Skin Color Has a Biological Basis. Race Does Not

Foreword by Susan Eckert (teacher)

This post is written as a collaboration between student and teacher. The topics in this post are challenging and complex. As a teacher, I have been dwelling on the genetics of race for years now and always felt that I did not do the topic justice in the classroom. I see this post as an opportunity to work with a student and make some progress on how to more effectively teach my students about the biological basis of race (beyond just saying there is none). All science in this post and the entire blog is supported by evidence. However, this post, like many on the blog, gives both student and teacher the space to discuss the intersection of science and morality. Science is a distinctly human effort to understand the natural world and it does not exist in a vacuum--history and context matters.

The Biology of Melanin by Shannon Huhn (student)

Did you know that your skin is the largest organ of your body, your first line of defense against pathogens and your primary defense against the sun's damaging rays thanks to melanin? Melanin is an invaluable pigment that is found in all humans (and in many other organisms)--its key functions that protect us from Earth’s harsh conditions are necessary for our survival. For example, did you know that the melanin you produce protects you every time you step outside? One of melanin’s prime functions is to protect the epidermis (the top layer of your skin) from the ultraviolet (UV) radiation from the sun. Melanocytes, cells where melanin is produced, can absorb UVA and UVB rays that can be harmful to your skin and increase the risk of skin cancer by damaging DNA. This is why your skin gets darker during the summer--your body produces more melanin in response to increased sun exposure.

The classic "farmer's tan" which results from the skin responding to increased UV exposure by producing more melanin. Source

Melanin also has some lesser known advantageous features, such as the ability to absorb scattered light rather than light beams within the eyeball, which can sharpen visual perception. Melanin is the biggest contributor to eye color--dark colored irises have a higher concentration of melanin and lightly colored irises have a lower concentration of melanin. There is no blue or green pigment that produces eye color in humans--it's all melanin and the way the light scatters as it hits the iris.

Different properties of melanin have been influenced by human evolution. For example, two different types of melanin have been the result of evolution. Eumelanin and pheomelanin can influence how dark or light your skin tone is--those with lighter skin have higher amounts of pheomelanin, and those with darker skin have higher amounts of eumelanin. Interestingly, we all have roughly the same amount of melanocytes and what differs is the amount and type of melanin the melanocytes produce. Since each person has different levels of these two types of melanin based on genetics/ancestry and the environment, there is a large variety of skin tones across the globe and in the US. Here is a TED talk on the beautiful variation of skin color among humans.

Variation in skin color in a family. Source

However, the amazing biological purpose of melanin has been stained through the detachment of its biological importance with the creation of the concept of race and the idea of racial superiority. The result of white colonizers adding value to skin color and associating darker skin with inferiority in 16th and 17th century North America set the foundations for a country that thrived in the hands of slavery and discrimination by creating complex systems that blatantly favored those with lighter skin. Although many Americans believe that we have made great strides to create a more equal nation, this simply isn’t true. Slavery and racial inferiority haven’t disappeared. The system has evolved from slavery to Jim Crow to the “war on drugs” to mass incarceration and police brutality. Most recently, this phenomenon has manifested with the murders of Black Americans at the hands of police officers, sparking greater media coverage across the country. Americans of all ages, races, and ethnicities have taken to the streets to demand change in institutions that only benefit those with lighter skin.

Black Lives Matters protestors in NYC on June 9th, 2020. Source

As the fight for racial justice continues in the coming political era, it is imperative that we keep biological concepts straight. That is, we must remember that the properties of melanin and melanin production that create skin color were caused by human evolution. It is our duty to keep in mind that race is a social construct; society’s perception of race has been convoluted by bigotry and hatred. However, the claims of racial superiority have persisted for so long that it would do more harm than good to try to detach the biology of melanin and the social constructs that have followed. We must educate ourselves on the biological and social aspects of skin color, and how we benefit from centuries-old systems. Without this, we will never be able to amplify Black voices and create a future that is just and equitable for all, regardless of one’s complexion.

Genetics and Race by Susan Eckert (teacher)

I'm going to get straight to the point: there is no biological basis of race. It is a social construct and my primary goal is to provide enough knowledge about the variation of the human genome to allow the reader to easily refute those that try to use science to promote an agenda of racist ideology. The idea of a biological basis for race has a long and dark history based on biological determinism, which led to eugenics, the justification of genocide, colonialism, and slavery. When I started college in 1990, I knew that I wanted to pursue a career in genetics. My freshman seminar was about eugenics and we read Stephen Jay Gould's Mismeasure of Man. Stephen Jay Gould was a paleontologist, evolutionary biologist, historian of science and a well-known science communicator. The book forcefully criticizes against biological determinism that used skull measurements, known as craniometry, and psychological testing, and then assigning worth to an individual based on these measurements. There has been some criticism about the book's data analysis but the premise of the book I stand behind.

