LONDON, Ontario — Did milk fuel a continent-wide growth spurt in Europe thousands of years ago? Scientists in Canada say that the evolution of lactose tolerance may explain why people in northern and central Europe increased in size between 4,000 and 7,000 years ago, while people elsewhere stayed at the same height or even got smaller.

To examine how human body size has changed, anthropologist Professor Jay Stock of Western University and his colleagues collated data from more than 3,500 skeletons from 366 archaeological sites in seven regions stretching back 30,000 years. They used skeletal measurements to estimate each individual’s height and the size of weight-bearing joints to estimate their weight.

They found that the average global height for men and women declined from 30,000 years ago onwards, reaching its minimum between 6,000 and 8,000 years ago. However, in central Europe, the average height rose between 4,000 and 7,000 years ago.

In northern Europe, heights increased between 2,000 and 8,000 years ago. The team found similar trends for body masses as well.

“The earliest evidence of dairy production is from around 9,000 years ago in western Asia, from where it spread around the world, reaching central Europe at least 7,400years ago,” Prof. Stock says, according to a statement from SWNS.

The research team believes that the “exceptional” growth resulted from those Europeans producing the enzyme lactase into adulthood, which allowed them to gain more nutrition from lactose, a sugar found in milk.

The study, published in the journal Proceedings of the National Academy of Sciences (PNAS), also finds that people in what is now Great Britain got smaller during the same period, despite being early milk drinkers.

“I see no systematic, numerical analysis to suggest it is much more than a guess that selection was stronger on lactase at this time when we see increases in body mass,” says Professor Mark Thomas from University College London (UCL).

South West News Service writer Mark Waghorn contributed to this report.

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