Race and genetics
by Nicholas D. Kristof
WE ALL SHARE A FAMILY TREE
Oxford, England I had my DNA examined by a prominent genetic specialist here, and what do you know! It turns out I'm African American.
The mitochondria in my cells show that I'm descended from a matriarch who lived in Africa, possibly in present-day Ethiopia or Kenya.
O.K., this was 70,000 years ago, and she seems to be a common ancestor of all Asians as well as all Caucasians. Still, these kinds of DNA analyses illuminate the raging scientific debate about whether there is anything real to the notion of race.
"There's no genetic basis for any kind of rigid ethnic or racial classification at all," said Bryan Sykes, the Oxford geneticist and author of "The Seven Daughters of Eve." "I'm always asked is there Greek DNA or an Italian gene, but, of course, there isn't…We're very closely related."
Likewise, The New England Journal of Medicine once editorialized bluntly that "race is biologically meaningless."
Take me. Sykes looked at a sequence of my mitochondrial DNA to place me on a kind of global family tree. It would have been nice to learn that my ancestors hailed from a fishing village on Loch Ness, but ancestry can almost never be pegged that precisely, and I appear to be a mongrel. One of my variants, for example, is scattered among people in Finland, Poland, Armenia, the Netherlands, Scotland, Israel, Germany and Norway.
On the other hand, is race really "biologically meaningless?" Bigotry has been so destructive that it's tempting to dismiss race and ethnicity as artificial, but there are genuine differences among populations. Jews are more likely to carry mutations for Tay-Sachs, Africans for sickle cell anemia. It's hard to argue that ethnicity is an empty concept when one gene mutation for an iron storage disease, hemochromatosis, affects fewer than 1 percent of Armenians but 8 percent of Norwegians.
"There is great value in racial/ethnic self-categorizations" for medicine, protested an article last year by a Stanford geneticist, Neil Risch, in Genome Biology. It warned against "ignoring our differences, even if with the best of intentions."
DNA does tend to differ, very slightly, with race. Profilers thought a recent serial killer in Louisiana was white until a DNA sample indicated he was probably black. (A black man has been arrested in the case.) As genetic science advances, the police may eventually be able to recover semen and put out an APB for a tall white rapist with red curly hair, blue eyes and perhaps a Scottish surname.
On the other hand, genetic markers associated with Africans can turn up in people who look entirely white. Indians and Pakistanis may have dark skin, but genetic markers show that they are Caucasians.
Another complication is that African Americans are, on average, about 17 percent white: They have mitochondria (maternally inherited) that are African, but they often have European Y chromosomes. In other words, white men raped or seduced their maternal ancestors.
"Genetics research is now about to end our long misadventure with the idea of race," Steve Olson writes in his new book, "Mapping Human History."
When I lived in Japan in the 1990's, my son Gregory had a play date with a classmate I hadn't met. I asked Gregory, then 5, whether the boy's mother was Japanese.
"I don't know," Gregory replied. "Well," I asked sharply, "did she look Japanese or American?" Although he'd lived in Tokio for years, Gregory replied blankly, "What does a Japanese person look like?"
He was ahead of his time. Genetics increasingly shows that racial and ethnic distinctions are real - but often fuzzy and greatly exaggerated. Genetics will increasingly show that most humans are mongrels, and it will make a mockery of racism.
"There are meaningful distinctions among groups that may have implications for disease susceptibility," said Harry Ostrer, a genetics expert at the New York University School of Medicine. "The right-wing version of this is 'The Bell Curve,' and that's pseudoscience - that's not real. But there can be a middle ground between left-wing political correctness and right-wing meanness."
I'll be searching for that middle ground this year as I'm celebrating Kwanzaa.