A Racialized Medical Genomics: Shiny, Bright and Wrong

A Racialized Medical Genomics: Shiny, Bright and Wrong

RACE-The Power of an Illusion
July 2005

Robert Wallace, Postdoctoral Fellow
Public Health Phylogeography
Department of Ecology and Evolutionary Biology
University of California, Irvine

Armand Marie Leroi announces in his Times op-ed that race is biologically real (New York Times, March 14, 2005). The crusty trope that race is a social artifact crumbles in the face of the bright new genomics, he asserts. Genetic variation may be greater within groups than between groups, as Richard Lewontin pointed out back in the dark ages of the 1970s, but only for single genes. Taken together, across genetic loci allelic distributions correlate into clusters long recognized as the five races: European, East Asian, African, Amerindian, and Australasian. So suck it up, constructionists, race is biologically intrinsic.

Moreover, get out of the way. The recognition that race is inherently biological, Leroi writes, can improve medical care, “as different races are prone to different diseases.” African Americans, for example, suffer greater prevalences of heart disease and prostate cancer. Even if such differences arise from socioeconomic causes, Leroi argues, we should—ignoring the man behind the curtain—embrace geneticists’ very important mission, “searching for racial differences in the frequencies of genetic variants that cause diseases.”

And yet much of Leroi’s article unravels his own argument. Leroi takes population geneticists to task for caving into political correctness by investigating “ethnic groups,” a euphemism that conflates human differences across scale. Never mind that population geneticists prefer the term less out of deference to present sensibilities than to the data themselves. Work by Luigi Cavalli-Sforza’s group (Cavalli-Sforza 2001, Underhill 2003), among others, show human history—back to our species’ origins—to be marked by layers of migration sweeping back and forth across the continents, gurgling here and there into local pools of idiosyncratic admixture. While the resulting genetic frequencies do not embody a homogenous mush, neither does a stark black and white favored by the new racialists result. Instead, genetic maps are marked by fine-scaled and functionally important population gradients…

…For one, according to Leroi, the pharmaceutical companies. As race can affect medical treatment, “many new drugs are now labeled with warnings that they may not work in some ethnic or racial groups.” That such effects need not be predominantly biological in origin apparently matters little. Leroi admits differences among races arise from population averages alone. But as we are unlikely to have individuals’ genomes sequenced any time soon, and presumably won’t be able to individualize medical treatment that way, we’ll just have to accept a racialized medical genetics. Nothing like an argument of expediency to convince a crowd. The pharmaceutical companies are doing it, so get with it, baby!

Here, Leroi, an evolutionary developmental biologist, bumbles back into the typology the Darwinian revolution revoked. As Ernst Mayr (1976, 2004) explained, until the early 19th century biologists classified species in essentialist terms. A specific type or specimen defined a species and any variation from the type was considered deviant or unreal. In statistical terms, a centroid measure such as the mean phenotype defined the species, while the variance was thought noise. Typological definitions accounted for the differences among species and, without variation, explained the impossibility of evolution.

Darwin and his colleagues turned biology on its head. The population thinking they introduced emphasized the variation in populations. As natural history studies accumulated, it became apparent individual organisms varied in just about any and all characteristics, both across and within species. Individuals even changed over the course of their lifespans. Here, averages became thought of as constructs and the variances the reality. Variation’s reality proved fundamental to Darwin’s natural selection. The greater the variation in the population, the faster natural selection works and adaptations arise…

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