deeds as well.

>>>> Read Also : ” Short Paragraph On Friendship & Its Importance  “

Therefore, helping others is not only beneficial for the person in need but also for the helper. It makes us feel good about ourselves and gives us a sense of purpose and meaning in life. It also has many practical benefits that can boost our career prospects and lead to positive changes in our society. So, next time you come across someone who needs help, don’t hesitate to lend a helping hand. It will make a big difference in their life and yours too.

2. Essay on helping others is Important:

Helping others is a fundamental aspect of human nature. We are all connected in this world, and our actions have the potential to impact those around us. Whether we realize it or not, helping others can bring immense satisfaction and fulfillment into our lives.

The act of helping others goes beyond just lending a hand or offering material assistance. It’s about showing compassion, empathy, and understanding towards others. It’s about being there for someone when they need it the most, without expecting anything in return. Helping others is not just a selfless act; it can also be a source of personal growth and development.

One of the main reasons why helping others is important is because it promotes a sense of community and belonging. When we help others, we create a sense of unity and togetherness, which is crucial for building strong relationships and fostering a supportive environment. It can also help break down barriers and promote understanding between different individuals or groups.

Furthermore, helping others can have a ripple effect in the community. When one person helps another, it often inspires others to do the same. This creates a domino effect of kindness and can lead to significant positive changes in society.

Helping others is also crucial for our own personal well-being. Studies have shown that acts of kindness can boost our mood, reduce stress and anxiety, and even improve our physical health. When we help others, we release feel-good hormones like serotonin and oxytocin, which can contribute to overall happiness and well-being.

Moreover, helping others can provide a sense of purpose and meaning in life. In today’s fast-paced world, it’s easy to get caught up in our own lives and lose sight of the bigger picture. By helping others, we are reminded that there is more to life than just ourselves and our own struggles.

It’s also important to note that helping others does not always have to be a grand gesture. Simple acts of kindness and compassion, such as listening to someone who is going through a difficult time or offering words of encouragement, can make a significant impact on someone’s life.

In conclusion, helping others is crucial for our own personal growth and well-being, as well as for creating a more compassionate and supportive society. It may seem like a small act, but the impact it can have on someone’s life is immeasurable. So let’s all strive to make helping others a priority in our lives and spread kindness wherever we go.

3. Short Essay on Helping Others:

Helping others is a selfless act that brings about joy, contentment and fulfillment in one’s life. It is an innate human characteristic to extend our hands towards those who are in need and offer whatever assistance we can provide. Whether it be helping a friend with their studies, aiding a stranger on the street or volunteering at a local charity organization, lending a helping hand not only benefits the receiver but also brings about a sense of satisfaction and purpose to the giver.

In today’s fast-paced world, where individualism and self-centeredness are on the rise, acts of kindness and generosity towards others have become scarce. However, it is important for individuals, especially students, to recognize the importance of helping others and make it a part of their daily lives.

By helping others, we not only make a positive impact on their lives but also contribute towards building a better society. Small acts of kindness, such as volunteering at a homeless shelter or donating clothes to those in need, can go a long way in making a difference in someone’s life.

Additionally, by actively participating in community service and helping those less fortunate, students can develop a sense of empathy and compassion towards others, which are essential qualities for building strong relationships and fostering a more inclusive society.

Moreover, helping others can also have positive effects on one’s mental health. Research has shown that individuals who engage in acts of kindness and generosity tend to experience lower levels of stress, anxiety, and depression. This is because helping others releases feel-good hormones such as oxytocin, dopamine and serotonin, which can help reduce stress and improve overall well-being.

Furthermore, lending a helping hand can also serve as a learning experience for students. By actively engaging in community service or volunteering at organizations that work towards social causes, students can gain valuable skills such as teamwork, leadership, and communication

4. Short Essay on Motivation for helping others:

Motivation is a powerful force that can drive individuals to act in ways that benefit not only themselves, but also those around them. One of the most selfless and altruistic forms of motivation is the desire to help others.

Helping others can take many forms, from volunteering at a local charity or donating money to a worthy cause, to simply lending a helping hand to a friend or stranger in need. But why do some people have such a strong motivation to help others, while others seem more focused on their own interests?

Research has shown that there are various factors that can contribute to an individual’s motivation for helping others. These may include personal experiences, values and beliefs, cultural influences, and even genetics.

For some people, the desire to help others may stem from a personal experience of receiving help themselves. This can lead to a sense of gratitude and a desire to pay it forward by helping others in need.

Others may be driven by their values and beliefs, such as the belief in equal rights and opportunities for all individuals. These individuals may see helping others as not only a moral obligation, but also as a way to create a more just and equitable society.

Cultural influences can also play a role in an individual’s motivation for helping others. In some cultures, the concept of community and collective well-being is highly valued, which can lead to a strong desire to help others in need.

Lastly, research has also suggested that genetics may play a role in an individual’s level of empathy and compassion, which can in turn influence their motivation to help others.

In conclusion, the reasons for an individual’s motivation to help others are complex and multifaceted. But regardless of the underlying factors, one thing is clear: helping others brings about a sense of fulfillment and purpose that cannot be achieved through self-interest alone.

5. College essay on helping others:

As a college student, it is easy to get caught up in our own personal goals and obligations. With the pressure of maintaining good grades, participating in extracurricular activities, and building a strong resume for future job prospects, helping others may not always be at the top of our list. However, being selfless and giving back to those in need can have numerous benefits for college students.

First and foremost, helping others is a great way to gain perspective and appreciate the things we have in our own lives. Many of us are fortunate enough to have access to higher education, a privilege that not everyone in the world has. By volunteering our time and efforts to help those less fortunate, we can learn to be grateful for what we have and gain a deeper understanding of the struggles and challenges faced by others.

In addition, helping others can also provide valuable learning opportunities. Through volunteering or participating in community service projects, college students can develop important skills such as leadership, communication, and problem-solving. These skills are not only beneficial for personal growth but are also highly valued by potential employers. Volunteering can also expose students to diverse cultures and perspectives, promoting a more well-rounded and empathetic outlook on life.

Moreover, by helping others, we can make a positive impact in our communities and contribute to the greater good. Whether it is through organizing a fundraiser for a local charity or tutoring students in need, our actions can have a meaningful impact on the lives of those around us. By being active members of our communities, we can create a ripple effect of kindness and inspire others to do the same.

Lastly, helping others can also have a positive impact on our mental health. Studies have shown that acts of kindness and generosity can increase happiness, reduce stress and anxiety, and improve overall well-being

6. Essay on Kindness to others:

As human beings, we have the ability to choose how we treat others. One of the most powerful ways we can impact those around us is by displaying kindness. It may seem like a small gesture, but showing kindness to others can have a ripple effect that extends far beyond what we could ever imagine.

Kindness is defined as the quality of being friendly, generous, and considerate. When we show kindness to others, we are displaying empathy and compassion towards them. It can be as simple as offering a smile, lending a helping hand, or listening without judgment.

The power of kindness lies in its ability to bring people together. In a world that is often divided by differences, acts of kindness can bridge the gap and create connections. It allows us to see beyond our own perspective and understand the struggles of others. It reminds us that we are all human and deserve love and respect.

Not only does kindness benefit those who receive it, but also those who give it. Studies have shown that acts of kindness can boost our mood, increase happiness, and reduce stress. It can even lead to a healthier heart and improved relationships.

In our fast-paced world, it’s easy to get caught up in our own lives and forget about those around us. But kindness doesn’t have to be a grand gesture. It can be as simple as holding the door open for someone, saying “thank you,” or offering a compliment. These small acts of kindness may seem insignificant, but they can make a huge difference in someone’s day.

Furthermore, kindness is not limited to only those we know. It can also be extended to strangers. In fact, random acts of kindness towards strangers can have an even greater impact as it shows that there are still good and caring people in the world.

7. Inspirational Story on helping others:

Once upon a time, in a small village surrounded by lush green fields and blooming flowers, there lived a young boy named Rohan. He was known for his kind heart and willingness to help others without expecting anything in return.

Rohan grew up with his parents who were farmers. They taught him the importance of hard work and helping those in need. Every day, Rohan would help his parents in the fields, and after finishing his chores, he would spend time with the villagers.

The villagers adored Rohan for his kind nature and willingness to lend a helping hand. They often shared stories of how he had helped them during difficult times. But little did they know that Rohan’s kindness was not limited to just humans.

One day, a severe storm hit the village and destroyed most of the crops. The villagers were worried about how they would survive without food. Rohan’s parents were also affected by the storm, and they had no other option but to leave their village in search of better opportunities.

Seeing his family and villagers in distress, Rohan knew he had to do something. He remembered how his parents had taught him to help others in need, and he decided to put that lesson into practice.

Rohan went from house to house, asking the villagers if they needed any help. He helped them fix their homes, gather whatever food was left after the storm, and even offered his own food supplies to those who needed it desperately.

However, Rohan’s helping nature did not end there. He ventured into the forest to find wild fruits and berries, which he distributed among the villagers. Some even called him a hero for his selfless acts.

But Rohan remained humble and continued to help without seeking recognition or praise. His kindness was contagious, and soon other villagers joined in to help each other during difficult times.

Slowly but steadily, the village was back on its feet, and the crops were growing again. Everyone in the village had learned an important lesson from Rohan – that helping others not only benefits them but also brings joy and satisfaction to oneself.

Years passed, and Rohan grew up to be a kind-hearted man who continued to help those in need. The villagers never forgot his acts of kindness, and they passed on his lessons to their children and grandchildren.

Rohan’s selfless actions had a lasting impact on the village, and it became known as the village of kind-hearted people who always helped each other. And Rohan’s name was remembered for generations to come as a symbol of kindness and compassion.

From this story, we can learn that helping others is not just about lending a hand during difficult times, but it is also about spreading kindness and making the world a better place. As they say, “No act of kindness, no matter how small, is ever wasted.” So let us all follow Rohan’s example and make helping others a way of life

8. Essay on helping hand:

In our fast-paced and competitive world, the concept of a “helping hand” has become more important than ever before. In simple terms, a helping hand refers to an act of assisting or supporting someone in need. This could be in the form of physical, emotional, or financial support.

One might argue that the idea of extending a helping hand is not new and has been a part of our society for centuries. However, the changing dynamics of our global community have made it even more crucial for individuals to lend a helping hand to those around them.

In today’s world, where people are constantly chasing success and material possessions, there is a growing sense of isolation and loneliness among individuals. This is where the concept of a helping hand comes into play. By reaching out and supporting those in need, we not only make a positive impact on their lives but also create a sense of community and belonging.

Moreover, extending a helping hand is not only beneficial for the receiver, but it also has several benefits for the giver as well. It allows us to step outside of our own problems and focus on someone else’s needs. This can bring a sense of purpose and fulfillment in our lives. Additionally, helping others can also boost our self-esteem and confidence, knowing that we have made a positive difference in someone’s life.

Furthermore, a helping hand can also have a ripple effect. By assisting one individual, we may inspire them to pay it forward and help others in need. This creates a chain reaction of kindness and compassion, ultimately leading to a more caring and supportive society.

In today’s interconnected world, where news of tragedies and disasters spread rapidly, it is easy to feel overwhelmed and helpless. However, by extending a helping hand to those affected, we can make a tangible difference and contribute towards rebuilding communities and lives.

In conclusion, the concept of a helping hand is more relevant now than ever before. It not only benefits individuals in need but also has positive effects on our own well-being and society as a whole. So let us all strive to be someone’s helping hand and create a world where kindness and compassion are the norm rather than the exception. As the saying goes, “A helping hand is no farther than at the end of your sleeve.” So let us all extend our sleeves and lend a helping hand whenever possible. And remember, every act of kindness matters.

9. Short Essay on how helping others benefit you:

Helping others is a fundamental human trait that has been ingrained in our society for centuries. It is an act of kindness that not only benefits the recipient, but also brings immense joy and satisfaction to the person who is offering help. In this short essay, we will explore how helping others can have a positive impact on your life.

Firstly, helping others allows us to develop empathy and compassion. When we lend a helping hand to someone in need, we put ourselves in their shoes and try to understand their struggles. This helps us build stronger connections with others and become more understanding individuals. Moreover, by seeing the impact of our actions on others, we learn to appreciate what we have and not take things for granted.

Secondly, helping others can boost our self-esteem and confidence. When we use our skills and knowledge to assist someone, it gives us a sense of purpose and accomplishment. This, in turn, helps us feel more confident about ourselves and our abilities. It also reminds us that we are capable of making a positive impact on others’ lives.

Thirdly, helping others can improve our mental health. It is a well-known fact that acts of kindness can release feel-good hormones in our brain, such as oxytocin and endorphins. These hormones are responsible for making us feel happy and content. By helping others, we can reduce stress, anxiety, and depression levels in ourselves and others around us.

In addition to the above benefits, helping others also allows us to expand our social circle and make meaningful connections. When we volunteer or engage in acts of kindness, we meet like-minded individuals who share the same values as us. This can lead to long-lasting friendships and a sense of belonging.

Lastly, helping others is a powerful way to contribute to society and make a positive impact on the world. By giving back to our communities, we can create a ripple effect of kindness and inspire others to do the same. This can lead to a more empathetic and compassionate society, creating a better world for future generations.

10. Short Essay on Satisfaction Comes from Helping Others:

We’ve all heard the saying, “It’s better to give than receive.” And while it may sound cliché, there is truth to this statement. There is a certain sense of satisfaction that comes from helping others. Whether it be through volunteering, lending a helping hand, or simply being there for someone in need, the act of helping others brings a sense of fulfillment that cannot be replicated by any material possessions.

So why is it that helping others brings us satisfaction? One of the main reasons is that it gives us a sense of purpose. In today’s fast-paced world, we often get caught up in our own lives and forget about the needs of those around us. By taking the time to help someone else, we are reminded that there is more to life than just our own personal pursuits. We are able to make a positive impact on someone else’s life and in turn, feel good about ourselves.

Moreover, helping others allows us to step outside of our comfort zones and gain new perspectives. It’s easy to get stuck in our own routines and thought patterns, but when we help someone else, we are exposed to different ways of thinking and living. This can broaden our understanding of the world and also help us appreciate what we have.

Another aspect of helping others that brings satisfaction is the connections we make with people. When we lend a helping hand or volunteer, we are often working alongside like-minded individuals who share similar values and goals. These shared experiences can lead to meaningful relationships and a sense of belonging.

Furthermore, the act of helping others can also boost our own self-esteem and confidence. By making a positive impact on someone else’s life, we are reminded that we have something valuable to offer. This can give us a sense of purpose and worth that may have been lacking before.

In conclusion, while it may seem counterintuitive, true satisfaction does not come from acquiring material possessions or achieving personal success. It comes from the act of helping others and making a positive impact in their lives. So, let us strive to be kind, empathetic, and selfless individuals who find joy in giving rather than receiving. As Mahatma Gandhi once said, “The best way to find yourself is to lose yourself in the service of others.”

11. Short Essay on My Greatest Passion is Helping others:

My greatest passion in life is helping others. For as long as I can remember, I have always had a strong desire to make a positive impact on the world around me. Growing up, my parents instilled in me the value of kindness and compassion towards others, and this has stayed with me throughout my life.

I believe that there is no greater joy than being able to bring a smile to someone’s face or make their day a little bit brighter. Whether it is through small acts of kindness, volunteering my time, or using my skills and knowledge to help those in need, I am always looking for ways to lend a helping hand.

One of the reasons why helping others is my greatest passion is because it allows me to connect with people from all walks of life. I have had the opportunity to work with individuals from different backgrounds, cultures, and experiences, and each interaction has taught me something valuable. By helping others, I am also able to learn and grow as a person.

Furthermore, helping others is not just about making a difference in someone else’s life; it also brings immense fulfillment and happiness in my own life. Knowing that I have made a positive impact, no matter how small, fills me with a sense of purpose and motivates me to continue helping others.

In today’s world, where there is so much negativity and division, I believe that acts of kindness and compassion towards others are more important than ever. My greatest passion for helping others will always be a driving force in my life, and I hope to inspire others to do the same. After all, as Mahatma Gandhi said, “The best way to find yourself is to lose yourself in the service of others.”

Q: How do you write an essay about helping others?

A: To write an essay about helping others, start with an introduction that highlights the significance of the topic, provide examples and personal experiences to support your points, discuss the benefits of helping others, and conclude with a strong summary.

Q: Why is it important to help others essay?

