European Skin Turned Pale Only Recently, Gene Suggests

Researchers have disagreed for decades about an issue that is only skin-deep: How quickly did the first modern humans who swept into Europe acquire pale skin? Now a new report on the evolution of a gene for skin color suggests that Europeans lightened up quite recently, perhaps only 6000 to 12,000 years ago. This contradicts a long-standing hypothesis that modern humans in Europe grew paler about 40,000 years ago, as soon as they migrated into northern latitudes. Under darker skies, pale skin absorbs more sunlight than dark skin, allowing ultraviolet rays to produce more vitamin D for bone growth and calcium absorption. “The [evolution of] light skin occurred long after the arrival of modern humans in Europe,” molecular anthropologist Heather Norton of the University of Arizona, Tucson, said in her talk.

The genetic origin of the spectrum of human skin colors has been one of the big puzzles of biology. Researchers made a major breakthrough in 2005 by discovering a gene, SLC24A5, that apparently causes pale skin in many Europeans, but not in Asians.

A team led by geneticist Keith Cheng of Pennsylvania State University (PSU) College of Medicine in Hershey found two variants of the gene that differed by just one amino acid. Nearly all Africans and East Asians had one allele, whereas 98% of the 120 Europeans they studied had the other (Science, 28 October 2005, p. 601).

Norton, who worked on the Cheng study as a graduate student, decided to find out when that mutation swept through Europeans.

Working as a postdoc with geneticist Michael Hammer at the University of Arizona, she sequenced 9300 base pairs of DNA in the SLC24A5 gene in 41 Europeans, Africans, Asians, and American Indians.

Using variations in the gene that did not cause paling, she calculated the background mutation rate of SLC24A5 and thereby determined that 18,000 years had passed since the light-skin allele was fixed in Europeans. But the error margins were large, so she also analyzed variation in the DNA flanking the gene. She found that Europeans with the allele had a “striking lack of diversity” in this flanking DNA—a sign of very recent genetic change, because not enough time has passed for new mutations to arise. The data suggest that the selective sweep occurred 5300 to 6000 years ago, but given the imprecision of method, the real date could be as far back as 12,000 years ago, Norton said. She added that other, unknown, genes probably also cause paling in Europeans.

Either way, the implication is that our European ancestors were brown-skinned for tens of thousands of years—a suggestion made 30 years ago by Stanford University geneticist L. Luca Cavalli-Sforza. He argued that the early immigrants to Europe, who were hunter-gatherers, herders, and fishers, survived on ready-made sources of vitamin D in their diet. But when farming spread in the past 6000 years, he argued, Europeans had fewer sources of vitamin D in their food and needed to absorb more sunlight to produce the vitamin in their skin. Cultural factors such as heavier clothing might also have favored increased absorption of sunlight on the few exposed areas of skin, such as hands and faces, says paleoanthropologist Nina Jablonski of PSU in State College.

Such recent changes in skin color show that humans are still evolving, says molecular anthropologist Henry Harpending of the University of Utah, Salt Lake City: “We have all tacitly assumed for years that modern humans showed up 45,000 years ago and have not changed much since, while this and other work shows that we continue to change, often at a very fast rate.”

September 25th, 2008 at 6:39 pm
First of all a race does not just pop up. We evolve.

NO, HUMANS EVOLVE. RACE IS A POLITCAL TERM RECENTLY INVENTED TO REPLACE THE TERM “VARIETY” TO IDENTIFY HUMANS WITH VARIED PHENOTYPES. TO EVOLVE ISN’T ALWAYS A “GOOD” OR “BETTER” THING. BACTERIA AND VIRUSES EVOLVE.

