There’s no such thing as racial purity

You probably know the story: Once upon a time, human beings evolved in Africa, looking much like the black people we know today, and then gradually spread out into the rest of the world over a few million years, evolving to look different in each place. This geographical spread created the different groupings we now know as races, each a branch off the human evolutionary tree: white people in Europe, people with similar facial features but brown skin in South Asia, people with narrower eyes in East Asia, and so on. Once each kind of people evolved in each place, they mostly stuck around there, mixing mainly with their own kind, over the millions of years – until the ages of sail and of transport innovations allowed them to move around the world, creating an era where the formerly separate races newly began to mix. This story is entirely wrong. In just a few decades, the study of ancient DNA has allowed us to learn a great deal about the movements of prehistoric human populations, in…