A: An essay on why it’s important to help others emphasizes the value of compassion, empathy, and the positive impact that helping others can have on individuals, communities, and society as a whole.

Q: What is the importance of helping others?

A: The importance of helping others lies in fostering empathy, building stronger communities, and creating a more compassionate and interconnected world.

Q: Why am I passionate about helping others?

A: Your passion for helping others may be driven by the sense of fulfillment, the opportunity to make a meaningful difference in people’s lives, a desire to contribute to positive change, and personal values or experiences that underscore the importance of altruism and empathy.

Leave a Comment Cancel reply

Save my name, email, and website in this browser for the next time I comment.

• Even more »

Account Options

• Try the new Google Books
• Advanced Book Search
• Algonquin Books
• Barnes&Noble.com
• Books-A-Million
• Find in a library
• All sellers  »

Selected pages

Other editions - View all

Common terms and phrases, about the author  (2022), bibliographic information.

Forgotten password

Please enter the email address that you use to login to TeenInk.com, and we'll email you instructions to reset your password.

• Poetry All Poetry Free Verse Song Lyrics Sonnet Haiku Limerick Ballad
• Fiction All Fiction Action-Adventure Fan Fiction Historical Fiction Realistic Fiction Romance Sci-fi/Fantasy Scripts & Plays Thriller/Mystery All Novels Action-Adventure Fan Fiction Historical Fiction Realistic Fiction Romance Sci-fi/Fantasy Thriller/Mystery Other
• Nonfiction All Nonfiction Bullying Books Academic Author Interviews Celebrity interviews College Articles College Essays Educator of the Year Heroes Interviews Memoir Personal Experience Sports Travel & Culture All Opinions Bullying Current Events / Politics Discrimination Drugs / Alcohol / Smoking Entertainment / Celebrities Environment Love / Relationships Movies / Music / TV Pop Culture / Trends School / College Social Issues / Civics Spirituality / Religion Sports / Hobbies All Hot Topics Bullying Community Service Environment Health Letters to the Editor Pride & Prejudice What Matters
• Reviews All Reviews Hot New Books Book Reviews Music Reviews Movie Reviews TV Show Reviews Video Game Reviews Summer Program Reviews College Reviews
• Art/Photo Art Photo Videos
• Summer Guide Program Links Program Reviews
• College Guide College Links College Reviews College Essays College Articles

Summer Guide

College guide.

• Song Lyrics

All Fiction

• Action-Adventure
• Fan Fiction
• Historical Fiction
• Realistic Fiction
• Sci-fi/Fantasy
• Scripts & Plays
• Thriller/Mystery

All Nonfiction

• Author Interviews
• Celebrity interviews
• College Articles
• College Essays
• Educator of the Year
• Personal Experience
• Travel & Culture

All Opinions

• Current Events / Politics
• Discrimination
• Drugs / Alcohol / Smoking
• Entertainment / Celebrities
• Environment
• Love / Relationships
• Movies / Music / TV
• Pop Culture / Trends
• School / College
• Social Issues / Civics
• Spirituality / Religion
• Sports / Hobbies

All Hot Topics

• Community Service
• Letters to the Editor
• Pride & Prejudice
• What Matters

All Reviews

• Hot New Books
• Book Reviews
• Music Reviews
• Movie Reviews
• TV Show Reviews
• Video Game Reviews

Summer Program Reviews

• College Reviews
• Writers Workshop
• Regular Forums
• Program Links
• Program Reviews
• College Links

Helping a Stranger

Favorite Quote: "You are only confined by the walls you build around yourself." "Follow your heart, but take your brain with you." "You were born to be real, not to be perfect."

I have been sitting here for hours watching a young man, no more than thirty, eat drink his coffee. I realize I've never seen such sadness inside a persons eyes before. Such an emptiness that I could never imagine where it came from. He in a sharp gray suit, but his ties undone. His hair hardly brushed. He stares at nothing and his hands clutch the coffee cup tightly. His knuckles white. My chin is rested on my palm and I watch him intently. Sighing, he sits up and drops his newly bought coffee into the trash and walks off. I'm so lost within my own wonder that I pick up my things and slowly follow him, not wanting to be noticed quit yet. He puts his hands in his pockets and stares into the sun set, as if waiting for someone to come running down from heaven to see him. To hold him. My eyes find his right hand and I spot a tiny silver ring for the first time, and realization comes to me. I feel tears prick my eyes for this stranger. I clutch my hand to my chest. pulling off the ring, this man gives another sad sigh and slips the ring into his pocket and turns to leave but I notice something he does not. The ring falls through a tiny hold and bounces off the concrete, rolling over until in stops at my feet. I'm so overcome with emotion for this man that I pick up the ring and hold it to my heart, wiping away fallen tears. He slumps farther up the street when I come to a stop in front of him. "Wait!" I cry out and slam into him. Surprised, he pulls himself upright and helps steady me, confusion replacing the nothing inside his eyes as I hold out my hand. "You dropped this," I say and drop the ring into his hand. I add more softly," She wouldn't want you to lose it." Startled, I see unshed tears form inside this man's eyes. He picks up the ring and slips it back onto his finger, closing his hand to make a tight his. Voice gruff, he whispers, "I know." Turning away, I give this man a sad smile and start walking away. One last glance over my shoulder and he's there again, staring into the sun set. But this time, he's smiling. Tears glistening his cheeks and he stands straighter, hair pushed out of his eyes. I swear he whispers someone's name, but I don't question it. Helping a stranger never felt for great.

Similar Articles

Join the discussion.

This article has 0 comments.

• Subscribe to Teen Ink magazine
• Submit to Teen Ink
• Find A College
• Find a Summer Program

Share this on

Send to a friend.

Thank you for sharing this page with a friend!

Tell my friends

Choose what to email.

Which of your works would you like to tell your friends about? (These links will automatically appear in your email.)

Send your email

Delete my account, we hate to see you go please note as per our terms and conditions, you agreed that all materials submitted become the property of teen ink. going forward, your work will remain on teenink.com submitted “by anonymous.”, delete this, change anonymous status, send us site feedback.

If you have a suggestion about this website or are experiencing a problem with it, or if you need to report abuse on the site, please let us know. We try to make TeenInk.com the best site it can be, and we take your feedback very seriously. Please note that while we value your input, we cannot respond to every message. Also, if you have a comment about a particular piece of work on this website, please go to the page where that work is displayed and post a comment on it. Thank you!

Pardon Our Dust

Teen Ink is currently undergoing repairs to our image server. In addition to being unable to display images, we cannot currently accept image submissions. All other parts of the website are functioning normally. Please check back to submit your art and photography and to enjoy work from teen artists around the world!

• Abstract/Non-Verbal Reasoning Test
• Academic Assessment Services (AAS) Scholarship Test (Year 7)
• Brisbane State High School Selective Test (Sit in Grade 5)
• Brisbane State High School Selective Test (Sit in Grade 6)
• GATE Test (Gifted & Talented) Academic Selective Test - ASET in WA
• IELTS General Training Writing
• IGNITE Program South Australia Exam (a Selective Schools Test offered by ACER®)
• NAPLAN Grade 5
• Narrative Writing (Written Expression) Test
• NSW Selective Schools Test (HSPT)
• Numerical Reasoning Test
• Persuasive / Argumentative Writing Test (with Topics & Real-Life Examples)
• QLD Academies SMT Selective Grade 7 Entry
• Reading Comprehension Test Practice (Grade 5, Grade 6, Grade 7)
• Scholarship Tests (Year 7 – Level 1) offered by ACER®
• Scholarship Tests (Year 7) Offered by Edutest®
• SEAL/SEALP (Select Entry Accelerated Learning Program) Exams Offered by ACER®
• Select Entry Accelerated Learning Programs (SEAL/SEALP) Offered by Edutest®
• Test Practice Questions - Free Trial
• The ADF Aptitude Test (Defence Force YOU Session)
• Verbal Reasoning Tests
• Victorian Selective Schools Test
• ONLINE COURSES
• TEST PAPERS
• WRITING PROGRAMS
• SITE MEMBERSHIP
• WRITING CLUB
• BLOG & ARTICLES
• FREE VIDEOS
• WRITING PROMPTS
• SAMPLE ESSAYS
• MASTERCLASS VIDEOS
• Get Started

QUESTION 18 - When I helped someone Write a creative piece to the following prompt: When I helped someone …

Struggling With Writing In English?

When i helped someone by shreya rao.

Helping people is a sign to them to show you care. I am sure everyone has helped someone else at least once, as it is a common thing. Further on in this essay I will state various times when I have helped someone.

Like many people, I have a sibling. He is younger than me so I help him many times. I help my brother with many things such as helping him with his homework, keeping him entertained when he is bored and ensuring of his safety. But sometimes there are significant events where he really needs my help such as when he gets bullied or badly injured and there is no one else around who can help him. Something like this happened at school. At lunch while I was enjoying my delicious sandwich my brother came up to me and said that his friends were running away from him. As an older sister I was alarmed and angry with those who upset my little brother. So, as most people would do, I took my brother's hand and he lead me to his friends. I told my brother's friends that this was an impolite thing to be doing and was unkind. As I was a senior in the school, my brother's friends did not argue and started to play with my brother.

Another instance when I have helped someone, was when I spotted a girl a little younger than I was who was injured and crying on the footpath. I approached her cautiously and bent down to ask her what had happened. She told me that she was going on a jog alone but she slipped and grazed her knees and hands and that now she couldn't get up. I straight away knew what to do. I asked her to calm down and not move so I could go and get my parents to assist her. Once I had gotten my parents and some bandages she told my parents what her parent's phone number was. We told the girl's parents where she was, and within five minutes they had come and picked her up.

You can help people whether you know them or not. Usually what I feel is that after you help someone you feel happy and glad about what you have just done. So go and help people in need because it will help you to feel happy too.

Your essay has received a general score of 5.33 on a scale from 0 to 10 #3 out of 100

Have A Question?

Published on February 23, 2022 by English Proficiency Editorial Team

IELTS Cue Card Sample Question  – Describe a Time When You Helped a Stranger 

If you ask those who have done the IELTS exam what the most challenging part of the test was, odds are they will say the cue card component, also known as the IELTS Speaking Part 2 . 

If you are wondering why, it is because in this section of the test, you will be assigned a topic with which you may not be acquainted, and you will have no option but to address it.

To make matters more challenging, you have less time to prepare and must talk for a longer period without interruptions or questions from the examiner. But do not panic. 

This article contains sample replies to the cue card topic ‘Describe a time when you helped a stranger.’ Continue reading to find out more.

What is the IELTS Cue Card Question?

How to answer this specific question: “describe a time when you helped a stranger” , sample response 1:, sample response 2: , vocabulary list for answering this question: “describe a time when you helped a stranger”.

The examiner will present you with a cue card with a topic printed on it in Task 2 of the IELTS Speaking Test . This card is referred to as a cue card . It will also give 3-5 bullet points that outline what you should discuss in your talk.

You have one minute to plan, during which you may jot down with the pen and paper provided to you.

You will be given 1-2 minutes to speak on the topic.

Then, the examiner will ask you one or two questions about your subject. This portion lasts about 3-4 minutes in total.

Topic/Question

Describe a Time When You Helped a Stranger

Guidelines to answer this question

You should say:

• When it was
• Where it was 
• Why that person needed help

And explain what and how you felt after helping them.  

• Recall a time when you helped a stranger. If you have no experience of helping a stranger, you can make up a story. The examiner will not know. 
• Once you have a subject to discuss, stick to it. There is no time to change your mind as you only have 60 seconds to plan. 
• Begin writing notes. State when and where it was and discuss why that person needed help. Do not forget to explain why you felt after helping them. 
• Manage your time well. You can do this by writing only keywords and sentences instead of sentences. 
• Employ sophisticated vocabulary. Make use of complex grammar structures as well. These two account for 50 percent of your marks in this part of the test. 
• Take quick notes, but make sure you understand what you have written later on. It is acceptable if the examiner does not recognize what you have written. Your grade is determined by the substance and delivery of your speech, not by your handwriting.
• You may wish to glance at your notes from time to time. It is permitted. The examiner will not prevent you from doing so. After all, it is why you are given a pen and a piece of paper.

Sample Responses: “Describe a Time When You Helped a Stranger”

“The specific occurrence I’d want to discuss happened during my undergraduate years when I assisted a poor family in our hometown. I can’t exactly recall the name of the person, but I know that he was a technician with a family of five. He had a tiny shop that repairs electronic devices. His modest shop was destroyed by a catastrophic typhoon, and he had no alternative source of income or the ability to repair it. 

I noticed him trying to calm his tiny children who were begging for food one day. This occurred near our college campus when I had gone to meet a classmate. I was so moved by the lovely but sad-looking children that I approached this person. He narrated what had transpired in a shaky voice. I bought them some fruits and snacks then asked them to hang around for a while. I went to my lecture and shared what happened to my three closest friends. Finally, we went to our class instructor and prepared an application about the person’s and his family’s plight. 

We were able to raise a large amount of money, which was beyond my expectations. We purchased food and clothing for this family with this money, and they were so appreciative that the husband and wife began crying and praying for us.  In terms of my emotions, I felt both satisfied and humbled. This is one of those times I realized how fascinating and fulfilling it is to assist someone. I felt blessed, and the man and his wife treated me as if I were a beloved friend.” 

Follow-up Question 1:

Do you like to help others?

“Yes, I enjoy helping others. I am overjoyed when I am able to assist someone. Whenever someone comes to me for assistance, I do my utmost to help him/her in any way I can.”

Follow-up Question 2: 

How do members of your community assist one another?

“I’m really fortunate to have very helpful people in our community. We try to help each other in any way we can. May it be donating money, helping out during events, or giving food, the people in our community never cease to help each other in times of need.”

“Man is a social being. We all have to provide and accept support from others on a regular basis. I’m going to tell you about a time when I assisted an accident victim. It happened when I was in Vinh last month for a wedding. We noticed a lady lying on her side with a lot of blood pouring from her head. The accident had occurred only 2 minutes before we saw them. 

She was with her husband, and they were on a scooter when they were hit by a fast automobile as they exited the gas station. We quickly pulled over to the side of the road and approached to see if we could assist.

Her spouse had minor injuries, but she was in critical condition. We quickly dialed the number of the government’s free ambulance service. The ambulance arrived in fifteen minutes. 

We did not move the lady since doing so could have aggravated her injury. She was breathing normally, but she was in a lot of agonies. In the ambulance, there was a first-aid crew led by a doctor. The ambulance crew carefully placed her on a stretcher and brought her to the nearest hospital. We obtained the phone numbers of the patient’s other relatives from her husband and called them. Actually, he was taken aback by his wife’s condition. We didn’t leave until they were settled. We were an hour late for the wedding, but we were glad we could aid those folks in need.”

Follow-up Question 1: 

Do you believe people nowadays are less willing to help others than in the past?

“Yes, I believe so. Today’s world moves at a fast pace. People have turned into workaholics. They have become self-absorbed. They seem not to have time to help others.”

Follow-up Question 2:

Do people trust each other as much as they used to?

“No, I don’t believe so. My grandparents and parents used to tell me that life used to be simpler and slower. People had faith in one another. Nowadays, it is quite difficult to find someone with whom you can put your trust. I think that people are changing just as the world is.”  

Below are some terms from the sample responses for the cue card topic ‘ Describe a time when you helped a stranger .’ with their definitions and example sentences for your reference. 

