How to Argue With a Racist: History, Science, Race and Reality

by Adam Rutherford

Much is made of establishing celebrity in your tangled thicket, and royalty even more so. In 2016, on the popular television programme Who Do You Think You Are?, British actor Danny Dyer discovered that he was twenty-two generations directly descended from the fourteenth-century British king Edward III. While few of us can establish this with genealogical records such as births, deaths and marriages, according to my calculations,* the chances of anyone with longstanding British ancestry being similarly descended from Edward III is effectively 100 per cent. It is true for Danny Dyer, and it is true for the majority of British people too. Go back a few centuries further and we reach a mathematical certainty referred to as the genetic isopoint. This is the time in history when the entire population is the ancestor of the entire contemporary population today. For the people of Europe, the isopoint occurs in the tenth century. In other words, if you were alive in the tenth century in Europe, and you have European descendants alive today, then you are the ancestor of all Europeans alive today (we estimate that up to 80 per cent of the population of tenth-century Europe has living descendants). Another way to think of it is like this: one branch of a family tree of two first cousins crosses in a shared grandparent; one branch of all European family trees cross through one individual in 1400 CE; at the isopoint, all branches of all family trees cross through all people for that po...