Ultimatum Game, Genes and Chimps

Greg Mankiw has an interesting post on the latest reseach on the ultimatum game, which he summarizes as follows: “The sense of fairness demonstrated by the ultimatum game is apparently genetic and intrinsically human.

Chimpanzees Are Rational Maximizers in an Ultimatum Game

by Keith Jensen, Josep Call, and Michael Tomasello published in Science 5 October 2007: 107-109.

In a game of fairness, chimpanzees act only to maximize their own benefits, whereas human toddlers also value social norms like cooperation and parity.

Abstract: Traditional models of economic decision-making assume that people are self-interested rational maximizers. Empirical research has demonstrated, however, that people will take into account the interests of others and are sensitive to norms of cooperation and fairness. In one of the most robust tests of this finding, the ultimatum game, individuals will reject a proposed division of a monetary windfall, at a cost to themselves, if they perceive it as unfair. Here we show that in an ultimatum game, humans’ closest living relatives, chimpanzees (Pan troglodytes), are rational maximizers and are not sensitive to fairness. These results support the hypothesis that other-regarding preferences and aversion to inequitable outcomes, which play key roles in human social organization, distinguish us from our closest living relatives.

Heritability of ultimatum game responder behavior

by Björn Wallace, David Cesarini, Paul Lichtenstein and Magnus Johannesson. Proceedings of the National Academy of Science in the United States. Published online before print October 1, 2007.

Experimental evidence suggests that many people are willing to deviate from materially maximizing strategies to punish unfair behavior. Even though little is known about the origins of such fairness preferences, it has been suggested that they have deep evolutionary roots and that they are crucial for maintaining and understanding cooperation among non-kin. Here we report the results of an ultimatum game, played for real monetary stakes, using twins recruited from the population-based Swedish Twin Registry as our subject pool. Employing standard structural equation modeling techniques, we estimate that >40% of the variation in subjects’ rejection behavior is explained by additive genetic effects. Our estimates also suggest a very modest role for common environment as a source of phenotypic variation. Based on these findings, we argue that any attempt to explain observed ultimatum bargaining game behavior that ignores this genetic influence is incomplete.

Full article (open access)


One thought on “Ultimatum Game, Genes and Chimps

  1. Pingback: Environmental Ideology and The Ascetic Meme « Complex Adaptive Systems

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