In gorillas, the pros and cons of sociality vary based on wider aspects of the social group

What is it about?

In humans, the social environment is one of the strongest predictors of health and lifespan. Similar patterns in other social mammals suggest that this is deeply rooted in our evolutionary history. Despite strong benefits to sociality for health, reproduction and survival, individuals are far from consistent in their social behavior, with many showing seemingly maladaptive traits. We used data from a close evolutionary relative, mountain gorillas, to examine how social traits of individuals and their wider social group influence health and reproduction. We show that the costs and benefits of individuals’ sociality are highly context dependent, differing between sexes and varying based on wider traits of their social groups. These findings can help explain why such a wide range of social traits are observed.

Featured Image

Photo by Luc Huyghebaert on Unsplash

Photo by Luc Huyghebaert on Unsplash

Why is it important?

Examining the health and fitness consequences of sociality through long-term studies of wild primates provides valuable evolutionary context for understanding the relationships between health and sociality in humans. In this study we are not only able to separate out social influences on illness compared to injury, but are able to do it in both males and females, in one of humans closest evolutionary relatives. By comparing across multiple groups we are also able to examine the interplay between between individual-based social traits (e.g. bond strength) and group-level traits (e.g. group size). Our findings highlight the context-dependent nature of the costs and benefits of sociality, likely shaping the diversity of social strategies observed among individuals.