Collaboration Drives Human Evolution

A recent article in the New York Times* surveys a range of recent studies that compare human beings with lower primates, such as chimpanzees. It turns out that one of the biggest differences is our ability to collaborate and to form social networks. As anthropologist Kim Hill says,

Humans are not special because of their big brains. That’s not the reason we can build rocket ships–no individual can. We have rockets because 10,000 individuals cooperate in producing the information.

One body of research compares mating patterns and kinship in chimpanzee bands and in early human tribes. The evolutionary story is a bit complex (as outlined in Dr. Bernard Chapais’ 2008 book Primeval Kinship), but basically, human beings mate in a pair whereas with chimps, the alpha male dominates all of the females, and the females mate promiscuously with many males, making it unclear who the father is (intentionally, so that none of the males will kill any of the infants). The pair bond of the humans made it much more obvious who your direct relatives were. And this made social relationships with nearby tribes much more complex; with chimps, other tribes are uniformly treated with hostility (because chimps cannot recognize relatives due to high promiscuity). But with human beings, some of the people in the neighboring tribes are your relatives. This ratcheted up the need for social awareness, and led to complex networks of alliances and collaboration.

A second body of research compares human and chimpanzee infants. Professor Michael Tomasello has shown that young children have an ability called “shared intentionality,” the ability to form plans with others to complete a joint task (in his book Why We Cooperate). Children, but not chimpanzees, can point to objects to convey information; and, children can figure out what someone else wants just by watching their eye gaze, which chimps cannot do. And get this: the white portion of the eyes for a human being is three times the size of other primates, which allows us to see where other people are looking. Chimpanzees infer gaze direction by looking at another’s head; but human infants do it by watching eyes.

(Also note: Bernard Chapais’s related article in Science magazine, 11 March 2011, Vol. 331, p. 1276)

*Nicholas Wade, “Supremacy of a social network,” New York Times, Tuesday March 15, 2011, page D4

Innate Cooperation

A new book by Michael Tomasello, Why We Cooperate, presents evidence that babies are born to be social and to help others. Tomasello argues that helping others is genetic, rather than learned. This is an important contribution to the “altruism” debate–why would a rational (i.e. self-interested) person expend energy helping someone else? The standard answer (of the rational choice/microeconomist paradigm) has been that helping is a social norm that emerges because, over time, helping someone else ultimately results in a gain for the helper. And once the social norm emerges, children learn it during socialization.

Tomasello’s book presents data showing that infants as young as 18 months old try to help others. For example, if they see an unrelated adult who needs help picking up a dropped object, they help right away. From the age of 12 months, if an adult pretends to have lost an object that the child can see, the child will point to the object. Eighteen or twelve months is too early for such behavior to have been learned from parents. As another piece of evidence, Tomasello reports that children don’t begin to help more after they’re rewarded for helping–which suggests it’s not influenced by training.

Tomasello also talks about research into how helping behavior evolves as children get older. When they’re three, they begin to get more selective; they’re nicer to another child who was just nice to them. And, they begin to expect other children to follow the same norms of helpfulness.

This argument seems to support the theory that helping behavior was selected for during evolution, which is consistent with the rational choice models of altruism. Regardless of the mechanism, I’m glad that we’re all this way!