Why Do We Care About Equality?

Equality animates ethics. But why? Is our interest in equality a product of European intellectuals? Or is it something rooted deeper in human nature? Sarah Brosnan joined to discuss.

“Why do we care about equality? Is it an invention of European Enlightenment? Or something rooted in human nature? Or the latter, why does it require constant fighting for?”

These questions launched episode 15 of the show (Spotify, Apple). My guest was philosopher Elizabeth Anderson. It was a great conversation, but we only focused on humans. Since then, I have wanted to make a sequel with a biologist. So here we go.

Photo: Monkeys grooming others. Grooming is important, but it might not be the only lubricant in primate relationships.

At the outset, we might notice a certain tension. Biology is rarely the favourite subject of social activists. Hierarchy, violence, and male domination are bread-and-butter topics in primatology. Predictably, people tend to react in two ways. One group uses this to justify their opposition (or apathy) vis-a-vis egalitarian movements. They take hierarchy and domination as inevitable and hard-wired. We cannot escape them because they are part of our nature. “Just check out a nature documentary,” one might say.

Another group rejects the importance of biology. Rather than debating an elusive “human nature” we should, their argument goes, focus on the diversity of human cultures. Freed by the chains of genetic determinism, we can craft an egalitarian utopia.

But what if this is a false dichotomy? What if the very forces opposing inequality and oppression are equally rooted in our biology?

To discuss this possibility, I was joined by primatologist Sarah Brosnan.

[TO LISTEN TO THE FULL CONVERSATION, FIND EPISODE 28 OF THE ON HUMANS PODCAST ON SPOTIFY, APPLE PODCASTS OR ELSEWHERE.]

Brosnan’s research is famous for a wildly popular video clip of a capuchin monkey who, frustrated by unequal treatment, throws a cucumber at the experimenter. You might have seen the video. If you haven’t, I urge you to watch it below. (It is only 58 seconds long.) Or you can get the full paper here.

I saw this clip years ago. It resonated with something in me. But what exactly? Why should we care about monkeys throwing cucumbers? What, if anything, can such experiments tell us about human values?

The taste for equal pay: How common is it?

Let’s start with that famous clip. What we see here is pretty self-explanatory: the capuchin monkey in question (named Lance) is happy to accept a small reward – a piece of cucumber – for a task. However, she gets visibly upset when her friend (named Winter) gets a much better reward – a grape – for the same task. She cannot be upset about cucumber as such. It was good-enough at first. She is upset for being unfairly treated.

So how common is this behaviour? Brosnan was quick to tell me, laughingly, that the theatrical side of this behaviour is quite unique to Lance.

“In full disclosure, most of my monkeys cannot do aimed overhand throwing.”¹

A more substantial caveat is that monkeys don’t typically reject the cucumber at the first instance. It takes a couple of rounds for the frustration to boil over. 

This said, the rest of what we see in the video is very typical behaviour. This is not only true for capuchins. “Inequity aversion”, as the reaction is known, is found in a variety of species from chimpanzees to bonobos and even dogs. (Interestingly, we haven’t found it in orangutans. This did not surprise me, though, as orangutans are the most notoriously solitary ape.)

But let’s return to the video for a moment. Why exactly is it so evocative? 

“I think it is so popular because I think most humans at some point have felt like Lance. They have been the ones who just wanted to throw their cucumber back and they probably couldn't because it was socially inappropriate. So I think it resonates.”

I agreed and disclosed that “throwing cucumbers” has long been a standardised part of my relationship vocabulary. Indeed, I think that the video does provide a certain emotional comradery, a feeling of being heard, of not being alone with our feelings. Brosnan agreed, saying that we probably all have felt like our reactions to unfairness are inappropriate.

“[People say things like] why should you care if somebody else's salary is higher if you're getting enough to pay your rent and food. And [the monkey example] suggests that it's not just that you've been told that you should want as much as everyone else. This is not just a human thing. This is not just a cultural thing. This I think is a fairly deeply rooted biological thing.”

