New research has found that the science of skin pigmentation may not be as simple as previously thought. A decade-long study involving the KhoeSan people of South Africa showed that there are far more genes involved in skin pigmentation.
More Complex Than Previously Believed
In previous studies, it was understood that there are only a handful of genes responsible for skin pigmentation among Eurasian and European populations. What's more, there is the idea that pigmentation occurs in a single direction, wherein it goes from light to dark in low latitudes and dark to light in high latitudes.
However, a decade-long study led by researchers from Harvard, Broad Institute of MIT, Stanford University, University of Colorado Anschutz, and the State University of New York at Stony Brook shows that there is more to skin pigmentation than previously thought.
KhoeSan People Of South Africa
In their long-term study, researchers conducted interviews and measured the age, height, and genders of about 400 members of two KhoeSan populations. They also used a reflectometer to measure their skin color.
The two groups they gathered their data from were the Khomani San and the Nama people, both of which are KhoeSan populations from South Africa with a much lighter complexion than the others who live closer to the equator.
Far More Genes Involved
What researchers found is that there are more genes involved in skin pigmentation than previously believed, many of which are yet to be discovered. In fact, only approximately 10 percent of the currently known variations can be linked to the variations in the KhoeSan people.
"Light skin pigmentation in the KhoeSan appears to be due to a combination of many small-effect mutations as well as some large-effect variants," said senior author Brenna Henn of SUNY Stony Brook. What's more, she explains that the light skin pigmentations possibly arose in southern Africa 100,000 years ago after ancient humans left Africa to go to Europe during the ancient human migration. The pigment then lightened to absorb more sunlight as they moved to higher latitudes.
Closer To The Equator
In addition to the genetic findings, researchers also found skin pigmentation also becomes more diverse in populations living closer to the equator. Basically, researchers found that there is more to skin pigmentation than just a few genetic differences.
As such, they believe that a larger and more diverse population is needed to fully understand the genetic "architecture" of the skin.
"Ultimately, in northern latitudes pigmentation is more homogenous, while in lower latitudes, it's more diverse — both genetically and phenotypically," said Alicia Martin of the Broad Institute of MIT.
The study is published in the journal Cell.