Additional Reading — IELTS Speaking Cue Card Questions

• Describe a Person You Admire
• Describe Your Best Friend
• Describe Someone Famous that You Want to Meet
• Describe a Person Who You Think is a Good Leader
• Describe a Neighbor You Like
• Describe a Place You Want to Travel Next
• Describe a Historical Place that You Have Been to
• Describe a Place You and Your Friend Went to Recently
• Describe a Place Where You Spend Most of Your Free Time
• Describe a Country that You Want to Visit
• Describe a Gift that You Have Received Recently
• Describe an Item of Clothing that You Bought for Someone
• Describe a Piece of Art that You Want to Buy
• Describe Something that You Recently Lost
• Describe a Vehicle that You Want to Buy
• Describe an Activity that You Find Enjoyable
• Describe a Place Where You Love to Shop
• Describe an Event that You Recently Attended
• Describe One of the Busiest Days of Your Life
• Describe a Hobby that You Do with Your Family
• Describe a Difficult Decision that You Made
• Describe a Time When You Felt Lucky
• Describe the First Time You Had a Mobile Phone
• Describe a Time When You Tried to Do Something but Weren’t Successful
• Describe Your Favorite Teacher
• Describe Your Favorite Photograph
• Describe Your Favorite Subject in School
• Describe Your Favorite Song
• Describe Your Favorite Actor
• Describe a Situation that Made You Upset
• Describe a Time When You Had an Argument with Someone
• Describe One of the Happiest Travels You Ever Had
• Describe an Incident When You Got Scared
• Describe a Time When You Felt Relieved
• Describe a Workaholic Person You Know
• Describe an Interesting Course You Took
• Describe a Time When Someone at Work Gave You a Compliment
• Describe a Quiet Place at School Where You Like Spending Your Free Time
• Describe a Time When Something Unfortunate Happened at Work

A group of language enthusiasts with a shared commitment to helping you succeed in your English language journey. With years of experience, relevant certifications, and a deep love for languages, we're here to provide you with the support and resources you need to excel in exams like IELTS, TOEFL, OET, Duolingo and many others. We take pride in helping individuals like you achieve their language goals.

Subscribe for English language proficiency tips

English Proficiency is not owned by or in any way affiliated with the institutions that handle the official Duolingo English Test, TOEIC®, TOEFL iBT®, IELTS, TOEFL ITP®, Cambridge C2, C1 Advanced, or any other English language proficiency exams listed or discussed on our website. We receive an affiliate commission for any purchases you may make on links to third party affiliate websites.

Essay on A Stranger

Students are often asked to write an essay on A Stranger in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on A Stranger

Who is a stranger.

A stranger is a person we do not know. We meet strangers every day. They could be in the park, at the store, or on the street. It’s normal to feel curious about them. We might wonder about their lives, their jobs, or where they come from.

Interacting with Strangers

It’s okay to talk to strangers in safe places. Always be polite and kind. But remember, it’s important to keep personal details private. Don’t share your name, address, or phone number. It’s best to talk about simple things like the weather or a favorite sport.

Strangers and Safety

Safety is crucial when dealing with strangers. Always stay in public areas. If a stranger makes you feel uncomfortable, it’s okay to walk away. Tell a trusted adult if something feels wrong. Remember, your safety comes first.

Strangers Can Become Friends

Sometimes, strangers become friends. You might meet someone at school or a club who starts as a stranger. Over time, as you get to know them, they might become a good friend. It’s a beautiful part of life.

250 Words Essay on A Stranger

A stranger is a person who is unknown or unfamiliar to you. This person could be someone you see in a park, at the bus stop, or in a store. You don’t know their name, where they live, or anything about their life. They are just like a book you haven’t read yet.

Meeting a Stranger

Meeting a stranger can be an interesting experience. You might feel curious about them. You might wonder about their life, their interests, and their story. Every person has a unique story, and a stranger is no different.

It’s important to remember that not all strangers are friendly. Some might mean harm. This is why it’s crucial to be careful. When you’re a kid, you should always stay near trusted adults and never go anywhere with a stranger.

Sometimes, strangers can become friends. Think about your best friend. There was a time when you didn’t know them, right? They were a stranger to you. But then, you got to know each other. You shared laughs, stories, and maybe even secrets. And just like that, a stranger became a friend.

The Beauty of Diversity

Strangers show us the beauty of diversity. They come from different places, have different cultures, and different ideas. This diversity makes our world more vibrant and exciting.

In conclusion, a stranger is someone unknown to us. While we should be careful around them for safety, they can also become our friends. They help us appreciate the diversity in our world.

500 Words Essay on A Stranger

Introduction.

A stranger is a person we do not know or recognize. We often meet strangers in public places like parks, buses, schools, and markets. Some strangers may become our friends, while others remain unknown. This essay will explore the concept of a stranger in a simple and easy-to-understand manner.

When we meet a stranger, we usually feel a mix of curiosity and caution. Curiosity because we want to know more about the person, and caution because we are unsure about their intentions. It’s natural to feel this way. We should always be careful when dealing with strangers, especially if they approach us in a way that makes us uncomfortable.

The Stranger’s Role

Strangers play an important role in our lives. They can teach us new things and introduce us to different cultures, ideas, and perspectives. For example, a stranger from a different country can tell us about their traditions, food, and way of life. This helps us learn about the world outside our own experiences.

While strangers can be interesting, we also need to remember safety. Children are often taught about “stranger danger”. This means they should be careful around people they don’t know. They should never go anywhere with a stranger or take anything from them. It’s good advice for everyone, not just children. We should always trust our instincts. If something doesn’t feel right, it’s better to be safe than sorry.

Strangers Becoming Friends

Every friend was once a stranger. It’s a strange thought, isn’t it? But it’s true. We meet new people, get to know them, and over time, some of them become our friends. This is one of the most exciting parts about meeting strangers. You never know who might end up being an important part of your life.

Strangers in the Digital World

In today’s digital world, we meet more strangers online than in person. We should be just as careful online as we are in real life. It’s easy for people to pretend to be someone they’re not on the internet. Always remember to protect your personal information and never share it with strangers online.

In conclusion, strangers are a part of our daily lives. They can offer new insights and perspectives, but we should always be careful and prioritize our safety. Remember, every friend was once a stranger, and who knows, the next stranger you meet could end up being a good friend. But always remember to be safe, whether you’re meeting strangers in person or online.

This essay has explored the concept of a stranger in a simple way. We learned about meeting strangers, their role in our lives, safety considerations, and the possibility of strangers becoming friends. We also discussed the role of strangers in the digital world. Remember, it’s okay to be curious, but it’s also important to stay safe!

That’s it! I hope the essay helped you.

If you’re looking for more, here are essays on other interesting topics:

• Essay on A Stormy Day
• Essay on A Soccer Match
• Essay on A Scenic Place

Apart from these, you can look at all the essays by clicking here .

Happy studying!

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

• Free Essays
• Citation Generator

Narrative Essay: Helping People

You May Also Find These Documents Helpful

Narrative essay.

One would think that purchasing your first home would be a very fascinating experience; after all it is one of the most major purchases of your entire life. In America, home ownership ties in with the American Dream and the spirit of working hard to one day earn through hard work a home with a white picket fence. My husband and I felt that it was time for us to reward ourselves for all the hard work we have been putting in over the years by purchasing our first home, which was well overdue. I quickly learned the process of purchasing your first home can be very frustrating and stressful. However, if you survive the home buying process the reward is priceless once you move into your “American Dream.”…

Selflessness In The Grapes Of Wrath

There seems to be an inexhaustible number of reasons that one person might go out of his way to assist another. One of the more interesting of these is to give to soothe one's conscience, or to avoid the guilt that comes with not offering help when you can. Ma Joad used this reason to feed the starving children at the first Hooverville they stayed at. She looked at those kids and tried to avoid giving them food so she could feed her family. Even Uncle Tom had a hard time eating his food with those hungry children looking on. Ma eventually soothed her conscience by giving the kids the dregs of the soup kettle, though she knew she should have given the entire helping to her family, as they had less than enough themselves.…

Mastro's Steak House Research Paper

I entered Mastro’s Steakhouse at approximately 7:00 PM on a Saturday night in New York City. I wore jeans and a nice white button down, with some Chuck Taylor’s. I paced the lobby many times before she walked through the double doors. Once she walked in, it was like time stopped.…

Christopher Awalt: The State Of Homelessness

Overall, helping others is a virtue and we should help someone who is worthy of help. What's more, people live in harmony and construct a caring society together and I think our world will become better in the…

Why Are Thoughtful Acts Important

Giving someone help can be easy. Providing help might come back to help someone else. For example, holding the door for someone whose arms are full will prevent them from dropping their stuff. In conclusion, thoughtful acts can benefit others.…

In today’s society, most people communicate using of cell phones. Just 15 to 20 years ago, cell phones were a rarity for the average person. The average income person could not afford a cell phone. Today, cell phones are affordable and the majority of people own them. The days of waiting until you are home to use a telephone or searching for a pay phone if you are out are long gone. In fact, pay phones are being removed, which increases the need for a cell phone. The government will provide a cell phone with limited monthly service for those that are low income and meet certain criteria. The cell phone has also created people to feel the need to be accessible to constant communication. The major problem lies with cell phone use while driving, which presents a constant danger on the road. In many instances, it is a deadly danger.…

Sajé's Essay Everyone Has Talent

When I provide assistance - even it is just a tiny one- , I really feel peace of mind. I still remember a specific experience that I could not give a hand at that time. The story happened when I was seven years old; in my first year in elementary school. There was a girl that was bullied by a group of girls from another class. I empathized with her. I wanted to help her, but I was afraid of that bullying girls too. I used to see her tears felled down over and over, so I always felt guilty toward her because I do not know why I felt that I could help her and stop those girls. When I grow up, I realized that I should not to blame those girls because they were just children; Actually, I think if I would blame anyone, I should blame our teachers. Now, when I think what I could do to help her at that time, I wish that I went to a teacher or to the principal to tell them about what that poor girl was facing. So, I try to help people as I can. I learned that I should not be silent when I see someone suffer; just do what I can do. If I could help, that would be amazing and that what I wanted, but if I could not, at least I…

Personal Narrative: Why I Didn T Help

I am going to talk about a time that I didn’t help someone, and why I chose not to, the consequences that occurred do to my choice to not be involved, and the repercussion that I suffered from it. There are various reasons why I chose not to help. I will break down three of those reasons, and I will explain to you the specific situation that I found myself in, and if my quick decision that I mad was worth it, and was it the right choice. We all have been wrong or misjudged a situation, I am going to share with you my experience.…

Social Work Personal Statement

You don’t ever really stop and think about why people need to be helped. Why you help them is a little easier, you help because it’s the right thing to do, well to me anyways. I help because I have a passion to, I have a want to help others. Some people don’t want help though. But I don’t think they actually don’t want help, I think they are just embarrassed or ashamed, or they don’t want anyone to know, or it’s a dignity thing, they don’t want to seem weak.…

narrative essay

Everyone in the world has a journey to find their passion. Whether it be short, long, thought-out or impulsive, people may find out what career field they'd like to join. Once one discovers their passion and what career path to follow, they are then made to pursue a degree that will help them excel. For some it took only moments to decide their fate; it takes some only a simple decision towards what path they want to take. It took me years of researching, exploring and see-sawing between numerous careers and different degrees to pursue. There were a few things I knew from the beginning along with a few things I picked up along the way that I wanted to do. I've always known I've wanted a degree from the beginning, but I started wanting a degree thinking it'd make me more money than average; I've learned since then it's almost the only way to get a decent job in this day and age. Now that I'm older, I finally decided my future as far as the degree I want and what I'd like to do with it. I've also decided how and where I'm going to obtain my degree. There are so many ways to go to college and get a degree; I could have gone to an online school, a 4 year university, a community college or even a mixture of all. With all the different choices in the world, it's a hard decision to make.…

Altruism: A Career In Social Work

Helping others have always came natural to me throughout my whole life, even as a child. My mother would always acknowledge how generous and warm-hearted that I was. I would literally give someone the clothing off my back or the shoes off my feet and would not think twice about it because I was and still is just that generous. According to social psychology, altruism is the motive to increase another’s welfare without conscious regard for one’s self-interest or simply selfishness in reverse. Some common examples of altruism are the Good Samaritan parable, helping a homeless person by offering a hot meal, and/or the act of someone risking his or her life to save another. Mostly all of my life I have been a very generous and selfless person.…

Making a difference

Helping others has always been my passion. Giving the gift of caring, showing love, giving help to other in the time of need, and showing respect to others shows my character in many ways. I will always try to make a difference in someone life with the gift that I have of helping when I can.…

The Controversy Of Helping Others

Although, I know that helping other people who might need your help, will make you feel better, but the other people have their own life, and they are big enough to think in their own. You should not always be helping others, I’m not saying that is wrong, but when you need help from them you will not receive the help you were expecting to get. Sometimes we can be so generous with them, and help those who need it in whatever they might need. But always remember that you also have a life, and not taking care of your life can cause you problems.…

I am an average 16 year who just can’t wait to grow up and face the real world and not have to worry about any rules or restrictions. On January 12th, 1996, my parents named me Asmaa, so I have to stick with that name for the rest of my life. Personally, I like the name because it’s the name of a very great person; more of a hero in Islam. Names in my family go with a pattern; but this only goes for girls. The pattern is the double ‘A’ at the end of the name. Shaymaa is the leader of the tribe yet she doesn’t control any of us. Next in line are me and my twin sister Alyaa. We are the decision makers in the household, everyone takes our opinion before doing anything or taking any steps .I would like to mention that I am the older twin; but that doesn’t really help me in anyway because she is treated as the ‘wiser one’. I am known as the smiley easy going twin and Alyaa is known as the serious harsher twin. There are 5 years between Omar and me, which makes me the mature older sister that he could come to for advice. Esraa is the little seven year old diva of the house. She likes to imitate models and celebrities and act like she rules the planet. The sixth child is five year old Tarek who just entered grade one this September. He believes that the world can’t survive without superheroes. Last but certainly not least is my life and my smile, the little flower of the house; Alaa. She is a year and 3 months old. In my mind; she completes the package very well. We kids call ourselves The Power of Seven. We’re 5 girls against 2 guys. Fortunately for us girls, we gang up against the guys and we always get what we want. The girls rule the house because they know how to fight for what they want, they know how to put up a good argument, and plus they’re the majority. Speaking of majority, I am two years away from being an official adult and getting the right to vote; a year and 4 months and day to be exact. I really want…

We ordered her favorite food. I couldn’t stop looking at her; looking at those eyes in which I had seen my life from the moment I met her.…

Related Topics

• Embarrassment

Your Best College Essay

Maybe you love to write, or maybe you don’t. Either way, there’s a chance that the thought of writing your college essay is making you sweat. No need for nerves! We’re here to give you the important details on how to make the process as anxiety-free as possible.

What's the College Essay?

When we say “The College Essay” (capitalization for emphasis – say it out loud with the capitals and you’ll know what we mean) we’re talking about the 550-650 word essay required by most colleges and universities. Prompts for this essay can be found on the college’s website, the Common Application, or the Coalition Application. We’re not talking about the many smaller supplemental essays you might need to write in order to apply to college. Not all institutions require the essay, but most colleges and universities that are at least semi-selective do.

How do I get started?

Look for the prompts on whatever application you’re using to apply to schools (almost all of the time – with a few notable exceptions – this is the Common Application). If one of them calls out to you, awesome! You can jump right in and start to brainstorm. If none of them are giving you the right vibes, don’t worry. They’re so broad that almost anything you write can fit into one of the prompts after you’re done. Working backwards like this is totally fine and can be really useful!

What if I have writer's block?

You aren’t alone. Staring at a blank Google Doc and thinking about how this is the one chance to tell an admissions officer your story can make you freeze. Thinking about some of these questions might help you find the right topic:

• What is something about you that people have pointed out as distinctive?
• If you had to pick three words to describe yourself, what would they be? What are things you’ve done that demonstrate these qualities?
• What’s something about you that has changed over your years in high school? How or why did it change?
• What’s something you like most about yourself?
• What’s something you love so much that you lose track of the rest of the world while you do it?

If you’re still stuck on a topic, ask your family members, friends, or other trusted adults: what’s something they always think about when they think about you? What’s something they think you should be proud of? They might help you find something about yourself that you wouldn’t have surfaced on your own.  

How do I grab my reader's attention?

It’s no secret that admissions officers are reading dozens – and sometimes hundreds – of essays every day. That can feel like a lot of pressure to stand out. But if you try to write the most unique essay in the world, it might end up seeming forced if it’s not genuinely you. So, what’s there to do? Our advice: start your essay with a story. Tell the reader about something you’ve done, complete with sensory details, and maybe even dialogue. Then, in the second paragraph, back up and tell us why this story is important and what it tells them about you and the theme of the essay.

THE WORD LIMIT IS SO LIMITING. HOW DO I TELL A COLLEGE MY WHOLE LIFE STORY IN 650 WORDS?

Don’t! Don’t try to tell an admissions officer about everything you’ve loved and done since you were a child. Instead, pick one or two things about yourself that you’re hoping to get across and stick to those. They’ll see the rest on the activities section of your application.

I'M STUCK ON THE CONCLUSION. HELP?

If you can’t think of another way to end the essay, talk about how the qualities you’ve discussed in your essays have prepared you for college. Try to wrap up with a sentence that refers back to the story you told in your first paragraph, if you took that route.

