Humans possess a remarkable ability to cooperate with unrelated strangers. Decades of research have provided substantial evidence on the importance of three supporting mechanisms of cooperation, considered as its evolutionary pillars: direct reciprocity, indirect reciprocity, and altruistic punishment. Here, we report evidence from a unique large lab-in-the-field study – conducted across 19 kindergartens with 964 children, 3 to 6 years of age – designed to study the roots of cooperation and its three supporting mechanisms. We find that out of the three pillars, only third party punishment is effective in promoting cooperation. We find this effect to develop with age, and to be driven by children’s fear of punishment and reacting to punishment itself. Although reciprocity does not promote cooperation, children do behave conditionally to their partners’ reputation, but fail to anticipate future benefits of building a positive reputation themselves. We also find that cognitive abilities have strong explanatory power for children’s cooperative behavior.
Lecture Hall (A-035)