Relationships of vervet mothers with sons and daughters from one through three years of age

Social relationships between mothers and juvenile offspring were examined in captive, socially-living vervet monkeys ( Cercopithecus aethiops sabaeus) to assess the effects of offspring age and sex, and the mother's dominance rank on behavioural interactions. The results indicate that both high-and low-ranking mothers approach and groom their daughters more than they approach and groom their sons. The frequency of both aggressive behaviour toward offspring and support of offspring in agonistic encounters with other group members is influenced by the mother's dominance rank, but not by offsprin sex. Compared to sons, daughters (particularly daughters of high-ranking females) approach and groom their mothers more often, and support their mothers more often in intra-group aggression. The results are discussed in terms of several predictions from parental investment theory and the concept of mutualism.