What distinguishes us from the chimpanzee?

Chimpanzees do not systematically make fair offers to their fellow chimpanzees, nor do they systematically refuse to accept unfair offers even though they could discriminate between the quantities available to themselves and their partners. Chimpanzees behave according to traditional economic models of self-interest, unlike humans, and chimpanzees do not share the human sensitivity to fairness. This is recently published in Science. It’s amazing how the researchers transformed the ultimatum game for use with chimpanzees, ultimate creativity.

This behavior is tested with the ultimatum game:

In laboratory settings, social scientists have observed subjects playing the “ultimatum game,” in which, say, with a total kitty of $10, Player A offers to split the cash with player B. If B accepts A’s offer, they divide the money accordingly, but if B rejects A’s offer, both players get nothing. “In thousands of trials around the world, with different stakes, people reject offers of 30 percent [$3 in our example] or less,” says Glaeser. “So typically, people offer 40 or 50 percent. But a conventional economic model would say that B should accept a split of even one cent versus $9.99, since you are still better off with a penny than nothing.” (If a computer, rather than a human, does the initial split, player B is much more likely to accept an unfair split

Humans will take into account the interest of others and are sensitive to norms of cooperation and fairness. Individuals will reject a unfair proposed division at a cost to themselves, if they perceive it as unfair. Chimpanzees however, are rational maximizers and are not sensitive to fairness.

Related information about “fairness and reason in the ultimate game
Ultimatum Game on Wikipedia

Discussed article
Chimpanzees are rationam maximizers in an ultimatum game.
Keith Jensen, Josep Call, Michael Tomasello
Science, 2007;318: 107-109.