Resource Competition and Human Aggression, Part I: A Review of Primitive War

The relationship between biological and cultural evolution is of major importance to the study of human ecology and social behavior. This paper argues that to an important and generally unrecognized extent, culture may evolve by the selective retention of non-genetic of traits that enhance the ability of individual human beings to survive and reproduce in a given environment. This implies that biological and cultural evolution may be truly complemetary. If so, it makes no sense either to view biological and cultural adaptations as independent phenomena or to assert that all forms of adaptation result from natural selection. The possible coevolution of human biology and culture therefore has important implications for understanding why people do what they do. In an attempt to asses the validity of a coevolutionary approach to human behavior, one of the favorite topics of the biology versus culture, instinct versus learning controversy is reconsidered: intergroup aggression. First, a model is proposed to account for the presence or absence of intergroup aggression resulting from resource competition between human social groups. From combined measures of resource deprivation and relative capability, the model predicts conditions where aggressive intergroup behavior would have a net benefit for the survival and reproduction of the individual aggresors despite its inherent costs. These predictions are then compared with several examples in a review of war and peace among small, stateless human societies. The evidence is consisten which the hypothesis that individuals maximize their survival and reproduction by living in social groups and participating in collective aggression when access to scare resources at stake. It is concluded that aggressive intergroup behavior may often be adaptive for individuals under conditions of resource competition and that this may help to explain the prevalence of warfare among human societies.