In 2003, the anthropologist Duana Fullwiley spent six months observing a team of biomedical research scientists. The team wanted to find out whether genetic variation could affect how different people respond to drugs, and to do so, they recruited a group of racially and ethnically diverse research subjects. They were a diverse team themselves, with good intentions to address a worthy problem—it’s well known that different races suffer from health problems at different rates and can respond differently to treatments. If they could trace these discrepancies to genetic differences between races, the team reasoned, they could explain, and perhaps start to resolve, these health disparities.

After observing their work, the anthropologist asked each of them a simple question: How would you define race?

“You know—probably I haven’t given that as much thought as I should have,” said the team’s lead scientist. Others fumbled, paused, or dodged the question. When pushed, one researcher acknowledged that racial categories didn’t mean that much but in the same breath insisted that defining races genetically was the way to go. Not one could offer a coherent answer.

British science journalist Angela Saini tells this story in her exceptional and damning book, Superior: The Return of Race Science. “Race was the entire premise upon which they were doing their research, but they were unable to tell her what it was,” writes Saini. “Their work instead seemed to rest upon a hope that if they just persisted, they would eventually come to find meaning in these categories. What they couldn’t yet define would then be defined. Somehow it would become real.”

In the 16 years since the anthropologist made her observations, scientists have still not found any meaningful biological definition of race. All human genomes are 99.5 percent identical, and although it’s true that the remaining 0.5 percent can vary in ways that correlate with geographical ancestry, these correlations do not strictly map to racial categories. If you hand a scientist your genome, she might be able to tell you something about the geographical distribution of your ancestors, but she cannot tell you what race you are. There’s simply nothing in the genome that’s an unambiguous marker of race. And yet, many scientists and doctors continue to use race as if it’s a meaningful biological category.

Saini’s book comes at a time when race science is making a startling comeback. Ethno-nationalists like Steve Bannon channel race science when alluding to the “naturally aggressive and violent” tendencies of black people. White nationalists chug milk as an absurd means of “celebrating” that people of northern European descent more commonly have a genetic trait that enables them to digest lactose as adults. Professional gadflies like Sam Harris fan the flames by presenting race science as forbidden knowledge that a politically correct left is trying to suppress. These are all disturbing turns, but what’s more surprising is the way race biology has creeped further into the mainstream: In 2018, prominent geneticist David Reich wrote an op-ed for the New York Times calling for a renewed look at this troubling line of scientific inquiry. In medicine, drugs are sometimes labeled for—and marketed to—different racial and ethnic groups. More broadly, the popular misconception that DNA ancestry tests prove “race” or “ethnicity” has also only helped reinforce the assumption of innate biological differences between what are, in fact, socially defined categories.

In Superior, Saini expertly chronicles the broader social forces that have reinvigorated race science. She’s at her strongest, however, when investigating the role scientists have consciously or unconsciously played in the origin, perpetuation, and resurgence of this deadliest of ideas. Scientists today tend to think of themselves as experts who deal only in scientific fact, rather than as unwitting agents of political ideologies. In the molecular machinery of cells, they see themselves as seeking a higher truth. But, writes Saini, scientists are not immune to the political forces that shape us all: “We automatically translate the information our eyes and ears receive into the language of race, forgetting where this language came from.” Like almost everyone else, Saini writes, scientists struggle to think outside of a biological conception of race.

For such a weighty topic, Superior is a surprisingly easy-to-read blend of science reporting, cultural criticism, and personal reflection. Taking us from a remote site in Western Australia where recently discovered cave drawings predate those in Europe to a posh area of Paris that contains the hidden ruins of a colonial-era “human zoo,” Saini connects the dots from the dawn of modern scientific ideas about race during the Enlightenment to their abandonment after the horrors of World War II to their revival by today’s milk-chugging white nationalists in the age of genomics and DNA ancestry testing. For many on the left, Saini’s book will reaffirm the simple narrative that far-right, fact-challenged white supremacists are abusing science for sinister political ends. But she’s also telling a far more complex and surprising story about the relationship between science and race today, one that is sure to challenge anyone who thinks these ideas are only kept afloat by avowed racists.

Saini interviews a number of scientists, who insist they are “apolitical” or that “the data speak for themselves.” They seem dismissive of the idea that cultural assumptions could shape their science. This blind spot is where Saini takes aim, showing again and again how conceptual muddiness around race leads even brilliant scientists astray. Take David Reich, the geneticist who wrote the New York Times op-ed. Reich calls race a social construct, then claims, “it is simply no longer possible to ignore average genetic differences among ‘races.’ ” He goes on to provide numerous examples to prove his point, but they confusingly commingle ancestry and race—a distinction Reich makes earlier in the very same op-ed. “The data, the theories, the facts themselves, are rotated and warped until they fit into a racial framework we can relate to,” Saini writes. “This is the power of race. It is the power to twist science to its own ends.”

To illuminate this power, Saini offers the cautionary tale of the search for “black genes.” In the United States, hypertension is far more common in black Americans than in other groups, and heart attacks and strokes are more likely to kill a black American than a white American. This has caused scientists to speculate there might be some intrinsic biological factor that explains these disparities. One hypothesis, put forth in the 1980s, was that black Americans metabolize salt differently as a legacy of the slave trade: Slaves who retained more salt would be less susceptible to dehydration and so more likely to survive when crossing the Atlantic. “It was an evocative story, giving the tragic brutality of slavery an extra poignancy,” Saini writes. “Sensitivity to salt, which had helped some through the brutal journey across the Atlantic, landed their unfortunate descendants in the twentieth century with the fatal scourge of hypertension.” The hypothesis felt so correct and compelling that by 2007 even Oprah and Dr. Oz were discussing it on TV. But for years, no one could find proof for the slavery-hypertension hypothesis, or for any other biological differences between black Americans and other groups that could explain the different rates of hypertension. “If anything could settle the debate once and for all,” Saini writes, “it would be the glittering new science of genomics.”

