Similarities in affiliation and aggression between cross-fostered rhesus macaque females and their biological mothers.

In female-bonded primate species, there is cross-generational consistency in female affiliative and aggressive behavior. This consistency could be the result of maternal effects, offspring learning, shared environment, and/or direct genetic inheritance of behavioral or psychological traits. In this study, I investigated possible similarities in affiliation and aggression between cross-fostered rhesus macaque females and their biological mothers. Ten female infants were cross-fostered at birth, and selected aspects of their affiliative and agonistic behavior over the course of their first 3 years of life were compared to the behavior of their foster and biological mothers. Average offspring rates of social contact and aggression across the 3 years, and in particular in Years 2 and 3, resembled those of their biological mothers whereas no clear behavioral similarities between offspring and foster mothers were observed at any age. Heritable variation in female social behavior may be maintained by natural selection and leads to adaptation to different socioecological niches within macque populations.