When defending against hostile enemies, individual group members can benefit from others staying in the group and fighting. However, individuals themselves may be better off by leaving the group and avoiding the personal risks associated with fighting. While fleeing is indeed commonly observed, when …

Cooperation is more likely when individuals can choose their interaction partner. However, partner choice may be detrimental in unequal societies, in which individuals differ in available resources and productivity, and thus in their attractiveness as interaction partners. Here we experimentally examine …