Ever since the fall of the Nazis, the world has tried to keep the biology of racial disparity under wraps. It has been acceptable to link racial differences to social and cultural factors. One race might underperform another because of upbringing or poverty. But suggesting biology as the cause for those differences - like "The Bell Curve" did a decade ago when it looked at academic achievement - was strictly taboo.
Now, a new and unexpected force - medicine - is pulling back the covers. By taking a close look at minute differences in people's genetic codes, researchers and drug companies are beginning to create racially based drugs and treatments.
Given the prospect of targeting treatment, some scientists argue that the subject at least ought not to be taboo. Even if race eventually proves to be a crude and insufficient means of understanding genetic differences, it can play an important interim role, they say. Others worry that these voices fail to capture the larger picture: how past claims of "scientific" race and ethnic differences, now debunked, have been used to oppress, even kill, minorities.
"To use the rhetoric of science to sell the idea that historical inequity should be embraced as biological inevitability is an insult to those who value a common humanity," wrote researcher Richard Cooper of the Loyola University medical school in a January article in the American Psychologist. "Race is not a concept that emerged from within modern genetics; rather, it was imposed by history, and its meaning is inseparable from that cultural origin."
Indeed, scholars in recent decades had concluded that racial designations are fuzzy, so hard to pin down that people's self-reporting of their race had become the only useful method of designating race. In the 1990s the work of the Human Genome Project - an international effort to sequence and map all human genes - seemed to add legitimacy to this view. At the genetic level, humans are nearly indistinguishable from one another, 99.9 percent alike.
But as the genome project neared completion in 2003, scientists began to look harder at the 0.1 percent of genes that differ. Their hope: that understanding these differences would open up a new era of medicine based on each patient's genetic makeup.
In recent months, race-based medicine has gained momentum:
• The Food and Drug Administration is expected to approve the drug BiDil in June, making it the first "ethnic drug" on the market. After failing in a broader study, BiDil was shown to be effective in treating heart failure in a clinical study that included only African-Americans.
• The HapMap Project, expected to be completed this year, aims to map haplotypes - sets of closely linked genes that tend to be inherited together. Such a map would be a rich resource, say researchers, in finding genes that affect diseases and individual responses to drugs. The project is studying samples from people in Nigeria, Japan, China, and the United States. Some worry that analyzing differences by country could be used to suggest racial differences.
• African-Americans need higher doses of one medication used to treat asthma than Caucasians, suggesting "an inherent predisposition" in blacks not to absorb the medicine as easily, says a study in the February issue of the journal Chest.
• A study in the American Journal of Human Genetics showed a correlation between the way participants identified themselves by race with groupings of genetic "signposts" among their DNA. "This shows that people's self-identified race/ ethnicity is a nearly perfect indicator of their genetic background," said Neil Risch, who led the study at Stanford University's medical school.
• A study by biotech firm Perlegen Sciences, published in a Feb. 18 edition of Science, found variations in the SNPs of people that matched their ethnic backgrounds. SNPs (single nucleotide polymorphisms) are small changes in the sequence of DNA between individuals.
"As more and more SNP patterns are discovered, and they coincide with social groups, they will place in the hands of those who want to see it evidence for the genetic explanation for complex behaviors," says Troy Duster, president of the American Sociological Association. The idea that intelligence, physical ability, predisposition to crime, or even religious beliefs may have a simple genetic explanation easily grabs the public's interest, he says. But these conclusions are "huge and unwarranted leaps from SNP patterns."
Much of what we're seeing in human illness can be explained by "issues as prosaic and mundane as access to healthy water and good nutrition," says Professor Duster, who teaches at New York University and the University of California at Berkeley. For example: A 2002 report by the Institute of Medicine showed that racial and ethnic minorities tend to receive lower-quality healthcare than whites, even if factors such as insurance status, income, age, and severity of condition are similar.
Many in the field are calling for broader international studies to make sure the bigger picture emerges. Studies comparing white and black Americans, for example, have shown that blacks have higher rates of hypertension, suggesting a genetic difference. But earlier this year research by Dr. Cooper and a team at Loyola showed that although African-Americans do show higher levels than North American whites, whites have higher levels than Nigerians and Jamaicans, who are "ethnically" black. Overall, the range of levels of hypertension among blacks in the study ranged from 14 to 44 percent while in whites it was higher, 27 to 55 percent.
" 'Race' and 'ethnicity' are poorly defined terms that serve as flawed surrogates for multiple environmental and genetic factors in disease causation, including ancestral geographic origins, socioeconomic status, education, and access to health care," wrote Francis Collins, the head of the National Human Genome Research Institute (NHGRI), last fall. "Research must move beyond these weak and imperfect proxy relationships to define the more proximate factors that influence health."
Race, Duster worries, "can leave its own indelible mark once given even the temporary imprimatur of scientific legitimacy by molecular genetics."
But other researchers say they expect to keep finding genetic racial differences and that society must learn to become comfortable with the idea. "New forms of scientific knowledge will point out more and more ways in which we are diverse," wrote geneticist James Crow, a professor emeritus at the University of Wisconsin, in a 2002 article. "I hope that differences will be welcomed, rather than accepted grudgingly. Who wants a world of identical people, even if they are Mozarts or Jordans?"
Even 0.1 percent in differences among humans includes millions of variables and "those differences are very important," says Kim Nickerson, co-editor of a special issue of American Psychologist in January focused on race and genes. Where the field is headed is far from settled, he adds. "We're years away from a practical application of much of what we might find in terms of the individual differences."
Can scientists - and the public - hold these two seemingly conflicting ideas in mind at once: that we are genetically different but we are also all one species?
"I think race is an important variable" in understanding genetics, says Vence Bonham, senior adviser to the NHGRI. But "individuals of the human race are of one race.... And we need to make sure that's the message that the public understands."