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  • Transcriber: Ivana Korom Reviewer: Krystian Aparta

  • My first year in graduate school, studying cooperation in monkeys,

  • I spent a lot of time outside,

  • just watching our groups of capuchin monkeys interact.

  • One afternoon, I was out back feeding peanuts to one of our groups,

  • which required distracting one of our males, Ozzie,

  • enough so that the other monkeys could get some.

  • Ozzie loved peanuts,

  • and he always tried to do anything he could to grab some.

  • On that day, however,

  • he began trying to bring other things from his enclosure to me

  • and trade them with me in order to get a peanut.

  • Now, capuchins are smart, so this wasn't necessarily a surprise.

  • But what was a surprise

  • was that some of the things that he was bringing me,

  • I was pretty sure he liked better than peanuts.

  • First, he brought me a piece of monkey chow,

  • which is like dried dog food --

  • it was even made by Purina --

  • and for a monkey, is about as worthless as it gets.

  • Of course, I didn't give him a peanut for that.

  • But he kept trying,

  • and eventually, he brought me a quarter of an orange

  • and tried to trade it with me for a peanut.

  • Now, oranges are a valuable monkey commodity,

  • so this trade seemed, shall I say, a little bit nuts?

  • Now you may be wondering how we know what monkeys prefer.

  • Well, we ask them,

  • by giving them a choice between two foods

  • and seeing which one they pick.

  • Generally speaking, their preferences are a lot like ours:

  • the sweeter it is, the more they like it.

  • So, much like humans prefer cupcakes to kale,

  • monkeys prefer fruits, like oranges or grapes,

  • to vegetables like cucumbers,

  • and all of this to monkey chow.

  • And peanuts are not bad.

  • However, they definitely don't prefer them to a chunk of orange.

  • So when Ozzie tried to trade a quarter of an orange for a peanut,

  • it was a surprise,

  • and I began to wonder if he suddenly wanted that peanut

  • because everybody else in his group was getting one.

  • In case you're wondering, I did give Ozzie his peanut.

  • But then I went straight to my graduate adviser,

  • Frans de Waal,

  • and we began to design a study

  • to see how the monkeys would respond

  • when somebody else in their group got a better reward than they did

  • for doing the same work.

  • It was a very simple study.

  • We took two monkeys from the same group

  • and had them sit side by side,

  • and they would do a task,

  • which was trading a token with me,

  • and if they did so successfully,

  • they got a reward.

  • The catch was that one monkey always got a piece of cucumber,

  • and the other monkey sometimes got a piece of cucumber,

  • but sometimes got a grape.

  • And if you'll recall,

  • grapes are much preferred to cucumbers

  • on the capuchin monkey hierarchy.

  • These are two of my capuchin monkeys.

  • Winter, on the right, is trading for a grape,

  • and Lance, on the left, is trading for a cucumber.

  • You can see that she -- and yes, Lance is actually a female --

  • is at first perfectly happy with her cucumber,

  • until she sees Winter trading for a grape.

  • Suddenly, Lance is very enthusiastic about trading.

  • She gets her cucumber, takes a bite and then --

  • throws it right back out again.

  • Meanwhile, Winter trades again and gets another grape

  • and has Lance's undivided attention while she eats it.

  • This time,

  • Lance is not so enthusiastic about trading.

  • But eventually, she does so.

  • But when she gets the cucumber this time around,

  • she doesn't even take a bite

  • before she throws it back out again.

  • Apparently, Lance only wants a cucumber

  • when she hasn't just watched Winter eat a grape.

  • And Lance was not alone in this.

  • All of my capuchins were perfectly happy with their cucumbers

  • as long as the other monkeys were getting cucumbers too.

  • But they often weren't so happy with their cucumbers

  • when other monkeys were getting a grape.

  • The obvious question is why?

  • If they liked those cucumbers before,

  • what changed?

  • Now, I'm a scientist,

  • and scientists are famously shy about reading too much into our studies,

  • especially when it comes to what other animals

  • are thinking or feeling,

  • because we can't ask them.

  • But still, what I was seeing in my monkeys

  • looked an awful lot like what we humans would call a sense of fairness.

  • After all,

  • the difference in that cucumber was that it came after Winter got a grape,

  • rather than before.

  • We humans are obsessed with fairness.

  • I have a younger sister,

  • and when we were little,

  • if my sister got a bigger piece of the pie than me,

  • even by a crumb,

  • I was furious.

  • It wasn't fair.

  • And the childhood me is not alone.

  • We humans hate getting less than another so much

  • that one study found

  • that if humans were given a hypothetical choice

  • between earning 50,000 dollars a year

  • while others earned 25,000 dollars,

  • or earning 100,000 dollars a year

  • while others earned 250,000 dollars,

  • nearly half the subjects

  • prefer to earn 50,000 dollars a year less money

  • to avoid earning relatively less than someone else.

  • That's a pretty big price to pay.

  • What drives people

  • to this sort of apparently irrational decision-making?

