Prehistoric people in Europe were consuming milk thousands of years before humans evolved the genetic trait allowing us to digest the milk sugar lactose as adults, finds a new study. The research, published in Nature, mapped pre-historic patterns of milk use over the last 9,000 years, offering new insights into milk consumption and the evolution of lactose tolerance.

Until now, it was widely assumed that lactose tolerance emerged because it allowed people to consume more milk and dairy products. But this new research, led by scientists from the University of Bristol and University College London (UCL) alongside collaborators from 20 other countries, shows that famine and exposure to infectious disease best explains the evolution of our ability to consume milk and other non-fermented dairy products. [1]

Figure 1. Famine and disease drove the evolution of lactose tolerance in Europe

Figure 1 shows while most European adults today can drink milk without discomfort, two thirds of adults in the world today, and almost all adults 5,000 years ago, can face problems if they drink too much milk. This is because milk contains lactose, and if we don't digest this unique sugar, it will travel to our large intestine where it can cause cramps, diarrhea, and flatulence; known as lactose intolerance. However, this new research suggests that in the UK today these effects are rare. [2]

At the beginning of that time span, migrating farmers introduced dairying to southeastern Europe’s Balkan Peninsula, where residents embraced regular milk drinking, the investigators say. Milk use then fluctuated over time in different parts of the continent. After about 7,500 years ago, relatively heavy milk use characterized western France, northern Europe and the British Isles. Dairying occurred less often in central Europe. [3]

Researchers believe that as crops failed prehistoric people would have been more likely to consume unfermented, high-lactose milk, and those who did not carry a copy of the lactase persistence gene variant would have been more likely to die before or during their reproductive years. [4]

References:

1. https://phys.org/news/2022-07-famine-disease-drove-evolution-lactose.html
2. https://www.sciencedaily.com/releases/2022/07/220727110700.htm
3. https://www.sciencenews.org/article/lactose-tolerance-milk-famine-disease-ancient-europe
4. https://www.thewellnews.com/health/famine-and-exposure-to-infectious-diseases-explain-human-ability-to-consume-milk/?amp=1

Cite this article:

Thanusri swetha J (2022), Famine and disease drove the evolution of lactose tolerance in Europe, AnaTechMaz, pp.62