Games like EverQuest and Dark Age of Camelot occasionally produce natural experiments in social science: situations that, through no intent of the designer, offer controlled variations on a phenomenon of theoretical interest. This paper examines two examples, both of which involve the theory of...

Understanding the roots of human cooperation among strangers is of great importance for solving pressing social dilemmas and maintening public goods in human societies. We study the development of cooperation in 929 young children, aged 3 to 6. In a unified experimental framework, we examine...

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...