Ancient Europeans lactose intolerant for 5,000 years
Scientists discover humans took centuries to adapt after adopting agriculutural way of life
Only about 5 per cent of people of Northern European descent are lactose intolerant - but it wasn’t always so. Photograph: Getty
Scientists have found that ancient Europeans could not tolerate lactose for 5,000 years after they adopted an agricultural way of life and 4,000 years after Neolithic farmers in Central Europe began making cheese.
They discovered this through analysing DNA extracted from the petrous bones in the skulls of ancient skeletons.
Lactose intolerance is an inability to digest the sugar in the milk of mammals.
According to the National Institutes of Health, only about 5 per cent of people of Northern European descent are lactose intolerant.
In an article published in science journal Nature Communications, the scientists also suggested that the major technological transitions in Central Europe between Neolithic, Bronze Age and Iron Age were associated with major changes in the genetics of the populations.
“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,” said Professor Ron Pinhasi from the UCD Earth Institute and UCD School of Archaeology, who is a joint senior author on the paper.
“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 studied extracted DNA from 13 ancient individuals buried at archaeological sites in the Great Hungarian Plain, a location known for being at the crossroads of major cultural transformations that shaped European prehistory. The skeleton samples dated from 5,700 BC (Early Neolithic) to 800 BC (Iron Age).
After years of experimenting, the researchers found the petrous bone, which protects the inner ear, to be ideal for ancient DNA analysis because it is one of the body’s densest bones.
“The high percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold,” Prof Pinhasi said. “This gave us anywhere between 12 per cent and almost 90 per cent human DNA in our samples, compared to somewhere between 0 per cent and 20 per cent obtained from teeth, fingers and rib bones.”
Lactose causes symptoms such as bloating, abdominal pain, nausea, diarrhoea and flatulence for the 65 per cent of the world’s population that have a reduced ability to digest it.