SHOULD I PROOFREAD MY ESSAY?

YES, proofread the essay, and have a trusted adult proofread it as well. Know that any suggestions they give you are coming from a good place, but make sure they aren’t writing your essay for you or putting it into their own voice. Admissions officers want to hear the voice of you, the applicant. Before you submit your essay anywhere, our number one advice is to read it out loud to yourself. When you read out loud you’ll catch small errors you may not have noticed before, and hear sentences that aren’t quite right.

ANY OTHER ADVICE?

Be yourself. If you’re not a naturally serious person, don’t force formality. If you’re the comedian in your friend group, go ahead and be funny. But ultimately, write as your authentic (and grammatically correct) self and trust the process.

And remember, thousands of other students your age are faced with this same essay writing task, right now. You can do it!

• Skip to main content
• Keyboard shortcuts for audio player

My Unsung Hero

After a serious car accident, a man pulled over — and continued to help for days.

Laura Kwerel

Apryle Oswald. Apryle Oswald hide caption

Apryle Oswald.

This story is part of the My Unsung Hero series from the Hidden Brain team. It features stories of people whose kindness left a lasting impression on someone else.

In 1997, Apryle Oswald was on a road trip with her boyfriend and two dogs, driving through a wide-open stretch of Nevada. Suddenly, one of the dogs tried to jump in the front seat. Oswald swerved and lost control of the car.

"I can picture it very, very clearly," she remembered. "The car did a somersault, back-over-front, for nearly a hundred yards."

Once it stopped, she unfastened her seatbelt and got out of the car, yelling for her boyfriend, John Williams, who had disappeared.

"All of a sudden I see him come running towards me, and then I collapse," she said. She learned later she had bruised lungs and splintered ribs. "And I remember laying on the ground, and I just couldn't get up ... I remember being cold — really, really cold."

They had 3 suitcases and faced 5 flights of stairs. That's when a stranger appeared

A funeral home worker tracked down a family — and uncovered a decades-old secret

At that point it was around midnight, with below-freezing temperatures. One of their dogs was badly injured, and needed attention. Williams tried to flag down the cars driving by, but no one slowed down. They started to panic.

"I ... remember him coming back and saying, 'Nobody's stopping, nobody's stopping,'" she said.

Williams eventually took off his coat and threw it at a truck coming by. "He got the guy to stop," Oswald said. "And that guy's ... the unsung hero."

Oswald doesn't recall his name, or what he looked like. But she remembers his deep voice, and how he wrapped her in a blanket.

"I recall in my mind ... this scratchy wool plaid blanket, and covering me up to make sure I was warm," she said.

Luckily the man had an emergency radio in his truck, so he called for help. An air medical helicopter arrived and evacuated Oswald to the hospital.

If her unsung hero had left after that, it would have been enough. She believes that if not for him, she might have died of hypothermia. But his generosity didn't end there.

The way a dying baby girl was cared for in 1980 helped shape her approach to nursing

No one could figure out the cause of her cough. Then a nurse practitioner had an idea

For the next three nights, the man drove Williams back and forth between his motel and the hospital, so Williams could visit her. He even drove their injured dog, Digby, to the veterinary clinic for blood transfusions.

"He just really cared," she said. "And he just went above and beyond."

She wishes she had gotten his phone number, to thank him again for saving her life — and for sticking around to help.

"I mean, who does that?" she said. "What an amazing person ... what an amazing thing for a stranger to do in the middle of a cold Nevada night."

After that, Oswald never saw the man again. But now, whenever she sees a person having car troubles, or who looks cold or hungry, she always stops. It's her way of paying the favor forward.

"If I go by somebody that needs help, I always think, 'Is there something I can do?'" Oswald said. "I feel compelled to help when I can."

My Unsung Hero is also a podcast — new episodes are released every Tuesday.

• car accident

• Download PDF
• Share X Facebook Email LinkedIn
• Permissions

Becoming a Co-Survivor—Reflections From the ICU

• 1 University of Michigan Medical School, Ann Arbor

I will never forget the first time I saw someone die. The cacophony of code pagers halted morning signout on inpatient cardiology, and we sprinted to a patient in cardiac arrest. He did not survive. I trudged back to the team room, thinking of the family who just lost the most important person in their world. I never imagined I would be in their shoes later that year, witnessing the cardiac arrest of one of my most important people—my dad.

A few days after my dad had urgent cardiac surgery, I was at his bedside in the same hospital where I was completing my medical school clerkships. One moment, we were smiling and discussing which cake we would get to celebrate his discharge. Then everything changed. In an instant, my dad became wide-eyed and started gasping for air with an intensity and desperation I had never seen before. I called out to him, panic in my voice: “Dad, are you okay?!… Dad, can you hear me?!… Dad, please wake up!…,” all met by silence. His eyes remained still and the color drained from his face as I rubbed his sternum with my knuckles, then reached my fingers down to his wrist. He had no pulse.

Read More About

Burns CJ. Becoming a Co-Survivor—Reflections From the ICU. JAMA Cardiol. Published online May 15, 2024. doi:10.1001/jamacardio.2024.1021

Manage citations:

© 2024

Artificial Intelligence Resource Center

Cardiology in JAMA : Read the Latest

Browse and subscribe to JAMA Network podcasts!

Others Also Liked

Select your interests.

Customize your JAMA Network experience by selecting one or more topics from the list below.

• Academic Medicine
• Acid Base, Electrolytes, Fluids
• Allergy and Clinical Immunology
• American Indian or Alaska Natives
• Anesthesiology
• Anticoagulation
• Art and Images in Psychiatry
• Artificial Intelligence
• Assisted Reproduction
• Bleeding and Transfusion
• Caring for the Critically Ill Patient
• Challenges in Clinical Electrocardiography
• Climate and Health
• Climate Change
• Clinical Challenge
• Clinical Decision Support
• Clinical Implications of Basic Neuroscience
• Clinical Pharmacy and Pharmacology
• Complementary and Alternative Medicine
• Consensus Statements
• Coronavirus (COVID-19)
• Critical Care Medicine
• Cultural Competency
• Dental Medicine
• Dermatology
• Diabetes and Endocrinology
• Diagnostic Test Interpretation
• Drug Development
• Electronic Health Records
• Emergency Medicine
• End of Life, Hospice, Palliative Care
• Environmental Health
• Equity, Diversity, and Inclusion
• Facial Plastic Surgery
• Gastroenterology and Hepatology
• Genetics and Genomics
• Genomics and Precision Health
• Global Health
• Guide to Statistics and Methods
• Hair Disorders
• Health Care Delivery Models
• Health Care Economics, Insurance, Payment
• Health Care Quality
• Health Care Reform
• Health Care Safety
• Health Care Workforce
• Health Disparities
• Health Inequities
• Health Policy
• Health Systems Science
• History of Medicine
• Hypertension
• Images in Neurology
• Implementation Science
• Infectious Diseases
• Innovations in Health Care Delivery
• JAMA Infographic
• Law and Medicine
• Leading Change
• Less is More
• LGBTQIA Medicine
• Lifestyle Behaviors
• Medical Coding
• Medical Devices and Equipment
• Medical Education
• Medical Education and Training
• Medical Journals and Publishing
• Mobile Health and Telemedicine
• Narrative Medicine
• Neuroscience and Psychiatry
• Notable Notes
• Nutrition, Obesity, Exercise
• Obstetrics and Gynecology
• Occupational Health
• Ophthalmology
• Orthopedics
• Otolaryngology
• Pain Medicine
• Palliative Care
• Pathology and Laboratory Medicine
• Patient Care
• Patient Information
• Performance Improvement
• Performance Measures
• Perioperative Care and Consultation
• Pharmacoeconomics
• Pharmacoepidemiology
• Pharmacogenetics
• Pharmacy and Clinical Pharmacology
• Physical Medicine and Rehabilitation
• Physical Therapy
• Physician Leadership
• Population Health
• Primary Care
• Professional Well-being
• Professionalism
• Psychiatry and Behavioral Health
• Public Health
• Pulmonary Medicine
• Regulatory Agencies
• Reproductive Health
• Research, Methods, Statistics
• Resuscitation
• Rheumatology
• Risk Management
• Scientific Discovery and the Future of Medicine
• Shared Decision Making and Communication
• Sleep Medicine
• Sports Medicine
• Stem Cell Transplantation
• Substance Use and Addiction Medicine
• Surgical Innovation
• Surgical Pearls
• Teachable Moment
• Technology and Finance
• The Art of JAMA
• The Arts and Medicine
• The Rational Clinical Examination
• Tobacco and e-Cigarettes
• Translational Medicine
• Trauma and Injury
• Treatment Adherence
• Ultrasonography
• Users' Guide to the Medical Literature
• Vaccination
• Venous Thromboembolism
• Veterans Health
• Women's Health
• Workflow and Process
• Wound Care, Infection, Healing
• Register for email alerts with links to free full-text articles
• Access PDFs of free articles
• Manage your interests
• Save searches and receive search alerts

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• Front Behav Neurosci

Why humans might help strangers

Nichola j. raihani.

1 Department of Genetics Evolution and Environment, University College London, London, UK

Redouan Bshary

2 Institut de Biologie, Université de Neuchâtel, Neuchatel, Switzerland

Humans regularly help strangers, even when interactions are apparently unobserved and unlikely to be repeated. Such situations have been simulated in the laboratory using anonymous one-shot games (e.g., prisoner’s dilemma) where the payoff matrices used make helping biologically altruistic. As in real-life, participants often cooperate in the lab in these one-shot games with non-relatives, despite that fact that helping is under negative selection under these circumstances. Two broad explanations for such behavior prevail. The “big mistake” or “mismatch” theorists argue that behavior is constrained by psychological mechanisms that evolved predominantly in the context of repeated interactions with known individuals. In contrast, the cultural group selection theorists posit that humans have been selected to cooperate in anonymous one-shot interactions due to strong between-group competition, which creates interdependence among in-group members. We present these two hypotheses before discussing alternative routes by which humans could increase their direct fitness by cooperating with strangers under natural conditions. In doing so, we explain why the standard lab games do not capture real-life in various important aspects. First, asymmetries in the cost of perceptual errors regarding the context of the interaction (one-shot vs. repeated; anonymous vs. public) might have selected for strategies that minimize the chance of making costly behavioral errors. Second, helping strangers might be a successful strategy for identifying other cooperative individuals in the population, where partner choice can turn strangers into interaction partners. Third, in contrast to the assumptions of the prisoner’s dilemma model, it is possible that benefits of cooperation follow a non-linear function of investment. Non-linear benefits result in negative frequency dependence even in one-shot games. Finally, in many real-world situations individuals are able to parcel investments such that a one-shot interaction is turned into a repeated game of many decisions.

Human helpfulness

One doesn’t have to observe humans in their natural habitat for long to witness many and varied examples of prosocial behavior, often directed towards complete strangers. People might vacate a seat on a crowded bus or train to let an elderly person sit down; hold open a door for others; or help a struggling parent to carry their pram down a flight of stairs. Humans also willingly donate resources, such as money or food, to others for example by giving to charity (e.g., Frey and Meier, 2004 ; Soetevent, 2005 ). These charitable donations are typically directed at recipients the helpful individual does not know or will expect to meet in the future. This propensity to help unrelated others who reside outside our regular social circle is striking when one considers that these helpful acts are seemingly unobserved and many of the interactions are unlikely to persist beyond the current round. To explain why humans are so helpful under conditions that seem to predict selfishness, researchers have attempted to bring this behavior into the laboratory by creating stylized games where subjects can cooperate with or help one another, but where payoffs are structured such that self-interested behaviors yield greater rewards. One of the most widely-used paradigms is the anonymous one-shot prisoner’s dilemma game (Luce and Raiffa, 1957 ). In this game, two interacting players simultaneously choose between cooperating or defecting. Payoffs are structured such that mutual cooperation yields higher payoffs for both than mutual defection, but defecting yields a higher individual payoff than cooperating regardless of how the partner behaves. Hence there is a temptation to defect even if the partner cooperates (see Figure ​ Figure1). 1 ). This game can be modeled with more than two players with similar incentives, yielding a temptation to defect when others cooperate: this is an n-player prisoner’s dilemma game (also commonly referred to as a public goods game, Ledyard, 1995 ). Regardless of whether the game is played with two or more than two players, in a one-shot prisoner’s dilemma the evolutionarily stable strategy (Maynard-Smith, 1982 ) is to defect. Another game that has been widely used is the dictator game (Kahneman et al., 1986 ). This is a two-player game where one player (the “dictator”) is endowed with a sum of money and can choose to give none, some or all of the endowment to the partner. The “receiver” in the game has no power and must accept any division of the endowment offered by the dictator. As in the prisoner’s dilemma game, individuals can maximize their earnings in the game by behaving selfishly and keeping the entire endowment.

Payoffs accruing to (Player 1, Player 2) according to each player’s decision to cooperate (C) or defect (D) in a social dilemma are shown. R is the reward for mutual cooperation, T is the temptation to defect, S is the sucker’s payoff and P is the punishment for mutual defection . A game satisfies the assumptions of the prisoner’s dilemma where T > R > P > S . The snowdrift game is captured wherever T > R > S > P . Thus, the prisoner’s dilemma and the snowdrift game differ only in the best possible response to a partner’s defection: in the prisoner’s dilemma, the best response is to defect whereas in the snowdrift game, the best response is to cooperate.

Empirical studies have shown that humans often cooperate in anonymous one-shot prisoner’s dilemma games (or give money in dictator games) despite the fact that not contributing is the optimal solution (Camerer, 2003 ; Henrich et al., 2005 ; Engel, 2011 ). It has been suggested that helping in the absence of obvious rewards emerges from proximate psychological mechanisms that make helping others subjectively rewarding for the actor (Andreoni, 1990 ; Fehr and Camerer, 2007 ; Harbaugh et al., 2007 ). To explain why these psychological mechanisms exist, one has to ask under which conditions they are likely to have been favored by Natural Selection. The two dominant current explanations—the “big mistake hypothesis” (also known as the “mismatch hypothesis”) and the “cultural group selection hypothesis”—mainly disagree on the question of whether anonymous one-shot interactions were absent in human evolutionary history until very recently, and hence whether helping strangers is based on a psychological constraint or is instead adaptive under certain circumstances (specifically, when interaction partners belong to the same cultural group) (Rand and Nowak, 2013 ). Here, we first present these two hypotheses in more detail. We then move on to discuss how the laboratory game settings may differ from real-life interactions with strangers not only with respect to population structure but also in other fundamental ways. Based on this assessment, we will argue that there are several plausible routes by which cooperative behavior towards strangers could increase an individual’s direct fitness (Table ​ (Table1). 1 ). We hope that this evaluation will stimulate researchers to use or develop new experimental paradigms, such that our knowledge of the proximate mechanisms that underpin cooperation can be complemented with a better understanding of the adaptive significance of such strategies.

The key features of different theories to explain why humans cooperate in ostensibly anonymous, one-shot encounters .

Cooperation—a big mistake?

Some researchers have argued that the expression of prosocial behaviors in laboratory anonymous, one-shot encounters can be explained by mis-firing of psychological mechanisms in a context we are not evolutionarily adapted to (e.g., Cosmides and Tooby, 1989 ; Hoffman et al., 1998 ; Ben-Ner and Putterman, 2000 ; Johnson et al., 2003 ; Tooby et al., 2006 ). The line of reasoning is that the proximate mechanisms underpinning human social behavior evolved in close-knit, small groups comprised of kin and stable interaction partners, where no interaction was ever truly one-shot or anonymous. In such an environment, an individual that was predisposed to help group members would likely have been compensated for their investment, either via indirect benefits to kin (Hamilton, 1964a , b ) or via personal benefits arising from future interactions with the recipient (Trivers, 1971 ) or observers (Nowak and Sigmund, 1998 ; Roberts, 1998 ). It is clear that these putative ancestral environments were fundamentally different to the modern day environment of most humans and especially to the artificial setup of most laboratory games. It is argued, therefore, that subjects in laboratory settings rely on psychological mechanisms that evolved in the context of repeated, non-anonymous interactions and that our predisposition to cooperate in the lab (or with strangers in the real world) might, therefore, be an evolutionary relic of times gone by. In support of the so-called (Boyd and Richerson, 2002 ; Fehr and Henrich, 2003 ) mismatch or big mistake hypothesis, there are several instances where imperfect human behavior can be attributed to the mismatch between our evolved psychology and our current environment. For example, the common tendency to be phobic of ancestrally dangerous stimuli (e.g., snakes, spiders) relative to more pressing modern-day threats (e.g., cars, guns); and the proclivity to ingest excessive quantities of foods that are high in sugar, fat and salt based on their relative abundance nowadays as compared with ancestral environments (Irons, 1998 ) can both be explained as psychological mechanisms that on average produced fitness enhancing outcomes in ancestral environments but that no longer deliver such benefits—and can even be harmful—in the modern world (Hagen and Hammerstein, 2006 ; Tooby et al., 2006 ).