Looking at the natural history, we notice that this reaction is most commonly found in highly cooperative species. Brosnan’s own explanation, coming from economics, is that inequity aversion is a lubricant for win-win cooperation. It is a smoke detector which allows us to notice when cooperation might not be the right path anymore. (For those familiar with the prisoner’s dilemma, this would be the moment when a player decides to start playing “defect” on subsequent rounds.) As Brosnan explains in her TED Talk, our sense of fairness allows us to differentiate “exploitation from cooperation”. It tells us to leave an exploitative situation and search for better partners to cooperate with. Indeed, what is telling is that Lance, the cucumber thrower, had no way to leave the situation. She could only get angry. But this is not the end of the story. As Brosnan explained in her TED Talk:

“It turns out that capuchins simply refuse to cooperate with other capuchins who don’t give them their share after they worked together.”

Inequity aversion can also create a virtuous cycle where sharing becomes beneficial for everyone. As Brosnan explained to me: 

“It's a benefit for me to withhold from doing something, [like monopolising resources,] if that's [would have ruined] our cooperative relationship.”

At this point, it would be tempting to conclude the following: our aversion to inequality is more than a cultural thing. It is something deep in us (and many other species). And so, while our biology might be (partially) responsible for the forces leading our species to exploitation and inequality, our biology is equally responsible for the ever-present resistance. We might even say that our very sense of fairness is built into our biology.

Or is it? Not everyone is convinced, at least not by the evidence so far. 

Let’s start with the unhelpful responses. Brosnan’s collaborator Frans de Waal has joked that a philosopher once wrote to him, saying that this cannot be the case because ideas of fairness and equality were invented during the French Revolution. This is an oddly circular argument. I don’t think it deserves a further response.

On a more technical front, there are scholars who claim that this is not actually about equality or even sociality. To put it colloquially, this is just about greed. According to this idea, Lance (the cucumber thrower) does not care about what Winter (the lucky monkey) gets. Rather, Lance simply realises that grapes are on offer. Then greed kicks in. 

This argument is associated with Michael Tomasello, author of the truly excellent Natural History of Human Morality. I have tremendous respect for him, but here, I struggle to read the evidence in his favor. So does Brosnan, who said that she thinks Tomasello would probably have come closer to her view by now. After all, Brosnan has used plenty of controls, such as waving the grape in front of Lance but not giving it to Winter. This frustruating-but-equal situation does not cause upset. (Brosnan also pointed out some technical issues with Tomasello’s own studies on chimpanzees, but I am worried the details might bore some readers.²)

How ethical is this, really? 

The more interesting counter argument runs as follows: Lance’s behaviour is interesting and humanlike, certainly. But it is not really about equality, not in an ideal sense. After all, she just wants more for herself. What would be more impressive is if Winter, who gets the grape, rejects it until Lance also gets one. This is, at least, what genuine ideals of equality should aspire for. 

Brosnan makes this explicit, saying that Lance’s response is not necessarily about fairness or high ideals about equality. After all, she just wants more for herself. But this is a start. Brosnan explained her thinking as follows:

“If I only notice when I'm getting treated unfairly, that doesn't necessarily make me a very nice or a very fair person. So if we're [talking about being a fair person], what we're assuming is someone who is paying attention to distributions and wants relatively even distributions. And that's not what we're seeing here. What we're seeing is her reacting in a very self-focused way. But [things have] to start somewhere.”

So this is not the end. But it is a start. And it is relatively easy to see how a more fully-fledged ideal of equality could develop from this start - especially when one becomes sympathetic to the inequity aversion of others, too. 

On the other hand, you might ask if we are expecting too much from high ideals. After all, many historians and activists would say that equality is not achieved by gifts from the top but by fights from the bottom. This might be true in a broad analysis of history. (Is it?) But here things get interesting. It turns out that “gifts from the top” do take place in the animal world, at least amongst group members. Indeed, chimpanzees are much more likely to reject a grape if their buddy gets a cucumber than if the buddy gets a grape. (According to Frans De Waal, they can also engage in a  solidarity strike where they reject the grape until their friend gets a grape too.) Brosnan is very measured about the implications, though. She told me:

“There are a few things to keep in mind. First, [rejecting the grape] was still swamped by the number of refusals of a cucumber because you got a grape. So they're much more upset by getting disadvantaged than they are by getting advantaged. The second thing is that, even if they are, we don't know why they're doing it. Are they doing it because they're worried that they're going to get beat up later? Are they worried about their future? Or are they doing it because they have this moral and ethical obligation for equality? Then again, I would say the same thing to humans.”

On the other side, Brosnan did note that rejecting the grape is actually a very high bar, perhaps too high. After all, one can be upset about inequality but still eat whatever is on offer. In the human case, she said:

“I can think unequal salaries are unfair and I can write letters to my congresspeople and protest but still accept my salary, even if I know I'm getting more than somebody.” 

