¿Por qué las personas se matan entre sí? Se han propuesto cientos de respuestas pero hasta ahora ninguna tenía por marco una teoría general de la naturaleza humana: la teoría de la evolución por seleccion NAtural. Es indudable que la mente y la conducata humanas son producto de la seleccion. Evolucionaron en funcion de su aptitud. Por lo tanto, cuando la aptitud esperada de un individuo puede ser incrementada a expensas del otro, se desencadena un conflicto. Matar al antagonista es la forma extrema de resolverlo.

The human race spends a disproportionate amount of attention, money, and expertise in solving, trying, and reporting homicides, as compared to other social problems. The public avidly consumes accounts of real-life homicide cases, and murder fiction is more popular still. Nevertheless, we have only the most rudimentary scientific understanding of who is likely to kill whom and why. Martin Daly and Margo Wilson apply contemporary evolutionary theory to analysis of human motives and perceptions of self-interest, considering where and why individual interests conflict, using well-documented murder cases. This book attempts to understand normal social motives in murder as products of the process of evolution by natural selection. They note that the implications for psychology are many and profound, touching on such matters as parental affection and rejection, sibling rivalry, sex differences in interests and inclinations, social comparison and achievement motives, our sense of justice, lifespan developmental changes in attitudes, and the phenomenology of the self.