Maternal influences on primate social development

Primate mothers have the potential to influence the development of species-typical aspects of their offspring's behavior as well as their individual sociosexual and reproductive strategies. If mothers experience psychosocial stress during pregnancy or lactation, their own stress hormones can have a long-term impact on their offspring's physiology. The mother's own behavior, especially weaning-related rejection, can be stressful to infants and have long-lasting effects on their infants' neuroendocrine reactivity to stress. Exposure to variable maternal style early in life has long-term effects on the development of offspring behavior, including exploration and play, affiliation and aggression, and parenting. Primate mothers influence the kinship- and rank-related social preferences of their offspring, typically by providing opportunities to interact with some individuals more than others. Although mothers can contribute to the development of sex-typical behavior in the offspring (along with other environmental and genetic factors), sex-typical behavior is generally not the product of maternal socialization. Mothers provide their offspring with opportunities for social learning but rarely teach their infants new skills. In primate species with despotic dominance hierarchies, maternal transmission of rank through agonistic aid to their offspring makes a crucial contribution to the offspring's fitness (as the daughters of high-ranking mothers reproduce more successfully than the daughters of low-ranking mothers). Future studies of maternal influences on social development could benefit from a deeper theoretical and experimental investigation of the evolutionary significance of these effects as well as of their underlying proximate mechanisms.