Altruistic Behavior in Primates
Prosocial behavior is a key component of human interaction, and its evolutionary origins are particularly interesting for scientists due to its immediate cost to the actor. Current literature on primate prosocial behavior reflects conflicting or incomplete evidence for varying hypotheses, such as reciprocity, kin theory, cooperative breeding, and inequity, leaving the evolutionary foundation for this behavior poorly understood. This review paper explores the various proximate and ultimate factors influencing primate prosocial behavior and synthesizes an overarching hypothesis that functions to connect the current fragmented state of the literature. It is proposed ecology supports kin selection, leading to an increase in cooperative breeding or reciprocal behaviors, which thus increase overall social tolerance. Proximate mechanisms such as underlying neuronal response and situational equity reinforce these behaviors, leading to the altruistic behavior displayed in some primates today.