Abstract
The current article examines the influence of genetics and evolution on acts of extreme and criminal violence among human primates. Moderate aggression can function to increase an organism's reproductive success; extreme violence can place the organism at unnecessary risk. Genetic polymorphisms that have been linked to extreme acts of violence are reviewed as is research elucidating how genetic risk and environmental stress may interact to increase risk of extreme violence. 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 humans.