Nevertheless, critics of the big mistake hypothesis have questioned the validity of assumption that ancestral social environments were devoid of anonymous one-shot encounters. Instead, it seems probable that even ancestral hunter-gatherers probably had some encounters with strangers with no obvious future follow-up, for example in the context of interactions outside their immediate social group (e.g., trading, feuds and so on, Lee, 1972 ; Wiessner, 1982 ; Keeley, 1996 ; Fehr and Henrich, 2003 ; Hill et al., 2011 ). It can be shown that, despite our evolutionary heritage, humans are able to identify interactions where helping is likely to yield a return benefit (e.g., by identifying kin, by predicting when behavior is likely to be observed or not, or when interactions are likely to be repeated)—and adjust behavior accordingly (Fehr and Henrich, 2003 ). For example, various studies have shown that people recognize and preferentially help kin over non-kin (Barber, 1994 ; Gurven, 2004 ); that we cooperate more when investments are public rather than anonymous (e.g., Milinski et al., 2002 ; Andreoni and Petrie, 2004 ; Soetevent, 2005 ; Lamba and Mace, 2010 ); and that we cooperate less when interactions will not be repeated or will end soon (e.g., Gächter and Falk, 2002 ; Gächter et al., 2008 ). Moreover, recent work has suggested that while people may use heuristics from daily life to guide cooperative decision making, these heuristics can be rapidly updated to reflect the conditions imposed in the artificial lab setting (Rand et al., 2012 , 2014 ). In fact even fish are apparently able to adjust levels of cooperation to the likelihood of repeated interactions (Oates et al., 2010 ). Thus, critics of the big mistake hypothesis have good arguments that humans do have the cognitive machinery to detect when an interaction is likely to yield direct return benefits, and to adjust behavior accordingly.

If, as seems likely, interactions with strangers probably did exist in our evolutionary history, why do humans have a psychology that seems geared towards cooperating in these contexts, given that the short-term, payoff-maximizing approach is apparently to defect under such conditions? For cooperative investments to come under positive selection, the behavior must form part of a strategy that on average increases the fitness of the bearer. In other words, cooperative actors must somehow ultimately be repaid for their investments. Broadly, it has been suggested that the ultimate benefits associated with making costly investments could arise either with or without assortative population structure (often referred to as group-level (or multi-level) and individual-level selection in the literature). We consider these two arguments in turn.

Between-group competition

Whenever populations are structured into groups of relatively stable composition, there is potential for competition between groups. The stronger such competition between groups is the more individual and group interests are closely aligned, and selection may favor strategies that prioritize unconditional contributions towards group success. The tendency for such “multi-level selection” to promote cooperation is seen at all levels of life and several of the major evolutionary transitions identified by Szathmáry and Smith ( 1995 ) rely on the repression of lower order conflict to bring about a higher-level advantage. According to accounts of helping based on between-group competition in humans (e.g., Gintis, 2000 ; Henrich, 2004 ; Boyd and Richerson, 2009 ), group-level benefits favor individual costly investments (even in the absence of obvious mechanisms to be directly compensated) because within-group helping generally predicts group success in the face of extinction threats (e.g., due to competition with other groups, environmental catastrophes etc., Gintis, 2000 ). Similar arguments emphasizing the importance of group-level benefits have been proposed by biologists for the evolution of helping behavior among non-relatives in cooperatively breeding groups (e.g., Kokko et al., 2001 ) and have been formulated with the notion of interdependence replacing the relatedness term in Hamilton’s rule (Roberts, 2005 ). Although group-level benefits could theoretically arise via genetic group selection, the high levels of between-group genetic variance that would be necessary to facilitate selection are thought to be unrealistic given the genetic evidence for (female) migration among groups (Seielstad et al., 1998 ; Bell et al., 2009 ). Moreover, since genetic between-group selection is thought to be a small force in large groups, it is unlikely to account for large-scale cooperation seen in modern day human societies. Thus, colleagues have focussed instead on the concept of cultural group selection, whereby immigrating individuals are expected to adopt the cultures of the new group, thereby reducing the behavioral variance that migrating individuals would otherwise have (Boyd and Richerson, 1982 ; Henrich, 2004 ; Bell et al., 2009 ). Cultural group selection of cooperative traits is thought to be facilitated by a general predisposition to learn socially from others, which would be adaptive where the cost of information acquisition was sufficiently high (Boyd and Richerson, 1982 , 2009 ; Henrich and Boyd, 2001 ; Guzmán et al., 2007 ; Richerson and Boyd, 2008 ; but see Eriksson and Coultas, 2009 ; André and Morin, 2011 ). Selection for social learning outside the cooperative domain could then facilitate the evolution of cooperative cultural norms within populations. If populations varied in these norms and if the outcomes of competition between populations varied according to within-group levels of cooperation, then cultural group selection could favor cooperative strategies. The benefits of within-group cooperation could, in turn, select for psychological predispositions to cooperate with in-group members while punishing defectors (i.e., “strong reciprocity”, Gintis, 2000 ; Fehr et al., 2002 ; Fehr and Henrich, 2003 ; Boyd and Richerson, 2009 ), even in anonymous, one-shot encounters. Evidence for cross-cultural variation in cooperative tendency across societies (Henrich et al., 2001 , 2005 , 2006 , 2010 ; Gächter and Herrmann, 2009 ; Gächter et al., 2010 ; House et al., 2013 ) has been touted as key evidence for the existence of between-group variation in cooperative norms that could be the basis for such selection (Henrich, 2004 ; Henrich et al., 2005 ).

Nevertheless, the assumptions underpinning the cultural group selection account of human cooperation have been subject to debate (Burnham and Johnson, 2005 ; Hagen and Hammerstein, 2006 ; West et al., 2011 ). For instance, while it is often assumed that the predisposition for conformity necessary to catalyze the emergence of within-group cooperation is an adaptive trait, it has been demonstrated that non-conformist transmission dominates conformist strategies in evolutionary models (Eriksson and Coultas, 2009 ). Moreover, analytical models have shown that a tendency for conformist transmission can undermine the evolution of helping behaviors (Feldman et al., 1985 ; Lehmann et al., 2008 ), not catalyze them as was originally predicted. Thus, in contrast to the predictions of the cultural group selection models, it is apparently easier for costly helping strategies to evolve under genetic systems of inheritance rather than via culture. Another central assumption of cultural group selection models is that individuals are constrained by a predisposition for conformity to blindly adopt the behaviors of others, even when strategic non-conformity would increase biological fitness (e.g., Gintis, 2003 ; Boyd and Richerson, 2009 ). The validity of this assumption is contested (Hagen and Hammerstein, 2006 ; André and Morin, 2011 ; El Mouden et al., 2014 ; Morin, 2014 ). Instead, it has been argued that the conditions under which cultural group selection would be expected to produce a maladaptive tendency to copy altruistic behavior are prohibitively restrictive (El Mouden et al., 2014 ; Morin, 2014 ) and, moreover, that antagonistic co-evolution should act to curb psychological predispositions to copy maladaptive actions (El Mouden et al., 2014 ). Indeed, strong empirical evidence suggests that people are sensitive to the benefits of imitation and do not copy blindly as supposed (Rendell et al., 2011 ; Morgan et al., 2012 ; Morin, 2014 ). More recently, it has also been suggested that asymmetries among individuals within groups can facilitate within-group cooperation when there is between-group competition, without having to resort to cultural transmission, reciprocity or punishment (Gavrilets and Fortunato, 2014 ). Specifically, when some individuals are able to benefit more than others from the production of a (within-group) public good (e.g., if they are dominant to others in the group), it pays for these individuals to invest more in the production of the public good, and this effect is particularly pronounced when groups are in competition with one another. Thus, population structure and between-group competition can facilitate within-group cooperation even in the absence of culturally transmitted tendencies to copy cooperative and punitive behaviors.

Empirical evidence for cultural group selection has also been called into question. While the existence of inter-cultural variation in cooperative norms (e.g., Henrich et al., 2001 , 2005 ) seemed initially supportive of the predictions of the cultural group selection models, more recent empirical work has shown that substantial within-culture variation in cooperation exists that can be explained by local demography and ecology rather than culture (Lamba and Mace, 2011 ; Nettle et al., 2011 ; Schroeder et al., 2014 ). The extent of within-culture variation has been demonstrated to be comparable to that previously observed between cultures (Lamba and Mace, 2011 ) and, since many of the former studies sampled only one or a few populations per culture, it is argued that much of the measured variation that has been attributed to cultural differences may not in fact exceed within-group variation in these traits. Furthermore, cultural group selection models do not predict unconditional help towards any recipient but instead only towards members of the relevant in-group. Out-group members should not receive help and may in fact be harmed (“parochial altruism”, Bernhard et al., 2006 ). There is no a-priori reason for human subjects in laboratory one-shot games to assume that the co-players are members of the in-group, and so deserving of help. One might just as easily expect that subjects assume that co-players are out-group members, which would not predict costly cooperative behavior. Finally, it appears biologically questionable that in-group members are indeed unfamiliar with each other and that they can be reasonably certain that there will not be any future interactions; such a scenario would be much more likely with out-group members. Thus, even with a cultural group selection account of cooperation, human behavior in stylized laboratory games still remains a puzzle because we have to understand why co-players are apparently treated as in-group rather than out-group members (Burnham and Johnson, 2005 ).

Direct benefits without between-group competition

The cultural group selection approach makes assumptions about population structure (grouping) and competition between these units without specifying whether a tendency to help strangers increases indirect fitness (through relatedness) or direct fitness (through interdependence). An alternative approach is to investigate conditions under which helping strangers may yield direct benefits in the absence of any specific population structure. One plausible suggestion is that human cooperation in one-shot games can be thought of as a strategy that minimizes costly error types (Burnham and Johnson, 2005 ; Yamagishi et al., 2007 ; Delton et al., 2011 ; Morin, 2014 ). Error management theory assumes that where there is uncertainty over the perceptual accuracy of the environment (such that all is not necessarily as it seems) and there are asymmetries in the costs of false-positive and false-negative error types, then evolution should favor strategies that minimize the costlier of the two error types (Johnson et al., 2013 ). It is important to bear in mind that Natural Selection is expected to favor strategies that on average increase the fitness of the bearer rather than to produce perfect behavior in every context. In other words, assessment errors mean that adaptive strategies will sometimes produce behavioral mistakes (West et al., 2011 ; Morin, 2014 ). For example, consider a meerkat who hears an alarm call indicating the likely, but only probabilistic, presence of a predator. In such a scenario there are likely to be asymmetric costs associated with erroneous behavioral responses. Responding to a false alarm call by fleeing incurs energetic and opportunity costs, while failing to flee when the threat is real incurs a far higher possible cost of being caught by a predator. Based on these asymmetric costs of behavioral errors, a strategy of “if hear alarm call, then flee” might be on average adaptive even if it produces several behavioral errors (i.e., fleeing in response to false alarms). In the context of interactions with strangers, it may well be the case that humans experience perceptual uncertainty over several features of the interaction, any or all of which may favor strategies that err on the side of caution by cooperating even when there is little ostensible benefit to doing so. The uncertainty could stem from inaccuracies in perceiving the likely duration of the interaction, whether the interaction is truly anonymous, or the payoff matrix of the interaction. We discuss how perceptual uncertainty in any of these features might select for broadly cooperative strategies below.

Misperceiving interaction duration or anonymity

It has been argued that cooperation can be favored by evolution if there is even a small possibility that the interaction will be repeated and if this possibility is fundamentally unpredictable (Delton et al., 2011 ). Such a strategy could be adaptive even if it produces several behavioral errors (i.e., cooperating when no return benefits are possible). In a laboratory setting, an experimenter can exogenously impose the one-shot structure on the game (such that subjects can be certain that the interaction is not repeated) but this is unlike real life interactions with strangers, where we might often experience a degree of uncertainty about whether we might meet again. Using agent-based simulations, Delton et al. ( 2011 ) showed, using a mix of agents playing either always-defect (ALLD) or the conditionally cooperative strategy tit-for-tat (TFT), that cooperation can indeed be favored so long as there is a non-zero probability that the interaction might be repeated (and the partner is TFT rather than ALLD). In this setting, uncertainty over the number of interactions favors cooperation also in interactions that turn out to be one-shot. Cooperation is favored because mistaking a repeated interaction for one-shot (and therefore defecting in the first round of the game) incurred a greater cost than mistaking a one-shot interaction for repeated (and therefore erroneously cooperating). This is due to the unforgiving nature of TFT, whereby defecting in the first round of the game prompts the partner to defect in the next round and thus establishes mutual defection for the duration of the interaction. Strategies that take a chance on the interaction being repeated (and the partner playing TFT) by cooperating in the first round could instead establish mutually productive, cooperative relationships with TFT partners. In support of the idea, it has additionally been argued that due to autocorrelation of individual locations over time, interacting with an individual once leads to an increased probability of interacting with the same individual again in the future (Krasnow et al., 2013 ). Thus, by definition, meeting a partner once implies that the interaction will be repeated and that conditionally cooperative strategies will prevail.

Nevertheless, the generality of these findings have been challenged on the grounds that only interactions with unrepentant (ALLD) and unforgiving (TFT) strategies were explored (McNally and Tanner, 2011 ; Zefferman, 2014a , b ). ALLD is unrepentant in the sense that it is committed to play defect in all rounds; it cannot change its behavior if the interaction turns out to be repeated. TFT is unforgiving in the sense that any defection by the partner will be immediately reciprocated with defection. By contrast, it was verbally argued that the importance of uncertainty for catalyzing one-shot cooperation might be substantially reduced if agents employed strategies that allowed for flexible responses, either an increased propensity to cooperate once the interaction extended beyond round one or a non-zero probability to forgive cheating partners in a repeated interaction (McNally and Tanner, 2011 ). This is because, with flexible strategies, the importance of cooperating in the first round would be reduced substantially since cooperation could still be established (or re-established) beyond round one (McNally and Tanner, 2011 ). Thus, the question of why individuals cooperate in ostensible one-shot interactions would remain unresolved. Indeed, the inclusion of repentant and forgiving strategies under the same conditions of uncertainty has subsequently been shown to vastly diminish the advantage to cooperating in (ostensible) one-shot interactions; in some cases actually reversing the direction of selection (Zefferman, 2014a ). Zefferman ( 2014a ) proposes that the failure of the model to predict one-shot cooperation when an arguably more realistic strategy set is considered emphasizes the importance of social learning of local cooperative norms (i.e., the cultural group selection approach) for explaining one-shot cooperation. Ultimately, empirical studies are likely to be important for understanding whether defection in an ostensible one-shot encounter precludes cooperation from being established (as predicted by Delton et al., 2011 ; Delton and Krasnow, 2014 ) or, instead, whether humans are more likely to forgive an interaction partner who starts by defecting but then switches to cooperation if the interaction continues.

While the Delton et al. ( 2011 ) model assumed that psychological responses to cooperate evolved in the context of directly reciprocal interactions, one also has to consider that under real world scenarios, actions might also be observed by uninvolved bystanders, who adjust their behavior towards the actor accordingly. For example, under indirect reciprocity models, helpful acts are reciprocated by third-parties rather than by recipients. Misperceiving that an interaction is unobserved by bystanders might carry similar costs to misperceiving the likely duration, in that erroneous defection incurs greater costs than erroneous cooperation in both scenarios. Thus, error-management might still play a role in sustaining cooperation but because individuals can never be certain that their actions are unobserved, rather than because they misperceive interaction duration. If there is even a slight possibility that actions will be observed—and if being seen as unhelpful carries greater costs than helping when no one is watching (as has been proposed in models of judgment bias, Rankin and Eggimann, 2009 )—then selection might favor psychological mechanisms that make us behave as though we are observed most of the time. Empirical evidence suggests that reputation concerns have an important influence on prosocial tendency: people are typically more cooperative in public rather than anonymous laboratory games (e.g., Andreoni and Petrie, 2004 ; Lamba and Mace, 2010 ) and even exposing people to subtle cues of being watched (in the form of eye images) increases prosocial behavior under some circumstances (e.g., Haley and Fessler, 2005 ; Bateson et al., 2006 ; but see Fehr and Schneider, 2010 ; Raihani and Bshary, 2012 for failed replications). The presence of potential observers is made even more important when one considers that, via gossip, one’s positive or negative actions could be broadcast to several “observers”, who need not even have been present at the time of the event (e.g., Sommerfeld et al., 2007 , 2008 ; Feinberg et al., 2014 ). Thus, an error-managing strategy might often cooperate—even when interactions seem to be anonymous—to minimize the reputation costs of not cooperating if the interaction turns out to be observed.

