Sex Differences in the Development of Independence of Infant Monkeys

Abstract

Numerous elements of the behavior of mother and infant monkeys caged in controlled environments were recorded during the first 15 weeks of the infants' lives. The data on these elements were analyzed for sex-related differences in mean occurrence and in developmental trends. Differences in mutual independence related to the sex of the infant began to emerge soon after birth. The male infants and mothers began life more dependent on each other, but within a few weeks showed a rapidly accelerating change to greater mutual independence. The mother played an active role in the instigation of the greater independence of a male by higher initial punishment, less retaining, less orientation to the infant and less carrying of the infant. There were no indications of sex differences in the infants' behavior to support the concept that differential development of independence is a function of the infants' instigation. However, males appeared to be responsive to their independence by becoming more interactive with the environment. They soon directed relatively less of their behavior towards their mothers.