Drought and disease exposure led to Europeans adapting to milk consumption, study suggests

Findings challenge long-held view that extent of milk use drove evolution of lactase persistence in humans

Famine and infectious diseases drove early Europeans to develop the ability to consume milk thousands of years before humans evolved the genetic trait enabling lactose digestion as adults, new research has found.

Milk contains the sugar lactose, and if humans don’t digest it, the molecule can cause cramps, diarrhoea, and flatulence in the large intestine – a condition known as lactose intolerance.

Most European adults in the modern world can drink milk without discomfort. However, two thirds of adults today, and almost all adults 5,000 years ago, are prone to face problems if they consumed too much milk.