Natural Selection For Skin Color Varies With Latitude

MedicalReseaerch.com Interview with:

These are South African individuals in a household that exemplify the substantial skin pigmentation variability in the Khomani and Nama populations. Picture taken with consent for publication.

These are South African individuals in a household that exemplify the substantial skin pigmentation variability in the Khomani and Nama populations. Picture taken with consent for publication.
Image by Brenna Henn

Alicia R. Martin PhD, Postdoc
Department of Genetics
Stanford University
Department of Medicine, Massachusetts General Hospital and Harvard Medical School
Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA and

Brenna M. Henn, Phd, Assistant Professor
Department of Ecology and Evolution
SUNY Stony Brook, NY 

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Skin pigmentation varies more in Africa than in any other continent, and yet genetic studies of this and other traits are massively underrepresented there. Previous Eurasian study biases have instead focused on populations that vary less and have fewer variants contributing to baseline skin color.

In our study, we compiled quantitative skin color measurements from a large, globally diverse set of individuals and populations to show that pigmentation varies more closer to the equator than in high latitude populations. We focused on the ‡Khomani San and Nama populations from South Africa, which diverged early along the modern human lineage from other populations and have lighter skin than equatorial Africans. We showed that skin pigmentation is roughly 100% heritable, but that previously identified genes make up a tiny fraction (~10%) of the variation present in these populations. We identified both known and new genes contributing to this variability.

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