Moral universalism, the extent to which individuals exhibit similar altruism and trust towards in-group and out-group members, varies widely across societies. We test the hypothesis from anthropology that the requirements of transhumant pastoralism - a livelihood in which populations seasonally...

While observational evidence suggests that people behave more prosocially towards members of their own ethnic group, many laboratory studies fail to find this effect. One possible explanation is that coethnic preference only emerges during times of stress. To test this hypothesis, we...

Kinship ties are a common institution that may facilitate in-group coordination and cooperation. Yet their benefits - or lack thereof - depend crucially on the broader institutional environment. We study how the prevalence of clan ties affect how communities confronted two well-studied...