“We are all Africans under our skin” is a common quote of Dr. Spencer Wells a population geneticist who heads the National Geographic Society Genographic Project. What does he mean?
Our species, Homo Sapiens, evolved in eastern Africa about 200,000 years ago. About 70,000 years ago due to various factors our species almost went extinct. It is estimated that our total population shrank to about 2,000 individuals. As a result of our near extinction, we are not nearly as genetically diverse as most other species. Humans are 99.9% identical from a DNA perspective. In fact, there is greater genetic variability within racial groups than between racial groups.
Humans migrated out of Africa into Europe about 70,000 years ago. Genetic studies of ancient remains find that the genetic markers for pale skin and other Caucasian features didn’t first arise until about 8,000 years ago. Thus, until quite recently, just a few thousand generations, all humans lived in Africa and until hundreds of generations ago, even humans living in ancient Europe had dark skin.
A closing quote from Dr. Wells: “The kinds of differences that people notice, such as skin pigmentation, limb length, or other adaptations are basically surface features that have been selected for in the environment. When you peer beneath the surface at the underlying level of genetic variation, we are all much more similar than we appear to be. There are no clear, sharp delineations.”