DEVELOPMENT OF MOTHER-INFANT RELATIONSHIPS IN JAPANESE MACAQUES (MACACA-FUSCATA)

This study investigates the development of mother-infant relationships in captive Japanese macaques (Macaca fuscata) in order to test the hypothesis that age-related changes in monkey mother-infant interactions are primarily mother-driven. During the first week of their life, infants spent about 90% of the observation time in ventroventral contact with their mother. As the infants grew, time in ventroventral contact decreased progressively. This decrease was associated with an increase in the tendency of the mothers to reject the infants' attempts to gain ventroventral contact and to an increase in the infants' role in maintaining such contact. A decrease in the tendency of the mothers to protect the infants and in the proportion of attuned locomotion due to maternal carrying was also observed. A relatively high degree of developmental consistency was shown to exist in the interdyadic differences observed, but these differences could not be unambiguously ascribed either to differences among mothers or to differences among infants. On the whole, these results confirm the notion that age related changes in macaque mother-infant interactions are primarily due to changes in the behaviour of mothers rather than of infants.