Sex differences in the mother-neonate relationship in wild baboons: social, experiential and hormonal correlates

► We studied causes of variability in the mother-neonate relationship in wild baboons. ► The more experience a mother had, the more initiative her newborn infant exhibited. ► At each level of maternal experience, sons exhibited more initiative than daughters. ► Suckling by daughters was predicted from maternal rank and prenatal oestrogens. ► Our results suggest sex differences in primate life history emerge early in infancy.