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Europeans became fairer 5000 years ago because of diet and sexual preference

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Evidence gathered by analyzing DNA from ancient Europeans has shown that 5,000 years ago, the residents of Europe had dark skin.

A team of researchers have found that Europeans gradually became lighter in color in the last 5,000 years. The team that conducted the study was composed of geneticists, archeologists and anthropologists from a number of universities from around the world. The international team published their findings in the online journal Proceedings of the National Academy of Sciences (PNAS).

"Prehistoric Europeans in the region we studied would have been consistently darker than their descendants today," said anthropologist Sandra Wilde from the Johannes Gutenberg University (JGU). "This is particularly interesting as the darker phenotype seems to have been preferred by evolution over hundreds of thousands of years. All our early ancestors were more darkly pigmented." Wilde is also one of the authors of the study.

The earliest Homo sapiens were known to have dark skin, eyes and hair that is still common in modern day Africans. As these early humans walked out of Africa, the effects of natural selection gradually caused changes in the features of various groups of humans around the world.

"In Europe, we find a particularly wide range of genetic variation in terms of pigmentation," said Karola Kirsanow, a scientist from the Palaeogenetics Group in Mainz University. "However, we did not expect to find that natural selection had been favoring lighter pigmentation over the past few thousand years." 

For humans living in areas that are exposed to large amount of UV light, high levels of the pigment melanin can help protect the body from the effects of UV light. UV light is known to damage DNA and cause a number of skin diseases. For humans who left Africa for the cooler areas of the north, lower levels of UV light may have caused a gradual decrease in the levels of melanin.

"We were expecting to find that changes in the human genome were the result of population dynamics, such as migration. In general we expect genetic changes due to natural selection to be the exception rather than the rule. At the same time, it cannot be denied that lactase persistence, i.e., the ability to digest the main sugar in milk as an adult, and pigmentation genes have been favored by natural selection to a surprising degree over the last 10,000 years or so," said study senior author Joachim Burger. "But it should be kept in mind that our findings do not necessarily mean that everything selected for in the past is still beneficial today. The characteristics handed down as a result of sexual selection can be more often explained as the result of preference on the part of individuals or groups rather than adaptation to the environment."

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