When Donald Trump invoked genetics at a campaign rally in Minnesota in September 2020, commentators were quick to connect his language to the eugenics and Nazi science of the early 20th century. “You have good genes, you know that, right?” Trump asked his nearly all-white audience. “You have good genes. A lot of it is about the genes, isn’t it, don’t you believe?” The implication was that—by dint of its race—his crowd was genetically distinct from, and superior to, the Black and brown immigrants that Trump consistently disparaged and targeted with his administration’s policies.
This perspective, explicitly endorsed by some on the political far right today, was once the mainstream scientific view. Today, however, most scientists don’t take the idea of biological races seriously—partly thanks to Richard Lewontin, a Harvard University evolutionary biologist who died in July at age 92. Lewontin made his name in the 1960s, when he demonstrated, using populations of wild fruit flies, that individuals of a species are far more genetically diverse than scientists had previously imagined.
In 1972, Lewontin took his interest in genetic diversity in an explicitly political direction when he published a paper demonstrating that only about 6 percent of human genetic variation exists between conventionally defined racial groups; the rest can be found within those groups. By surveying how alternative versions of particular blood proteins—coded for by subtle variations of the same genes—were distributed throughout the human population, he was able to figure out just how much genetic overlap exists among racial groups.
If, for example, all white people had turned out to have type A blood and all Black people type B, the idea of genetically distinct racial groups would have been partly validated. But if half of people in both groups had type A blood and half had type B, all of the genetic variation would exist within the groups, not between them. Reality, Lewontin found, was far closer to the latter scenario. More recent experiments surveying a much wider variety of genes have validated Lewontin’s findings.
He concluded the 1972 paper with a statement that would look shockingly political in the scientific journals of today. “Human racial classification is of no social value and is positively destructive of social and human relations,” he wrote. “Since such racial classification is now seen to be of virtually no genetic or taxonomic significance either, no justification can be offered for its continuance.” The paper was seminal—according to Google Scholar, it has been cited more than 3,000 times—and constitutes a major pillar of support for the aphorism “race is a social construct.”
“The idea that there was more variation within a group than across groups is an old one. That had been there for decades,” says Jonathan Marks, professor of anthropology at the University of North Carolina at Charlotte. “What Lewontin did was put numbers on it. And that was very powerful.”
Since the 1970s, new technologies have changed the landscape of genetics markedly: Large-scale genomic studies have shifted the way that scientists understand the relationship between genes and behavior. “Lewontin was prescient in anticipating that, with the major public investment in genomics, genetics would take a primary seat in terms of trying to explain disease—as well as, increasingly so, social behavioral traits,” says Sandra Lee, professor of medical humanities and ethics at Columbia University. As the power and sophistication of genetic technologies continue to grow, Lewontin’s work remains remarkably current.
One of Lewontin’s great bugbears was his Harvard colleague E. O. Wilson, who held strong and influential opinions about the role of genetics in determining social behavior in animals and humans alike. With his 1975 book Sociobiology: The New Synthesis, Wilson popularized the idea that behaviors ranging from altruism to aggression to sexual mores can best be explained by reference to evolutionary pressures. Lewontin believed that Wilson unjustifiably assumed—largely on the basis of animal research—that many human behaviors and characteristics, from creativity to conformity, must have been selected for during the evolutionary history of the species. Lewontin argued that this idea represented just one more resurgence of the regressive conviction that biology was destiny, which, he said, had been used to shore up social hierarchies for centuries.