You said their were no caucasian type skeletons. Were there any African skeletons? No. Homo neanderthalensis, homo floresiensis, homo sapiens, etc. ….IF IT IS A GIVEN BY MAINSTEAM SCIENCE, AND IT IS, THAT ALL HUMANS ORIGINATED IN AFRICA AND MIGRATED BACK AND FORTH OUT OF AFRICA, AND AFRICAN MITOCHONDRIA, BY ALL GENETIC STUDIES DONE, DEMONSTRATES THE POINT OF ANCESTRAL ORIGINS, IT WOULD ONLY FOLLOW THAT THE FURTHER BACK YOU GO IN TIME, THE LESS LIKELY YOU ARE TO HAVE WHITE PRESENCE SINCE THE ALLELE THAT CODES FOR WHITE SKIN HAS BEEN PROVEN BY WHITE SCIENTISTS TO BE RECENT AS 5-6,000 YEARS. SO NO, THERE WOULD NOT HAVE BEEN ANY CAUCASIAN SKELETONS SINCE THEY DIDN’T EXIST THEN.

You contradicted yourself aslo in saying, “Nina Jablonski claims that dark skin evolved pari passu with the loss of body hair and was the original state for the genus Homo.” But you said “1.5 million years ago when human beings first began to evolve in Africa, they had Black skin.” If they alread had black skin then why would you say black skin evolved from loss of body hair. OOPS. So they started off with black skin but then somehow grew more body hair but then lost it and became dark? What??

YOU ARE REACHING. HE QUOTED ANOTHER AUTHOR WHO BASICALLY IS TALKING ABOUT MAN EVOLVING FROM AN APE LIKE STATE TO HUMAN. LOSING THE ANIMAL HAIR, WALKING UPRIGHT, ETC. THE SKIN WOULD HAVE BEEN NATURALLY DARK BECAUSE OF CLIMATE. YOU ARE SO ANGRY AT THE TRUTH OF YOUR ORIGINS YOU ARE REACHING DOWN TO THE ABSURD AND RIDICULOUS.

And also I was thinking since you say Africans are the oldest race wouldnt that mean theyre the least evolved? Since you say caucasians are a new race wouldnt that mean theyre more evolved?

THE PYRAMID IS OLDER THAN THE EMPIRE STATE BUILDING. WE CAN DUPLICATE THE EMPIRE STATE BUILDING AND HAVE MANY TIMES. NO ONE YET HAS DUPLICATED THE TECHNOLOGY THAT WENT INTO THE BUILDING THE PYRAMID. YOUR PARENTS ARE OLDER THAN YOU. ARE YOU BETTER THAN THEY ARE BECAUSE YOU ARE THE LATEST MODEL? GROW UP AND GROW A BRAIN.

Also you said, “a more advanced people, the Neolithic, migrated to Europe from the Middle East” the middle east is not Africa. People did not wake up one day and were white and had blonde hair and blue eyes its called evolution.

AFRICANS LEFT AFRICA AS HAPLOGROUPS “M” AND “N” INDICATES, THAT IS MAJOR HAPLOGROUP L3, AND WENT ALL POINTS NORTH, EAST AND WEST. BLACK AFRICANS SETTLED THE MEDITERRANEAN, EUROPE ASIA AND POINTS WEST TO THE AMERICAS. THIS HAS BEEN PROVEN BY GENETIC TESTING TIME AND AGAIN. BACK AND FORTH MIGRATION TO THE LAST GLACIAL MAXIMUM AND FOLLOWING ITS THAW, IS THE REASON FOR THE DIVERSITY IN PHENOTYPES. MANY BLACKS GOT CAUGHT IN THE LAST ICE AGE WHICH AFFECTED EUROPE MOSTLY AND PARTS OF ASIA. WHILE THERE, THEY UNDERWENT A SEVERE MUTATION. THIS IS THE GENE VARIANT THAT MR ANNU WAS TALKING ABOUT. IT REVERSED PIGMENTATION, A NATURAL STATE OF HUMANS. THIS EVIDENCE IS INDISPUTED BY ANYONE INTELLIGENT ENOUGH TO DO RESEARCH. YOU MAY SIMPLY DO A BLOOD TEST. MTDNA. THEN COME BACK AND LET’S DISCUSS THIS SOME MORE.

Also you said, “a more advanced people, the Neolithic, migrated to Europe from the Middle East” the middle east is not Africa. People did not wake up one day and were white and had blonde hair and blue eyes its called evolution.