Alexandra D. Owens; Review: The biology of Skin Color. The American biologic Teacher 1 April 2016; 78 (4): 356. Doi: https://doi.org/10.1525/abt.2016.78.4.356

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When observing images of human being populations around the globe, the is difficult not to notification our variance in skin color. This visible range is not frequently seen in other species and even sets us apart from ours primate relatives. Like numerous other traits, skin color is one that exists together a an outcome of advancement through herbal selection. How and also why has actually this trait developed with together variety? What was once a an enig has been solved thanks to anthropology and genetics.

You are watching: The biology of skin color


In HHMI"s newest video, Dr. Nina Jablonski, a penn State organic anthropologist and also author the Living Color: The Biological and also Social an interpretation of Skin Color, takes viewers follow me on her search to fix the secret of skin color. The journey begins with one explanation the melanin, which come in two forms: reddish-yellow (i.e., pheomelanin) and black and also brown (i.e., eumelanin). Eumelanin in specific is responsible because that protecting our human body from harmful ultraviolet (UV) radiation that penetrates cells, possibly causing mutations. The narrative further defines that melanin protects cell by developing supernuclear caps the absorb UV rays, protecting the nucleus.


With this in mind, the film explores the connection in between UV intensity and skin color. Utilizing data gathered by NASA in the 1980s, a map overlay the UV radiation measurements throughout the globe is presented. The an outcome illustrates a clean gradient from the equator, with exceptions through altitude and also places with constant cloud cover. This map is then compared to a map of skin color based on skin reflectometer measurements collected by anthropologists studying aboriginal populations. A correlation does indeed exist. Wherein UV radiation is strong, skin is dark, in both equatorial and high-altitude regions. This data indicate that humans adapted to miscellaneous solar conditions over time.


Additional proof gathered through DNA sequencing comes to the forefront of the film. Geneticist Dr. Rick Kittles defines genetic mite MC1R, i beg your pardon codes because that a protein supplied in the production of eumelanin. Approximately the globe, over there is sport in this sequence, yet not in African populations where the bulk have the MC1R allele. Fossil evidence argues this has been current for about 1.2 million years. While palliation of skin cancer is the assumed explanation for its presence, skin cancer fatalities happen after reproductive age, which would certainly not have an affect on reproductive success. Rather, folate might be the influencing factor. Part birth defects are an ext common in pregnant women with a deficiency in folate, and strong sunlight breaks under this nutrient together it circulates in blood ship of the skin. This would certainly make melanin prominent in reproductive success.


This leaves the question: Why aren"t us all dark skinned if melanin gives an advantage? The price lies in the migrations of populations. While UV is harmful, UVB – a type of UV – is an essential for the synthesis of vitamin D. Close come the equator, humans get much more than sufficient UV exposure because that vitamin D synthesis to take place, even through dark skin. Yet, together populations relocate north, UV exposure decreases. It is more complicated to absorb UVB in these areas. Selective pressure for MC1R lessens and also variation occurs together a result. Supporting evidence is checked out in polar aboriginal populations the still have dark skin but additionally have a diet wealthy in vitamin D. If we need to protect ourselves native UV, over there is quiet a advantage from absorption, resulting in a balancing act driving skin colors variation. Today, v the capability to live in a range of environments, this might mean cultural adaptations such together vitamin supplements. Together her quest involves an end, Dr. Jablonski reflects that skin color is a flexible trait that transforms over time – one the is inherited separately of any kind of other trait.

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This video clip would it is in a an excellent addition to any unit ~ above evolution, adaptation, or hereditary variation. It is very engaging and also adds an individual relevance the is often absent from these topics the instruction. HHMI provides added resources because that both the teacher and also the student. The movie guide consists of background information, discussion questions, and a created assessment through key. College student resources had interactive and also traditional animations that assistance the scientific research content extended in the video, each around three minutes in length. The piece I uncovered most valuable was the task “Human Skin Color: evidence for Selection.” below you will discover a series of instance studies based upon the video. Each situation study provides real data in the kind of charts, graphs, and other visuals the students deserve to analyze and also interpret. This permits for applications of an abilities while tho engaging her classroom. Visit the website come learn more about how this video clip may attach with your middle school, high school, or university course.


REMY DOU teach high institution life scientific research for eight years before becoming an Albert Einstein differentiated Educator Fellow. He currently works as a Graduate Assistant at Florida global University contributing come STEM education and learning research. For shaft queries: rdou002

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