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Twentieth Annual Darwin College Lecture Series 2005

CONFLICT

Lecture 3   :   4 February

WHY APES AND HUMANS KILL

Richard Wrangham

Biography  |   Abstract   |   Printable Version

Abstract

Human warfare is often claimed to be biologically aberrant partly because in his celebrated book 'On Aggression,' Konrad Lorenz reported that animals are inhibited from killing members of their own species. But we now know that Lorenz was wrong. Many species regularly kill their own, including chimpanzees. These facts have re-opened the questions of whether and how human evolutionary biology has affected our propensity for war. In addressing this problem it is useful to separate two styles of animal violence, i.e. "predatory kills" and "lethal battles." Predatory kills are attacks on helpless victims. Their commonest form is infanticide, but in a few species they also include coalitionary attacks among adults. Thus among chimpanzees and nomadic hunter-gatherers, small groups sometimes kill rivals from neighboring communities; current data indicate that death rates from this style of intergroup aggression are approximately equal in the two species. The pervasiveness of this pattern suggests that both species have had an evolutionary history of lethal violence, and are cognitively adapted for successful killing. But by contrast, there is no evidence for humans that lethal battles have been important in evolution. Lethal battles are escalated contests between competitive equals in which the outcome is uncertain and both opponents are likely to suffer high costs or deaths. Coalitionary lethal battles are absent or exceptional among chimpanzees and hunter-gatherers, and are rare in animals generally. They occur most prominently among social insects and in modern (post-agricultural) warfare, associated with despotic hierarchies. Even though lethal battles are evolutionarily novel in the human lineage, however, they incorporate biologically adaptive patterns such as self-deceptive assessments of relative competitive power. In sum, while chimpanzees and humans have evolved to kill when the killing is easy, hierarchically organized armies have created a new logic for conflict.

The lectures are given at 5.30 p.m. in The Lady Mitchell Hall, Sidgwick Avenue, with an adjacent overflow theatre with live TV coverage. Each lecture is typically attended by 600 people so you must arrive early to ensure a place.