Partitioning aggression

Human Nature: Nasty or Nice?

Have aggression and violence been ramped up in human evolution or dialed down? This sounds like a question that empirical research might have settled long ago, but it remains strangely contentious. In PNAS, Richard Wrangham (1) proposes that debates persist because too many evolutionary anthropologists mistakenly conceive of aggression as unitary and that a well-established distinction between “proactive” and “reactive” aggression holds the key to a resolution.

In what Wrangham calls the Hobbes–Huxley paradigm, people are considered violent animals whose destructive tendencies must be contained by cultural constraints and penalties. The alternative Rousseau–Kropotkin paradigm sees our species as naturally peaceable and interprets violence as a consequence of some execrable aspect of modernity. Twentieth-century versions of these visions have tended to be less overtly political but scarcely less flamboyant. Raymond Dart (2), the discoverer of Australopithecus, for example, proposed that “the loathsome cruelty of mankind to man forms one of his inescapable characteristics and differentiative features,” which he attributed to our “carnivorous and cannibalistic” origins. In a popular book translated into English as On Aggression, the Nobel Prize-winning ethologist Konrad Lorenz (3) asserted that only two species routinely kill their own kind: rats (Rattus norvegicus) and ourselves.

Neither Dart nor Lorenz knew anything about the behavior of common chimpanzees (Pan troglodytes) in the wild (although Jane Goodall had begun her famous studies at Gombe when Lorenz wrote). These apes, our close cousins, certainly kill one another too. Wrangham is one of the scientists who followed Goodall to Gombe, where he added to our knowledge of the opportunistic lethal raiding that constitutes a kind of chronic “warfare” between chimpanzee communities. He has noted how the deliberateness and cooperativeness of that …