Social affiliation matters: both same-sex and opposite-sex relationships predict survival in wild female baboons

Abstract

Social integration and support can have profound effects on human survival. The extent of this phenomenon in non-human animals is largely unknown, but such knowledge is important to understanding the evolution of both lifespan and sociality. Here, we report evidence that levels of affiliative social behaviour (i.e. 'social connectedness') with both same-sex and opposite-sex conspecifics predict adult survival in wild female baboons. In the Amboseli ecosystem in Kenya, adult female baboons that were socially connected to either adult males or adult females lived longer than females who were socially isolated from both sexes-females with strong connectedness to individuals of both sexes lived the longest. Female social connectedness to males was predicted by high dominance rank, indicating that males are a limited resource for females, and females compete for access to male social partners. To date, only a handful of animal studies have found that social relationships may affect survival. This study extends those findings by examining relationships to both sexes in by far the largest dataset yet examined for any animal. Our results support the idea that social effects on survival are evolutionarily conserved in social mammals.

Adaptations for social cognition in the primate brain

“…), for example, dominance rank was not the best predictor of two measures of female reproductive success: offspring survival and longevity. Instead, females with the highest fitness were those with the strongest and most persistent bonds with other females [22][23][24][25]. Similar correlations between cooperative social bonds and components of fitness have been observed in a variety of other social mammals, including in particular humans [6].…”

Allostatic load and biological anthropology

“…As both humans and nonhuman primates are gregarious social animals who depend on their local conspecifics for aid in moderating life's stressors, research on allostatic load can contribute to socioecology as well as behavioral ecology theory. For example, olive baboons with high social connectedness had lower basal cortisol than those less socially connected (Ray & Sapolsky, 1992;Sapolsky, Alberts, & Altmann, 1997 connectedness have significantly reduced mortality risk (Archie, Tung, Clark, Altmann, & Alberts, 2014;Silk et al, 2010). Integrating allostasis theory and assessing ALIs across research on nonhuman primates alongside social and behavioral data also likely will aid research initiatives directed at improving health and management of captive populations, as well as informing conservation decision-making.…”

Sociality and health: impacts of sociality on disease susceptibility and transmission in animal and human societies

“…Variation in survival is relatively straightforward to determine, provided individuals can be recognized and followed, but survival estimates are generally complicated by dispersal, and causes of mortality must be separated into those due to extrinsic causes (primarily predation) and those attributable to infection and non-infectious diseases. For example, Chapman et al [116] use demographic data collected over decades to make inferences about the effects of stress and new parasites on population dynamics in red colobus monkeys, and recent studies revealed that survival is affected by social relationships in female baboons [117] and male bottlenose dolphins [118].…”