Cruel to be kind: The role of the evolution of altruistic punishment in sustaining human cooperation in public goods games

People cooperate in public goods games even when an individual’s utility maximizing strategy is to defect. A form of non-institutionalized punishment called altruistic punishment—or strong reciprocity—may explain this cooperative behavior. I consider laboratory experiments of public goods games that provide evidence of altruistic punishment and proximate explanations for that behavior. I also present theories of the evolution of altruistic punishment via group-selection, multi-level selection, and gene and culture co-evolution. Furthermore, I consider criticisms of both laboratory results and evolutionary theories that suggest weaknesses in the current research on altruistic punishment. In sum, we will likely never have a definitive explanation of the origins and evolution of human cooperation. I conclude, however, that altruistic punishment may form an integral part of that trajectory