Cooperation and the social brain hypothesis in primate social networks

TL;DR

This study investigates how primate brain size influences social network structures that facilitate cooperation, supporting the social brain hypothesis with empirical data linking neocortex size to cooperative social behaviors.

Contribution

It provides empirical evidence that larger neocortex sizes in primates are associated with social networks that better support cooperation, integrating brain data, social network analysis, and cooperation theory.

Findings

Positive correlation between brain size and cooperation in social networks

Neocortex size predicts network structures conducive to cooperation

Results hold after controlling for other network structural properties

Abstract

The social brain hypothesis states that the relative size of the neocortex is larger for species with higher social complexity as a result of evolution. Various lines of empirical evidence have supported the social brain hypothesis, including evidence from the structure of social networks. Social complexity may itself positively impact cooperation among individuals, which occurs across different animal taxa and is a key behavior for successful group living. Theoretical research has shown that particular structures of social networks foster cooperation more easily than others. Therefore, we hypothesized that species with a relatively large neocortex tend to form social networks that better enable cooperation. In the present study, we combine data on brain and body mass, data on social networks, and theory on the evolution of cooperation on networks to test this hypothesis in primates. We have found a positive effect of brain size on cooperation in social networks even after controlling for the effect of other structural properties of networks that are known to promote cooperation.