In "Peacemaking Among Primates," Frans de Waal calls attention to an important but recently overlooked perspective in ethology, the study of the evolution of behavior. A relatively new science, ethology incorporates theories of behavior that go back at least 200 years, when scientists first looked to the natural world for a blueprint of the social contract, the basis for human behavior. Since then, they have moved from the picture of man as a "noble savage," born into an Eden and then corrupted, to the post-Darwinian vision of man as another animal subject to fierce competition for limited resources in order to survive.

On a January day in 1880, a different view came to the attention of Peter Kropotkin, known historically as the ideologue of anarchism, when he heard about a lecture presented at the Russian Congress of Naturalists by a well-known zoologist, who suggested that besides the law of mutual struggle--species locked in a gladiatorial battle for existence--there was a corresponding and even more important law of mutual aid. Three years later, Kropotkin read the same suggestion in Darwin's "The Descent of Man" and set to work collecting data, which he published, in 1902, as "Mutual Aid," a chronicle of cooperative behavior in the progressive evolution of the species.

Kropotkin reissued "Mutual Aid" in 1915 in order to set the record straight. He insisted that the war then destroying civilization as he knew it was not inevitable. People cooperate even under siege, he argued: Witness the peasant women who thrust bread and apples into the hands of German and Austrian prisoners as they trudged through the streets of Kiev. Mutual aid, he asserted, is a necessary correlative of competition among social animals, including human beings.

But this optimistic view of nature did not win much favor as the 20th Century continued with wars and genocide expanded to levels previously unimagined. Biologists and ethologists, along with psychologists and sociologists, sought the roots of this violence in the evolutionary past.

The roots were not hard to find. Violence is dramatic and easy to document. Tracking hostile behaviors in other species fulfilled the expectations of those who read these acts as a genetic necessity, a selection of evolution. However, while aggression is a successful adaptation among other species, it becomes a fatal flaw in humans who still react instinctively, hair standing on end, adrenaline flowing, to hostile movements, responding with nuclear weapons instead of sharpened canines.