Political Science

Warfare is a collective action problem, and groups often stand to benefit from the quick and coordinated action that leaders can provide. This basic principle is as true in modern political contexts as it has been across our evolutionary history, and there is growing evidence that leadership has evolved, in part, to solve such collective action problems. Despite the material and reproductive benefits of leadership for groups, leaders may also seek private gains at the expense of group interests. Drawing upon insights from social and evolutionary psychology, I explain how leaders solve collective action problems in warfare, but also how leaders manipulate audience preferences when their own interests do not align with group interests. Specifically, when leaders anticipate great private gain from foreign aggression while facing steep public resistance at home, leaders will misframe the conflict as defensive rather than offensive in nature. I provide an evolutionary analysis that explains why leaders exploit this framing specifically, and I identify the specific aspects of conflict framing that are most likely to be exploited toward this end.

In a previous issue of this journal, Adam Goodwin (2010) argued that applications of 'orthodox' evolutionary theory in international relations are reductionist, necessarily privilege an individualist ontology, and doom social theorising to the false assumption that humans are by nature selfish and competitive. As an alternative, Goodwin presents Kropotkin's Mutual Aid framework both for overcoming the reductionism of 'orthodox' evolutionary theory and for establishing a holist ontology cantered around the autonomy of social forms. I argue that Goodwin's representation of 'orthodox' evolutionary theory is in fact far from orthodoxy and instead rests on misunderstandings both of how natural selection operates and what it operates to produce-adaptations. I show that modern evolutionary theory rests on neither individualist nor holist ontologies, and instead demonstrates that humans are by nature neither hawkish nor dovish. I provide examples on the evolution of cooperation and war to demonstrate that modern evolutionary theory can explain a range of pro-and antisocial behaviours and that fears of biological reductionism in international relations are misplaced.

The use of evolutionary theory for explaining human warfare is an expanding area of inquiry, but it remains obstructed by two important hurdles. One is that there is ambiguity about how to build an evolutionary theory of human warfare. The second is that there is ambiguity about how to interpret existing evidence relating to the evolution of warfare. This paper addresses these problems, first by outlining an evolutionary theory of human warfare, and second by investigating the veracity of four common claims made against the use of evolutionary theory for explaining warfare. These claims are: (1) ancestral warfare was not frequent or intense enough to have selected for psychological adaptations in humans for warfare; (2) the existence of peaceful societies falsifies the claim that humans possess adaptations for fighting; (3) if psychological adaptations for warfare exist, then war is an inevitable and universal component of the human condition; (4) modern warfare and international politics is so qualitatively different from ancestral politics that any adaptations for the latter are inoperative or irrelevant today. By outlining an evolutionary theory of war and clarifying key misunderstandings regarding this approach, international relations scholars are better positioned to understand, engage, and contribute to emerging scholarship on human warfare across the social and evolutionary sciences.

The study of warfare from an evolutionary perspective has expanded rapidly over the last couple of decades. However, it has tended to focus on the ancestral origins, prevalence, and instruments of war rather than adaptationist analyses of its underlying psychology. I argue that our evolved coalitional psychology may contain a set of distinct evolved heuristics designed specifically for offensive and defensive coalitional aggression. Data from two survey experiments are presented, in which subjects were given scenarios depicting offensive or defensive aggression and were told to make decisions, for example, regarding their willingness to participate in the conflict, their opinions of others who did not choose to participate, and their expectations benefit. The results indicate that humans do indeed distinguish readily between these two domains and that their willingness to participate, as well as their emotional responses toward others, is highly contingent upon this informational cue in adaptively relevant ways. In addition, and consistent with parental investment theory, data reveal a range of sex differences in attitudes toward coalitional aggression in the two conflict domains. Beyond the study of warfare, this project has implications for our understanding of the relationship between individual behavior and group dynamics, as well as for our understanding of the mechanisms by which the psychological framing of political events can lead to important social outcomes.

The evolution and history of warfare has been investigated by philosophers, historians, practitioners, social scientists and life scientists. Common questions in this endeavour are: How far back into human evolution and history do we find evidence of warfare? How frequent was warfare in any given historical period? How lethal was warfare? In short, scholarship on the evolution and history of warfare has focused on questions of origins, frequency, and intensity.

