Science has had a complicated history with the word “race.” In the 19th century, Dr. Samuel Morton believed humans could be divided into five races following a specific hierarchy of intelligence. He assumed he could measure their intelligence based on measurements of their skull capacity, which is a line of thought now seen as the origin of scientific racism.

At minimum, people like Morton used “race” to categorize humans into different subspecies. This doesn’t make sense in light of modern ecology, which says different subspecies must be defined by differences in genetics – not something as simple as skull capacity. When scientists first sequenced full human genomes and then compared them to each other, they began to doubt that humans could be subdivided into different subspecies the way other organisms are. 

Scientists grew even more skeptical of human subdivisions when they compared the history of humans to that of our closest relative, the chimpanzee. Since genetic tests could show that chimpanzee populations have evolved into distinct races, scientists wondered whether humans have done the same. For a species to evolve into two separate subspecies, the two subgroups must be unable to mate with each other for a long enough period of time that they develop distinct characteristics from one another. Most of the time, separate species evolve when geographic barriers such as a mountain or river separates a small group of individuals from their original community. Chimps, for instance, drifted apart genetically as they found themselves secluded in different geographic regions. Humans, however, are incredibly mobile and our ancestors were able to surpass any potential geographic barrier that separated groups enough to produce subspecies. In addition, most scientists concede that humans have not been on Earth nearly long enough to evolve into subspecies. For reference, humans evolved about 200,000 years ago while chimpanzees evolved over 5 million years ago.

Scientists compared human and chimpanzee DNA to investigate genetic differences.

In the end, the true test of whether or not different “races” are in fact subspecies was our genetics. Scientists used DNA from both chimpanzees and humans from around the globe to determine if they could create a phylogenetic tree — in essence, a family tree showing evolutionary lineage — for each species. First, they evaluated how different the DNA from two samples of either humans or chimps must be from each other to signal a new subspecies. Next, they tried to match these genetic differences to known boundaries, such as differences in geographic location. The studies pointed to one major fact: unlike the chimpanzees, no “trademark” group of genetic differences could distinguish one major group of humans from another. In other words, chimpanzees could be subdivided into subspecies, but humans could not.

Further studies finally debunked race as a biological marker for humans for two key reasons. First, we cannot distinguish a “white” person, for example, from a “black” person by looking at their genetics, alone. Skin color is determined by a number of genes, and so even if a certain set of genes suggests someone may have dark skin, an entirely separate set of genes could also make their skin lighter. In addition, humans are so mixed that any physical features that may have arisen, such as height or skin color, do not clearly “belong” to one group of people. Moreover, the traits we might see in a particular white person — blond hair, blue eyes, light skin — are not grouped together in our DNA. In other words, many characteristics that we consider as racial traits are not inherited as a fixed combination. Having light skin has nothing to do with one’s having blue eyes (or being tall, or liking math, for that matter).

So while there are differences between people – sometimes physical ones we can pick up on – these variations are relatively small and the lines are blurred between different populations. These groups cannot be biologically defined because we’re much more similar to each other genetically than we are different from each other physically.

The second reason scientists don’t think race has a biological basis is that even when they are able to group humans in quasi-distinct categories, their genetics reveal that their divisions do not line up with the social concept of race. In fact, there is more genetic diversity in Africa alone than in all other continents combined. There is so much variation within one “race” that two random Italian people are likely to be just as genetically different from each other as a Korean person and an Italian person.

Still, people — including some scientists — continue to hold onto the idea that race is linked to inherited traits. They ask questions like, “If race has no biological grounding, how can one explain why African American women in the United States are more likely to die from breast cancer than Caucasian women? Or why Native Americans have the highest rates of diabetes?”

But a true comparison between these different categories of people would require, like all scientific experiments, a controlled environment (which in many cases may not be ethically or practically possible). In the US, individuals of different races tend to not have equal access to healthcare, healthy food, and proper living conditions. These differences can exacerbate the onset of disease in underserved communities because individuals may find it more challenging to take care of their own health. Due to these social factors, we cannot draw conclusions about an individual’s innate or genetic predisposition to certain medical outcomes.

The label of race has, undoubtedly, a prominent cultural impact. And yet, it has no scientific basis.

So, if racial groups provide very weak proxies for genetic diversity, should the idea of race be phased out altogether? Well, maybe not. Scientists continue to use race as an experimental variable, but not for the reasons that one might expect. On one hand, a doctor running a clinical trial should not make medical predictions based on a person’s race, since his or her assumptions could lead to errors. For example, many physicians once considered cystic fibrosis to be a “white” disease, according to Michael Yudell, a professor of public health at Drexel University in Philadelphia. This skewed research efforts towards European countries and prevented clinicians from correctly diagnosing the disease in African Americans. Researchers have made little to no effort investigating this disease in Africa.

According to Yudell, a doctor should, instead, consider the social conditions to which their patient’s race might have been subjected to — such as living conditions, medical history, life stresses, etc. This consideration would allow researchers to target their treatment towards those who are most likely to have the disease being studied. Discrimination does produce disparities in health, so scientists and doctors should make sure experiments and clinical trials include equal representation, as this may produce results that are generalizable to more people.

What about phasing out race beyond scientific and medical scenarios? While the different races in which humans are categorized have no biological basis, the word “race” should not yet be eliminated from our vocabulary. Race is a construct based largely on skin color and, in some cases, language and geographical location, that has affected countless individuals and groups throughout history and present day. Simply ignoring race because we know it is man-made is not the same thing as finding equality.   

Striving for a colorblind society can be counterproductive if it causes people to avoid topics related to racism instead of responding to them. Labels like race give credit to those individuals who needed to travel further in order to reach the same finish lines. In fact, recognizing that race has no biological grounds could be the first step towards addressing the social factors that have allowed racial discrimination and inequality to persist. Yes, our diversity and individuality come from differences in our DNA. But instead of using our diversity to divide us, we can use our differences in perspectives, and in our strengths, to make a difference in our world. 


  • Ege Yalcindag

    Ege Yalcindag is a fourth-year undergraduate student at the University of Chicago studying biology and French who hopes to attend medical school after college. Along with cuddling newborns in the NICU, she loves singing with her a cappella group, painting, and drinking tea. She can be found on Twitter ( or LinkedIn (

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On April 8th, 2024, a total solar eclipse will sweep across North America, from Mexico to the Maine-Canadian border. For those who experienced the spectacular solar eclipse of 2017, this one will be similar, crossing the United States from west to east and passing through or near several major metropolitan areas. And while its path is quite different this time, Carbondale, Illinois, a reasonable destination for Chicago-area residents, will once again be on the line of totality.    

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