NONFICTION REVIEW

Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are. By Frans de Waal. Riverhead. $25.95. 288 pages.

Verdict: An enlightening look at ourselves.

Robert Ardrey's 1961 book "African Genesis" startled the world. Ardrey traced the human lineage back to a "line of killer apes." With such a lethal background, he wrote, "What should we wonder at? Our murders and massacres and missiles, and our irreconcilable regiments?"

This view of humanity as a warlike society was reinforced by field studies of our closest relative, the chimpanzee. Despite their previous reputation as Edenic vegetarians, on-the-ground research revealed them to be violent communities of brutish thugs who beat rivals to death, hunted monkeys and ate them.

It seemed our past destined us to a bloody future. Then, in the 1970s, scientists began studying bonobos.

Bonobos, once called pigmy chimpanzees, are gracile versions of ordinary chimps. Like chimps, they are social animals who live in groups, but their personalities are quite different, almost opposites, in fact. In his interesting, easy-to-read book, "Our Inner Ape," Frans de Waal, a respected primatologist and Emory University professor, recounts what he and other scientists have learned about this species.

Bonobos are less aggressive than chimps. They have come up with a far better method of resolving problems: Rather than force, bonobos use sex. They are a swinging species, and they sometimes "do it" while swinging. They also do it upside down and sideways, backward and forward, males with males, females with females . . . well, you get the picture.

Interestingly, we humans are as closely related to bonobos as we are to chimps, with about 98 percent of our DNA common to both species. Here is how de Waal characterizes our two nearest relatives:

"One is a gruff-looking, ambitious character with anger-management issues. The other is an egalitarian proponent of a free-spirited lifestyle."

The question is: Which ape are we? Peaceable, sexy, female-dominated bonobos or warlike, male-dominated chimps?

De Waal approaches the question by comparing the roles power, sex, violence and kindness play in communities of the two species. He uses these observations to shed light on the human condition and the evolution of human morality. Because de Waal was personally involved in many of these studies, he has a store of anecdotes, which he regularly tosses off to enliven the science.

To bring home the point about the bonobo's lively sex life, for example, de Waal tells the story of a zookeeper who had previously worked with chimps. Imagine his surprise on his first day with bonobos when one greeted him with a kiss --- a full, tongue-in-the-mouth French kiss.

Another story illustrates perfectly, if less happily, the hardball nature of chimpanzee politics. Male chimps build alliances with one another. An alpha male might form a coalition to help him stay in power, and lower-ranking chimps often get together to dethrone an alpha male. The winners get more sex and more food; the losers slide down the hierarchy. These power struggles are usually violent and occasionally deadly.

One of de Waal's favorite chimps, an alpha male named Luit, fell victim to the political rough-and-tumble. One morning de Waal found him in a bloody heap in his cage, with deep wounds all over his body. His testicles and some of his fingers and toes had been bitten off. Two lower-ranking males, who had been plotting for months to displace Luit, had attacked him that night. It was a vicious battle, and Luit died from his wounds.

After decades of studying bonobos and chimpanzees, de Waal has reached some conclusions. First, though, he points out that the differences between the two species, while great, are not black and white. Sometimes, chimps can be kind, and bonobos can be aggressive. Clearly, we share characteristics with both species. Like them, we are intensely social animals who rely on one another. We are capable of enormous violence and cruelty, as well as great kindness and generosity. We are, de Waal says "the bipolar ape."

But de Waal is after bigger game than this straightforward conclusion. He believes that the studies of chimps and bonobos can enlighten us about the origins of morality. Immanuel Kant claimed that morals were arrived at by "pure reason," but de Waal believes that morals spring from emotions and that apes experience those emotions. He cites numerous examples that show their capacity for kindness, for cooperation, for altruism --- the building blocks of human morality.

One especially revealing story concerned the actions of a bonobo named Kuni after a starling flew into a glass wall. Kuni picked up the stunned bird, climbed to the top of a tree, carefully unfolded its wings, and tossed it to safety.

Clearly, our closest relatives are capable of empathy, leading de Waal to conclude that "the building blocks of morality clearly predate humanity." Thus, morality, "our noblest achievement," did not spring from reason or from the pens of philosophers. It did not come from culture or religion; morality is a gift from our primate ancestors.

Phillip Manning is a Chapel Hill, N.C., writer; his book reviews and essays on science are available online at www.scibooks.org.