Evolutionary Perspective on Prosocial Behaviors in Nonhuman Animals

Abstract

Prosocial behaviors have long been considered a hallmark of humans. However, observational and experimental studies have revealed that nonhuman animals also show a variety of prosocial behaviors, but the likely evolutionary path of prosocial behaviors has remained unclear. In this chapter, I hypothesize that some psychological factors, namely, inequity aversion, interdependence and tolerance, may have played facilitating roles in the convergent evolution of prosocial behaviors. In experimental studies, some primates who show inequity aversion, such as chimpanzees and capuchin monkeys, have also shown robust prosocial behaviors, although the partner’s begging behaviors may be influential. Proactive prosocial behaviors occur in cooperative breeder primates with high levels of allomaternal care, who also show high levels of interdependence. High levels of tolerance and prosocial behaviors toward partners including strangers have been reported particularly in bonobos. I also discuss how the convergent evolution hypotheses of prosocial behaviors applies not only to primates but also non-primate species, by reviewing recent experimental studies on birds and domestic animals. Finally, I propose some possible future study directions for extending explorations of the evolutionary route of prosocial behaviors.