Ask the Scholars

Well, of course, DNA can tell you a little bit about ancestry. The more similar two species are, the more closely related they are by common descent. It's a bit more complicated with human populations because there's two ways that human populations can be similar to one another. Either they can have a common ancestry or they can be similar because they've had recent genetic unions reflected in what Cole Porter called the "urge to merge." This is what geneticists call gene flow. Unfortuna...