We analyze an experimental public goods game in which group members can endogenously determine whether they want to supplement a standard voluntary contribution mechanism with the possibility of rewarding or punishing other group members. We find a large and positive effect of endogenous...

We study the development of cooperation in 929 young children, aged 3 to 6. In a unified experimental framework, we examine pre-registered hypotheses about which of three fundamental pillars of human cooperation – direct and indirect reciprocity, and third-party punishment – emerges earliest...