Social Development of Rhesus Monkeys with Restricted Social Experience

Abstract

Monkeys, raised in isolation from other monkeys, were observed during the period from 25 to 85 days of age (Phase I), and observations were resumed 120 days later for 30 additional days (Phase n). The dominant social response initially was clasping; occasionally this was accompanied by mouthing and by thrusting. The incidence of clasping declined steadily and there was a corresponding growth in the frequency of social play. The mean age of onset for play was 40 days. At the beginning of the second phase of testing, clasping was again the dominant activity; but it was quickly surpassed by play. Aggression and adult forms of grooming and sexual behavior were never observed.