The Behavioral Development of Mother-Infant Relations in the First Six Months of the Infant's Life in the Japanese Monkey (Macaca fuscata fuscata) (1)

Abstract

Many studies have been reported on the development of mother-infant relations in nonhuman primates which indicate the importance of early mother-infant relations on the development of the infant. The present study was designed to clarify the development of filial cling and maternal embrace and grooming in the first six months of the infant's life. In the past, we have mainly studied relations between the infant's age of maternal isolation and the patterns of stereotyped behavior induced by the isolation. But this should be based on the study of the development of the mother-infant relations under the normative condition. This is the major reason why the present study was conducted.The subjects used in the present investigation were three multiparous adult females and their male infants. The adult females were trapped in a freeranging group of Japanese Monkeys at Katsuyama, Okayama Prefecture and were raised at Osaka University Laboratory where they were fertilized (Table 1). Each of the pregnant females was housed in a 60×93×125 cm cage. The observation started at their parturition. All infants were males. Mother-infant interaction was observed for 15 minutes, once or twice a week.Results were as follows.1) The infant's locomotion tended to increase and filial cling was inclined to decrease in the first three months of the infant's life (Fig. 1 and Fig. 2).2) Maternal embrace tended to decrease as same as filial cling did in the first three months (Fig. 3). Maternal grooming, however, did not show this tendency (Fig. 4).3) The infant's locomotion and filial cling was affected by maternal embrace in the first three months of the infant's life, and by both maternal embrace and grooming after that time.4) This suggests that the behavioral development of the infant is affected by maternal behavior even in the early months of the infant's life.