On the Human Primate: Three in the Morning & the Golden Rule

As economic inequality increases in many wealthy nations in recent years, a debate develops around the question of why inequality is bad for national economies and bad for citizens.

by Frans de Waal edited by O Society July 25, 2019

How often do we see rich people march in the street shouting that they’re earning too much? Or stockbrokers complaining about the “onus of the bonus”? Protesters typically are blue-collar workers yelling that their jobs shouldn’t go overseas or that they should earn more. A more exotic example was the 2008 march through the capital of Swaziland by poor women who felt that the king’s wives had overstepped their privileges by chartering an airplane for a shopping spree in Europe.


Fairness is viewed differently by the haves and have-nots. The underlying emotions and desires aren’t half as lofty as the ideal itself. The most recognizable emotion is resentment. Look at how children react to the slightest discrepancy in the size of their pizza slice compared with their siblings’. They shout, “That’s not fair!” but never in a way transcending their own desires

Evidence-based tips for teaching empathy in children

An experiment with capuchin monkeys by Sarah Brosnan, of Georgia State University’s CEBUS Lab, and myself illuminated this emotional basis. These monkeys will happily perform a task for cucumber slices until they see others getting grapes, which taste so much better. They become agitated, throw down their measly cucumbers, and go on strike. A perfectly fine vegetable becomes unpalatable! Not all economists, philosophers and anthropologists were happy with our interpretation, because they traditionally consider the “sense of fairness” uniquely human. But by now there are many other experiments, even on dogs, confirming our initial findings.

Obviously, things get extremely political if one claims a desire for income equality has evolutionary backing, but it is hard to deny the collapse of the world economy in 2008 was partly due to a massive misjudgment of human nature. We’re considerably less selfish and more social than advertised.

Inequality and Violence

Frans de Waal is a Dutch-American primatologist known for his popular books, such as Chimpanzee Politics: Power and Sex among Apes (1982) and The Age of Empathy: Nature’s Lessons for a Kinder Society (2009). He teaches at Emory University in Atlanta where he directs the Living Links Center at the Yerkes National Primate Research Center.

What happens when two monkeys are paid unequally? Fairness, reciprocity, empathy, cooperation: caring about the well-being of others seems like a very human trait. But Frans de Waal shares some surprising behavioral tests on primates and other mammals to show how many of these moral traits all of us share.

Was the Golden Rule Born in the Mind of a Monkey?

A captivating video clip of monkey behavior from primatologist Frans de Waal becomes a surprising piece of ammunition in this discussion.

The video illustrates a famous 2003 experiment by de Waal and his colleague Sarah Brosnan. It begins with a capuchin monkey rewarded with a cucumber slice for handing a rock to the experimenter. The monkey happily performs this task and collects her payment—until the monkey next to her is given a more desirable reward, a grape, for doing the same job. The first monkey then flings the unappetizing cucumber from her cage. In the study, the monkeys often refuse to hand over a rock if they see the other monkey get grapes while they themselves continue to get cucumbers.

Frans de Waal says his research with primates shows “instead of fairness and justice being intellectual products, something we have arrived at through reason, they are embedded in basic emotions, some of which are found in other primates,” possibly through a shared evolutionary history. “This is basically the [Occupy] Wall Street protest you see here,” de Waal says at the end of the video clip.

If his point about fairness is right, then arguments about inequality take on a biological imperative—greater equality can be seen as the “natural order” of things, and inequality as an inherently destructive force. As de Waal himself argues in his book, The Age of Empathy, our capacity for building a stable society rests in part on knowing what kind of animals we humans are.

For more on de Waal’s thinking on primate morality, see “The Cosmopolitan Ape

For a social-justice activist, the message from the monkeys may seem clear: Equal effort deserves equal pay, and any society that ignores this simple principle is messing with a deeply rooted instinct for fairness. But within the scientific world, far from settling the nature of fairness, Brosnan and de Waal’s classic study prompted a stream of research to show just how complex and fragile fairness can be in primate and human interactions.

If you watch the video of the capuchin monkeys, it may seem obvious the underpaid monkey is objecting to unfair treatment. But a sense of fairness may not be what’s driving the monkey’s behavior. Imagine there is no second monkey in the experiment, just one monkey and an experimenter with a bowl full of cucumbers and another full of grapes.


If the monkey were given the cucumber as a reward in that case, she might also object to it; not because it was unfair, but just because the cucumber doesn’t seem very appealing once the monkey knows there are grapes to be had. The monkey who rejects cucumbers may be less like a political protester and more like a two-year-old swatting away a proffered apple slice when a well-stocked candy jar is in full view.

To show fairness is involved, experiments need to demonstrate monkeys are more reluctant to do a task when another monkey actually receives better payment, as compared with a situation in which the better reward is simply clearly visible. When such controls are applied, the results of the studies are mixed: Some primate species, like the highly-social capuchin monkeys, do show sensitivity to social inequity, yet chimpanzees generally seem less preoccupied with fairness.


“This is basically an Occupy Wall Street protest you see here.”

On the whole, evidence for a concept of fairness in other primates is much more limited than it is in adult humans. They don’t exactly write manifestos listing their demands. Monkeys and apes don’t reject an unequal distribution if the food is freely given rather than paid out in exchange for a task.