Finally, in 2009, a team found five genetic variants associated with blood pressure in black Americans. People were excited about the results, and the study was part of a movement to search for genetic causes of racial health disparities. “In that moment it felt as though there really might be a whole host of tangible genetic differences between races that would help science get to the root of disproportionate ill health in black Americans,” Saini writes. Millions of dollars were poured into similar genetic research. Then, in 2012, when another team tried to replicate the results in twice as many people, the effects of the five gene variants disappeared into the background.

The hunt for genetic culprits, which, again, grew out of an honest desire to find a solution, seemed to blind many scientists to nonbiological explanations. A 2011 study discovered that level of education predicted whether a black American would have hypertension far better than genetic ancestry. Further studies found other nongenetic factors that could explain the higher rates, including living in a city, eating a diet high in salt, or excessive stress. “Despite heavy resources poured into finding a gene, researchers have still found no association or mechanism that can fully account for higher hypertension in black Americans,” Saini writes. “The weight of evidence so far points elsewhere.”

There’s a far simpler explanation for what causes higher hypertension or, really, any health disparity between racial groups. Saini interviews Dorothy E. Roberts, a law and sociology professor at the University of Pennsylvania. Roberts points out that trying to attribute health disparities to genetic variation already makes no sense—some black Americans have mostly European ancestry, some have mostly Asian ancestry, and some have mostly Native American ancestry. Any individual black American could have almost any genetic background—ancestry is not synonymous with race. What black Americans have in common is that America has created a deeply unequal world for black Americans to inhabit. Black Americans have, on average, less access to health care and less money to spend on health care. They have less access to healthy food. They are more likely to live in polluted areas. We know that these lived experiences correlate with worse health outcomes and shorter life spans. “The most plausible, to me the only possible, explanation could be because of inferior social conditions,” Roberts told Saini.

What’s at stake here, scientifically, is that scientists’ focus on genetics to explain racial health disparities may come at the expense of other, much-needed research. If it’s racism that has very real health consequences, and if racism could in fact better explain perceived racial differences than genetics, then we should be investing more in studying health and racism. But addressing how unequal housing, food, education, and wealth lead to poor health is much less attractive—both scientifically and commercially—than inventing a special pill to help black people.

This is an argument that many sociologists, historians of science, and others have put forward for decades. Even some scientists recognized this early in the age of genomics. In 2004, Francis Collins, then director of the National Human Genome Research Institute, wrote, “In many instances, the causes of health disparities will have little to do with genetics, but rather derive from differences in culture, diet, socioeconomic status, access to health care, education, environmental exposures, social marginalization, discrimination, stress and other factors.”* In other words, if you are a black American with cancer, it’s likely less about a “black gene” than about the American experience of being black.

But in the years since, biomedical researchers have continued their search for genetic explanations without appearing to consider the relevance of lived experience. In 2016, a team led by public health researchers and former New York City Health Commissioner Mary T. Bassett searched the medical literature since 2000 and found 47,855 review articles discussing race and health. Only 1,996—about 4 percent—contained any mention of “racism.” According to Saini, Bassett’s paper is a warning “that scientists were too often turning to biology to answer questions that could so clearly be better explained by social inequality.”

Racialized thinking is such a deep part of America’s national psyche—the psyche of scientists included—that there’s an overwhelming pull to seek out biological mechanisms to explain racial health disparities. In the case of blood pressure and salt sensitivity, Saini reminds us, “People wanted so much for the story to be true, to be able to link the trauma of slavery to the trauma of black American deaths today, that they couldn’t look past it to more mundane explanations.”

Too heavy a focus on race-based medicine not only has public health implications; it also has political ones. As ethno-nationalism surges, the tacit stamp of scientific approval for race as a biological category is increasingly dangerous. No matter what scientists’ intentions, race-based medicine and biomedical research reinforces the notion of innate biological differences between racial groups, feeding racist ideas. “This doesn’t mean that racial categories shouldn’t be used in medicine or in science more generally,” writes Saini. But it does mean that when using racial categories, Saini writes, scientists “should fully understand what they mean, be able to define them, and to know their history. They should at least know what race is.”

It’s easy to see why scientists might bristle at Saini’s work. Both here as in her previous book, which focuses on science and gender, Saini holds a mirror up to the modern scientific enterprise, and the reflection is not flattering. I can find at least one explanation for scientists’ naïveté in my own experiences as a former research scientist and current instructor of aspiring research scientists: Scientists are required to take ethics courses, but these courses tend to focus on the ethical behaviors of scientists and the ethical ramifications of science. In other words, we consider how science percolates out of the lab and into the broader culture. What we tend not to address is how the broader culture finds its way back into the lab to influence our science. A small step would be for us to spend more time thinking not only about how our science shapes society, but also how society shapes our science. (After reading Saini’s books, I suggested we add such a section to the ethics course my department offers.) The best scientists relentlessly question their own scientific assumptions. It might make for even better science if they used this same self-awareness to question their cultural ones.