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A distinctive feature across human societies is our interest in justice and fairness. People will sometimes invest in extremely costly behavior in order to achieve fair outcomes for themselves and others. Why do people care so much about justice? One way to address this is comparatively, exploring behaviors related to justice and fairness in other species. In this paper, I review work exploring responses to inequity, prosocial behavior, and other relevant behaviors in non-human primates in an effort to understand both the potential evolutionary function of these behaviors and the social and ecological reasons for the individual differences in behavior. I also consider how these behaviors relate to human behavior, particularly in the case of experimental studies using games derived from experimental economics to compare non-human primates’ responses to those of humans in similar experimental conditions. These results emphasize the importance of a comparative approach in order to better understand the function and diversity of human behavior.


This article was originally published in the Proceedings of the National Academy of Sciences. Copyright © 2013 National Academy of Sciences.

The post-peer-reviewed-version is available here with the permission of the author.