This paper lays out an evolutionary theory for the cognitive foundations and cultural emergenceof the extravagant displays (e.g., ritual mutilation, animal sacrifice, and martyrdom) that have sooften tantalized social scientists, as well as more mundane actions that influence cultural...

In the past decade, nearly 20 studies have found a strong, persistent pattern in surveys and behavioral experiments from over 40 countries: individual exposure to war violence tends to increase social cooperation at the local level, including community participation and prosocial behavior. Thus...