Welcome to brain Stuff from how Stuff Works High brain Stuff Lauren Vogel bomb here for ages. Humans have divided our species into groups based upon skin color. The shade of one's complexion has been a powerful influence upon human culture, affecting everything from where we live and how much money we make, to how much political power we have, and throughout history, racial divisions based upon skin color have led
to violence and war. That's all persisted because people cling to the belief that people of different skin colors are inherently different from one another, even though scientists have been telling us for years that race is a distinction that we invent in our minds, that there isn't much actual difference in the genetic makeup of humans of various hues. Now, an international team of researchers has published a groundbreaking study in the journal Science that may demolish the concept of
race as a biological concept once and for all. It found that genetic variations for lighter skin color neither exists solely nor originate in European populations, challenges the idea of using skin color as a racial classification and shows that skin color may only be skin deep. The scientists examined the genetic origins of skin color in Africans, who vary widely in shade, from the dark skin of the Dinka people in South Sudan to the light complexions of the
sun in South Africa. As an accompanying news story in the journal Science explains, the team used a light meter to measure the degree to which more than two thousand individuals skin reflected light. They also gathered blood samples for genetic studies. The focus upon Africans was significant because most studies of the genetic underpinnings of race have been based upon European subjects, a choice that's provided an incomplete and
perhaps misleading picture. We spoke with the studies corresponding author, Sarah Tishkoff, who's a genetics and biology professor at the University of Pennsylvania, via email. She said this is part of a general bias that exists in human genetic studies, which focus primarily on European populations. This results in a bias in our knowledge about genetic factors influencing both normal
variable traits like skin color as well as disease risk. Specifically, studies that focused only on Europeans missed many of the genetic variants which we identified as associated with skin color. This is because there's less genetic and phenotypic I. E. Skin color variation in that population compared to Africans. Also, many of the variants identified in Europeans are of recent origin.
Prior to our study, it wasn't recognized that variants associated with both light and dark skin are common in Africa, and many are very old. Also, our study shows that both light and dark skin has been evolving in humans. Prior to our study, that emphasis has been only on why light skin is adaptive in Europeans. Our study changes our understanding of the evolutionary history of variation and skin color. The scientists identified eight genetic variations in four regions of
the human genome that influenced skin shade. Using genetic information from nearly one thousand, six hundred people, They examined more than four million single nucleotide polymorphisms. That is, places where the familiar DNA code made up of proteins represent by the letters G, A, T, and C may differ by only one letter. Those genes turn out to be the ones that have spread all over the planet, showing that many of the gene variations that cause light skin color
in Europeans actually originated in Africa. The ubiquitous nature of skin color genes and their persistence over thousands of years makes racial divisions seem pretty much meaningless from a biological viewpoint. Tishkov said, I think that work strengthens what so many geneticists and sociologists already know that race cannot be defined
based on genetic criteria. There have been many abuses committed in the past and in the present based on that assumption, so hopefully this and other studies will help dispel the notion of genetically defined racial groups due to genetic variants shared among populations around the world. The new data also shines a light on human evolution, supporting the notion of an early history migration of biologically modern humans out of Africa following the southern coast of Asia into Australo Melanesia,
plus a secondary migration into other regions. Tishkov to build upon the study and explore other questions that remain about the genetics of skin color, she said in her email. We want to better understand the biological mechanisms by which these variants are impacting skin pigmentation. Our study has implications
for better understanding skin pigmentation disorders and melanoma risk. We're also looking at the genetic basis of other adaptive traits, as well as genetic and environmental factors influencing disease risk in ethnically diverse African populations. Today's episode was written by Patrick J. Keiger and produced by Tristan McNeil. For more on this and the lots of other evolutionary topics, visit our home planet, as to works dot com.