Scientific racism is the misuse of science to claim that certain racial or ethnic groups are biologically superior to others. It is not legitimate science but a pattern of pseudoscientific ideologies that has recurred for centuries, using the authority and language of research to justify slavery, forced sterilization, immigration restrictions, and genocide. Understanding how it worked, and where its traces still linger, matters because many of its assumptions were embedded so deeply into institutions that some are only now being identified and removed.
How Scientific Racism Operates
At its core, scientific racism starts with a conclusion (that one racial group is superior) and works backward, selectively gathering or manipulating data to support that belief. It treats race as a fixed biological category with predictable effects on intelligence, behavior, and health, when modern genetics has shown that race is primarily a social classification. The 1950 UNESCO Statement on Race put it plainly: “Race is less a biological fact than a social myth, and as a myth it has in recent years taken a heavy toll in human lives and suffering.”
What makes scientific racism distinct from ordinary bigotry is its packaging. By dressing prejudice in measurements, charts, and academic language, proponents gave racial hierarchies the appearance of objective truth. This made the ideas far more durable and far more dangerous, because they could be cited in courtrooms, legislatures, and medical textbooks as established fact.
Skull Measurements and Early Pseudoscience
One of the most influential early practitioners was Samuel Morton, a Philadelphia physician who in the 1830s and 1840s amassed a large collection of human skulls from around the world. Morton measured the internal volume of each skull by filling it with white pepper seed (and later lead shot), then used those measurements to rank five racial groups by supposed intelligence. His results conveniently placed Caucasians at the top, with what he called the “Teutonic Family” (Germanic peoples like the English) having the largest cranial capacity of all human groups. Africans were ranked at the bottom.
The problems with Morton’s work were extensive. The biologist Stephen Jay Gould later argued that seed, unlike lead shot, could easily be manipulated as it was packed into the skull cavity. Morton likely overstuffed Caucasian crania and only sparingly filled others, systematically underestimating the brain size of non-white groups. Morton also ignored the overlapping ranges within his own data. Skulls from every racial group varied widely in size, but Morton’s published summaries obscured this, presenting neat averages that reinforced a predetermined hierarchy. Gould’s broader diagnosis still holds: Morton carried “a priori conviction of racial ranking so powerful that it directed his tabulations along preestablished lines.”
Morton’s work became enormously influential. His measurements were cited to justify white Anglo-Saxon superiority, the doctrine of manifest destiny, and the enslavement of Africans, all with the veneer of empirical research.
Eugenics: From Theory to Forced Sterilization
The next major chapter came through eugenics, a term coined in 1883 by the English statistician Francis Galton, a cousin of Charles Darwin. Galton defined eugenics as “the study of agencies under social control that may improve or impair the racial qualities of future generations.” He claimed that intelligence, health, and social behavior were all determined by heredity and race.
Eugenicists misunderstood genetics in fundamental ways. They believed complex traits like intelligence were inherited in simple, predictable patterns, and that complex diseases were purely the result of genetic inheritance. Based on these flawed premises, they argued that society could be “improved” by encouraging reproduction among those they deemed fit and preventing it among those they deemed unfit. The methods they endorsed included involuntary sterilization, segregation, and social exclusion.
By the 1920s, eugenics had become a global movement with popular, elite, and governmental support across Germany, the United States, Great Britain, Italy, Canada, Mexico, and other countries. In the U.S., at least 60,000 people were involuntarily sterilized under laws in 30 states, a practice that continued into the 1970s. Eugenicists also shaped immigration policy directly. Harry Laughlin, designated as the “Expert Eugenics Agent” to the House Committee on Immigration and Naturalization, argued that people from eastern and southern Europe (Russia, Poland, Italy, the Balkans) were disproportionately “unfit.” Under his guidance, Congress passed the Johnson-Reed Immigration Restriction Act of 1924, which set strict national-origin quotas and completely excluded immigrants from Asia.
The most extreme application came in Nazi Germany. Between 1933 and 1945, the Nazi state used eugenics as the intellectual foundation for a campaign of forced sterilization affecting at least 400,000 people and the euthanasia of at least 70,000 adults and 5,200 children. These programs were a precursor to the Holocaust.
The Post-War Reckoning
The horrors of Nazi Germany forced a global confrontation with the ideas that had enabled them. In 1950, UNESCO convened a panel of scientists who produced a landmark statement declaring that human races “can be and have been differently classified by different anthropologists,” that race is secondary to the broader concept of population, and that “there is no definitive evidence that there exist inborn differences between human groups” in mental traits. The statement framed race as biologically meaningless in the way it had been used to rank human worth.
This did not end the debate. Scientific racism proved resilient, resurfacing in new forms whenever social and political conditions were receptive.
The IQ Controversy
Perhaps the most prominent modern revival came with the 1994 publication of “The Bell Curve” by Richard Herrnstein and Charles Murray, which argued that intelligence differences between racial groups were partly genetic and had policy implications. The book drew intense criticism from scientists across disciplines. Critics argued that it was methodologically flawed and intellectually dishonest, that there was no reason based on existing knowledge to believe differences in intelligence among racial or ethnic groups had any genetic component, and that making broad distinctions between ethnic groups to study supposed biological sources of intelligence was scientifically useless. Others pointed out that the authors lacked a general theory for why racial differences would exist, a prerequisite for responsible investigation of the question.
“The Bell Curve” illustrated a recurring feature of scientific racism: presenting contested and incomplete evidence as settled science, in ways that consistently reinforce existing social hierarchies.
Traces in Modern Medicine
Some of the most surprising legacies of scientific racism are embedded in clinical tools still used in healthcare. For decades, equations used to estimate kidney function included a “race correction factor” that automatically assigned higher kidney function scores to Black patients. The widely used MDRD equation included a Black race coefficient of 1.21, meaning a Black patient’s kidney function was calculated as 21% higher than a non-Black patient with identical lab results, age, and sex. A later equation, CKD-EPI, included a correction factor of 1.159.
These correction factors were based on observed differences in a single lab value, but the studies behind them were deeply flawed. In the MDRD study, researchers assigned race based on skin color rather than self-identification. More fundamentally, the equations failed to account for actual biological disease risk factors or the social and historical context of racism, poverty, and marginalization that drive health disparities. The result was that Black patients could appear to have healthier kidneys than they actually did, potentially delaying referrals for specialist care or transplant eligibility.
Similar race-based corrections have been used in pulmonary function tests and other clinical algorithms. These examples show how perceptions of racial difference can become embedded within practices presented as empirical and objective, persisting long after the pseudoscience that inspired them has been discredited.
Institutional Acknowledgments
In recent years, major professional organizations have begun formally reckoning with their roles in perpetuating scientific racism. In 2021, the American Psychological Association issued an apology acknowledging its involvement in developing and promoting eugenics theories that supported white racial superiority, endorsing practices like institutionalization and sterilization, and supporting anti-miscegenation laws and racial segregation. The same year, the National Association of Social Workers published a report acknowledging that the social work profession actively supported the aims and practices of eugenics programs.
These statements represent a broader pattern of institutions confronting how scientific authority was used to legitimize racial harm. The kidney function equations, for instance, have been revised in recent years to remove race-based corrections. But the process of identifying and dismantling these embedded assumptions is ongoing, touching fields from medicine to psychology to public policy, precisely because scientific racism was so effective at making its claims appear routine and objective.