Us and Them: Understanding Your Tribal Mind
by David Berreby
Little, Brown, 2005

Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are
by Frans de Waal
Riverhead Books (Penguin Group), 2005

No man is an island. In fact, people are less happy and healthy alone than when they are in a group--of kin, of countrymen or indeed of anybody with whom they can identify, however fleetingly. But tribes are tricky, at once so solid and yet so evanescent--je suis Marxiste, runs the apocryphal French graffito, tendance Groucho. We switch allegiance from one Thousand-Year Reich to another at the drop of the hat. At the dictates of some distant demagogue, your good neighbor can become a deadly foe.

On July 7, 2005, suicide bombers blew themselves up on three London subway trains and a bus, killing themselves and more than 50 other people in the cause of radical Islam. The abiding horror is that the bombers were not foreign insurgents--Them--but were British, born and raised; in Margaret Thatcher's defining phrase, One of Us. The crisis of tribal identity that the horror unleashed will, eventually, change the characteristics of what we mean by "Britishness," qualifying the laissez-faire multicultural consensus that has held for the past half a century.

Such is the mutability of tribes, entities forever changing with reference to one another, and the protean subject of David Berreby's brave book. Berreby's quest is to understand what he sees as a fundamental human urge to classify and identify with "human kinds." We project this urge onto what we see. Are races and human kinds real? The fact that they change all the time, and we can switch from one to another so easily, suggests not. Instead, Berreby says, our ideas of the "human-kind code" are based "on facts about how we relate to [other] people at the moment we categorize them--what we want, or expect, or fear from them."

Having an inbuilt facility to distinguish between Us and Them was a valuable resource, related to that essential ability to create artificial groupings from what, to a robot, would be entirely distinct objects. We take this talent for granted, but what would life be like if we lacked it: if we were like Funes, the cripple created by Jorge Luis Borges in his story Funes the Memorious--a man with mental recall so powerful that he could not stand back and objectify what he saw? Funes saw each dog, each leaf, each cloud as sui generis: his inability to form categories left him utterly unable to make sense of the world.

This vital trick serves us well. But when applied to people, it can cause problems, especially when different kinds of people are all mixed up together, as they are in London, one of the most polyglot cities on the planet. The current crisis swirling around Islam and Britishness, what some see as a symptom of the imminent failure of the multicultural consensus, could have been predicted by the fate of the "contact" hypothesis, in which prejudice is meant to be weakened by familiarity. That foreign-looking man in the hooded jacket will be less threatening if you know he's just Bernie from next door. Most scholars now think, Berreby says, that the contact hypothesis is a muddle: "Actual contact sometimes makes people more prejudiced. On many American college campuses ... the emphasis on diversity has led students to join one of these diverse human kinds and shun much contact with the others." Bernie could be your friend for life--or your worst enemy.

Do we remain forever prey to our irrepressible urges to classify, to create outcasts, Untermenschen, untouchables? Because "human kinds" are epiphenomena, results of unspoken contracts between fickle human minds and changeful reality, we can rise above them. "Human kinds exist because of human minds," Berreby concludes. "But how you choose to live with them is up to you." We can actively choose the kinds we want, for evil or for good. Since the bombings, London mayor Ken Livingstone has had posters put up all over the city promoting our unity. "Seven Million Londoners," it reads, "Only One London." Livingstone, like Margaret Thatcher at the opposite end of the political spectrum, is a consummate politician who knows how to play on our instincts.

In times of universal crisis and brouhaha, what we really need is a sense of perspective. Our Inner Ape, written by a scientist with a lifetime's experience around apes, is perhaps the most humane treatment of the human condition you can read, for all that it is mostly about chimpanzees. So-called common (but extremely rare) chimpanzees (Pan troglodytes) live in male-dominated societies characterized by shifting allegiances and extreme violence. So far, so Berreby. Their close cousins, the even less frequent pygmy chimps, or bonobos (P. paniscus), live in matriarchal societies where the stress is on reconciliation, all anxieties smoothed over by liberal applications of sex, in all possible combinations. If chimps are from Mars, bonobos are from Venus. Really? It's tempting to see these creatures as cartoon characters, caricatures of ourselves, done up as clowns or, more seriously, as metaphors for the human condition. De Waal plays this up to engage our interest but is at pains not to overdo it. Chimps and bonobos are not Looney Tunes humans; neither are they human ancestors, but creatures with a long evolutionary history of their own, which has provoked its own adaptive responses, its own repertoire of behaviors. Chimps are many things, but they are not One of Us.

The essential difference between humans and chimpanzees is that we form nuclear families, whereas chimps, so human in many ways, have no such institution. Although we stray from the path more often than we care to admit, human society is all about the age-old business of boy meets girl and sets up home under a roof, so much so that it explains such things as the size of our testicles, the manifest oddities of the female reproductive system, and why we prefer to have sex in private. At root, we define ourselves with reference to our families and closest kin and work outward from there. But we can learn a great deal more of our own humanity by comparing ourselves with something closely related but still Other. And this, in the final analysis, is the lesson of both books. Tribal allegiance means nothing unless there are other tribes out there against which we can get our measure.