Rob Boyd: UCLA Department of Anthropology

Recent discussions of human cooperation assume that the theory reciprocal altruism provides an established explanation for human cooperation, and that therefore, alternative explanations invoking cultural group selection face a burden of proof. In this talk, I argue that this assumption is not justified. The theory of reciprocal altruism does predict that cooperative behavior among small groups of unrelated individuals will evolve, but this theory is not supported by most empirical data. The theory of reciprocal altruism also predicts that cooperative behavior is evolutionarily stable, but also predicts that any other behavior is equally likely to be stable, and thus does not provide a sufficient explanation for the commonness of large scale human cooperation. I also argue that the theory of cultural group selection is cogent, and consistent with much empirical data.