Lynn Fairbanks: UCLA Department of Psychiatry & Biobehavioral Sciences

The ability to form and maintain social relationships is an important attribute that has broad implications for health and fitness in humans and nonhuman primates. In this presentation, I will describe the development of a quantitative measure of sociability in the Vervet Research Colony, a multigenerational pedigreed colony of vervet monkeys, and present evidence for the consistency, specificity and heritability of sociability as a trait. Mean Sociability scores are affected by life history variables, including age, sex, male emigration, and the presence of infants, but longitudinal analysis indicates that individual differences are maintained over time and across life stages. Because of the importance of matrilineal social relationships in primate societies, including the social ‘inheritance’ of dominance rank for females, there is a possibility of maternal environmental effects on sociability. To account for this, we include a component for shared maternal environment in a statistical genetics analysis to identify the contributions of genetic and maternal effects on trait variation, using the extended pedigree. The results indicate there are strong genetic contributions to variation in Sociability scores for both males and females, with maternal effects accounting for a smaller but statistically significant portion of the variance for females but not for males. The final part of the presentation will provide evidence for effects of variation in sociability on male reproductive success.