Further Studies of Skin Colour Challenge Racial Misconceptions
Recent studies have started to shed new light on how wrong assumptions are about the relationship between race and skin colour.
Gizmodo reports, in a new study of indigenous southern African people published in Cell, researchers report that the number of genes involved in skin pigmentation increase in number, as well as complexity, the closer they reside to the equator.
The team are from the Broad Institute of MIT and Harvard, Stanford University, and Stony Brook University. Brenna Henn, a study of the author and researcher at Stony Brook, explained, “It’s often under-appreciated how much skin pigmentation variation there is in Africa. Between people in Ghana and South Africa there is a big difference in skin pigmentation. Even within this one population in South Africa we see a lot of variation. Some people are quite light-skinned and some are quite dark-skinned.”
During the study, the researchers spent seven years with KhoeSan people, interviewing them, recording details such as height, age, gender, and using a reflectometer to measure skin colour.
After which they then genotyped each sample, looking at hundreds of thousands of spots on the genome to identify markers associated with pigmentation, and sequenced those particular regions. They later them compared the new dataset to one which was comprised of 5,000 people from across the globe.
Although it would be assumed the closer people are to the equator, the darker they are, and the further away they are, the lighter they are in pigment. However, the results from this study present a far more complex view. They discovered that, in the north, they found, it’s generally true that the farther north in latitude you go, the lighter the complexion.
But, the closer you move to the equator, the more complex things become. It is here that a greater number of genes begin to affect skin colour, resulting in an increased chance of variability. This is known as “stabilising selection.”
The scientists managed to successfully attribute approximately 10% of that variation to genes already known to impact skin colour.
From studying this, the team also discovered new insights into particular genes. A mutation in one gene, named SLC24A5, is thought to have cropped up in Europe some 10,000 to 20,000 years ago. However, in the KhoeSan population, it appears much more frequently than would be expected, suggesting that it either first arose in the KhoeSan people, firsy entered into the population through mating thousands of years ago, or perhaps even it showed up more frequently over time because it produced some genetic advantage to the KhoeSan people specifically.
The latest study, alongside the above previous coverage from us, proves how colour lines are meaningless. Skin colour is the result of a number of different genes working together in different combinations to produce different colours of skin.
The most recent study suggests a new perspective. In genetics, the vast majority of data has been gathered from Northern Eurasian populations, and that in turn has created a biased and incomplete portrait of how the genetics of things such as skin colour, really work.
Brenn concluded, “There’s been so little research done outside of European populations. We wanted to see if our models would apply to other populations. It turns out it doesn’t.”