The other day, while teaching a lecture class, one of us mentioned in passing that the average African American, according to a 2014 paper, is about 24 percent European and less than 1 percent Native American. A student responded that these percentages were impossible to measure, since “race is a social construction.”
Given our country’s history of scientific racism — and all of the horrible crimes and abuses that African Americans have been subjected to in the name of science — the fact that race is a social invention and not a biological reality cannot be repeated too much. However, while race is socially constructed, genetic mutations — biological records of ancestry — are not, and the distinction is a crucial one.
To be fair, we really can’t blame this student for being confused. To varying degrees, we have all inherited a muddled understanding of race, ancestry and phenotype from the Enlightenment, an era when European savants freed themselves from biblical explanations of the species and claimed the right to tell all of humankind — particularly Africans and people of African descent — who we supposedly are. But if we don’t disentangle these concepts, we may miss the great promise of using genetics to push back against a very long and sad history of the misuse of science for pernicious purposes.
To understand that history, it is helpful to look back at the origins of racial “science” in Europe. One of the key moments in the evolution of modern concepts of race occurred in France in 1741, when the members of Bordeaux’s Royal Academy of Sciences held a continentwide essay contest on the “cause” of dark skin and textured hair among African populations. Why, they asked, were Black people Black?
While various explanations of Black skin had been circulating since antiquity, the 1741 contest was almost certainly the first time that a scientific institution had taken up the question, extending an invitation to Europe’s best thinkers to invent origin stories about a so-called subspecies of humans based on their appearance.
The resulting essays — which came from as far as Holland, Sweden and Ireland — offer a unique window into 18th-century understandings of race. Participants wrote that blackness came from the vapors that emanated from the skin or from darkened sperm, that the power of a pregnant mother’s imagination had imprinted the color on her child, that the stifling heat and humidity of the tropics stained the skin and clouded the humors. Others hinted at the mutation of an original prototype race into humankind’s many varieties — somewhat closer to what we believe today. The most influential entry was submitted by a surgeon who, while living in the New World, had dissected the bodies of enslaved Africans. This doctor — the only contestant who ultimately published his essay — inspired a number of other anatomists to hunt for specific (and of course bogus) physiological structures in African bodies.
In a way, this contest signaled a new era of “scientific racism.” In the decades that followed, naturalists increasingly subdivided the human species into several so-called races by things like skin color, hair texture, skull shape and, most perniciously, according to supposedly transcendent essences. As Immanuel Kant put it in 1764, the fact that a man “was very black from head to foot,” was “clear proof that what he said was stupid.” See a Black face, see stupidity, and from this vicious cycle, there was no escape. This is how race ultimately came to function: as a way to divide us. And it has done so with remarkable success — and often brutal results — for hundreds of years.
Fast-forward to our era, when new advancements in technology are once again changing the way we think about human origins. With the recent rise in availability of tools for individual genetic analysis, tens of millions of people have eagerly had their DNA tested — hoping, among other things, to find out where their ancestors hail from.
Commercial DNA tests vary widely, and some trace DNA to more than 2,000 regions worldwide. These companies use autosomal (referring to the chromosomes in our genomes that are not our sex chromosomes) analysis to measure shared mutations — known as single nucleotide polymorphisms, or SNPs — that we have inherited from our ancestors, helping to reveal where they were living over the past few hundred years.
The specificity with which this new technology is able to determine individual origins is staggering. For example, one of us, Henry Louis Gates Jr., knows, purely through his DNA, that he is descended from an Irish American man who fathered his great-great-grandmother’s oldest son, because Gates’s y-DNA signature is one that he shares with a ton of men in Ireland. CeCe Moore, a well-known genetic genealogist, has identified that forebear’s name and biographical details, long a mystery in the Gates family, by analyzing the family trees of all of the people with whom Dr. Gates shares DNA in publicly available databases. On his mother’s line, he is descended from a white woman, most likely from England, who had a child with a man of sub-Saharan African descent at some point during the time of slavery, though their identities have been lost.
It would be an understatement to say that he was astonished to learn that his recent ancestral mutations trace back equally to sub-Saharan Africa and to Europe. As a friend of his joked: Who could have guessed that a Black scholar who has spent so much of his professional life searching for his long-veiled African ancestry would finally find it — only to discover that he’s half a white man. That friend’s joke allowed him to make a point: There is no category for white in genetic analysis; half of his ancestry traces back to regions in Europe. We should never forget that whiteness, like Blackness, is just another social fiction.
There can be fewer more dramatic demonstrations that race is a social construction than his own DNA results. And therein lies the promise of this new science. DNA, used in this way, can restore a remarkable amount of information about the ancestors whose traces we carry around every day in our genomes. The multitude of population clusters, regions and genetic groups reflected in DNA tests counters existing narratives that try to reduce the astonishing variety of the human community to the four or five socially constructed races of man about which prior generations of students learned in biology class.
That’s why, as historians who study race, we believe that we’re once again entering a new era. If, throughout the 18th, 19th and 20th centuries, science put an enormous amount of effort into dividing the human species into separate categories, 21st-century genetic analysis promises to reveal just how meaningless those categories are — and how connected we’ve been all along.
At a time when our society is deeply divided and when a surge of antisemitic, anti-Asian, Islamophobic and anti-Black racism threatens the social fabric, it feels urgent that we develop new language for discussing the relationship between identity, ancestry, history and science. DNA analysis could help create that language by offering more nuanced ways of looking at individual origins and a more unifying narrative about our shared heritage
But, of course, where there is promise, there is also peril. Race is, to steal a line from Wordsworth, “too much with us.” Its history is too long, its presence and usage too common, for it to magically disappear anytime soon. While, biologically speaking, the idea of individual human races with different origins is as farcical as the medieval belief that elves cause hiccups, the social reality of race is undeniable. And genetics — or, for that matter, any science — has the potential to be misused, co-opted by racist ideologies and employed to bolster harmful narratives about racial purity or biological superiority.
But if we can, at the very least, embrace the understanding that race (a toxic social construction) and ancestry (a shared genetic history) are not only distinct but also fundamentally opposed — and teach that in our classrooms — it could go a long way toward freeing us from some of the binds in which scientific racism have trapped us.
The stories embedded in our genes beg to be told. They tell of ancestral diversity that stretches back thousands of years and ultimately underscores all that we — despite superficial physical differences — have in common.
Dr. Gates is the director of the Hutchins Center for African & African American Research at Harvard University. Dr. Curran is a professor at Wesleyan University. They edited the forthcoming book “Who’s Black and Why? A Hidden Chapter From the Eighteenth-Century Invention of Race.”
The Times is committed to publishing a diversity of letters to the editor. We’d like to hear what you think about this or any of our articles. Here are some tips. And here’s our email: letters@nytimes.com.
Follow The New York Times Opinion section on Facebook, Twitter (@NYTopinion) and Instagram.
