Drinking milk made ancient humans taller and heavier, according to a new study, which also found milk consumption had a direct impact on modern-day lactose intolerance patterns in Europe.
A researcher from Queen’s University Belfast provided data for the study, published on Tuesday, which compared skeletons from archaeological sites spread over 25,000 years.
The research, led by University of Western Ontario, found that between 2,000 and 7,000 years ago, increased human size was found in regions where people had higher levels of genes that allow the production of enzymes that digest milk into adulthood, called lactase persistence.
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This process of evolution led to the pattern of lactose intolerance seen in modern times, where people in the north of Europe are more lactose tolerant than people in southern Europe.
The study, published in the journal Proceedings of the National Academy of Sciences, involved a team of 16 researchers comparing the stature and body mass of 3,507 skeletons from 366 different archaeological sites. This created a large comparative data set to examine human body variation over time and geographic location.
The data set used in the study was primarily based on European samples. The researchers said this was due largely to more frequent archaeological exploration within the continent.
Dr Eóin Parkinson, from the school of natural and built environment at Queen’s University Belfast, who provided data for the study, said the research illustrated that drinking milk led to increased skeletal growth in some parts of the world.
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“Everyone probably has memories from their childhood of being told to drink up their milk to help them grow. We can almost think of this in the context of our own evolutionary story and we see trends in dairy consumption going back as far as 7,000 years ago having an impact on how people process dairy products today,” he said.
“Drinking milk and the consumption of dairy products is a vital component in food culture in many parts of the world, so it is interesting to understand the underlying biological processes related to these practices.”
Dr Parkinson said that in some parts of northern and central Europe, where local environments were not suited to newly imported Asian crops, “human societies responded through increased consumption of milk”.
Prof Jay Stock, from the University of Western Ontario, who led the study, said milk drinking has been “culturally important” in different continents, adding there are genetic legacies to that consumption. “There are high frequencies of lactase persistence genes in populations in western Africa, the Rift Valley and the horn of Africa, as well as some parts of Arabia and Mongolia,” he added.