Recent thinking on the evolution of human cognition and morality increasingly emphasizes the importance of cooperative behavior to the lifeways of human ancestors. This is due, in part, to the unique and striking ability of humans to engage in altruism and complex cooperative tasks across many contexts and with kin and strangers alike. But such thinking is also informed by formal evolutionary models that aim to show how cooperative behaviors might emerge and remain stable against the threat of free riding or defection. Drawing on his collaborative work with Rory Smead on the evolution of spite, Forber will revisit these formal investigations. Considering the effects of harmful social behaviors reveal new evolutionary possibilities, particularly for small groups of adept learners. These new possibilities require us, at the very least, to reevaluate the roles of both prosocial and antisocial behavior in human evolution.