When you think about race, you probably think about skin color. Although the shade of your skin might seem to be the most variable trait in regards to race, we know surprisingly little about it. That's especially true when it comes to Africa and the wide variety of skin tones found there.
Now, a landmark new study has seen scientists investigate the genetics of skin color among people in Africa. Their study, published in the journal Science, gathered genetic information from over 1,500 people and data on skin color from over 2,000 people from some of the most diverse regions of the African continent, making it the largest study of its kind to date.
According to the researchers, their findings challenge the idea of a biological concept of race.
“When people think of skin color in Africa most would think of darker skin, but we show that within Africa there is a huge amount of variation, ranging from skin as light as some Asians to the darkest skin on a global level and everything in between,” said Sarah Tishkoff, a geneticist at the University of Pennsylvania, in a statement.
Their analysis found eight genetic variants within the human genome that are associated with skin pigmentation. They discovered that most variants associated with light skin (now most common in Europeans) and dark skin appear to have both originated in Africa. Furthermore, the oldest version of these variants in most cases was associated with lighter skin, suggesting that moderately pigmented skin evolved before darkly pigmented skin.
Most of these genetic variants associated with light and dark pigmentation appear to have emerged more than 300,000 years ago – a time before the origin of modern humans. Some variants even emerged up to 1 million years ago.
"If you were to shave a chimp, it has light pigmentation," Tishkoff added, "so it makes sense that skin color in the ancestors of modern humans could have been relatively light. It is likely that when we lost the hair covering our bodies and moved from forests to the open savannah, we needed darker skin. Mutations influencing both light and dark skin have continued to evolve in humans, even within the past few thousand years."
The region with the strongest ties to skin color was the area around the SLC24A5 gene, which arose more than 30,000 years ago. A variant of this is believed to play a role in lighter skin colors found in European and south Asian populations. It turns out that it’s also common in some populations in Ethiopia and Tanzania. Similar variants around MFSD12, OCA2, and HERC2 were shown to lighten the skin of the African San hunter-gatherer population as well as in Europeans.
In sum, the history of skin color is a lot more complex and muddled than we thought. This in itself challenges the centuries-old idea that race, skin color, and genetics are all neatly linked together.