David Reich in the New York Times:
In 1942, the anthropologist Ashley Montagu published “Man’s Most Dangerous Myth: The Fallacy of Race,” an influential book that argued that race is a social concept with no genetic basis. A classic example often cited is the inconsistent definition of “black.” In the United States, historically, a person is “black” if he has any sub-Saharan African ancestry; in Brazil, a person is not “black” if he is known to have any European ancestry. If “black” refers to different people in different contexts, how can there be any genetic basis to it?
Beginning in 1972, genetic findings began to be incorporated into this argument. That year, the geneticist Richard Lewontin published an important study of variation in protein types in blood. He grouped the human populations he analyzed into seven “races” — West Eurasians, Africans, East Asians, South Asians, Native Americans, Oceanians and Australians — and found that around 85 percent of variation in the protein types could be accounted for by variation within populations and “races,” and only 15 percent by variation across them. To the extent that there was variation among humans, he concluded, most of it was because of “differences between individuals.”
In this way, a consensus was established that among human populations there are no differences large enough to support the concept of “biological race.” Instead, it was argued, race is a “social construct,” a way of categorizing people that changes over time and across countries.
It is true that race is a social construct. It is also true, as Dr. Lewontin wrote, that human populations “are remarkably similar to each other” from a genetic point of view.
But over the years this consensus has morphed, seemingly without questioning, into an orthodoxy. The orthodoxy maintains that the average genetic differences among people grouped according to today’s racial terms are so trivial when it comes to any meaningful biological traits that those differences can be ignored.