Effects of maternal style on infant behavior in Japanese macaques (Macaca fuscata).

We assessed the association of maternal style and infant behavior of group-living Japanese macaques during the first year of infant development. We tested the hypothesis that different mothering styles were correlated with the behavioral repertoire of infants at three different developmental stages. We expected that infants of rejecting mothers would show a higher level of enterprise and that infants of protective mothers would be less interested in the external environment. We found evidence that maternal style affects infant behavior during the early developmental phase, but this influence becomes smaller as the infant grows older and approaches complete independence. Maternal protectiveness appears to have long-lasting effects on infant exploration as infants of protective mothers tended to be less attracted by the external environment. On the other hand, mater- nal rejection appears to have long-lasting effects on infant interaction with other group members as more rejected infants tended to initiate a significantly higher number of contacts with other juveniles and adults. These results suggest that both maternal rejection and maternal protectiveness play an important role in the independence of the offspring, in opposite directions. That is, rejection promotes independence whereas protectiveness delays it.