Homicide adaptations

We propose Homicide Adaptation Theory as a new explanation for why people kill. Multiple homicide mechanisms have evolved as effective context-sensitive solutions to distinct adaptive problems. Killing historically conferred large fitness benefits: preventing premature death, removing cost-inflicting rivals, gaining resources, aborting rivals' prenatal offspring, eliminating stepchildren, and winnowing future competitors of one's children. Homicidal ideation is part of evolved psychological design for killing, functioning to mobilize attention, rehearse scenarios, calculate consequences, and motivate behavior. Because being killed inflicts temporally cascading costs on victims, selection has forged death-prevention strategies, producing co-evolutionary arms races between homicidal strategies and anti-homicide defenses.

► Homicide Adaptation Theory is a new explanation for why people kill. ► Historically, conspecific killing could have conferred large fitness benefits. ► Context sensitive psychological mechanisms produce homicide to solve distinct adaptive problems. ► Being killed inflicts cascading costs on victims, selecting for death-prevention strategies. ► Homicide strategies and anti-homicide defenses co-evolved.