Scientifically, Race Is Only Skin Deep And Not Very Useful
WOE BETIDE scientists who find themselves on the “politically correct” side of a debate. All their opponents have to do is slap that label on them and they’re toast.
So it has gone for biologists who conclude that the popular conception of race — typically defined by skin color, facial features and hair type — has no deeper, biological relevance. They are met with disdain or worse by their opponents, who believe that race is indeed scientifically and medically meaningful. If race is only skin deep, ask the traditionalists, how can anthropologists infer the race of a skeleton? Why do blacks respond differently from whites to some heart drugs?
The answer emerging from genetics labs is that it isn’t race that accounts for such differences, but the much narrower, more precise groupings of ancestry or ethnicity.
The debate over whether race matters biologically has been largely abstract, but that’s about to change. Earlier this year, the Food and Drug Administration recommended that scientists running clinical trials of new drugs ask participants their race and ethnicity: American Indian, Asian, black, white, or Pacific Islander; Hispanic/Latino or not. The premise is that physiological response to a drug — complications as well as how well it works — reflects genes, and that those genes can be predicted by which of these 10 categories you fall into. Race couldn’t get any more biologically valid than that.
IN THE WAKE of the FDA’s “draft guidance,” however, prominent geneticists are warning that analyzing drug response by self-reported race is a recipe for medical disaster. For one thing, self-report is inherently problematic. Six million Americans in the 2000 census picked two or more races to describe themselves. But the problem is more fundamental.
Response to medication does partly reflect a patient’s genes, but not those genes that reflect race, argues Craig Venter of the Center for the Advancement of Genomics, Rockville, Md., who led the private effort to sequence the human genome. Analyzing response to drugs based on self-reported race, therefore, “could result in misleading and biologically meaningless conclusions,” he and TCAG’s Susanne Haga argue in a recent issue of the journal Science.
Sickle-cell anemia, for instance, is more common in parts of sub- Sahara Africa than it is globally. But if you focus sickle-cell prevention efforts on blacks, you’ll miss the millions of southern Italians, eastern Mediterraneans, Middle Easterners and southern Indians who also carry the defective gene. Wherever malaria was common, so is the sickle-cell gene.
Geneticists find that when they add up the tiny genetic variations that make one person different from the next, there are more differences within races than between races. In December, scientists led by Marcus Feldman of Stanford University reported that 93% to 95% of genetic variations reflect within-group differences. Less than 5% reflect differences between races.
Obviously, people whose ancestors lived for generations in one region of the world look different from people whose ancestors inhabited a climatically different region. The descendants of Vikings look different from the descendants of Nubians. Skin color, facial features and hair type reflect genes selected by evolution to allow their carriers to thrive in the place they call home.
ANCESTRY REFLECTS something genetically real, explaining why forensics can identify a skeleton’s race, says anthropologist C. Loring Brace of the University of Michigan, Ann Arbor. Some DNA sequences differ enough from population to population that scientists can tell a skeleton comes from someone whose ancestors were, say, Bretons and not Maori, or Lapps and not Manchurians. From that, you can identify the subject’s native continent, and thus the broader category of race.
Focusing on race, however, runs the risk of missing the trees for the forest. “Assigning a racial classification to someone hides the biological information that you need to make intelligent medical decisions,” says Prof. Feldman. “An African-American or Hispanic could have any mix of ancestries.”
In fact, genes coding for skin color, facial features and hair type are atypical. Differences between races in those genes simply do not reflect larger, medically meaningful differences. As Prof. Feldman and colleagues write in the journal Nature, genes for hair and skin and facial features “vary between races much more than genes in general.”
The thousands of other genetic traits, invisible to the naked eye, do not neatly sort themselves by one’s ancestral continent. If you group people by ABO blood groups, Europeans and Africans are more closely related. If you group people by genetic traits that matter medically — the justification for race-based health data — the utility of race is just about nil.
Knowing ancestry, in contrast, could well prove useful in understanding variable responses to drugs. Best of all is a patient’s actual genetic information. Because race alone can mislead, confusing race and ancestry could be devastating for medical practice. Sometimes, politically correct is scientifically correct, too.
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