  • After all,

  • throwing away your cucumber because someone else got a grape

  • only makes sense if it makes things more fair.

  • Otherwise, Winter has a grape, and you have nothing.

  • Of course humans are not capuchin monkeys.

  • But on the surface,

  • sacrificing 50,000 dollars

  • because somebody else is going to earn more money than you

  • makes no more sense than throwing away that cucumber.

  • Except maybe it does.

  • Some economists think

  • that the sense of fairness in humans is tied to cooperation.

  • In other words, we need that sense of fairness

  • when we're working with somebody else

  • to know when we're getting the short end of the stick.

  • Think about it this way.

  • Let's say you have a colleague at work who's having a hard time

  • and needs a little extra help.

  • You're probably more than happy to help out,

  • especially if she does the same for you when you need it.

  • In other words, if things even out.

  • But now,

  • let's say that colleague is always slacking off

  • and dumping extra work on you.

  • That's infuriating.

  • Or worse,

  • what if you're doing all the work, and she's getting paid more.

  • You're outraged, right?

  • As well you should be.

  • That righteous fury is your sense of fairness

  • telling you that, well, it's not fair.

  • You need to get your fair share from the people you're working with,

  • or it's exploitation, not cooperation.

  • You may not be able to leave every job where you're treated unfairly,

  • but in a perfect world,

  • one without racism and sexism

  • and the frictions associated with finding a new job,

  • it's your sense of fairness that would let you know

  • when it was time to move on.

  • And if you couldn't?

  • Well, that smoldering frustration might make you throw your cucumbers too.

  • And humans are not alone in this.

  • In the previous study, there was nothing Lance could do about it,

  • but what if there had been?

  • It turns out

  • that capuchins simply refuse to cooperate with other capuchins

  • who don't give them their share after they worked together.

  • And refusing to work together with another monkey

  • is a pretty straightforward way of leveling the playing field.

  • Apparently, no monkey getting anything at all

  • is better than another monkey getting more.

  • But much like you and your coworker,

  • they're perfectly happy with a little short-term inequality

  • as long as everything evens out over the long run.

  • This economic connection between fairness and cooperation

  • makes sense to me as an evolutionary biologist.

  • After all,

  • your ancestors didn't get to pass on their genes

  • because they did well in some absolute sense,

  • but because they did better than others.

  • We don't call it survival of the fit,

  • we call it survival of the fittest.

  • As in more fit than others.

  • It's all relative.

  • OK.

  • So my capuchins don't like it when they get less than another.

  • And they're perfectly happy to sacrifice their cucumbers

  • to level the playing field.

  • That's great.

  • But what we would call a sense of fairness in humans

  • also means that we care when we get more than someone else.

  • What about my monkeys?

  • It turns out

  • that primates do notice when they get more than others,

  • or at least some of them do.

  • My capuchins do not.

  • But in one of my studies,

  • my chimpanzees would sometimes refuse a grape

  • if another chimpanzee in their group got a cucumber,

  • which is pretty impressive, given how much my chimpanzees like grapes.

  • However, they were still more upset when they got less than another chimp

  • as compared to when they got more.

  • You may not think it's fair when you have more than your neighbor,

  • but you really don't think it's fair when your neighbor has more than you.

  • Here's an important question, though.

  • Why do we care about inequality or unfairness

  • when we are the ones who are unfairly benefiting?

  • If evolution is about survival of the fittest,

  • wouldn't it make sense to grab any advantage you can get?

  • Here's the thing though.

  • I do better if I get more than you, sure.

  • But best of all is if you and I can work together

  • and get more than either one of us could have gotten on our own.

  • But why would you work with me if you don't think I'm going to play fair?

  • But if you think I'm going to notice when I've got more than you

  • and do something about it,

  • then you will work with me.

  • Evolution has selected us to accept the occasional short-term loss

  • in order to maintain these all-important long-term relationships.

  • This is true in chimpanzees,

  • but it is even more important in humans.

  • Humans are incredibly interconnected and interdependent,

  • and we have the advanced cognitive abilities

  • to be able to plan far into the future.

  • And to recognize the importance

  • of maintaining these cooperative partnerships.

  • Indeed, if anything,

  • I think we are likely underplaying

  • how important the sense of fairness is for people.

  • One of the biggest differences between humans and capuchin monkeys

  • is the sheer magnitude and ubiquity of cooperation in humans.

  • In other words,

  • we're a lot more cooperative than capuchin monkeys are.

  • Legal and economic systems literally only exist

  • if we all agree to participate in them.

  • And if people feel left out of the rewards and benefits

  • of those systems,

  • then they stop participating,

  • and the whole system falls apart.

  • Many of the protests and uprisings we're seeing,

  • both in the US and around the globe,

  • are explicitly framed in terms of fairness,

  • which is not surprising to me.

  • Whether it's about disproportionate access to resources,

  • or that some groups are being disproportionately impacted

  • by the legal system or the effects of a virus,

  • these protests are the logical outcome

  • of our long evolutionary tendency to reject unfairness

  • combined with our long history of social stratification.