From steroids to nation states: An integrated evolutionary approach to violent crime

Most evolutionary psychologists emphasize the individual level of analysis concerning violent crime and other dependent variables. This paper outlines a strategy for evolutionary explanation of societal variation across time as well as space and applies it to crimes of violence. The central idea is that individual adaptations for reproductive competition play out differently depending both on developmental context and societal conditions, including the marriage market. Violent crimes (murders, rapes, and assaults) are substantially higher in countries with a relative scarcity of men according to research using INTERPOL and World Health Organization data [Barber, N. (2000a). The sex ratio as a predictor of cross-national variation in violent crime. Cross-Cultural Research, 34, 264–282, Barber, N. (2009). Countries with fewer males have more violent crime: Marriage markets and mating aggression. Aggressive Behavior, 35, 49–56]. This is an apparent contradiction given that males are more criminally violent and likely reflects increased direct mating competition that evokes increased testosterone production for humans as for other species. The empirical evidence is discussed in terms of direct reproductive competition and various alternative explanations, particularly the “culture of violence” and socialization experiences are considered.