Saturday, December 28, 2019

How a Genetic Mutation Led to the White Race

Imagine a world where everyone had brown skin. Tens of thousands of years ago, that was the case, say scientists at Pennsylvania State University. So, how did white people get here? The answer lies in that tricky component of evolution known as a genetic mutation. Out of Africa It has long been assumed in scientific circles that Africa is the cradle of our human civilization​ and that it was there that our  ancestors shed most of their body hair around  2 million years ago. They quickly evolved dark skin for protection from skin cancer and other harmful effects of UV radiation. Then, says a 2005 study conducted at Penn State, when humans began leaving Africa 20,000 to 50,000 years ago, a skin-whitening mutation appeared randomly in a sole individual. That mutation proved advantageous as humans moved into Europe. Why? Because it allowed the migrants increased access to vitamin D, which is crucial to absorbing calcium and keeping bones strong. Sun intensity is great enough in equatorial regions that the vitamin can still be made in dark-skinned people despite the ultraviolet shielding effects of melanin, explains  Rick Weiss of the Washington Post, which reported on the findings.  But in the north, where sunlight is less intense and more clothing must be worn to combat the cold, melanins ultraviolet shielding could have been a liability. Just a Color This makes sense, but did scientists identify as well a bona fide race gene? Hardly. As the Post notes, the scientific community maintains that race is a vaguely defined biological, social and political concept...and skin color is only part of what race is—and is not. Scientists still say that race is more of a social construct than a scientific one because people of the so-called same race have more distinctions in their DNA than people of different races do. In fact, scientists posit that all people are roughly 99.5 percent genetically identical. The Penn State researchers findings on the skin-whitening gene show that skin color accounts  for a minuscule biological difference between humans. The newly found mutation involves a change of just one letter of DNA code out of the 3.1 billion letters in the human genome—the complete instructions for making a human being, the Post reports. Skin Deep When the research was first published, scientists and sociologists feared that the identification of this skin-whitening mutation would lead people to argue that whites, blacks, and others are somehow inherently different.  Keith Cheng, the scientist who led the team of Penn State researchers, wants the public to know thats not so. He told the Post, I think human beings are extremely insecure and look to visual cues of sameness to feel better, and people will do bad things to people who look different. His statement captures what racism is in a nutshell. Truth be told, people may look different, but theres virtually no difference in our genetic makeup. Skin color really is just skin deep. Not so Black and White Scientists at Penn State continue to explore the genetics of skin color. In  a study published in Science on October 12, 2017, researchers report their findings of even greater variants in skin color genes among native Africans. Such diversity, says  evolutionary geneticist Sarah Tishkoff, the lead author of the study, likely means that we cant even speak of an African race, much less a white one.

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.