Despite reluctance, articles covering evolutionary psychology and behavioral genetics approaches to violence have begun to appear in leading criminological and psychological journals. In the area of genetics, a monoamine oxidase A (MAOA) gene and the catechol-O-methyltransferase (COMT) gene (genetic polymorphisms) have consistently been shown to relate to antisocial behaviors. However, the available evidence suggests that the MAOA gene is perhaps the one gene that is most consistently related to extreme violence. In the area of evolution, extreme violence is viewed as high-end variance in an evolutionarily adaptive process in which the propensity for aggression and violent behavior, in moderate doses, has been adaptive for individual behavior. From behavioral genetics and evolutionary models of violence, a better understanding of which individuals are at greatest risk for extreme violence may be found. This article examines the influence of genetics and evolution on acts of extreme and criminal violence among human primates. Table, figure, and references