Milk may have contributed to the growth spurt in ancient Europeans

Analysis of ancient human skeletons shows that the increase in size and weight in some regions has coincided with an increase in lactose tolerance.

The study found that people in northern and central Europe increased in size between 7,000 and 4,000 years ago, while people elsewhere remained the same height or got smaller.

The researchers say that the growth of some Europeans was probably due to the fact that they developed lactose tolerance earlier.

The ability to produce the enzyme lactase as adults and digest milk is thought to have played a significant role in the health and evolution of ancient humans.

Studies have shown that those who could consume milk without health complications were able to overcome acute hunger, due to which lactase tolerance spread through natural selection.

To measure the effect of lactose tolerance on human size, Jay Stock of Western University in Ontario, Canada, and colleagues collated data from 3,507 skeletons from 366 archaeological sites across seven regions—the Levant, Southern, Central, and Northern Europe. the Nile Valley, South Asia and China – 30,000 years ago.

The researchers used skeletal measurements to estimate the height of the individuals and the size of the weight-bearing joints to estimate their weight.

They found that the global average height of men and women declined from 30,000 years ago, reaching its lowest point between 8,000 and 6,000 years ago. But in Central Europe growth increased between 7000 and 4000 years ago, and in Northern Europe it increased between 8000 and 2000 years ago. Similar trends were observed for body weight.

The earliest evidence of dairy production dates back to about 9,000 years ago in Western Asia, from where it spread throughout the world, reaching Central Europe at least 7,400 years ago.

The authors suggest that the exceptional growth was the result of these European populations becoming lactose tolerant, allowing them to get more nutrients from milk. In other parts of the world at that time, people only consumed fermented milk products such as yogurt and cheese, which contain less lactose.

Although the data cannot prove that lactase persistence was the cause, the researchers argue that this is a compelling explanation. “We show that the timing and geography of body size increases are consistent with what we see in lactase persistence, and lactose is such an important component of the diet because it provides very, very energy-rich and nutrient-dense food sources. Stock says.

However, the study found that people in Britain actually got smaller over the same period, despite drinking milk early.

“The authors have done a pretty fantastic job on height by assessing body weight and how it has changed over time. But I don’t see any systematic numerical analysis that would suggest that this is much more than suggesting that selection was stronger on lactase at a time when we are seeing an increase in body weight, ”says Mark Thomas from University College London.

Previous research has shown that people got smaller when they abandoned the hunter-gatherer lifestyle to grow crops, as relying on a single crop would be less nutritious.

But the new study found strong evidence that people were getting smaller before they turned to farming, hinting that there was another reason for their decline, Thomas says.