More than a quarter-billion dairy cows help supply the demand for milk worldwide. Scientists had long thought the popularity of milk helped explain the evolution of the genetic feature allowing many people to digest lactose, the sugar found in milk, as adults. However, a new study published July 28 in the journal Nature suggests prehistoric people in Europe were drinking milk thousands of years before they evolved this trait. These new findings suggest the popularity may not have driven the rise of this variation—famine and disease may have instead.
