Evolution, Biology, and Aggression

There are numerous complementary approaches to the biology of aggression, ranging from genetic to cognitive research. Arguably, the most successful of them have been guided by hypotheses derived from evolutionary theory. In contrast to the view that human aggression is symptomatic of psychological impairment, social disorganization, or both, evolution-minded hypotheses typically begin from the premise that aggression has been designed by natural selection to serve one or more adaptive functions, and that the mechanisms involved can be sensitive to cues of reproductive consequences in the social environment. Specifically, anatomical, physiological, and psychological adaptations for aggression are expected to evolve when they help individuals secure resources and matings for themselves and for their genealogical kin. From a theoretical perspective, contexts of predation, sexual competition, and sexual conflict are especially likely to foment aggression. A considerable body of research on aggression in nonhuman animals reinforces the adaptationist position, and central findings of this viewpoint—such as differential risk of violence according to sex and kinship—are closely mirrored in humans. Although many features of human aggression are likely the result of adaptations designed to yield these very features, others are more plausibly understood as byproducts of adaptations designed for different purposes. In either case, evolutionary approaches can help to identify the mechanisms underlying aggression and thereby provide ways to reduce its impact.