Ancient Europeans farmed dairy—but couldn’t digest milk

In the past 10,000 years, populations living far apart in Europe, Africa, South Asia, and the Middle East separately acquired a key genetic change. People with that ability and living in dairy farming cultures got a boost in nutrition and had more children, according to researchers.

The story of people consuming milk products but not being genetically sensitive has been challenged by recent findings. A study combines large archaeological data sets on dairy farming with ancient DNA and finds that people used to eat dairy for thousands of years. The researchers think that illness and famine may have turned Lactose Sensitivity from uncomfortable to deadly.

Jessica Hendy is an archaeologist at the University of York who was not involved in the study.

In the new study, archaeologists found evidence of milk from over 6000 pieces of ancient pottery, taken from 556 European sites. The rise and fall of dairy farming was tracked by analyzing the fats in the pottery. They compared this with lactase persistence in published human genomes from the same region and period.

Changes in lactase persistence didn't match up with fluctuations in dairy use. Periods of shrinking populations, famines, and times of greater population density were identified by using archaeological records.

According to Mark Thomas, a human evolutionary geneticist at University College London, people who were sick or starving could be at risk of being Lactose-insensitive. Thomas says that if you are severely malnourished, then you have serious problems if you get gypsies when you drink milk. It's one of the biggest causes of death in the world.

When combined with sickness and starvation, the selection pressure grew strong enough to cause the spread of lactase persistence.

It's an exciting avenue for research. She cautions that estimating ancient population fluctuations is difficult.

The research is in line with previous results such as the late arrival of widespread lactase persistence in Central Europe. She says the new study brings a lot of data to the table. Warinner says the story of dairy farming has been surprising. It helps us to appreciate the complexity of the past.