Inter-group variation in abnormal behavior in chimpanzees ( Pan troglodytes) and rhesus macaques ( Macaca mulatta)

The present study was designed to explore whether abnormal behavior patterns in captive chimpanzees and rhesus macaques can provide additional data relevant to the question of social transmission of behavior in non-human primates. We categorically defined the degree to which various abnormal behaviors were displayed in eight chimpanzees ( Pan troglodytes) and 21 rhesus macaque ( Macaca mulatta) groups. Group membership, that was independent of biological relatedness, housing environment, gender and individual variance, significantly affected the expression of various abnormal behaviors. Variance in the expression of abnormal behaviors across groups of chimpanzees and rhesus monkeys suggests that social learning processes are involved in the propagation of these behaviors and thus, the study of abnormal behaviors may be a suitable method for further examining the question of culture in non-human primates.