Why Can't We All Just Get Along? Evolutionary Perspectives on Violence, Homicide, and War

Abstract

We review and discuss the evolutionary psychological literature on violence, homicide, and war in humans and nonhumans, and in doing so argue that an evolutionary perspective can substantially enhance our understanding of these behaviors. We provide a brief primer on evolutionary psychology, describing the basic tenets of the field. The theories of sexual selection and parental investment are explained and subsequently used to highlight the evolutionary logic underlying the use of violence by humans and other animals. Our examination of violent behavior begins with a focus on nonhuman animals, reviewing the different contexts in which violence occurs and discussing how an evolutionary perspective can explain why it occurs in these contexts. We then examine violence in humans and illustrate the similarities and differences between human and nonhuman violence. Finally, we summarize what an evolutionary perspective can offer in terms of understanding violence, homicide, and war, and discuss directions for future research.

When Violence Pays: A Cost-Benefit Analysis of Aggressive Behavior in Animals and Humans

“…Let us take aggressiveness as an example of an aspect of human nature for which there are still many unanswered questions (Buss and Dentley, 2006; Buss and Shackelford, 1997; Liddle, Shackelford, and Weeks-Shackelford, 2012). Two such questions are: why is it that humans seem to have a high potential for violent aggression toward their conspecifics?…”

The evolutionary interplay of intergroup conflict and altruism in humans: a review of parochial altruism theory and prospects for its extension

“…Comprehensive overviews of the different forms, motivations and outcomes of violent intergroup conflicts present in human ( pre-)history can be found in the literature [6,[43][44][45]. Notable are Keeley's descriptions of societies whose different subgroups constantly engage in violent conflicts, but do not aim at their enemies' total annihilation [6].…”

The Conditions Favoring Between-Community Raiding in Chimpanzees, Bonobos, and Human Foragers

“…This assumption was found empirically to work well for small coalitions of males in primates, wolves, and lions (Bissonnette et al 2009;Liddle et al 2012). It is probably too conservative in that chimpanzees' total fighting ability increases more than linearly with the number of individuals that join (Wilson et al 2002), but this merely means that our results are likely to be somewhat conservative.…”