Animal analogues of ostracism: Biological mechanisms and social consequences

Abstract

Utilizing a behavioral-biological perspective, this article examines the functions, causes, and costs of ostracism in nonhuman primates. Among nonhuman primates, ostracism may serve many functions other than promoting the cohesiveness of the group from which an individual is excluded. These functions include range extension, population regulation, outbreeding, and the diffusion of learned traditions. A variety of behavioral and biological processes contribute to the genesis and expression of ostracism. Behaviorally, female choice and the ability to form effective alliances seem to be critical for an adult male monkey to avoid being ostracized. Biologically, the integrity of the frontal lobes and adequate functioning of serotonergic neurotransmitter systems are essential to escape forced exile from the group. There is evidence that indicates that ostracism exacts a substancial physiological cost, including altered immune function, decrements in information processing, and changes in the metabolism of drugs. Moreover, recent studies suggest that several biological indices, including low concentrations of whole blood serotonin, may be markers that can be used to identify individual at risk for ostracism.