■■ Some cultures have norms of aggression, such as the Yanomami of Venezuela and Brazil, a cultural group well known for its aggressive tendencies both within the group and toward outsiders and often referred to as the “fierce people” (Sponsel, 1998). Research among mobile forager band societies has shown that most lethal aggression events are perpetrated by lone individuals and stem from accidents, interfamilial disputes, within-group executions, or interpersonal motives (such as competition over a woman) rather than coalitionary-type group-based action against other groups (i.e., war; see Fry & Soderberg, 2013).