Skin color has been used as a landmark of race dating back to centuries. Is skin color an accurate characteristic of the difference between races? Dr. Tishkoff and colleagues have proven this notion is false, publishing the first large-scale study on the genetics of skin color in Africans. The study identified eight genetic variants in the human genome that influence pigmentation (either promoting lighter skin or darker skin color). The gene variants are seen across the world, an example is individuals from Europe and hunter-gatherers in Botswana both having light skin colors (a gene dating back around 900,00 years ago). The shared genes are identified in humanity’s distant ancestors, dating back before Homo sapiens emerged. The research conducted provides evidence that gene variants on skin color are widely distributed and conserved through centuries of evolution thereby refuting the biological concept of race.
Understanding skin color begins with melanosomes which are sacs containing pigment molecules. There are two types of pigment cells, eumelanin which is a mixture of brown-black and pheomelanin, a mixture of yellow-red. The more eumelanin you have, then the darker the skin and vice versa. This theory has been studied heavily in people of European ancestry. The gene mutation of SLC24A5 causes individuals with paler skin due to less pigment being produced in the melanosomes. Even though there is plenty of research documenting pale skin in European descendants, Nicholas G. Crawford (co-author of the study) states that there is a small amount of research done in regards to why people have dark skin.
The study conducted by Dr. Tishkoff and colleagues started in the 2000’s, examining 1,570 individuals from Ethiopia, Tanzania and Botswana. Dr. Tishkoff was interested in African populations, since she noted there is a large amount of skin color variation presumably due to the genetic variants identified in the study. The study identified eight gene variants that accounted for 29% of the variety in skin color present in the individuals analyzed. One of the genes is MFSD12 which had no known purpose initially in the body. Researchers altered the gene to investigate its function in lab mice and found that the mice (who were initially red) turned gray with the presence of MFSD12 gene. The conclusion was MFSD12 gene functions in producing eumelanin (brown-black) and expressing darker skin tones in individuals. This gene along with the other 7 are present in many populations across the globe; meaning that the variants for skin color existed in our distant forbears prior to Homo sapiens(expressing dark, light or even a blended single skin color).
Another concept about the wide spectrum of skin color is said to be due to population’s exposure to sunlight. People who live closer to UV light are said to have darker skin color (more pigmentation cells) to protect the skin. While individuals living in places with less light have lighter skin to help absorb sunlight (utilized in the production of Vitamin D). The evidence from this study supports this theory but also adds that people’s skin color has not solely evolved due to evolution favoring ultraviolet light exposure.
The explanation for these gene variants seen across the globe is gene flow. Dark-skinned individuals of Australia, New Guinea and parts of India were probably introduced to genes by Africans through migration. Gene flow can also be seen in light skinned individuals in Britain who retain Neanderthal gene variants that date back to African ancestry (when Africans migrated to Europe and Asia). The migration and interbreeding of individuals from different continents has led researchers to realize there is a large mixture of genes causing the widespread skin color spectrum. It is not as simple as saying dark-skinned individuals are from one continent and light-skinned individuals have ancestors from another continent. This study expresses that there is a mixture of genes in which very distant ancestors contained both genes (dark and light pigments) and through evolution a divide occurred along with environmental factors (such as UV light).
Skin color is evident in every individual and usually the first thing you notice about someone but I’ve learned that it is not as simple a concept as you might think. I have lived in various countries around the world where the population varies in skin color despite a common environment. Now knowing about several gene mutations shared by individuals, I can better understand why we have different (but ancestrally similar) skin colors. Having learned this semester about skin color and UV exposure in relation to evolution, this study added to the complexity and made me think what other factors might determine one’s skin color. The theory that skin color was present in ancestors long before Neanderthals and presumably had a mixture of both light and dark skin reiterates how skin color is just a phenotypic expression and doesn’t necessary have a race attached to it. The interbreeding of individuals and migration of people is clearly evident even centuries ago since there are common ancestral genes we all share. The evolution of skin color is more complex than we think and with research like Dr. Tishkoff, we are given more information that can be added to better understand the evolution of skin color. Assuming based on skin color that an individual is a part of a particular race does not hold any validity. Furthermore this study shows that we share common ancestry of skin color genes even before humans existed leading to the question, could we be considered one race? In today’s world with vast diversity of individuals and constant migration (gene flow), could a new skin color variant be added to the spectrum?
Article Source: Zimmer, C. (2017, October 12). Genes for Skin Color Rebut Dated Notions of Race, Researchers Say. The New York Times. Retrieved October 14, 2017 from https://www.nytimes.com
Original Paper: Tishkoff,S., Crawford, N. (2017) Loci associated with skin pigmentation identified in African populations. Science. DOI:10.1126/science.aan8433. Retrieved from http://science.sciencemag.org/content/early/2017/10/11/science.aan8433
Chanel Athulathmudali
Biology In the news 
The skin color is mostly used to distinguish human appearance. The most interesting part of this article is that ultraviolent light does not determine individual skin color alone but there are also certain genes involve. It is good to know that the presence or absence of a gene called SLC24A5 play role in selecting skin color. My understanding is that light skin people have less pigment due to mutation of SLC24A5 , what exactly is the cause of this gene mutation?
The article that I read this week stated that most people associate Africans with dark skin but different groups of people in Africa have different skin color……….why? the answer is simple, it must be the gene variants!
Edith Okeke
http://www.sciencemag.org/news/2017/10/new-gene-variants-reveal-evolution-human-skin-color
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The most interesting thing to me about this article is how relevant it is to today and how much it could influence a very wide variety of peoples thinking. The emphasis on race as a whole is something to be discredited on many accounts and this study gives a brilliant example of why. If it was shared widely it could have potential to change some particularly stubborn people’s minds on a very important topic. I also found the bit about the MFSP12 gene and the way it changed mice fur very interesting. It took me slightly by surprise that the one gene changed the fur completely.
If I had the chance to ask Dr. Tishkoff any questions I would first want to know what sparked the idea he had for this study initially. I would also be interested to know what steps led him to the different discoveries he has made so far and what he plans to do next.
This study challenged my ideas of skin color being based mainly on UV exposure. It was clear to me that genetics and the passing down of genes related to skin color was what decided the shade of skin but I still thought that that was mainly determined by ancestors location in relation to UV exposure. This study showed a completely different side of things that influence skin color and added another level to my understanding of the multiple factors leading to the color of skin.
There isn’t anything necessarily that I have read in educational articles or scientific studies regarding this, however, there something popping up almost daily in the news, on television and other media sources, and in everyday passing of conversation of something having to do with race or someone’s feelings towards a specific race or something awful that happened due to feelings on a particular race. An example of this would be an online article I saw recently about the increase in acts of racism since the recent election. The validity and credibility of this source could definitely be questionable as it is not academic whatsoever, but it does show an example of how prevalent feelings based on race still are and what studies like this could help change.
http://www.slate.com/articles/news_and_politics/politics/2016/12/hate_in_america_a_list_of_racism_bigotry_and_abuse_since_the_election.html
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