Human Nature

, Volume 23, Issue 1, pp 5–29 | Cite as

Intergroup Aggression in Chimpanzees and War in Nomadic Hunter-Gatherers

Evaluating the Chimpanzee Model
  • Richard W. WranghamEmail author
  • Luke Glowacki


Chimpanzee and hunter-gatherer intergroup aggression differ in important ways, including humans having the ability to form peaceful relationships and alliances among groups. This paper nevertheless evaluates the hypothesis that intergroup aggression evolved according to the same functional principles in the two species—selection favoring a tendency to kill members of neighboring groups when killing could be carried out safely. According to this idea chimpanzees and humans are equally risk-averse when fighting. When self-sacrificial war practices are found in humans, therefore, they result from cultural systems of reward, punishment, and coercion rather than evolved adaptations to greater risk-taking. To test this “chimpanzee model,” we review intergroup fighting in chimpanzees and nomadic hunter-gatherers living with other nomadic hunter-gatherers as neighbors. Whether humans have evolved specific psychological adaptations for war is unknown, but current evidence suggests that the chimpanzee model is an appropriate starting point for analyzing the biological and cultural evolution of warfare.


Lethal raiding Peace Imbalance-of-power Cultural war-risk hypothesis Parochial altruism 



Steven LeBlanc kindly shared ideas and knowledge of the hunter-gatherer literature. For comments on the manuscript we are grateful to Joyce Benenson, Robert Hinde, Steven LeBlanc, Lys Stevens, and Michael Wilson. Chris Boehm, Elizabeth Cashdan, Carol Ember, Lars Rodseth, and two anonymous referees were particularly helpful with their advice and critiques.


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© Springer Science + Business Media, LLC 2012

Authors and Affiliations

  1. 1.Department of Human Evolutionary BiologyHarvard University, Peabody MuseumCambridgeUSA
  2. 2.Department of Human Evolutionary BiologyHarvard UniversityCambridgeUSA

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