Humans are an ultrasocial species. This sociality, however, cannot be fully explained by the
canonical approaches found in evolutionary biology, psychology, or economics …

Although theory suggests individuals are more willing to incur a personal cost to benefit
ingroup members, compared to outgroup members, there is inconsistent evidence in support …

Humans are a puzzling species. On the one hand, we struggle to survive on our own in the
wild, often failing to overcome even basic challenges, like obtaining food, building shelters …

Broadly defined, social dilemmas involve a conflict between immediate self-interest and
longer-term collective interests. These are challenging situations because acting in one's …

We review emerging research on the psychological and biological factors that underlie
social group formation, cooperation, and conflict in humans. Our aim is to integrate the …

I review evidence that individuals associate themselves—or identify—with groups in two
fundamental ways: ingroup bias and conformity to group norms. The evidence spans many …

Ingroup favouritism–the tendency to favour members of one's own group over those in other
groups–is well documented, but the mechanisms driving this behavior are not well …

We review psychological research on intergroup conflict. First, we outline psychological
perspectives on forms and functions of groups. Second, we present the most influential …

Some of the most fundamental questions concerning our evolutionary origins, our social
relations, and the organization of society are centred around issues of altruism and …

This article develops a model for analyzing social identity and applies it to the political
economy of income redistribution, focusing on class and national identities. The model …