Partner choice via exploration

Many of the games used to explore cooperation under laboratory settings impose a forced-play structure on subjects: players cannot choose who they want to interact with or to leave unproductive relationships (Axelrod and Hamilton, 1981 ). While cooperation can evolve under such circumstances in artificial simulations (e.g., via clustering or assortment of cooperators, Nowak and May, 1992 ; Fletcher and Doebeli, 2009 ; but see Hauert and Doebeli, 2004 ), network reciprocity based on spatial structure does not seem to support cooperation in empirical studies (Grujić et al., 2014 ). Indeed, assuming that players are constrained to use pure strategies and are forced to interact with one another is unlikely to reflect the conditions under which real-word relationships operate. Instead, individuals are typically able to choose interaction partners, and can choose to continue interactions with cooperative partners while terminating relationships that prove unproductive (e.g., Noë and Hammerstein, 1994 ; Baumard et al., 2013 ).

The possibility for partner choice might therefore favor unconditionally helpful strategies if being observed as helpful increases the chance of being chosen for future interactions. Importantly, the chooser need not make costly investments to reimburse the helper for their actions. Instead, simply being chosen for a mutually productive interaction (e.g., producing offspring, cohabiting) could compensate the helper for their initial investment (e.g., Bshary and Grutter, 2006 ; McNamara et al., 2008 ). According to the “competitive altruism” theory, competition for interaction partners occurs within a biological market (Noë and Hammerstein, 1994 ); and individuals who produce the strongest signals of quality (via helping) will be preferred as partners (Roberts, 1998 ; Lotem et al., 2003 ; Barclay, 2011 ). Empirical evidence suggests that competitive altruism might be an important mechanism underpinning human helping behavior: people choose interaction partners based on cooperative reputation (e.g., Barclay and Willer, 2007 ; Sylwester and Roberts, 2010 , 2013 ) and avoid defectors (Rockenbach and Milinski, 2011 ), hence individuals compete with one another to advertise helpful actions (Raihani and Smith, in press ).

The possibility for partner choice could also promote cooperation, even with unknown individuals in an anonymous setting, because individuals can use cooperative first moves to test the response of the partner and then decide whether to continue the interaction or not. Error-management might still play a role but, unlike the Delton et al. ( 2011 ) model, the cost of not cooperating would be that one misses out on the chance to have a mutually productive relationship with the partner, rather than that one is stuck in a mutually destructive relationship. It has been demonstrated that where there is extrinsically maintained variation in cooperative tendency within a population (maintained by differences in quality or ability to invest in the partner, McNamara and Leimar, 2010 , or by mutation, immigration, recombination or epistasis, McNamara et al., 2004 ), then this variation could select for cooperative strategies because this is a way to identify whether the partner is also cooperative (McNamara et al., 2004 ). In such scenarios cooperation can evolve whenever the benefit of interacting with a cooperator outweighs the benefit of occasional exploitation. Variability in cooperativeness, together with a long lifespan during which to reap the benefits of a productive partnership, can then pave the way for the evolution of choosiness because, given sufficient variation in partner quality it can pay to leave a less cooperative partner in hope of finding a more cooperative individual next time (Sherratt and Roberts, 1998 ; McNamara et al., 2008 ). In many real-world scenarios, initial cooperative acts might often be low cost (in comparison to the potential benefits of establishing a mutually productive relationship) but investments could increase as the relationship becomes more established (e.g., Roberts and Sherratt, 1998 ). For example, while we do not routinely see people handing out $100 bills to strangers, low cost helpful acts, such as holding a door open or assisting with heavy bags, are relatively commonplace. These low cost investments are consistent with the idea that cooperation could be used as an exploratory strategy to strike up mutually productive relationships with other individuals in the population. Nowadays, modern technology may even allow us to develop long-distance relationships as a consequence of chance encounters where we help or are helped by others.

Alternative payoff matrices

Most theoretical and laboratory studies of cooperation in humans have assumed a prisoner’s dilemma type payoff-matrix, where benefits scale linearly with investments. In such scenarios, the payoff-maximizing strategy in a one-shot game is to defect regardless of how the partner(s) behave. As a consequence, explanations based on assortment, repeated interactions or relatedness are typically invoked to account for the emergence and stability of cooperative behavior. The assumption that all social dilemmas have the structure of an n-player prisoner’s dilemma is, however, flawed (Kollock, 1998 ; Archetti and Scheuring, 2011 ). Alternative social dilemmas with different payoff matrices can yield evolutionarily stable cooperative strategies without having to invoke assortment, relatedness or repeated interactions (e.g., Doebeli and Hauert, 2005 ; Archetti, 2009a , b ; Archetti and Scheuring, 2011 ). For example, consider the 2-player snowdrift game. This game describes two drivers traveling in opposite directions when they come across a snowdrift blocking the road. Neither driver can get home unless the road is cleared. Although each driver prefers the other to do the clearing, each would also rather clear the snowdrift himself than for the snowdrift to not be cleared at all. As a consequence, in the two-player snowdrift game, the best response to a cooperative partner is to defect, while the best response to a defecting partner is to cooperate. Thus, the strategic payoffs differ markedly from those in more frequently used prisoner’s dilemma, where defecting always yields the highest payoff (Doebeli and Hauert, 2005 ; Figure ​ Figure1). 1 ). An n-player snowdrift game is often referred to as a volunteer’s dilemma (Diekmann, 1985 ). In its simplest form, this game assumes that a public good will be produced if one player cooperates and that additional investments do not increase the magnitude of the public good. Thus, unlike the traditional n-player prisoner’s dilemma, benefits are a non-linear function of investment and cooperation is therefore expected to be under negatively frequency dependent selection. As in the snowdrift game, the benefit of the public good being produced is larger than the cost associated with producing it, such that all players would do best to invest to produce the public good if no one else does so.

Relaxing the assumption of linearity has far-reaching consequences for the emergence and stability of cooperative strategies in n-player games. Specifically, when individuals are unsure about how others are likely to behave in a non-linear public goods game, then the best strategy is to cooperate probabilistically (where the probability depends on the cost to benefit ratio of cooperating and group size, Archetti, 2009a , b ; Archetti and Scheuring, 2011 , 2012 ). Such probabilistic strategies will emerge even in non-repeated games without spatial assortment or interactions among relatives. Where players differ in their ability to invest, or in the benefit that they can extract from the public good being produced, then this can also offer a potential solution to a non-linear public goods game, with those players who will reap the largest benefit from investing being more likely to contribute to the public good (e.g., see Gavrilets and Fortunato, 2014 ; Szolnoki and Perc, 2014 ). With respect to the assumption of linearity in benefits, n-player prisoner’s dilemma games lie at one end of a spectrum with threshold Public Goods Games (i.e., volunteer’s dilemmas) at the other end. All intermediate cases (where benefits are a sigmoidal function of investment in the public good) resemble the volunteer’s dilemma more than the traditional n-player prisoner’s dilemma in that they also yield a stable mixed equilibrium of cooperators and defectors in the population, even in the absence of other incentives to cooperate (Archetti and Scheuring, 2011 ). Thus, it has been argued that many biological examples of cooperation in social dilemmas are more likely to yield non-linear rather than linear benefits, which has profound implications for our understanding of how cooperation evolves and is maintained in these scenarios (Kummerli et al., 2007 ; Archetti, 2009a ; Sherratt et al., 2009 ; Archetti et al., 2011 ; Archetti and Scheuring, 2012 ). For example, the costly production of invertase in yeast, alarm calling in animal groups and the formation of fruiting bodies in social amoebas are all examples that can be described as non-linear public goods games where cooperation is under negative frequency dependent selection (Gore et al., 2009 ; Archetti and Scheuring, 2011 ; Archetti et al., 2011 ). Yeast growth requires the costly production of the enzyme invertase to hydrolyze sucrose into smaller glucose molecules which can be imported into the cell (Gore et al., 2009 ). Although invertase production is costly and can be parasitized by non-producing cells, a complete lack of invertase can be lethal, meaning that producer cells outperform non-producers when rare. Conversely, at high densities of producers, non-producing cells have an advantage because they can parasitize the invertase being produced by the other cells (Gore et al., 2009 ).

For humans, it is less clear whether the majority of the social dilemmas that have shaped our social behavior ought to be described with linear or with non-linear payoff functions. In the case of punishment, which has been modeled as a second-order public good (and often therefore explained in terms of cultural group selection, e.g., Boyd et al., 2003 ), it has been argued that the payoffs of investing in punishment (in terms of increased within-group cooperation) are likely to scale non-linearly with number of punishers, thereby providing a direct individual-level solution for its existence (Raihani and Bshary, 2011 ). Other social dilemmas that have been explained in terms of cultural group selection, for example contributions to group defense during war, might also be more likely to have non-linear than linear payoffs. Group survival, which is the typical currency for payoffs associated with cooperating in warfare, is likely to be a non-linear function of contributions to defense, meaning that the payoffs associated with increasing within-group cooperation are by definition non-linear. It may turn out to be the case that linear public goods problems exist mainly in artificial laboratory settings and that subjects use strategies and psychology that evolved predominantly in the context of non-linear games when they participate. Specifically, if most real-world public goods problems are non-linear in nature and if there is always a certain degree of uncertainty about whether others will contribute to produce the public good (thereby obviating the need for the subject’s own investment), selection may have favored strategies that either probabilistically cooperate (when cooperation is binary) or that invest intermediate amounts (when cooperation is a continuous variable) (c.f. Kummerli et al., 2010 ), even in one-shot games.

Parceled investments

Finally, we would like to highlight an additional discrepancy with the way laboratory prisoner’s dilemma experiments are set up compared with how interactions typically occur in the real-world. In many experimental games, the act to cooperate or to defect is an all-or-nothing action where players press a button, and typically learn about each other’s choices post hoc . On the other hand, interactions with strangers in our evolutionary past (e.g., in the context of trades) are highly unlikely to have involved exchange of closed boxes where players only found out after separating what the other put in the box. Instead, real-world interactions with strangers might often have involved simultaneous or parceled exchanges, where individuals could monitor the behavior of one another, make behavioral adjustments in real time and—importantly—terminate unproductive exchanges prematurely (e.g., Connor, 1992 ; Hart and Hart, 1992 ). For example, most female lions approach intruders simulated by playbacks more slowly if they teamed up with laggard female group members, apparently looking back regularly to check the spatial configuration of self vs. partners (Heinsohn and Packer, 1995 ). Theoretical models have shown that where cooperation is not an all-or-nothing event but investments can instead can be parceled and adjusted in real time, then prisoner’s dilemma type situations can be solved cooperatively, even in one-shot anonymous games (Friedman and Hammerstein, 1991 ; Connor, 1995 ; Johnstone and Bshary, 2002 ). The key issue is that stable cooperation does not rely on repeated interactions but on repeated decisions. The question of whether encounters between strangers (either currently, or in our evolutionary past) are more likely to involve single vs. multiple decisions remains open for empirical exploration.

We have discussed potential explanations for the observation that humans help complete strangers under natural conditions and often cooperate in laboratory anonymous one-shot games. While the extent to which humans encountered such situations in our evolutionary past necessarily remains an open debate, it is clear that such encounters happen today. Moreover, it appears that we are at least partly adapted to adjust behavior to such situations. Our aim was to identify functional explanations for why humans regularly help strangers under natural conditions. The main take-home message is that the laboratory settings deviate from natural encounters in various important ways that make helping in real-world encounters potentially under positive selection while it is clearly not in the lab setting. Error-management arguments suggest that during natural encounters it is very hard to assess whether an interaction will be one-off and/or whether the interaction will remain truly anonymous. Furthermore, while lab games typically impose a forced-play scenario on subjects, in real-life individuals can choose to pursue productive relationships and abandon unproductive partners. This possibility for partner choice might select for helping behavior even with unknown strangers. Another issue is that in real-world interactions, the payoffs might often be a non-linear function of total investment, causing helping to be under negative frequency dependent selection rather than being altruistic. Finally, as soon as interactions involve multiple decisions, stable cooperation may be achieved even between strangers without any future perspective. We note that these different explanations are not mutually exclusive and that different explanations are likely to apply to different real-world scenarios. One way to explore the importance of the different explanations we proposed would be to use a wider variety of laboratory games, that replicate conditions that are likely to prevail in real-world interactions with strangers.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