Despite the fact that scientific interest in these questions is perhaps broader and more methodologically sophisticated than ever, consensus on these questions remains elusive for at least two reasons. First, the archaeological record of warfare is incomplete. Second, we do not agree on what warfare is or how to unambiguously distinguish it from other forms of violence. Beyond an agreement that warfare is something more than violence between two individuals, there is little consensus on the proper scope of our main unit of analysis.

Given these hurdles, it would seem that an investigation into the evolutionary origins of human warfare is destined merely to perpetuate academic stalemates, in which old arguments are continuously repackaged with each new discovery of a mass grave or ‘peaceful’ society. Although this is a rather pessimistic view, I establish it at the forefront of this chapter since my argument will be that these hurdles (e.g. knowledge of ancestral phenomena and consensus on definitions) are not insurmountable. Entire disciplines thrive on their ability to successfully infer and model the unobserved past based on imperfect historical, geological and archaeological evidence. And the question of definitions must be placed in its proper scope – as a methodological, rather than ontological, consideration.

De Dreu and Gross offer a compelling synthesis of a growing lit- erature on the psychology of attack and defense. I argue that human raiding ecology suggests the need to endogenize attacker- defender move order as well as opportunities for tactical mis- match available to defenders. Perhaps most significantly, I draw attention to the surprising lacunae in sex differences across attack and defense.

The scientific study of the evolution of human coalitional aggression has exploded over the last three decades. In four parts, I explore and integrate many of the useful frameworks that have emerged to describe and explain the human practice of intergroup violence. First, we have a clearer understanding of the general conditions required for the evolution of adaptations for coalitional aggression. Second, given an understanding of these conditions, we can more usefully examine the historic and prehistoric record for evidence of the existence of these conditions. Third, I explore and integrate current lab and field evidence for psychological adaptations for coalitional aggression. This section reveals a core dynamic underlying all forms of coalitional aggression: the form of intergroup engagement is functionally linked with the emergent patterns of intragroup dynamics. In other words, how we fight “abroad” determines how we cooperate “at home,” and vice versa. I examine five areas of inquiry that suggest special design for coalitional aggression. These are: the collective action problem of coordinated violence; parochial altruism; attacker-defender asymmetries; leader-follower dynamics; sex differences in the costs and benefits of violence. Fourth, and to conclude, I offer speculation on the historical emergence of modern human warfare. I do not use “coalitional aggression” and “warfare” interchangeably; rather, evolved psychological adaptations for small-scale coalitional aggression are what make the historical emergence of large-scale human warfare possible.

Integrating the individual insights of psychology with the sociological perspectives of constructivism constitutes a laudable goal. Indeed, the chapters in this volume go a far distance toward establishing the theoretical and empirical basis for such a synthesis. Combining the microfoundational aspects of individual psychology within a larger social, institutional, and political context offers an opportunity to explore the reciprocal and mutually determinative relationships between people and their environments. In providing a critical response to these chapters, several implicit aspects of the dominant arguments appear hidden in plain sight. First, one of the unexamined yet problematic assumptions that undergirds much of the discussion in this volume revolves around the suggested causal impact of ideas on behavior. While constructivists often assert this link as self-evident , most psychologists more fully appreciate the frequent disconnect between these phenomena. Second, the assimilations presented here, while not inaccurate, represent an unrealistically narrow theoretical conception of identity in psychology while simultaneously eliding a profound ontological difference between psychology and constructivist notions of human behavior. This means not that efforts to create a cohesive model remain quixotic in nature but rather that attempts to devise a unified theory may require a broader conception of psychology than that found exclusively or primarily in social identity theory. Moreover, incorporating other psychological approaches allows for a clearer explanation of the origins of preferences, a puzzle that currently limits both rationalist and constructivist applications to international relations...

Describes the ancestral conditions that could allow for the evolution of adaptations for warfare in humans. The evolution of adaptations for warfare is possible when there are low-cost/highbenefit opportunities for violence, and it is also possible even if violence is costly, as long as fitness benefits can outweigh these costs in particular mating contexts. Additionally, in some species such as humans, the existence of warfare adaptations presumes the existence of a coalitional psychology able to track a broader range of group dynamics. In short, the evolution of adaptations for warfare is possible when reproductive benefits can outweigh the variable costs of violence and when those opportunities can be taken advantage of by an evolved coalitional psychology.