Three Is Not Enough

• DOA, male, 5'11" . . . black:

When U.S. police call in a forensic anthropologist to identify the race of a skeleton, the scientist comes through 80 to 85 percent of the time. If race has no biological validity, how can the sleuths get it right so often? The forensic anthropologist could, with enough information about bone structure and genetic markers, identify the region from which the corpse came -- south and west Africa, Southeast Asia and China, Northern and Western Europe. It just so happens that the police would call corpses from the first two countries black, from the middle two Asian, and the last pair white. But lumping these six distinct populations into three groups of two serves no biological purpose, only a social convention. The larger grouping may reflect how society views humankind's diversity, but does not explain it.

• African-Americans have more hypertension:

If race is not real, how can researchers say that blacks have higher rates of infant mortality, lower rates of osteoporosis and a higher incidence of hypertension? Because a social construct can have biological effects, says epidemiologist Robert Hahn of the U.S. Centers for Disease Control and Prevention. Consider hypertension among African-Americans. Roughly 34 percent have high blood pressure, compared with about 16 percent of whites. But William Dressler finds the greatest incidence of hypertension among blacks who are upwardly mobile achievers. "That's probably because in mundane interactions, from the hank to the grocery store, they are treated in ways that do not coincide with their self-image as respectable achievers," says Dressier, an anthropologist at the University of Alabama. "And the upwardly mobile are more likely to encounter discriminatory white culture." Lab studies show that stressful situations -- like being followed in grocery stores as if you were a shoplifter -- elevate blood pressure and lead to vascular changes that cause hypertension. "In this case, race captures social factors such as the experience of discrimination," says sociologist David Williams of the University of Michigan. Further evidence that hypertension has more to do with society than with biology: black Africans have among the lowest rates of hypertension in the world.

If race is not a biological explanation of hypertension, can it offer a biological explanation of something as complex as intelligence? Psychologists are among the strongest proponents of retaining the three conventional racial categories. It organizes and explains their data in the most parsimonious way, as Charles Murray and Richard Herrnstein argue in "The Bell Curve." But anthropologists say that such conclusions are built on a foundation of sand. If nothing else, argues Brace, every ethnic group evolved under conditions where intelligence was a requirement for survival. If there are intelligence "genes," they must be in all ethnic groups equally: differences in intelligence must be a cultural and social artifact.