Sci­en­tists spot genes be­hind skin color

Iran Daily - - Health -

level and ev­ery­thing in be­tween.

“We iden­tify ge­netic vari­ants af­fect­ing these traits and show that mu­ta­tions in­flu­enc­ing light and dark skin have been around for a long time, since be­fore the ori­gin of mod­ern hu­mans.

“Skin color is a clas­sic vari­able trait in hu­mans and it’s thought to be adap­tive.

“Anal­y­sis of the ge­netic ba­sis of vari­a­tion in skin color sheds light on how adap­tive traits evolve, in­clud­ing those that play a role in dis­ease risk.”

There are ben­e­fits to both light and dark skin. For ex­am­ple, darker skin is be­lieved to help pro­vide some pro­tec­tion against the Sun’s ul­tra­vi­o­let rays.

Africans don’t often de­velop the dead­li­est skin cancer, melanoma, the re­searchers said.

On the other hand, lighter skin im­proves sun­light-trig­gered vi­ta­min D in re­gions with lower amounts of sun­light, the study au­thors added.

Most of the skin color-linked ge­netic vari­ants iden­ti­fied in the study ap­pear to have orig­i­nated more than 300,000 years ago.

Some emerged roughly one mil­lion years ago, well be­fore the ad­vent of mod­ern hu­mans, ac­cord­ing to the re­port.

In many cases, older ver­sions of these vari­ants were as­so­ci­ated with mod­er­ately pig­mented skin, which sug­gested that our an­cient an­ces­tors had lighter rather than darker skin.

She said, “If you were to shave a chimp, it has light pig­men­ta­tion, 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.”

She also said the study high­lights the di­ver­sity of Africans and chal­lenges bi­o­log­i­cal no­tions of race.

She said, “Many of the genes and new ge­netic vari­ants we iden­ti­fied to be as­so­ci­ated with skin color may never have been found out­side of Africa, be­cause they are not as highly vari­able.

“There is so much di­ver­sity in Africa that’s not often ap­pre­ci­ated. There’s no such thing as an African race.

“We show that skin color is ex­tremely vari­able on the African con­ti­nent and that it is still evolv­ing.

“Fur­ther, in most cases the ge­netic vari­ants as­so­ci­ated with light skin arose in Africa.”

UPI

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