For humans, as for other species, the behavior of others can have a significant impact on one’s reproductive success, either directly or indirectly through one’s kin, social exchange partners, friends, mates, or coalitional allies. For example, one can be cheated in a social exchange, a family member can be the target of physical violence, a mate can commit adultery, or a group member can defect during a collective action. All else equal, design features that cost-effectively motivated the expenditure of energy to deter behaviors imposing a cost on oneself or on members of one’s social network would have out-