Evolved psychology in a novel environment

The human “environment of evolutionary adaptedness” can only be inferred indirectly. In contrast, the behavior of some nonhuman animals can be compared among “natural” and various altered environments. As an example, male immigration tactics in unprovisioned versus provisioned macaque (Macaca) populations are compared using Tooby and Cosmides’s (1992) framework for evolutionary functional analysis. In unprovisioned populations, social groups contain few males, and immigrant male takeovers of alpha rank occur frequently. In provisioned populations, groups contain many males, and males almost invariably enter social groups at very low rank and rise in rank only as more dominant males emigrate or die. Male conformity to the “seniority rule” is hypothesized to represent the behavioral output of an evolved decision-making algorithm (psychological mechanism) that takes into account (1) the net payoff of each rank in the dominance hierarchy and (2) the power of male group size as a predictor of the likelihood of successful immigrant takeover. Joseph H. Manson is Assistant Professor of Anthropology at the University of California, Los Angeles. His research interests are social relationships in nonhuman primates and humans, with particular emphases on mate choice, courtship tactics, intrasexual competition, and (currently) mother-infant relationships and infant handling. He has conducted fieldwork on rhesus macaques at Cayo Santiago and white-faced capuchins in Costa Rica.