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Europeans Were Lactose Intolerant After Agriculture

Oct 21, 2014 04:49 PM EDT

DNA from an ancient human skull is shedding new light on the prehistory of Europe, showing that our ancestors were lactose intolerant for the first 5,000 years after they adopted agricultural practices, according to a new study.

Thousands of years before they evolved genes that could process lactose - natural sugar in the milk of mammals - Europeans were dealing with dairy. It wasn't for 5,000 years after agriculture - 4,000 years after the onset of cheese-making among Central European Neolithic farmers - that they could actually enjoy their dairy without having to run for the bathroom after.

For the study, an international team of scientists examined ancient DNA extracted from 13 individuals in archaeological burial sites located in the Great Hungarian Plain, an area known to have been at the crossroads of major cultural transformations that shaped European prehistory. The bones at the site span about 5,000 years, from 5,700 BC to 800 BC, ranging across the Stone, Copper, Bronze and Iron Ages.

After much experimentation, the researchers found that the petrous bone, a pyramidal bone at the base of the skull, was the best place for DNA analysis.

"The high percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold," the study's joint senior author Ron Pinhasi, an archaeologist at the University College Dublin in Ireland, said in a statement. "This gave us anywhere between 12 percent and almost 90 percent human DNA in our samples compared to somewhere between 0 percent and 20 percent obtained from teeth, fingers and rib bones."

Such accurate DNA analysis revealed surprising findings from the skeletons.

"Our findings show progression towards lighter skin pigmentation as hunter and gatherers and non-local farmers intermarried, but surprisingly no presence of increased lactose persistence or tolerance to lactose," added Pinhasi.

"This means that these ancient Europeans would have had domesticated animals like cows, goats and sheep, but they would not yet have genetically developed a tolerance for drinking large quantities of milk from mammals."

The scientists detailed their findings in the journal Nature Communications.

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