Francis Ysidro Edgeworth, the grandfather of modern economic theory, referred to individual self-interest as “the first principle of pure economics.” Until recently, economists routinely equated being rational with being selfish. The assumption was that, because humans are biological creatures, we’d been programmed by Darwinian evolution to put our own interests first—survival, after all, is a tough competition. As a result, even seemingly altruistic traits, such as giving money to charity or helping strangers in need, were seen as traits ultimately rooted in self-interest.

Richard Dawkins, for instance, has claimed that “we are survival machines—robot vehicles blindly programmed to preserve the selfish molecules known as genes. This gene selfishness will usually give rise to selfishness in individual behavior.” Although Dawkins allows for morality in social life, it must be socially imposed on a fundamentally selfish agent. “Let us try to teach generosity and altruism,” he advises, “because we are born selfish.” Such learned behaviors—for instance, children are taught to share at a young age—must struggle against our supposedly self-serving nature. As the evolutionary biologist Michael Ghiselin asserts, “What passes for cooperation [in nature] turns out to be a mixture of opportunism and exploitation. . . Scratch an altruist, and watch a hypocrite bleed.”

Programmed to Care?

In recent years the tide has swung dramatically against such a bleak view of human nature, however. Researchers are increasingly coming to understand that people are also “programmed” to care about others. A recent contribution to this theme comes from neuroscientist Ernst Fehr at the University of Zurich and colleagues. In a study, the researchers explored a particular type of unselfishness known as inequality aversion. Suppose individual A has $10, and individual B has a lesser amount, say $5. We say individual A is inequality averse if he shares some of his cash with individual B, thus reducing the inequality between them. We say individual B is inequality averse if he is willing to sacrifice some part of his money, provided individual A’s endowment is reduced to an even greater degree, so that, once again, the inequality between the two is reduced.

Fehr and colleagues show that, in a sample of 229 children between the ages of three and eight years, younger subjects overwhelmingly conform to selfish (self-regarding) preferences. They don’t like to share and aren’t interest in reducing inequality. In contrast, the vast majority of the older subjects are inequality averse when put in either the advantageous (individual A) or inadvantageous (individual B) position.

Moreover, the researchers find that the older children are “rational” in the sense that they are more willing to share when the cost of doing so is low than when the cost is high. Finally, the children tend to be more inequality averse in dealing with “ingroup” members, or children from their own school or day care. This preference for sharing with ingroup members occurred even the sharing game was purely anonymous, so no child could determine the identity of the other players.

This experiment is not the first to indicate that children are inequality averse, and that this behavior increases with age. I recall a beautiful video made by the social psychologist Jonathan Haidt, which showed two three-year-olds sitting side by side while their teacher sat in front of them, giving out highly valued gold star stickers. For every gold star she handed to one child on the right, she handed two stars to the child on the left. Both children were very happy with their prizes, smiling gleefully with each new addition. When the same scenario was presented to two four-year-olds, however, the situation was completely different. In this case, the child that only received one sticker became less and less happy over time, and eventually began throwing the gold stars back at the teacher.

Haidt also reports the following experiment he performed on his two sons. Every morning he gave each a glass of orange juice. On Monday, both glasses were full, on Tuesday, three quarters full, Wednesday half full, Thursday one quarter full, Friday half full, Saturday three quarters full, Sunday, full. He repeated this orange juice sequence for a while, and the sons were very contented each day. Then, one day, he gave one child a full glass, and the other a glass three quarters full. As you might imagine, the “deprived” child bitterly protested his deplorable situation.

The primatologists Frans B. M. de Waal and Sarah Brosnan report  a similar reaction of adult chimpanzees, where one receives a banana (highly valued) and the other receives a cucumber slice (valued, but much less so than a banana). In both cases, inequality aversion takes the form of sacrificing one’s own reward, regardless of whether it’s cucumber slices or gold stars, to show displeasure with the source of inequality.

Strategic Behaviors

Although it’s now generally recognized that children are inequality averse, one experimental difficulty has been separating out strategic behavior, such as reputation building, from true preferences for sharing. In other words, I may share with you because in the future, you may reciprocate, or I may punish you at personal cost because the next time, you will be more careful to give me my “fair share.” These are purely strategic behaviors that can be attributed to perfectly selfish individuals.

The Fehr study differs from prior studies of inequality aversion in children by scrupulously preventing such an interpretation. They made all behaviors anonymous so children could never identify their partners, and therefore could not sacrifice in hopes of gaining in the future. This strategy contrasts with previous studies, which either watched children at play or analyzed teacher-pupil interactions. Although these studies found consistent pro-social behavior—the children demonstrated a willingness to share—they could not ascertain whether it was calculated selfishness or true other-regarding behavior.

It is instructive to compare and contrast human behavior regarding others with that of our nearest biological relative, the chimpanzee. My assessment of the literature is that female chimps, at least, reveal a high level of kin altruism (fathers exhibit virtually none).” Chimps of both sexes also demonstrate a fair amount of reciprocal altruism, as in mutual grooming and coalition formation, and show considerable concern for the plight of other chimps. On the other hand, chimpanzees show virtually no real inequality aversion, in the sense that they do not share with non-kin except as a means of not being pestered by beggars, and do not sacrifice to reduce their personal disadvantage. In this sense, inequality aversion seems to be a rather human innovation.

Are you a scientist? Have you recently read a peer-reviewed paper that you want to write about? Then contact Mind Matters editor Jonah Lehrer, the science writer behind the blog The Frontal Cortex and the book Proust Was a Neuroscientist.