In a lab, non-human primates generally act in their own interest when choosing how to dole out resources, while humans are more likely to share equally with a partner. Chimps don’t turn down unequal offers in a task known as the “ultimatum game,” in which one partner decides how to divide up some resources and the other partner either accepts the offer or decides neither partner will get anything. People often sacrifice resources in order to express contempt for an unequal offer, whereas chimps typically take what they can get, fair or not.


Experimental comparisons between humans and non-human animals are notoriously tricky, and there may be many reasons primates don’t respond to unfairness in the particular ways measured in experiments. In some cases, non-human animals may notice an unequal outcome, but the experimental setup doesn’t offer the option for a useful response. And since a monkey can’t verbally object to the injustice, we may never know how they really feel about it.


How Elites, Interest Groups, and Average Citizens Affect American Politics

In other cases, experimental tasks may be complicated and primates fail to fully grasp their consequences. So while there’s evidence equity plays a role in animal behavior, scientists continue to debate how much this really shows fairness is an instinct we share with non-human animals.

Another way of approaching the question is to look at how fairness shapes the behavior of human children; a very early sensitivity to fairness would support the idea it’s at least partly innate rather than entirely the product of cultural indoctrination.

And indeed, babies distinguish between fair and unfair behavior in others at a very young age. In a study by Alessandra Geraci and Luca Surian, 12- to 18-month-old babies watched short videos in which one “fair” animated character gave a toy to each of two other characters, while another “unfair” character handed two toys to a single character, leaving the other empty-handed. Afterwards the children were offered pictures of the fair and unfair characters and were told to pick one of them. Fourteen of 17 babies chose the fair character rather than the unfair one, suggesting infants may value fairness in others long before they’re capable of having conversations about morality and ethics.

Studies show it takes a surprisingly long time for children to incorporate fairness into their own actions. Three- and 4-year-olds do readily object to an unequal distribution of resources if they’ve received the short end of the stick. However, like non-human primates, they rarely protest when they’re on the winning end of an unequal distribution. This makes it hard to know whether it’s unfairness they dislike, or simply getting less stuff than others.


Three in the Morning

So he has no use [for categories], but relegates all to the constant. The constant is the useful; the useful is the passable; the passable is the successful; and with success, all is accomplished. He relies upon this alone, relies upon it and does not know he is doing so. This is called the Way.

But to wear out your brain trying to make things into one without realizing that they are all the same – this is called “three in the morning.” What do I mean by “three in the morning”? When the monkey trainer was handing out acorns, he said, “You get three in the morning and four at night.” This made all the monkeys furious. “Well, then,” he said, “you get four in the morning and three at night.” The monkeys were all delighted. There was no change in the reality behind the words, and yet the monkeys responded with joy and anger. Let them, if they want to. So the sage harmonizes with both right and wrong and rests in Heaven the Equalizer. This is called walking two roads.

~ Chuang Tzu

Discussion on Making All Things Equal


As children become aware of their social reputations, they start to behave in ways they know are valued by others.

In deciding how to distribute resources, preschoolers strongly favor divisions in which they come out ahead of others; not only are they likely to claim more than their own share, they even show a spiteful tendency to sacrifice resources if it means they can have more than someone else.

A study by Mark Sheskin and colleagues shows when given a choice between allotting two prize tokens each to themselves and another child and claiming one for themselves while giving none to the other, 5- and 6-year-olds preferred the latter. If humans come predisposed to value fairness—and the study with young babies suggests we do—then it would appear the abstract notion of fairness is in play with other, more self-serving impulses as well.


It’s not until closer to 8 years of age children show a robust tendency to divide resources equally. And even then, they may be more concerned with appearing fair to others than with actually being fair.

In a study led by Alex Shaw, children between 6 and 11 years of age had to decide how to allocate a nice prize and a lesser prize between themselves and another child. They were told that they could either just choose who got which prize, or they could flip a coin to determine the outcome. The older children (ages 9 to 11) chose to flip the coin 53 percent of the time, as opposed to 37 percent among the younger group.

Yet when they were given the option to flip the coin in private and report the outcome, the “impartial” coin flip magically landed in their favor 62 percent of the time. This suggests even for the older children, unfairness itself doesn’t necessarily cause distress—at least, not enough to make them give up the good prize. But as children become aware of their social reputations, they start to behave in ways they know are valued by others.

The Myth of America Meritocracy

As they approach adulthood, children show a steadily increasing tendency to distribute resources equally or even altruistically. But paradoxically, they may become less egalitarian in certain ways over the course of their development. Ernst Fehr and his colleagues find children more likely to deprive their peers of resources, even at a cost to themselves, if they are told the other children came from a different school than if they were told they belonged to the same school.

The dark side of decision-making in groups: Nastiness to outsiders

This bias against members from a different group increased with age into the teen years, even though on the whole, teens are less likely than younger kids to behave selfishly in this study. In other words, teens tend to behave more generously overall, but treat in-group and out-group members more unequally. For example, at ages 8 and 9, children made spiteful choices 41 percent of the time with in-group members and 44 percent of the time with out-group members, as compared with 17 versus 33 percent for 12- and 13-year-olds.

This growing body of research points toward conclusions much more nuanced than simply, “We are wired for equality” or “We are wired for selfishness.” Ultimately, knowing what kind of animals we humans are may help us better understand to what degree fairness is really an innate, primate value, as opposed to a product of an exceptional modern moment.




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