Behavioral Effects of Prolonged Partial Social Isolation in the Rhesus Monkey

48 rhesus monkeys, reared from birth in partial social isolation and ranging in age from 2 mo. to 13½ yr., and 12 feral-born monkeys, comparable in age to the 12 oldest partial isolates, were each scored for home-cage behavior. The survey showed that most partial isolates' behavioral levels declined with increasing age, males exhibiting more disturbance activity, more threats, and less grooming than females. The oldest partial isolates showed less locomotion and exploration but considerably more disturbance activity than their feral-born counterparts. The deficits produced by prolonged partial social isolation are discussed.