Tag Archives: Ancestry

What DNA Says About Human Ancestry—and Bigotry

I found this article interesting. The original source can be found here. Specifically:

Mitochondrial DNA indicates that all living humans descend from one maternal source—christened Mitochondrial Eve—who lived in Africa between 100,000 and 200,000 years ago. Similarly, the Y chromosome shows that all men have a common ancestor, Y-chromosome Adam, who lived at the same time. (Actually, both analyses indicate that modern humans descend from a small founding population of about 5000 men and an equal number of women.) The time estimates are based on assumptions on how frequently genetic mutations occur. The mutation clocks of mitochondrial DNA and the Y chromosome tick at different speeds, so the fact that they both indicate humans emerged at the same historical moment makes this evidence much more convincing…

Not only is our concept of race arbitrary, but it is based on a relatively insignificant difference between people. Skin pigment, eye shape, and hair type are all determined by genes. Indeed, as the human genome is mapped, geneticists might be able to reconstruct what mummies or other ancient people looked like. But the physical ”stereotypes” of race, writes Cavalli-Sforza, ”reflect superficial differences.” For example, light skin color is needed in northern climates for the sun’s ultra- violet light to penetrate into the body and transform vitamin D into a usable form. This mutation may well have arisen at different times, in different ancestral groups, on different points along the DNA. That’s true for cystic fibrosis, which occurs almost exclusively in people of European descent but is caused by several different mutations…

In other words, ”white people” do not share a common genetic heritage; instead, they come from different lineages that migrated from Africa and Asia. Such mixing is true for every race. ”All living humans go back to one common ancestor in Africa,” explains Paabo. ”But if you look at any history subsequent to that,” then every group is a blend of shallower pedigrees. So, he says, ”I might be closer in my DNA to an African than to another European in the street.” Genetics, he concludes, ”should be the last nail in the coffin for racism.” …

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