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. (shrink)

Primatological and archaeological evidence along with anthropological accounts of hunter-gatherer societies indicate that lethal between-group violence may have been sufficiently frequent during our ancestral past to have shaped our evolved behavioral repertoire. Two simulations explore the possibility that heroism (risking one's life fighting for the group) evolved as a specialized form of altruism in response to war. We show that war selects strongly for heroism but only weakly for a domain-general altruistic propensity that promotes both heroism and other privately costly, (...) group-benefiting behaviors. A complementary analytical model shows that domain-specific heroism should evolve more readily when groups are small and mortality in defeated groups is high, features that are plausibly characteristic of our collective ancestral past. (shrink)

With armed conflict in the Persian Gulf now upon us, Harvard archaeologist Steven LeBlanc takes a long-term view of the nature and roots of war, presenting a controversial thesis: The notion of the "noble savage" living in peace with one another and in harmony with nature is a fantasy. In Constant Battles: The Myth of the Peaceful, Noble Savage , LeBlanc contends that warfare and violent conflict have existed throughout human history, and that humans have never lived in ecological balance (...) with nature. The start of the second major U.S. military action in the Persian Gulf, combined with regular headlines about spiraling environmental destruction, would tempt anyone to conclude that humankind is fast approaching a catastrophic end. But as LeBlanc brilliantly argues, the archaeological record shows that the warfare and ecological destruction we find today fit into patterns of human behavior that have gone on for millions of years. Constant Battles surveys human history in terms of social organization-from hunter gatherers, to tribal agriculturalists, to more complex societies. LeBlanc takes the reader on his own digs around the world -- from New Guinea to the Southwestern U.S. to Turkey -- to show how he has come to discover warfare everywhere at every time. His own fieldwork combined with his archaeological, ethnographic, and historical research, presents a riveting account of how, throughout human history, people always have outgrown the carrying capacity of their environment, which has led to war. Ultimately, though, LeBlanc's point of view is reassuring and optimistic. As he explains the roots of warfare in human history, he also demonstrates that warfare today has far less impact than it did in the past. He also argues that, as awareness of these patterns and the advantages of modern technology increase, so does our ability to avoid war in the future. (shrink)