Glowacki defines peace as harmonious relationships between groups maintained without the threat of violence, where groups can be anything from families to nation states. However, defining such contentious concepts like “peace” and “groups” is a difficult task, and we discuss the implications of Glowacki's definitions for understanding intergroup relationships and their evolutionary history.

Folk stories featuring prosocial content are ubiquitous across cultures. One explanation for the ubiquity of such stories is that stories teach people about the local socioecology, including norms of prosociality, and stories featuring prosocial content may increase generosity in listeners. We tested this hypothesis in a sample of 185 Hadza hunter-gatherers. We read participants a story in which the main character either swims with another person (control story) or rescues him from drowning (prosocial story). After hearing the story, participants played (...) a dictator game with dried meat sticks and then were given a recall test of facts presented in the story. There was moderate evidence for a small effect of the prosocial story: participants who heard the prosocial story gave an estimated 0.22 [90% HDI: −0.12–0.57] more meat sticks than those who heard the control story. However, the association between generosity and sex, marital status, and region of residence was stronger; men gave more than women, unmarried participants gave more than married participants, and participants living in a region with more exposure to markets gave more than participants living further from markets. There was no evidence that the prosocial story was more easily recalled than the control story. These results provide some support for the hypothesis that prosocial stories can increase prosociality in listeners, though the effect of hearing a single story is small. (shrink)