Tuesday, May 7, 2013
A genetic survey concludes that all Europeans living today are related to the same set of ancestors who lived 1,000 years ago
Family researchers have long known that if you go back far enough, everyone with a European connection ends up being related to Charlemagne. The concept was laid out scientifically more than a decade ago. Now Coop and University of Southern California geneticist Peter Ralph have come up with the evidence. "Anyone alive 1,000 years ago who left any descendants will be an ancestor of every European," the researchers say. Those conclusions are based on a survey of genetic sequences from more than 2,000 individuals spread from Ireland to Turkey. Ralph and Coop used computer software to search for telltale strings of DNA coding that are common to wide segments of the European population. The length of such strings can be used as a statistical yardstick to determine relatedness: Longer strings suggest that a common ancestor lived more recently. The researchers were surprised to find that even individuals living as far apart as Britain and Turkey shared a chunk of genetic material 20% of the time. To explain that degree of genetic commonality, the researchers say those pairs of individuals would have to have a huge number of common genealogical ancestors 1,000 years ago — a number that takes in everyone who was alive in Europe back then. People who live closer together tend to be more closely related, as you'd expect. The survey also found that the degree of relatedness varied among present-day European populations: Italians tended to have lower levels of relatedness, to each other and to other Europeans. That may be because there was a long history of distinct cultures in that region, the researchers suggest. Eastern Europeans, in contrast, showed more relatedness than the average, perhaps due to the Slavic expansion into that region more than 1,000 years ago.