Got milk tolerance? Only about one-third of adults on earth can properly digest dairy. A project uniting archaeologists, chemists and geneticist is studying the history of milk in Europe, where “lactose persistence”, the ability to digest milk as an adult, is thought to have emerged only seven and a half thousand years ago. There’s been a wave of discoveries suggesting that a number of “lactose hot spots” where ancient humans developed the genetic mutation for tolerating milk – experienced significant advantages which allowed ancient humans to survive and changed the course of human history. Mark Thomas is an evolutionary geneticist at University College London and co-founder of LeCHE, a collaborative research project that traces lactose persistence in early Europe.