Sex differences in social development during the first 4 years in a free-ranging group of Japanese monkeys, Macaca fuscata

Abstract

The behavioural development of a birth cohort (14 males, six females) during the first 4 years of life in the Awajishima free-ranging group of Japanese monkeys is described. The study focused on maturational changes in the relationships of immature males and females with their mothers and with other group members. Males tended to interact with their mothers less frequently than did females. Certain individuals interacted with their mothers more frequently than others during the first 4 years of life. Individuals were also consistent in their social interactions with group members other than their mothers. Males maintained close relationships with males of similar age, primarily through social play, from approximately the second year onward. This indicates that the males' preference for association with males of similar age precedes peripheralization and that peripheralization does not bring about essential changes in their social relationships with group members. Females preferred relationships with female group members of various ages, and also relationships with infants and fully adult males. This may explain why females remain in the central part of the group throughout their lives. The results of the study suggest that the preparation for adult male/female social roles starts as early as the second year of age.