Dr. Robert Kurzban
University of Pennsylvania

Responding to Non-cooperation in Dyads and Groups: Clues to Reciprocal Psychology

Unlike other species, humans cooperate in large, distantly related groups, a fact that has long presented a puzzle to biologists. The pathway by which adaptations for large-scale cooperation among non-kin evolved in humans remains a subject of vigorous debate. Results from theoretical analyses and agent-based simulations suggest that evolutionary dynamics need not yield homogeneous populations, but can instead generate a polymorphic population that consists of individuals who vary in their degree of cooperativeness. A series of experiments investigated how participants in laboratory environments respond to non-cooperation in the context of dyadic and group interactions. We find heterogeneity, but that this heterogeneity is systematic rather than random. In addition, we find that although there is evidence for a "taste" for punishing non-cooperators, this taste seems very limited when punishing is private, suggesting an important role for the importance of reputation in decisions pertaining to punishment of non-cooperators.