Age-related changes in the social behavior of tufted capuchin monkeys

Aging capuchin monkeys showed decreased rates of affiliation, combined with increased selectivity in the choice of social partners. These results parallel what is commonly observed in humans, and cast doubts on interpretations of human social aging that require an understanding of the finiteness of lifetime.

The effects of aging on the social behavior of nonhuman primates is little understood, especially in New World monkeys. We studied the members of a colony of tufted capuchin monkeys (Sapajus sp.) in order to evaluate age related changes in their social behavior. We conducted observations on 25 subjects aged 4-36 years, living in captive social groups. We found that affiliative interactions (grooming and proximity) decreased with age, and that grooming was increasingly directed to a single preferred partner. Manipulation of objects in the environment also decreased with age, while locomotion and aggression showed no change. Overall, these results concur with previous findings on both human and nonhuman primates, and cast doubts on interpretations of age associated changes in human social behavior that rely of uniquely human advanced cognitive capacities.