• André J.-B., Morin O. (2011). Questioning the cultural evolution of altruism . J. Evol. Biol. 24 , 2531–2542. 10.1111/j.1420-9101.2011.02398.x [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Andreoni J. R. (1990). Impure altruism and donations to public goods: a theory of warm-glow giving . Econ. J. 100 , 464–477 10.2307/2234133 [ CrossRef ] [ Google Scholar ]
• Andreoni J., Petrie R. (2004). Public goods experiments without confidentiality: a glimpse into fund-raising . J. Pub. Econ. 88 , 1605–1623 10.1016/s0047-2727(03)00040-9 [ CrossRef ] [ Google Scholar ]
• Archetti M. (2009a). Cooperation as a volunteer’s dilemma and the strategy of conflict in public goods games . J. Evol. Biol. 22 , 2192–2200. 10.1111/j.1420-9101.2009.01835.x [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Archetti M. (2009b). The volunteer’s dilemma and the optimal size of a social group . J. Theor. Biol. 261 , 475–480. 10.1016/j.jtbi.2009.08.018 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Archetti M., Scheuring I. (2011). Coexistence of cooperation and defection in public goods games . Evolution 65 , 1140–1148. 10.1111/j.1558-5646.2010.01185.x [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Archetti M., Scheuring I. (2012). Game theory of public goods in one-shot social dilemmas without assortment . J. Theor. Biol. 299 , 9–20. 10.1016/j.jtbi.2011.06.018 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Archetti M., Scheuring I., Hoffman M., Frederickson M. E., Pierce N. E., Yu D. W. (2011). Economic game theory for mutualism and cooperation . Ecol. Lett. 14 , 1300–1312. 10.1111/j.1461-0248.2011.01697.x [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Axelrod R., Hamilton W. (1981). The evolution of cooperation . Science 211 , 1390–1396. 10.1126/science.7466396 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Barber N. (1994). Machiavellianism and altruism: effect of relatedness of target person on Machiavellian and helping attitudes . Psychol. Rep. 75 , 403–422 10.2466/pr0.1994.75.1.403 [ CrossRef ] [ Google Scholar ]
• Barclay P. (2011). Competitive helping increases with the size of biological markets and invades defection . J. Theor. Biol. 281 , 47–55. 10.1016/j.jtbi.2011.04.023 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Barclay P., Willer R. (2007). Partner choice creates competitive altruism in humans . Proc. Biol. Sci. 274 , 749–753. 10.1098/rspb.2006.0209 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Bateson M., Nettle D., Roberts G. (2006). Cues of being watched enhance cooperation in a real-world setting . Biol. Lett. 2 , 412–414. 10.1098/rsbl.2006.0509 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Baumard N., André J.-B., Sperber D. (2013). A mutualistic approach to morality: the evolution of fairness by partner choice . Behav. Brain Sci. 36 , 59–78. 10.1017/S0140525x11002202 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Bell A. V., Richerson P. J., McElreath R. (2009). Culture rather than genes provides greater scope for the evolution of large-scale human prosociality . Proc. Natl. Acad. Sci. U S A 106 , 17671–17674. 10.1073/pnas.0903232106 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Ben-Ner A., Putterman L. (2000). On some implications of evolutionary psychology for the study of preferences and institutions . J. Econ. Behav. Organ. 43 , 91–99 10.1016/s0167-2681(00)00110-4 [ CrossRef ] [ Google Scholar ]
• Bernhard H., Fischbacher U., Fehr E. (2006). Parochial altruism in humans . Nature 442 , 912–915. 10.1038/nature04981 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Boyd R., Gintis H. M., Bowles S., Richerson P. J. (2003). The evolution of altruistic punishment . Proc. Natl. Acad. Sci. U S A 100 , 3531–3535. 10.1073/pnas.0630443100 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Boyd R., Richerson P. J. (1982). Cultural transmission and the evolution of cooperative behavior . Hum. Ecol. 3 , 325–351 10.1007/bf01531189 [ CrossRef ] [ Google Scholar ]
• Boyd R., Richerson P. J. (2002). Group beneficial norms can spread rapidly in a structured population . J. Theor. Biol. 215 , 287–296. 10.1006/jtbi.2001.2515 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Boyd R., Richerson P. (2009). Culture and the evolution of human cooperation . Philos. Trans. R. Soc. Lond. B Biol. Sci. 364 , 3281–3288. 10.1098/rstb.2009.0134 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Bshary R., Grutter A. S. (2006). Image scoring and cooperation in a cleaner fish mutualism . Nature 441 , 975–978. 10.1038/nature04755 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Burnham T. C., Johnson D. D. P. (2005). The biological and evolutionary logic of human cooperation . Anal. Kritik 27 , 113–135. [ Google Scholar ]
• Camerer C. (2003). Behavioral Game Theory: Experiments in Strategic Interaction. Princeton, New Jersey: Princeton University Press. [ Google Scholar ]
• Connor R. C. (1992). Egg-trading in simultaneous hermaphrodites: an alternative to Tit-for-Tat . J. Evol. Biol. 5 , 523–528 10.1046/j.1420-9101.1992.5030523.x [ CrossRef ] [ Google Scholar ]
• Connor R. C. (1995). Impala allogrooming and the parcelling model of reciprocity . Anim. Behav. 49 , 528–530 10.1006/anbe.1995.0070 [ CrossRef ] [ Google Scholar ]
• Cosmides L., Tooby J. L. (1989). Evolutionary psychology and the generation of culture, part II: case study: a computational theory of social exchange . Ethol. Sociobiol. 10 , 51–97 10.1016/0162-3095(89)90013-7 [ CrossRef ] [ Google Scholar ]
• Delton A. W., Krasnow M. M. (2014). An independent replication that the evolution of direct reciprocity under uncertainty explains one-shot cooperation: commentary on Zeffermann . Evol. Hum. Behav. 35 , 547–548 10.1016/j.evolhumbehav.2014.07.004 [ CrossRef ] [ Google Scholar ]
• Delton A. W., Krasnow M., Cosmides L., Tooby J. (2011). Evolution of direct reciprocity under uncertainty can explain human generosity in one-shot encounters . Proc. Natl. Acad. Sci. U S A 108 , 13335–13340. 10.1073/pnas.1102131108 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Diekmann A. (1985). Volunteer’s dilemma . J. Confl. Resol. 29 , 605–610 10.1177/0022002785029004003 [ CrossRef ] [ Google Scholar ]
• Doebeli M., Hauert C. (2005). Models of cooperation based on the prisoner’s dilemma and the snowdrift game . Ecol. Lett. 8 , 748–766 10.1111/j.1461-0248.2005.00773.x [ CrossRef ] [ Google Scholar ]
• El Mouden C., André J.-B., Morin O., Nettle D. (2014). Cultural transmission and the evolution of human behaviour: a general approach based on the Price equation . J. Evol. Biol. 27 , 231–241. 10.1111/jeb.12296 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Engel C. (2011). Dictator games: a meta-study . Exp. Econ. 14 , 583–610 10.1007/s10683-011-9283-7 [ CrossRef ] [ Google Scholar ]
• Eriksson K., Coultas J. C. (2009). Are people really conformist-biased? an empirical test and a new mathematical model . J. Evol. Psych. 7 , 5–21 10.1556/jep.7.2009.1.3 [ CrossRef ] [ Google Scholar ]
• Fehr E., Camerer C. F. (2007). Social neuroeconomics: the neural circuitry of social preferences . Trends Cogn. Sci. 11 , 419–427. 10.1016/j.tics.2007.09.002 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Fehr E., Fischbacher U., Gächter S. (2002). Strong reciprocity, human cooperation and the enforcement of social norms . Hum. Nat. 13 , 1–25 10.1007/s12110-002-1012-7 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Fehr E., Henrich J. (2003). “ Is strong reciprocity a maladaptation? ,” in Genetic and Cultural Evolution of Cooperation , ed Hammerstein P. (Cambridge, MA: MIT Press; ), 55–82. [ Google Scholar ]
• Fehr E., Schneider F. (2010). Eyes are on us, but nobody care: are eye cues relevant for strong reciprocity? Proc. Biol. Sci. 277 , 1315–1323. 10.1098/rspb.2009.1900 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Feinberg M., Willer R., Schultz M. (2014). Gossip and ostracism promote cooperation in groups . Psychol. Sci. 25 , 656–664. 10.1177/0956797613510184 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Feldman M. W., Cavalli-Sforza L., Peck J. L. (1985). Gene-culture coevolution: models for the evolution of altruism with cultural transmission . Proc. Natl. Acad. Sci. U S A 82 , 5814–5818. 10.1073/pnas.82.17.5814 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Fletcher J. A., Doebeli M. (2009). A simple and general explanation for the evolution of altruism . Proc. Biol. Sci. 276 , 13–19. 10.1098/rspb.2008.0829 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Frey B. S., Meier S. (2004). Pro-social behavior in a natural setting . J. Econ. Behav. Organ. 54 , 65–88 10.1016/j.jebo.2003.10.001 [ CrossRef ] [ Google Scholar ]
• Friedman J. W., Hammerstein P. (1991). “ To trade, or not to trade; that is the question ,” in Game Equilibrium Models I: Evolution and Game Dynamics , ed Selten R. (Berlin, Heidelberg: Springer; ), 257–275. [ Google Scholar ]
• Gächter S., Falk A. (2002). Reputation and reciprocity: consequences for the labor relation . Scand. J. Econ. 104 , 1–26 10.1111/1467-9442.00269 [ CrossRef ] [ Google Scholar ]
• Gächter S., Herrmann B. (2009). Reciprocity, culture and human cooperation: previous insights and a new cross-cultural experiment . Philos. Trans. R. Soc. Lond. B Biol. Sci. 364 , 791–806. 10.1098/rstb.2008.0275 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gächter S., Herrmann B., Thöni C. (2010). Culture and cooperation . Philos. Trans. R. Soc. Lond. B Biol. Sci. 365 , 2651–2661. 10.1098/rstb.2010.0135 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gächter S., Renner E., Sefton M. (2008). The long-run benefits of punishment . Science 322 :1510. 10.1126/science.1164744 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gavrilets S., Fortunato L. (2014). A solution to the collective action problem in between-group conflict with within-group inequality . Nat. Commun. 5 :3526. 10.1038/ncomms4526 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gintis H. (2000). Strong reciprocity and human sociality . J. Theor. Biol. 206 , 169–179. 10.1006/jtbi.2000.2111 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gintis H. (2003). The hitchhiker’s guide to altruism: gene-culture coevolution and the internalization of norms . J. Theor. Biol. 220 , 407–418. 10.1006/jtbi.2003.3104 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gore J., Youk H., can Oudenaarden A. (2009). Snowdrift game dynamics and facultative cheating in yeast . Nature 459 , 253–256. 10.1038/nature07921 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Grujić J., Gracia-Lázaro C., Milinski M., Semmann D., Traulsen A., Cuesta J. A., et al.. (2014). A comparative analysis of spatial Prisoner’s Dilemma experiments: conditional cooperation and payoff irrelevance . Sci. Rep. 4 :4615. 10.1038/srep04615 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Gurven M. (2004). To give and to give not: the behavioral ecology of human food transfers . Behav. Brain Sci. 27 , 543–559 10.1017/s0140525x04000123 [ CrossRef ] [ Google Scholar ]
• Guzmán R. A., Rodríguez-Sickert C., Rowthorn R. (2007). When in Rome, do as the Romans do: the coevolution of altruistic punishment, conformist learning and cooperation . Evol. Hum. Behav. 28 , 112–117 10.1016/j.evolhumbehav.2006.08.002 [ CrossRef ] [ Google Scholar ]
• Hagen E. H., Hammerstein P. (2006). Game theory and human evolution: a critique of some recent interpretations of experimental games . Theor. Popul. Biol. 69 , 339–348. 10.1016/j.tpb.2005.09.005 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Haley K. J., Fessler D. M. T. (2005). Nobody’s watching? Subtle cues affect generosity in a one-shot game . Evol. Hum. Behav. 26 , 245–256 10.1016/j.evolhumbehav.2005.01.002 [ CrossRef ] [ Google Scholar ]
• Hamilton W. (1964a). The genetical evolution of social behaviour I . J. Theor. Biol. 7 , 1–16 10.1016/0022-5193(64)90038-4 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Hamilton W. (1964b). The genetical evolution of social behaviour II . J. Theor. Biol. 7 , 17–52. 10.1016/0022-5193(64)90039-6 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Harbaugh W. T. W., Mayr U. U., Burghart D. R. D. (2007). Neural responses to taxation and voluntary giving reveal motives for charitable donations . Science 316 , 1622–1625. 10.1126/science.1140738 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Hart B. L., Hart L. A. (1992). Reciprocal allogrooming in impala, Aepyceros melampus . Anim. Behav. 44 , 1073–1083 10.1016/S0003-3472(05)80319-7 [ CrossRef ] [ Google Scholar ]
• Hauert C., Doebeli M. (2004). Spatial structure often inhibits the evolution of cooperation in the snowdrift game . Nature 428 , 643–646. 10.1038/nature02360 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Heinsohn R., Packer C. (1995). Complex cooperative strategies in group-territorial African lions . Science 269 , 1260–1262. 10.1126/science.7652573 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Henrich J. (2004). Cultural group selection, coevolutionary processes and large-scale cooperation . J. Econ. Behav. Organ. 53 , 3–35 10.1016/s0167-2681(03)00094-5 [ CrossRef ] [ Google Scholar ]
• Henrich J., Boyd R. (2001). Why people punish defectors: weak conformist cransmission can stabilize costly enforcement of norms in cooperative dilemmas . J. Theor. Biol. 208 , 79–89. 10.1006/jtbi.2000.2202 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Henrich J., Boyd R., Bowles S., Camerer C. F., Fehr E., Gintis H. M., et al. (2001). In search of homo economicus: behavioral experiments in 15 small-scale societies . Am. Econ. Rev. 91 , 73–78 10.1257/aer.91.2.73 [ CrossRef ] [ Google Scholar ]
• Henrich J., Boyd R., Bowles S., Camerer C. F., Fehr E., Gintis H. M., et al.. (2005). “Economic man” in cross-cultural perspective: behavioral experiments in 15 small-scale societies . Behav. Brain Sci. 28 , 795–855. 10.1017/s0140525x05000142 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Henrich J., McElreath R., Barr A., Barrett C., Bolyanatz A., Cardenas J. C., et al.. (2010). Markets, religion, community size and the evolution of fairness and punishment . Science 327 , 1480–1484. 10.1126/science.1182238 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Henrich J., McElreath R., Barr A., Ensminger J., Barrett H. C., Bolyanatz A., et al.. (2006). Costly punishment across human societies . Science 312 , 1767–1770. 10.1126/science.1127333 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Hill K. R., Walker R. S., Bozicevic M., Eder J., Headland T., Hewlett B., et al.. (2011). Co-residence patterns in hunter-gatherer societies show unique human social structure . Science 331 , 1286–1289. 10.1126/science.1199071 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Hoffman E., McCabe K., Smith V. (1998). Behavioral foundations of reciprocity: experimental economics and evolutionary psychology . Econ. Inq. 36 , 335–352 10.1111/j.1465-7295.1998.tb01719.x [ CrossRef ] [ Google Scholar ]
• House B. R., Silk J. B., Henrich J., Barrett H. C., Scelza B. A., Boyette A. H., et al.. (2013). Ontogeny of prosocial behavior across diverse societies . Proc. Natl. Acad. Sci. U S A 110 , 14586–14591. 10.1073/pnas.1221217110 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Irons W. (1998). Adaptively relevant environments versus the environment of evolutionary adaptedness . Evol. Anthropol. 6 , 194–204 10.1002/(sici)1520-6505(1998)6:6<194::aid-evan2>3.0.co;2-b [ CrossRef ] [ Google Scholar ]
• Johnson D. D. P., Blumstein D. T., Fowler J. H., Haselton M. G. (2013). The evolution of error: error management, cognitive constraints and adaptive decision-making biases . Trends Ecol. Evol. 28 , 474–481. 10.1016/j.tree.2013.05.014 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Johnson D. D. P., Stopka P., Knights S. (2003). Sociology: the puzzle of human cooperation . Nature 421 , 911–912. 10.1038/421911b [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Johnstone R. A., Bshary R. (2002). From parasitism to mutualism: partner control in asymmetric interactions . Ecol. Lett. 5 , 634–639 10.1046/j.1461-0248.2002.00358.x [ CrossRef ] [ Google Scholar ]
• Kahneman D., Knetsch J. L., Thaler R. (1986). Fairness as a constraint on profit seeking: entitlements in the market . Am. Econ. Rev. 76 , 728–741. [ Google Scholar ]
• Keeley L. H. (1996). War before Civilisation: The Myth of the Peaceful Savage. Oxford, UK: Oxford University Press. [ Google Scholar ]
• Kokko H., Johnstone R. A., Clutton-Brock T. H. (2001). The evolution of cooperative breeding through group augmentation . Proc. Biol. Sci. 268 , 187–196. 10.1098/rspb.2000.1349 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Kollock P. (1998). Social dilemmas: the anatomy of cooperation . Annu. Rev. Sociol. 24 , 183–214 10.1146/annurev.soc.24.1.183 [ CrossRef ] [ Google Scholar ]
• Krasnow M. M., Delton A. W., Tooby J., Cosmides L. (2013). Meeting now suggests we will meet again: implications for debates on the evolution of cooperation . Sci. Rep. 3 :1747. 10.1038/srep01747 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Kummerli R., Burton-Chellew M. N., Ross-Gillespie A., West S. A. (2010). Resistance to extreme strategies, rather than prosocial preferences, can explain human cooperation in public goods games . Proc. Natl. Acad. Sci. U S A 107 , 10125–10130. 10.1073/pnas.1000829107 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Kummerli R., Colliard C., Fiechter N., Petitpierre B., Russier F., Keller L. (2007). Human cooperation in social dilemmas: comparing the snowdrift game with the prisoner’s dilemma . Proc. Biol. Sci. 274 , 2965–2970. 10.1098/rspb.2007.0793 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Lamba S., Mace R. (2010). People recognize when they are really anonymous in an economic game . Evol. Hum. Behav. 31 , 271–278 10.1016/j.evolhumbehav.2010.02.002 [ CrossRef ] [ Google Scholar ]
• Lamba S., Mace R. (2011). Demography and ecology drive variation in cooperation across human populations . Proc. Natl. Acad. Sci. U S A 108 , 14426–14430. 10.1073/pnas.1105186108 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Ledyard J. (1995). “ Public goods: a survey of experimental research ,” in Handbook of Experimental Economics , eds Kagel J., Roth A. (Princeton: Princeton University Press; ). [ Google Scholar ]
• Lee R. B. (1972). !Kung spatial organization: an ecological and historical perspective . Hum. Ecol. 1 , 125–147 10.1007/bf01531351 [ CrossRef ] [ Google Scholar ]
• Lehmann L., Feldman M. W., Foster K. R. (2008). Cultural transmission can inhibit the evolution of altruistic helping . Am. Nat. 172 , 12–24. 10.1086/587851 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Lotem A., Fishman M., Stone L. (2003). From reciprocity to unconditional altruism through signalling benefits . Proc. Biol. Sci. 270 , 199–205. 10.1098/rspb.2002.2225 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Luce R. D., Raiffa H. (1957). Games and Decisions. New York: Wiley. [ Google Scholar ]
• Maynard-Smith M. (1982). Evolution and the Theory of Games. Cambridge, UK: Cambridge University Press. [ Google Scholar ]
• McNally L., Tanner C. J. (2011). Flexible strategies, forgiveness and the evolution of generosity in one-shot encounters . Proc. Natl. Acad. Sci. U S A 108 :E971. 10.1073/pnas.1115225108 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• McNamara J. M., Barta Z., Fromhage L., Houston A. I. (2008). The coevolution of choosiness and cooperation . Nature 451 , 189–192. 10.1038/nature06455 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• McNamara J. M., Barta Z., Houston A. I. (2004). Variation in behaviour promotes cooperation in the Prisoner’s Dilemma game . Nature 428 , 745–748. 10.1038/nature02432 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• McNamara J. M., Leimar O. (2010). Variation and the response to variation as a basis for successful cooperation . Philos. Trans. R. Soc. Lond. B Biol. Sci. 365 , 2627–2633. 10.1098/rstb.2010.0159 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Milinski M., Semmann D., Krambeck H. (2002). Reputation helps solve the ‘tragedy of the commons’ . Nature 415 , 424–426. 10.1038/415424a [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Morgan T. J. H., Rendell L. E., Ehn M., Hoppitt W., Laland K. N. (2012). The evolutionary basis of human social learning . Proc. Biol. Sci. 279 , 653–662. 10.1098/rspb.2011.1172 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Morin O. (2014). Is cooperation a maladaptive by-product of social learning? The docility hypothesis reconsidered . Biol. Theor. 9 , 286–295 10.1007/s13752-014-0181-z [ CrossRef ] [ Google Scholar ]
• Nettle D. D., Colléony A. A., Cockerill M. M. (2011). Variation in cooperative behaviour within a single city . PLoS One 6 :e26922. 10.1371/journal.pone.0026922 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Noë R., Hammerstein P. (1994). Biological markets: supply and demand determine the effect of partner choice in cooperation, mutualism and mating . Behav. Ecol. Sociobiol. 35 , 1–11 10.1007/bf00167053 [ CrossRef ] [ Google Scholar ]
• Nowak M. A., May R. M. (1992). Evolutionary games and spatial chaos . Nature 359 , 826–829 10.1038/359826a0 [ CrossRef ] [ Google Scholar ]
• Nowak M. A., Sigmund K. (1998). Evolution of indirect reciprocity by image scoring . Nature 393 , 573–577. 10.1038/31225 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Oates J., Manica A., Bshary R. (2010). The shadow of the future affects cooperation in a cleaner fish . Curr. Biol. 20 , R472–R473. 10.1016/j.cub.2010.04.022 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Raihani N. J., Bshary R. (2011). The evolution of punishment in n-player public goods games: a volunteer’s dilemma . Evolution 65 , 2725–2728. 10.1111/j.1558-5646.2011.01383.x [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Raihani N. J., Bshary R. (2012). A positive effect of flowers rather than eye images in a large-scale, cross-cultural dictator game . Proc. Biol. Sci. 279 , 3556–3564. 10.1098/rspb.2012.0758 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Raihani N. J., Smith S. (in press). Competitive helping in the real world . Curr. Biol. [ PubMed ] [ Google Scholar ]
• Rand D. G., Greene J. D., Nowak M. A. (2012). Spontaneous giving and calculated greed . Nature 489 , 427–430. 10.1038/nature11467 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Rand D. G., Nowak M. A. (2013). Human cooperation . Trends Cogn. Sci. 17 , 413–425. 10.1016/j.tics.2013.06.003 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Rand D. G., Peysakhovich A., Kraft-Todd G. T., Newman G. E., Wurzbacher O., Nowak M. A., et al.. (2014). Social heuristics shape intuitive cooperation . Nat. Commun. 5 :3677. 10.1038/ncomms4677 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Rankin D. J., Eggimann F. (2009). The evolution of judgement bias in indirect reciprocity . Proc. Biol. Sci. 276 , 1339–1345. 10.1098/rspb.2008.1715 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Rendell L., Fogarty L., Hoppitt W. J. E., Morgan T. J. H., Webster M. M., Laland K. N. (2011). Cognitive culture: theoretical and empirical insights into social learning strategies . Trends Cogn. Sci. 15 , 68–76. 10.1016/j.tics.2010.12.002 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Richerson P. J., Boyd R. (2008). Not by Genes Alone: How Culture Transformed Human Evolution. Chicago, IL: University of Chicago Press. [ Google Scholar ]
• Roberts G. (1998). Competitive altruism: from reciprocity to the handicap principle . Proc. Biol. Sci. 265 , 427–431 10.1098/rspb.1998.0312 [ CrossRef ] [ Google Scholar ]
• Roberts G. (2005). Cooperation through interdependence . Anim. Behav. 70 , 901–908 10.1016/j.anbehav.2005.02.006 [ CrossRef ] [ Google Scholar ]
• Roberts G., Sherratt T. (1998). Development of cooperative relationships through increasing investment . Nature 394 , 175–179. 10.1038/28160 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Rockenbach B., Milinski M. (2011). To qualify as a social partner, humans hide severe punishment, although their observed cooperativeness is decisive . Proc. Natl. Acad. Sci. U S A 108 , 18307–18312. 10.1073/pnas.1108996108 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Schroeder K. B., Pepper G. V., Nettle D. (2014). Local norms of cheating and the cultural evolution of crime and punishment: a study of two urban neighborhoods . PeerJ 2 :e450. 10.7717/peerj.450 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Seielstad M. T., Minch E., Cavalli-Sforza L. L. (1998). Genetic evidence for a higher female migration rate in humans . Nat. Genet. 20 , 278–280. 10.1038/3088 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Sherratt T. N., Roberts G. (1998). The evolution of generosity and choosiness in cooperative exchanges . J. Theor. Biol. 193 , 167–177. 10.1006/jtbi.1998.0703 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Sherratt T. N., Roberts G., Kassen R. (2009). Evolutionary stable investment in products that confer both an individual benefit and a public good . Front. Biosci. (Landmark Ed.) 14 , 4557–4564. 10.2741/3548 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Soetevent A. R. (2005). Anonymity in giving in a natural context-a field experiment in 30 churches . J. Pub. Econ. 89 , 2301–2323 10.1016/j.jpubeco.2004.11.002 [ CrossRef ] [ Google Scholar ]
• Sommerfeld R., Krambeck H., Milinski M. (2008). Multiple gossip statements and their effect on reputation and trustworthiness . Proc. Biol. Sci. 275 , 2529–2536. 10.1098/rspb.2008.0762 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Sommerfeld R. D., Krambeck H.-J., Semmann D., Milinski M. (2007). Gossip as an alternative for direct observation in games of indirect reciprocity . Proc. Natl. Acad. Sci. U S A 104 , 17435–17440. 10.1073/pnas.0704598104 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Sylwester K., Roberts G. (2010). Cooperators benefit through reputation-based partner choice in economic games . Biol. Lett. 6 , 659–662. 10.1098/rsbl.2010.0209 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Sylwester K., Roberts G. (2013). Reputation-based partner choice is an effective alternative to indirect reciprocity in solving social dilemmas . Evol. Hum. Behav. 34 , 201–206 10.1016/j.evolhumbehav.2012.11.009 [ CrossRef ] [ Google Scholar ]
• Szathmáry E., Smith J. M. (1995). The major evolutionary transitions . Nature 374 , 227–232. 10.1038/374227a0 [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Szolnoki A., Perc M. (2014). Coevolutionary success-driven multigames . EPL 108 :28004 10.1209/0295-5075/108/28004 [ CrossRef ] [ Google Scholar ]
• Tooby J., Cosmides L., Price M. E. (2006). Cognitive adaptations for n-person exchange: the evolutionary roots of organizational behavior . MDE Manage. Decis. Econ. 27 , 103–129. 10.1002/mde.1287 [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]
• Trivers R. L. (1971). The evolution of reciprocal altruism . Q. Rev. Biol. 46 , 35–57 10.1086/406755 [ CrossRef ] [ Google Scholar ]
• West S. A., El Mouden C., Gardner A. (2011). Sixteen common misconceptions about the evolution of cooperation in humans . Evol. Hum. Behav. 32 , 231–262 10.1016/j.evolhumbehav.2010.08.001 [ CrossRef ] [ Google Scholar ]
• Wiessner P. (1982). “ Risk, reciprocity and social influences on !Kung-San economics ,” in Politics and History in Band Societies , eds Leacock E., Lee R. (Cambridge, UK: Cambridge University Press; ), 61–84. [ Google Scholar ]
• Yamagishi T., Terai S., Kiyonari T., Mifune N., Kanazawa S. (2007). The social exchange heuristic: managing errors in social exchange . Ration. Soc. 19 , 259–291 10.1177/1043463107080449 [ CrossRef ] [ Google Scholar ]
• Zefferman M. R. (2014a). Direct reciprocity under uncertainty does not explain one-shot cooperation, but demonstrates the benefits of a norm psychology . Evol. Hum. Behav. 35 , 358–367 10.1016/j.evolhumbehav.2014.04.003 [ CrossRef ] [ Google Scholar ]
• Zefferman M. R. (2014b). When repentance and forgiveness are possible, direct reciprocity does not explain one-shot generosity, even under arbitrarily high levels of uncertainty . Evol. Hum. Behav. 35 , 548–549 10.1016/j.evolhumbehav.2014.07.003 [ CrossRef ] [ Google Scholar ]

