What function do larger social groups provide for primates?

Larger social groups provide enhanced protection from predators, which is a critical factor in the survival of primates. When animals form larger groups, it becomes more challenging for predators to successfully single out and attack an individual, as the sheer number of individuals can deter potential threats. This phenomenon is often referred to as the "dilution effect," where the risk of any one individual being caught decreases as group size increases. Additionally, larger groups can engage in collective vigilance, where individuals take turns watching for predators while others feed or engage in other activities, further enhancing overall safety. This protection is a significant evolutionary advantage, as it can lead to greater survival rates among group members, thereby increasing reproductive success within the group.

In contrast, access to communal nesting sites, increased territory size, and better food sharing practices, while relevant to primate social behavior, do not primarily address the critical survival aspect associated with predator avoidance. Hence, the focus on enhanced protection from predators is a fundamental reason for the evolution of larger social groups among primates.