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...

Political ideology has been hypothesized to be associated with cooperation and national parochialism (i.e., greater cooperation with members of one’s nation), with liberals thought to have more cooperation with strangers and less national parochialism, compared to conservatives. However,...