FIRST STEPS IN THE MACAQUE WORLD - DO RHESUS MOTHERS ENCOURAGE THEIR INFANTS INDEPENDENT LOCOMOTION

This study investigated early interactions between 28 rhesus macaque, Macaca mulatta, mothers and their infants living in captive social groups to assess whether mothers actively encouraged their infants' independent locomotion and if such encouragement could be considered teaching. Mothers differed in their tendency to break contact with their infants in the first days of infant life, and this tendency increased significantly with previous reproductive experience. Mothers that left their infants early in life were also more likely to engage in backward walking and lip-smacking to their infants than mothers that did not leave their infants early in life. Infants that were left by their mothers in their first days of life broke and made contact with their mothers for the first time earlier than infants that were not left by their mothers. Interruption of contact with infants early in their life had no apparent immediate benefits to mothers but did have immediate risks because it increased the probability of infant kidnapping by other group members. Mothers whose infants gave a distress vocalization after the first interruption of contact broke contact with them less frequently in subsequent days than mothers whose infants did not vocalize. Although some of these findings are open to other interpretations, altogether they strongly suggest that some mothers actively encourage their infants' independent locomotion, that maternal encouragement is sensitive to infant competence, and that encouraged infants display some locomotor skills earlier in life than they would have without maternal encouragement.