by Armand Marie Leroi. In particular:
The dominance of the social construct theory can be traced to a 1972 article by Dr. Richard Lewontin, a Harvard geneticist, who wrote that most human genetic variation can be found within any given "race." If one looked at genes rather than faces, he claimed, the difference between an African and a European would be scarcely greater than the difference between any two Europeans. A few years later he wrote that the continued popularity of race as an idea was an "indication of the power of socioeconomically based ideology over the supposed objectivity of knowledge." Most scientists are thoughtful, liberal-minded and socially aware people. It was just what they wanted to hear.
Three decades later, it seems that Dr. Lewontin's facts were correct, and have been abundantly confirmed by ever better techniques of detecting genetic variety. His reasoning, however, was wrong. His error was an elementary one, but such was the appeal of his argument that it was only a couple of years ago that a Cambridge University statistician, A. W. F. Edwards, put his finger on it.
The error is easily illustrated. If one were asked to judge the ancestry of 100 New Yorkers, one could look at the color of their skin. That would do much to single out the Europeans, but little to distinguish the Senegalese from the Solomon Islanders. The same is true for any other feature of our bodies. The shapes of our eyes, noses and skulls; the color of our eyes and our hair; the heaviness, height and hairiness of our bodies are all, individually, poor guides to ancestry.
But this is not true when the features are taken together. Certain skin colors tend to go with certain kinds of eyes, noses, skulls and bodies. When we glance at a stranger's face we use those associations to infer what continent, or even what country, he or his ancestors came from - and we usually get it right. To put it more abstractly, human physical variation is correlated; and correlations contain information.
Genetic variants that aren't written on our faces, but that can be detected only in the genome, show similar correlations. It is these correlations that Dr. Lewontin seems to have ignored. In essence, he looked at one gene at a time and failed to see races. But if many - a few hundred - variable genes are considered simultaneously, then it is very easy to do so. Indeed, a 2002 study by scientists at the University of Southern California and Stanford showed that if a sample of people from around the world are sorted by computer into five groups on the basis of genetic similarity, the groups that emerge are native to Europe, East Asia, Africa, America and Australasia - more or less the major races of traditional anthropology.
One of the minor pleasures of this discovery is a new kind of genealogy. Today it is easy to find out where your ancestors came from - or even when they came, as with so many of us, from several different places. If you want to know what fraction of your genes are African, European or East Asian, all it takes is a mouth swab, a postage stamp and $400 - though prices will certainly fall.
Yet there is nothing very fundamental about the concept of the major continental races; they're just the easiest way to divide things up. Study enough genes in enough people and one could sort the world's population into 10, 100, perhaps 1,000 groups, each located somewhere on the map. This has not yet been done with any precision, but it will be. Soon it may be possible to identify your ancestors not merely as African or European, but Ibo or Yoruba, perhaps even Celt or Castilian, or all of the above.
The identification of racial origins is not a search for purity. The human species is irredeemably promiscuous. We have always seduced or coerced our neighbors even when they have a foreign look about them and we don't understand a word. If Hispanics, for example, are composed of a recent and evolving blend of European, American Indian and African genes, then the Uighurs of Central Asia can be seen as a 3,000-year-old mix of West European and East Asian genes. Even homogenous groups like native Swedes bear the genetic imprint of successive nameless migrations.
Some critics believe that these ambiguities render the very notion of race worthless. I disagree. The physical topography of our world cannot be accurately described in words. To navigate it, you need a map with elevations, contour lines and reference grids. But it is hard to talk in numbers, and so we give the world's more prominent features - the mountain ranges and plateaus and plains - names. We do so despite the inherent ambiguity of words. The Pennines of northern England are about one-tenth as high and long as the Himalayas, yet both are intelligibly described as mountain ranges.
So, too, it is with the genetic topography of our species. The billion or so of the world's people of largely European descent have a set of genetic variants in common that are collectively rare in everyone else; they are a race. At a smaller scale, three million Basques do as well; so they are a race as well. Race is merely a shorthand that enables us to speak sensibly, though with no great precision, about genetic rather than cultural or political differences.
But it is a shorthand that seems to be needed. One of the more painful spectacles of modern science is that of human geneticists piously disavowing the existence of races even as they investigate the genetic relationships between "ethnic groups." Given the problematic, even vicious, history of the word "race," the use of euphemisms is understandable. But it hardly aids understanding, for the term "ethnic group" conflates all the possible ways in which people differ from each other.