As early humans shifted from hunting and gathering to agriculture, their genomes shifted, too. But according to new research, the adaptations that allow us to enjoy dairy products without digestion problems may have arisen much later than expected in some populations.

The new study, published Tuesday in Nature Communications, sequenced the genetic information of 13 individuals who lived on the Great Hungarian Plain during the 5,000 years leading up to the Iron Age. The area represents a good cross-section of human development at the time, the researchers reported, showing a transition from hunter-gatherer cultures to farming.

In studying the genetic information of these individuals, the researchers found that shifts in culture could be pegged to corresponding shifts in genes. In other words, new practices – like farming or heavy-metal working –didn’t appear from nowhere.

“The genomes do seem to shift as new technologies come about,” co-author and Trinity College Dublin professor Daniel Bradley said. “You can’t look at this and think that farming and metallurgy are technologies that come into the culture by osmosis. They come with people. Genomes and technology migrate together.”

More surprising were the findings related to lactose tolerance. “We thought we’d look at some genes that had been previously discussed as being important, that we knew human populations had selected for during the course of human pre-history,” Bradley said.

In Europe – and particularly in Ireland, Bradley’s neck of the woods – lactose tolerance, or the ability to break down the sugar in non-human milk, is incredibly common. But it’s not something that humans had in the early days of our evolution. A genetic variation allows humans to digest lactose.

“Ireland is the place in the world with the highest concentration of lactose tolerance,” Bradley said, “and undoubtedly that’s to do with a heavy reliance on drinking unprocessed milk in pre-history, and a culture focused on dairying.”
Source: Washington Post