Agriculture Linked to DNA Changes in Ancient Europe

Friday, November 27th, 2015

After agriculture arrived in Europe 8,500 years ago, people’s DNA underwent widespread changes, altering their height, digestion, immune system and skin color:

Previous studies had suggested that Europeans became better able to digest milk once they began raising cattle. Dr. Reich and his colleagues confirmed that LCT, a gene that aids milk digestion, did experience intense natural selection, rapidly becoming more common in ancient Europeans. But it didn’t happen when farming began in Europe, as had been supposed. The earliest sign of this change, it turns out, dates back only 4,000 years.

While agriculture brought benefits like a new supply of protein in milk, it also created risks. Early European farmers who depended mainly on wheat and other crops risked getting low doses of important nutrients.

So a gene called SLC22A4 proved advantageous as soon as Europeans started to farm, Dr. Reich and his colleagues found. It encodes a protein on the surface of cells that draws in an amino acid called ergothioneine. Wheat and other crops have low levels of ergothioneine, and the new variant increases its absorption. That would have increased the chances of survival among the farmers who had the gene.

Yet this solution created a problem of its own. The same segment of DNA that carries SLC22A4 also contains a variation that raises the risk of digestive disorders like irritable bowel syndrome. These diseases, then, may be an indirect consequence of Europe’s pivot toward agriculture.

Dr. Reich and his colleagues also tracked changes in the color of European skin.

The original hunter-gatherers, descendants of people who had come from Africa, had dark skin as recently as 9,000 years ago. Farmers arriving from Anatolia were lighter, and this trait spread through Europe. Later, a new gene variant emerged that lightened European skin even more.

Why? Scientists have long thought that light skin helped capture more vitamin D in sunlight at high latitudes. But early hunter-gatherers managed well with dark skin. Dr. Reich suggests that they got enough vitamin D in the meat they caught.

He hypothesizes that it was the shift to agriculture, which reduced the intake of vitamin D, that may have triggered a change in skin color.

The new collection of ancient DNA also allowed Dr. Reich and his colleagues to track the puzzling evolution of height in Europe. After sorting through 169 height-related genes, they found that Anatolian farmers were relatively tall, and the Yamnaya even taller.

Northern Europeans inherited a larger amount of Yamnaya DNA, making them taller, too. But in southern Europe, people grew shorter after the advent of farming.

Dr. Reich said it wasn’t clear why natural selection favored short stature in the south and not in the north. Whatever the reason, this evolutionary history still shapes differences in height across the continent today.


  1. A Boy and His Dog says:

    Stepping over snow banks? Just a guess. But it seems like torso length is relatively the same globally, while Europeans tend to have long legs.

  2. Isegoria says:

    Europeans (Whites) have shorter limbs than Africans (Blacks) and longer torsos. Applied Anatomy and Biomechancis in Sport discusses this (on page 98.)

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