WASHINGTON -- Thanks to spectacular advances in molecular biology and genetics, most scientists now reject the concept of race as a valid way to divide human beings into separate groups.
Contrary to widespread public opinion, researchers no longer believe that races are distinct biological categories created by differences in the genes that people inherit from their parents. Genes vary, they say, but not in ways that correspond to the popular notion of black, white, yellow, red or brown races.
"Race has no basic biological reality," said Jonathan Marks, a Yale University biologist. "The human species simply doesn't come packaged that way."
Instead, a majority of biologists and anthropologists, drawing on a growing body of evidence accumulated since the 1970s, have concluded that race is a social, cultural and political concept based largely on superficial appearances.
"In the social sense, race is a reality; in the scientific sense, it is not," said Michael Omi, a specialist in ethnic studies at the University of California in Berkeley.
Luigi Cavalli-Sforza, an eminent professor of genetics at Stanford University, agreed. "The characteristics that we see with the naked eye that help us to distinguish individuals from different continents are, in reality, skin-deep," he said. "Whenever we look under the veneer, we find that the differences that seem so conspicuous to us are really trivial."
Scientists concede that people do look different, primarily because of the varied environments in which their ancestors lived. And they agree that as a social concept, race matters a great deal. The color of a person's skin, the texture of his hair, or the shape of her eyes can be sources of love, pride and partnership - or fear, hatred and injustice.
Many government policies - such as housing, schools and voting rights - treat "minorities" differently than whites. Resentment over "affirmative action" is a burning political issue in this year's elections. Educators, police and the military routinely ask for racial identification. The Census Bureau officially classifies every American by race, although its categories are widely criticized.
The idea that races are not the product of human genes may seem to contradict common sense.
"The average citizen reacts with frank disbelief when told there is no such thing as race," said C. Loring Brace, an anthropologist at the University of Michigan. "The skeptical layman will shake his head and regard this as further evidence of the innate silliness of those who call themselves intellectuals."
The new understanding of race draws on work in many fields.
"Vast new data in human biology, prehistory and paleontology ... have completely revamped the traditional notions," said Solomon Katz, an anthropologist at the University of Pennsylvania.
This is a switch from the prevailing scientific dogma of the 19th and much of the 20th century. During that period, most scientists believed that humans could be sorted into a few (usually three, four or five) inherited racial types distinguished primarily by skin color.
Government policies were based on alleged racial inequalities, including U.S. immigration laws designed to screen out "inferior" foreign stocks, bans on interracial marriage and the genocidal horrors of Nazi Germany.
As recently as 1985, anthropologists split 50-50 when one of their number, Leonard Lieberman of Central Michigan University, asked in a survey if they believed in the existence of separate biological races.
A dwindling number of scholars still cling to notions of gene-based racial superiority. In his controversial 1994 book, "The Bell Curve," Charles Murray, a political scientist, asserted that African-Americans inherit lower intelligence than persons of Asian or European descent.
In response to the uproar over "The Bell Curve," the American Anthropological Association adopted a statement declaring that "differentiating species into biologically defined 'races' has proven meaningless and unscientific as a way of explaining variation, whether in intelligence or other traits."
A leading holdout is Philippe Rushton, a Canadian geneticist who continues to claim that crime and violence are biologically determined tendencies.
"Among humans, three major races of Mongoloids, Caucasoids and Negroids are typically considered," Rushton wrote in the February 1996 Journal of Current Anthropology. "Genetic research has built a strong case for the importance of heritable factors [meaning genes] in personality, psychopathology, violent crime and other social variables."
"Rushton is dead wrong," snapped John Moore, chairman of the anthropology department at the University of Florida, reflecting the majority view.
As a sign of the change, Lieberman said, most anthropology textbooks published in this decade have stopped teaching the concept of biological race.
In part, the new consensus is an effort by scientists to stop the misuse of race to justify the evils of racism.