All this said, we can safely conclude the following: there is evidence that some primates do sometimes prefer equal outcomes, even if inequality would have served them well. Is this evidence of impartial ideals of equality in animals? Too early to say. But we do find the effect, even when using a very conservative measure. For me, this is impressive enough.

Can monkeys learn more egalitarian social norms?

There was much more in this conversation. I won’t touch upon everything in here. But there is one fascinating aspect which merits a mention. This is the capacity of primates to learn more egalitarian social norms. 

This is a critical finding. Granted, monkeys seem to dislike inequality, at least when they are at the bottom. But most primates still live in contexts of extreme inequality. I don’t want to downplay the possibility that nature documentaries overplay the violence and hierarchy present in a given species. Nor would I like to sideline bonobos or northern muriqui monkeys who offer an antidote to primatology’s most hierarchical generalisations. But it would be foolish to deny that the average primate community is hardly an inspiring place for egalitarians.

Importantly, though, primates can mend their ways. A famous example comes from wild savanna baboons. This is a species with notoriously violent battles for status and hierarchy. Violence and inequality, one could argue, is in their biology. But “biology” is a flexible beast. And it turns out that cultural learning is part of baboon biology, too. 

This evidence comes from a famous paper by Robert Sapolsky and Lisa Share. The paper describes a curious incident where the most aggressive males of a baboon group die due to bovine tuberculosis from an infencted meat. This story is almost fable-like, as it was exactly their violence which proved fatal to the top-ranking baboons. As Brosnan explained, it was only the dominant males who got killed, because:

“... they were the ones who were able to invade the neighbouring territory and get to the dumpster where the infected meat was.“

This is ironic enough. But what happened next is most interesting. Instead of other baboons taking the lead in violence, the group develops a “pacific” culture of reduced violence and less marked status hierarchies. New “immigrant” baboons quickly accepted this novel lifestyle. A new baboon culture was born. The optimism is tangible. As Sapolsky explains in an article for The Greater Good Science Centre:

“High-ranking males rarely harassed subordinates and occasionally even relinquished contested resources to them. Aggression was less frequent, particularly against third parties. And rates of affiliative behaviours, [like] grooming or sitting together soared. There were even instances, now and then, of adult males grooming each other—a behavior nearly as unprecedented as baboons sprouting wings.” 

Brosnan also talked about another study with a similar outcome. 

“There's another paper that's not as well known, but it was an experimental study in the lab where Frans de Waal had older stump-tailed macaques put in with younger rhesus macaques. And so rhesus macaques have much stricter dominance hierarchies and are much more aggressive. [What happened was that] the stump-tailed macaques acted as sort of tutors to the rhesus macaques and the rhesus macaques grew up much less aggressive. They had stump-tailed macaque behaviors.” 

Brosnan is, like Sapolsky, careful to say that hierarchies did not get completely extinguished.

“It's not in either one of these cases that they got rid of the dominance hierarchies, but they just became much less aggressive and the dominance hierarchies flattened out a bit” 

All the same, these are important findings. 

“These studies suggest that there's a fair amount of malleability to [hierarchies and violence] and that there are probably both cultural and environmental influences impacting how they form.”

So what about humans?

So far, we have focused on apes and monkeys. Studying them can be humbling. Their behaviour can be eerily familiar. But we are not monkeys. Nor are we chimpanzees. We are humans. The obvious question emerges: what, if anything, makes us different from chimpanzees, baboons, or macaques? And given that we are none of these species, is there one which still serves as the best model? Brosnan doesn’t think so. This was a superbly interesting point, although she made it as a casual remark. 

“I think one of the interesting things about humans is [we] have these multiple overlapping relationships that are really important. So we've got the pair bonds, like the calatricids and the owl monkeys and the gibbons; we've got the close relationships among males like you see in chimpanzees; we've got close relationships among females like you see in capuchin monkeys and bonobos; and we've got the close relationships between males and females like you see in baboons. (These are not pair-bonded species, but you see these friendships between male and female baboons.) So I would argue that there's no one species that is a sort of best model. You really need to look at all of them.” 

It seems that one thing does make us unique: the diversity of our relationships. But is this all? We did not dig too deep into this question with Brosnan. But we were earlier critical of Michael Tomasello’s work. It might be fair to highlight that I think his work is generally superb in this area. 

