Excerpt from Us and Them by David Berreby, plus links to reviews, author biography & more

Nonetheless, these two viewpoints - human kinds as categories and human kinds as entities that happen to be made of people - are looking at one phenomenon. All human kinds have aspects of both, though the proportions can change over time. Half a century ago in North America, "homosexual" was mostly a category for people. Today in many Western nations, gays and lesbians are seen as an entity that wants, hopes, decides, and votes. On the other hand, the Norwegian community of New York City used to be an entity, with neighborhoods, clubs, and churches that helped organize people's lives. "Norwegians" made up a thing made of people. Today New York's Norwegians, despite annual parades, are mostly members of a category for people.

Underlying our myriad human kinds, then, is a fundamental unity. It is reflected in the way people blur distinctions. Most people don't blink at the much-used phrase "moderate Hutus," for example, even though "moderate" and "militant" describe political convictions and the Hutu are an ethnic group. Yes, it's birth that makes you a Brahmin, but it takes training to live as one; yes, you must sign up for army service, but many a son and grandson of military officers has enlisted because he felt "born to it." You become an employee of a corporation to make a living, but you can come to feel a family-like love for the place - like those Apple Computer employees who were said to bleed in the six colors of the company logo.

In fact, people speak about all human kinds with one language; something said about one can be said about any other. For example, when the American political commentator Paul Begala interviewed a prominent congressman, J. C. Watts, for a television program in 2002, he began: "Let me say, I'm a liberal. You're a conservative. That's not our biggest difference. I'm white, you're black, that's not our biggest difference. I'm a Texas Longhorn and you're an Oklahoma Sooner, and . . ."

"That's our biggest difference," Watts said. "That's the biggest," Begala replied. "That's bigger than anything else."

It wasn't, of course. Banter about college football was, in fact, a demonstration that there was a way in which they were not different. They were getting in sync, establishing that there is a human kind to which they both belong: powerful Washington guy. (For men of this tribe, as the journalist Nicholas Lemann noted, sports joshing is a way to signal that "membership in a community of important people trumps the enmity the system forces them to act out.") Notice, though, what made the conversation possible: the way politics, race, and sports fandom can be talked about as if they were the same. Why should these different human kinds, with their different purposes and histories, feel equivalent? One reason is that they share mental processes. Your ability to think of people as "German" partly depends on your general ability to categorize anything- to divide a flood of perceptions into birds and trees, gears and Gummi bears, hip-hop on the radio and grapes in a bowl on the table. Pigeonholes for people get some of their qualities from the mental equipment that makes pigeonholes for everything.

Categories of all sorts help explain what's happened and predict what will come next. Human kinds help predict what people will do, and there too they draw from a general capacity to find causes and patterns. "Today is cloudy and humid" is information that licenses you to predict that it might rain. Similarly, "He is a graduate of the University of Oklahoma" is a piece of information that lets you predict a stranger likely will follow the Sooners through football season.

Copyright © 2005 by David Berreby.  No part of this book maybe reproduced without written permission from the publisher.