They are group territoriality and a fission-fusion grouping system with sufficient variance in power between groups that aggressors can easily kill victims without being harmed themselves. Given that nonlethal intergroup hostility is widespread (Crofoot and Wrangham 2009), why does this pattern of killing occur only in particular species such as chimpanzees and humans? According to the imbalance-of-power hypothesis (Wrangham 1999), a combination of two features favors an evolved tendency of lethal intergroup killing. Selection has accordingly favored male tendencies to search for and take advantage of safe circumstances to cooperate in killing members of neighboring rival groups. It therefore tends to lead to a long-term rise in survival and reproductive success for members of the group. Success in killing shifts the long-term balance of power toward the aggressors by increasing their numerical superiority and hence their ability to win future contests over resources. Males benefit their groups by severely attacking members of neighboring groups, but they do so only in carefully selected contexts (local “imbalances of power”) that impose little risk of harm on the aggressors. The model proposes that chimpanzee groups (also known as communities) compete with each other over land, food, and females (Williams et al. 1981 van der Dennen 2002 Wilson and Wrangham 2003 Wrangham 1999, 2006 Wrangham and Peterson 1996). 1979), similarities between chimpanzee intergroup aggression and human warfare have prompted a “chimpanzee model” of war proposing intergroup killing as strategic and adaptive (Goodall 1986 Manson and Wrangham 1991 Roscoe 2007 Trudeau et al. Since the 1971 discovery that wild chimpanzees ( Pan troglodytes) sometimes kill members of neighboring groups (Goodall et al. 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. To test this “chimpanzee model,” we review intergroup fighting in chimpanzees and nomadic hunter-gatherers living with other nomadic hunter-gatherers as neighbors. 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. According to this idea chimpanzees and humans are equally risk-averse when fighting. 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. Chimpanzee and hunter-gatherer intergroup aggression differ in important ways, including humans having the ability to form peaceful relationships and alliances among groups.
0 kommentar(er)