Advertisement

Supported by

‘Film Geek’ Review: A Cinephile’s Guide to New York

The director Richard Shepard details his lifelong obsession with movies in this enthusiastic video essay.

• Share full article

By Calum Marsh

Richard Shepard, the director of the black comedies “Dom Hemingway” and “The Matador,” is a lifelong cinephile with a voracious appetite for movies.

“Film Geek,” a feature-length video essay composed primarily of footage of films that Shepard saw growing up in the 1970s in New York City, delves deep into his obsession. In a voice-over, he recounts his childhood, when he was “addicted to movies, to watching them, to making them.” He is enthusiastic, and the movie aspires to make that enthusiasm infectious.

I appreciate Shepard’s affection: I also grew up loving movies, and I found his wistful reminiscences of being awed by “Jaws” and “Star Wars” relatable. But Shepard’s level of self-regard can be stultifying. For minutes at a time, he simply rattles off the titles of various movies that he saw as a child. I appreciate that seeing “Rocky” made a strong impression on him. I did not need to know that he lost his virginity in the apartment building where John G. Avildsen, the director of “Rocky,” once lived.

“Film Geek” has been compared to Thom Andersen’s great documentary from 2003, “Los Angeles Plays Itself,” and on the level of montage, they share a superficial resemblance: “Film Geek,” like Andersen’s essay film, is brisk and well edited.

But “Los Angeles Plays Itself” is also a thoughtful and incisive work of film criticism, whereas Shepard describes movies in clichés, when he describes movies at all. More often he is talking about himself, a subject of interest to far fewer viewers.

Film Geek Not rated. Running time: 1 hour 35 minutes. In theaters.

Explore More in TV and Movies

Not sure what to watch next we can help..

“Megalopolis,” the first film from the director Francis Ford Coppola in 13 years, premiered at the Cannes Film Festival. Here’s what to know .

Why is the “Planet of the Apes” franchise so gripping and effective? Because it doesn’t monkey around, our movie critic writes .

Luke Newton has been in the sexy Netflix hit “Bridgerton” from the start. But a new season will be his first as co-lead — or chief hunk .

There’s nothing normal about making a “Mad Max” movie, and Anya Taylor-Joy knew that  when she signed on to star in “Furiosa,” the newest film in George Miller’s action series.

If you are overwhelmed by the endless options, don’t despair — we put together the best offerings   on Netflix , Max , Disney+ , Amazon Prime  and Hulu  to make choosing your next binge a little easier.

Sign up for our Watching newsletter  to get recommendations on the best films and TV shows to stream and watch, delivered to your inbox.

A stranger paid Buzunesh Deba her 2014 Boston Marathon prize money. Why? ‘It was just about righting a wrong.’

Doug Guyer was looking to do the right thing when he wrote a $75,000 check to Buzunesh Deba this month.

When he heard Deba’s voice on the phone, he knew he had.

“Buzu called me when she got my overnight letter, and I’m telling you, in my 62 years I’ve never heard someone say thank you with more genuine gratitude in my life,” Guyer said. “You knew it meant the world to her. She said, ‘This is life-changing. You don’t know what this can do for me. I’m getting back into training.’ ”

In the eyes of Guyer, the check for Deba was an overdue payment for justice delayed after the Boston Athletic Association’s decision to adhere to guidelines of world athletics groups when it comes to addressing injustices.

Advertisement

Deba was the second-place finisher in the 2014 Boston Marathon women’s division, but eight years ago, she was declared the race’s winner after a two-year investigation disqualified the first-place finisher that day, Rita Jeptoo , for doping.

The $75,000 payday for winning the race, plus $25,000 more for setting a course record, was Deba’s, but in order to pay her, the BAA followed — and is still following — the guidelines of world athletic associations that allow it to seek payback of prize money directly from Jeptoo.

When Guyer read about Deba in an April article in the Wall Street Journal , he did not understand why she was still waiting for the money.

“I wasn’t trying to get a story out of this at all,” said Guyer, who was the junior quarterback at Boston College when freshman Doug Flutie took over early in the 1981 season. “That’s not the premise. It was just about righting a wrong that’s been wrong for 10 years.

“Obviously [the BAA] had a chance to do that, but they went the legal routevs. my point, the common-sense route. Take the legal route if you have to, but pay Buzu eight years ago and then claw back with your attorneys and everything else you’re doing. And they’re doing a lot.

“But I guess when you’re trying to set a precedent but it’s not happening in a time frame, eight years is a lot of time to go by for legalities.”

In other words, Guyer believes the BAA could do things differently.

“I get that this might set a precedent, but good, let’s set a precedent,” he said.

Guyer made it clear he is not trying to criticize the BAA. He is trying to see if it can come around to his way of thinking, which he tried to explain in an email to Jack Fleming, president and CEO of the BAA.

“I said, ‘Jack, you guys are way better than this; there’s ways to do this. I know you’re following the legal route, I know you’re following the governing body route of the World Athletics, I get all that. However, this family over here in the Bronx is trying to compete on a worldwide basis and 75 grand, now 100 grand with a $25,000 bonus, would mean the world to them.’ “

The BAA did not change its tack. It has the support of World Marathon Majors, an organizing group of the six global major marathons: Boston, London, New York, Chicago, Berlin, and Tokyo.

“‘World Athletics’ rules are incorporated into World Marathon Majors’ Code of Conduct,” said a World Marathon Majors spokesperson in an email to the Globe. “Therefore, World Marathon Majors supports the stance of the Boston Athletic Association on this matter.”

In a statement to the Globe, the BAA said that, in addition to having no further comment on the matter, “We are in the process of attempting to recover the prize money awarded to Ms. Jeptoo, so that it can be repaid to Ms. Deba.

“While we believe that Ms. Deba is due the prize money as she is the rightful winner of the 2014 women’s race, there are policies held by World Athletics and supported by World Marathon Majors that we, along with the other members of the organization, follow.”

On a pro bono basis, the Washington, D.C.-based WilmerHale law firm is working on behalf of the BAA to get the prize money back from Jeptoo.

Guyer said his inbox and phone have been busy since the story about his check to Deba appeared in the Wall Street Journal Monday .

One call in particular, from Jeff Dziama, Guyer’s senior captain on the BC football team when Guyer was a freshman, left him a bit flabbergasted.

“He said, ‘You know, out of the millions of people that read the first story about her, they all felt she earned this money, and I bet many people wanted to take action on it but only one person did,’ ” Guyer said. “And then he says he’s proud of me.

“And I’m like, how can a senior captain be proud of a little freshman? Even though it’s 45 years later, I still look up to him like he’s my big brother.”

Guyer is the founder and president of Wildlife Designs and managing partner of CMA Media Group. He was the co-founder and CEO of Brandshare, an e-commerce media networking company that was sold in 2022.

Guyer hopes the publicity about Deba will help her find not only the time to train for another Boston Marathon but also find sponsors who can financially support her and her two young children and husband, Worku Beyi, who Guyer said drives an Uber to help make ends meet for the family, which lives in the Bronx.

“Let’s talk about Buzu and her journey and how honorable she was through all of this,” said Guyer. “She was never throwing the BAA under the bus, nor was I.

“I want Buzu to be front and center. I know she’s shy, and she’s sweet and kind and genuine — everything you want in someone that a corporate company would want to sponsor.”

Michael Silverman can be reached at [email protected] .