Born to kill? A critical evaluation of homicide adaptation theory

Given the enormous harm that results from the intentional killing of humans by other humans, the development of etiological theories of homicide is an important task. Homicide Adaptation Theory (HAT) is one such attempt to explain why homicide occurs. In short, the proponents of HAT propose that humans possess a number of specific, evolved adaptations for killing that have been selected for because they managed to successfully solve recurrent adaptive problems in our ancestral past. In this paper it is argued that, although evolutionary approaches can potentially advance our understanding of homicide in important ways, the available evidence does not support the existence of specific adaptations for killing in humans. Specifically, I argue that the proponents of HAT have not provided: (a) a thorough analysis of the evolutionary costs and benefits of killing; (b) evidence for ‘special design’ features of homicide; or (c) a systematic comparative appraisal of killing among different species. Given this lack of evidence, HAT suffers in terms of its explanatory worth, relative to alternative evolutionary hypotheses, such as the idea that homicide is a by-product of other evolved adaptations.