The Biology of Skin Color

Our human ancestors in Africa likely had dark skin, which is produced by an abundance of the pigment eumelanin in skin cells. (See the related animation.) In the high ultraviolet (UV) environment of sub-Saharan (or equatorial) Africa, darker skin offers protection from the damaging effects of UV radiation. Dr. Jablonski explains that the variation in skin color that evolved since our human ancestors migrated out of Africa can be explained by the tradeoff between protection from UV and the need for some UV absorption for the production of vitamin D.

This film is appropriate for science classes from middle school to college. The content connects to key concepts in biology, human biogeography, genetics, and anatomy and physiology. Chemistry and biochemistry classes will appreciate the focus on the effects of UV radiation on DNA, folate degradation, and vitamin D synthesis.

An interactive version of the film, with embedded assessment pause points, is available to stream at http://www.hhmi.org/biointeractive/skin-color-interactive-video

Watch this video on our YouTube channel »

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SD (WMV) 143 MB
Transcript (PDF) 211 KB

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Tips From Teachers

“I use this film in my AP Biology class during my evolution unit, with an activity based on Tom Shelberg's article,'Teaching How to Answer "Why" Questions about Biology' in the January 2001 issue of American Biology Teacher. One of the questions I ask is 'Why does skin color tend to get lighter as people live farther away from the equator?' After some discussion, we then watch the film and the students realize that, not only has skin color been evolving, but so has our understanding of the process. Having a resource with relevance to both biology and society gives us a great start to the year.” -- Karen Lucci (Hopewell Central High School, NJ)