When Did European Adults Finally Evolve to Drink Milk?
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There will be a flood of ancient DNA evidence coming out soon, including analyses of genes not just denoting ancestry but also functional DNA. Here’s a preview from last year.

From Science a year ago:

Warrior skeletons reveal Bronze Age Europeans couldn’t drink milk

Ability to digest dairy as an adult evolved later—and much more quickly—than scientists thought

About 3000 years ago, thousands of warriors fought on the banks of the Tollense river in northern Germany. They wielded weapons of wood, stone, and bronze to deadly effect: Over the past decade, archaeologists have unearthed the skeletal remains of hundreds of people buried in marshy soil. It’s one of the largest prehistoric conflicts ever discovered.

I wrote about the Tollense River battle four years ago when I got into the Late Bronze Age Collapse. Archaeologists’ back-of-an-envelope calculations are that there were 4,000 combatants, which sounds like a lot for a site at 54 degrees north. It took a long time to adapt Fertile Crescent crops to the latitude of Edmonton, Canada.

So, what were all the warriors getting their calories from? Milk?

I guess not:

Now, genetic testing of the skeletons reveals the homelands of the warriors—and unearths a shocker about early European diets: These soldiers couldn’t digest fresh milk.

Searching for more insight into the battle, researchers sequenced the DNA of 14 of the skeletons. They discovered the warriors all hailed from central Europe—what is today Germany, Poland, and the Czech Republic. Unfortunately, their genetic similarity offers little insight into why they fought.

“We were hoping to find two different groups of people with different ethnic backgrounds, but no,” says study co-author Joachim Burger, a geneticist at the Johannes Gutenberg University of Mainz. “It’s disappointingly boring.”

I suspect they need more than 14 skeletons to be sure of getting samples from both sides. Lots of battles turn into massacres when one side breaks and runs. I guess analysis of the bones might suggest whether most died from wounds from the front (a battle) or the back (a massacre).

However, two of the 14 skeletons were women, suggesting a more complex scene than archaeologists had reconstructed.

The study, published today in the journal Cell Biology, turned up a different surprise, too. None of the warriors had the genetic mutation that allows adults to digest milk, an ability known as lactase persistence that’s common in many Europeans.

Other studies have shown lactase persistence was common in parts of Germany by 500 C.E., and widespread across the region by 1000 C.E. So the gene must have spread before that time, but after the battle just 2000 years earlier. That means that within about 100 generations, the mutation had penetrated populations across Europe. “That’s the strongest selection found in the human genome,” Burger says.

The finding only deepens the mystery of lactase persistence. In a 2007 study, Burger showed that Europe’s first farmers, living more than 8000 years ago, weren’t lactase persistent either. At the time, he argued that the mutation gradually spread along with the development of agriculture and herding, a theory supported by signs of milking and cheese- and yogurt-making in Stone Age Europe. People able to digest milk, the argument went, would be able to get more calories from their herds than those without, and more of their children would survive to pass on the gene.

But the Tollense skeletons show that at least 6000 more years went by before the gene for lactase persistence caught on. The DNA results also quash the theory, first proposed in 2015, that the gene for lactase persistence was imported to Western Europe at about 5000 B.C.E. by cow-herding nomads from the steppes of modern-day Ukraine and Russia, the Yamnaya people.

I thought that was a Cochran and Harpending theory in their 2010 book?

The results leave scientists more puzzled than ever about exactly when and why Europeans began to drink milk. “Natural genetic drift can’t explain it, and there’s no evidence that it was population turnover either,” says Christina Warinner, a geneticist at Harvard University and the Max Planck Institute for the Science of Human History who was not involved with the study. “It’s almost embarrassing that this is the strongest example of selection we have and we can’t really explain it.”

[Comment at Unz.com]

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