APA Dictionary of Psychology

n. the systematic study of the biological basis for social behavior. Sociobiologists believe that populations tend to maintain an optimal level of density (neither overpopulation nor underpopulation) by controls such as aggression, stress, fertility, emigration, predation, and disease. Such controls are held to operate through the Darwinian principle of natural selection. See also evolutionary psychology. [pioneered by U.S. biologist Edward O. Wilson (1929–  )] —sociobiological adj.