As a brief overview of Tomasello’s thinking, he sees humans sharing a lot of characteristics with other primates, especially great apes. For example, both humans and chimpanzees feel sympathy and spontaneously help others in need. Young children and chimps do this often and without needing adults to tell them to do so. So here we are similar.

However, Tomasello thinks that humans are unique in our reaction to fairness and equality. As we saw, he disagrees with Brosnan (and me) about some details. But his most important finding seems to still stand: humans are uniquely sensitive to teamwork. The evidence comes mainly from tasks where children and chimpanzees have to pull ropes to get rewards. During the conversation with Brosnan, I tried to summarise the findings as follows:

“Young children and chimps are completely fine if they pull their own ropes and they get their own food. They are pretty fine doing the task and they're pretty fine with inequality. But if they pull the same rope, if it's a joint task, then it is the most automatic thing for children to share whatever they get, even if it comes unequally distributed. [On the other hand, if chimpanzees] pull the same rope and get different amounts, well, either they just stick to different amounts or the dominant individual grabs it all. And therefore the other one doesn't want to cooperate in the next round. In humans they just keep pulling together, getting more and sharing more.” 

I asked if Brosnan agreed with this basic picture. She hesitated to give a clear answer but certainly did not reject it outright. 

I find Tomasello’s studies fascinating. His conclusions are so, too. I have heard him say, on several occasions, that humans learn to think of others as genuinely equal and that we discover this ‘moral truth’ by working together. In other words, by doing teamwork and noticing that we can play interchangeable roles we genuinely discover that we are, in some deep sense, equal.

I wish we would have spent more time on this issue with Brosnan. One reason is that Tomasello’s work offers also some insights into one of the most thorny issues around equality: what exactly are we trying to equalise? Do we want equality of outcome? Or equality of opportunity? If former, what if someone slacks and doesn’t work ? If the latter, what should we do about the opportunities afforded by inequality from, say, parental wealth? These are really difficult questions. We touched upon them briefly towards the end of our conversation. Do listen to the episode if you are interested. But curiously, one of Tomasello’s most interesting papers tackles this head-on. After years of careful studies with children, Tomaello concludes that children don’t care about material equality as such. Rather, they care about “equality of respect”. In a paper with Jan Engelman, he writes:

“The evidence thus suggests that children are not primarily preoccupied with the material ‘stuff’ in distributive contexts; they are concerned instead with the social meaning of the act of distribution … Any account that focuses only on the material stuff, no matter how nuanced, cannot capture this dimension of social meaning … The question is what underlies children’s aversion to inequity, and our claim is that the foundation of their aversion is not equality of resources per se, but rather equality of respect.”

This reminds me strongly of my conversation with philosopher Elizabeth Anderson. Exploring anthropology, history, and philosophy, Anderson arrived at a surprisingly clear (and novel) formula for thinking about equality. She did not use the term respect, but I head echoes. Needless to say, I recommend listening to the episode if you are interested. It touches upon these issues and much more. For example, we talk about property rights in animals and ways in which “romantic” bonds bend ideas of equality. The full conversation is a bit over 1 hour. You can listen to it wherever you get your podcasts. There are some links below. Just find the show and episode 28. I hope you enjoy it! 

Thank you for reading! 

Take care,

Ilari

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1. All quotations have been simplified by deleting filler words, filler phrases, and parts not critical for the argument. I have decided to hide all these edits to ensure legibility.

2. Brosnan’s first complaint was that Tomasello only runs five to six rounds with chimpanzees. She runs 20 to 30. And inequity aversion gets more and more likely to further you go. A more interesting issue the way chimpanzees were tested. She said:

“Chimpanzee testing is tricky because you can only test them in an enclosure that you have. You can't just pick them up and move them around like you can with, say, a rat or a goldfish. The way their test boxes are set up [is that] the chimps are across from one another. Mine are side by side. And we know [that] in humans that makes a huge difference! If you are sitting next to someone, it evokes this shared sort of [feeling that] we're doing this together, whereas if you're sitting across from someone it's more of a competitive situation. And so I suspect that that made a big difference as well.” 

Brosnan also told me that Tomasello’s team did eventually find inequity aversion in their bonobos, even with their suboptimal techniques. I would love to discuss this with Tomasello himself. I have sent him an invitation. For now, I am sold by Brosnan’s position.