Craniometry. Source

If there is no biological basis for race, the logical question is where did the idea of biologically distinct races come from. We can trace the use of science to promote distinct races back to the publication of a book in 1775 by a German physician and scientist named Johann Friedrich Blumenbach, who used craniometry to create a model of five distinct races. With advances in genetics, we can easily analyze whether there is a genetic basis for race and the answer is a definitive no. If we work with the popular notion that there are five distinct races (African, European, Asian, Oceania, and Native American), there is more genetic variability within the races than between them. Homo sapiens are 99.6-99.8% identical. There are no trademark alleles (specific versions of a gene) that distinguishes one supposed race from another. Skin color is often used to distinguish race and as Shannon explained above, the type and amount of melanin produced determines an individual's skin color. Genes that control melanin production, however, are a tiny part of the human genome and they assort independently of traits that racists use to promote their agenda, namely intelligence and behavior. White supremacists have moved on from craniometry to misrepresenting genetic data to support their view. Some white supremacists do have a solid understanding of genetics but they cherry pick the data to align with their racist world view. Apart from being morally repugnant, the approach of finding data to align with a preconceived notion is anathema to how science works.

. . . 

One year, I had a class that gently teased me for declaring one too many times that I used to be a genetic counselor. I can see their eyes rolling if they read the next sentence. Teaching is a second career for me--prior to teaching I was a genetic counselor. Why am I stating this yet again? Well, because for 9 years, I was focused solely on human genetics and a patient's ancestry played a role in both medical research and clinical care. In a medical setting, those in healthcare do routinely ask about a patient's ancestry. The operative word is ancestry, sometimes ethnicity, but not race. Gathering data about ancestry played a role in the clinical and research genetic setting because although there is no biological basis that supports distinct races, humans do cluster into broad geographical regions and knowing the ancestral history of an individual is helpful for disease screening. Mutations that arise in an egg or sperm are random but how the environments acts upon these mutations is anything but. If a mutation provides an advantage for survival and reproduction, then we say that the environment selects for that trait and it becomes more common in the population. This is called natural selection and it's the reason why people whose ancestors lived in equatorial regions tend to have more melanin: like Shannon explained, the molecule protects cells from damaging UV rays. An excellent film from the Howard Hughes Medical Institute's BioInteractive division beautifully explains the evolution of skin color as it relates to biogeography. Sometimes, though, evolution results in a disease gene being more common in people who live or whose ancestors lived in a specific region. Two classic examples are sickle cell anemia and cystic fibrosis. Sickle cell anemia is more prevalent among those living in an area where there is a high risk of malaria. Being a carrier for the disease gene (one disease gene and one gene without the sickle cell mutation) provides protection against the deadly disease. It's also more prevalent among those whose ancestors lived in areas where malaria was a risk even though the selective pressure is no longer present. Cystic fibrosis, on the other hand, is more common among White individuals, although why is still a mystery.

. . . 

So what does this all mean for the classroom? How do I teach about race when we get to the genetics unit in AP Bio? Should I even talk about it at all? It's not a topic that most biology textbooks tackle and it's not specifically in my curriculum. Genetic variation, however, is and that is why I have gone there, although not at the level I would like, and why I will continue to explore the topic with my students. The general population holds a lot of misconceptions about the biology of human variation and that of course includes students and teachers as well. Some teachers are tackling it head on. And resources to help teachers navigate the topic in the classroom do exist. 

It's crucial to stress that even though there is no evidence for a biological basis for race, we can't simply say we don't see color and act as if the social construct of race and racial identity do not matter. Instead, we should understand the role evolution and biogeography play in human genetic variation, fight racism with scientific knowledge, commit to ending racial injustice, and learn about and celebrate human genetic and cultural diversity.

Addendum: There are many hyperlinks in this blog post. The articles I (Susan) have linked to below are the ones I recommend the most.
An excellent blog post that tackles the genetics of human variation in more detail
An article in the journal Nature Genetics that dives much deeper into the science
An article in The Atlantic that focuses on the difficulty of teaching race in HS biology classes

If you have questions or concerns about the content of this post, please email Susan Eckert at seckert@montclair.k12.nj.us or suseckert@gmail.com