Europeans appear to be more closely related than previously thought.
Scientists who compared DNA samples from people in different parts of the continent found that most had common ancestors living just 1,000 years ago.
The results confirm decade-old mathematical models, but will nevertheless come as a surprise to Europeans accustomed to thinking of ancient nations composed of distinct ethnic groups.
“What’s remarkable about this is how closely everyone is related to each other,” said Graham Coop of the University of California, Davis, who co-wrote the study published on Tuesday in the journal PLoS Biology.
Coop and his fellow author Peter Ralph of the University of Southern California used a database containing more than 2,250 genetic samples to look for shared DNA segments that would point to distant shared relatives.
While the number of common genetic ancestors is greater the closer people are to each other, even individuals living more than 3,000km apart had identical sections of DNA that can be traced back roughly to the Middle Ages.
The findings indicate that there was a steady flow of genes between countries as far apart as Turkey and Britain, or Poland and Portugal, even after the great population movements of the first millennium AD, such as the Saxon and Viking invasions of Britain, and the westward drive of the Huns and Slavic peoples.
The study did find subtle regional variations. For reasons still unclear, Italians and Spaniards appear to be less closely related than most Europeans to people elsewhere on the continent.
“The analysis is pretty convincing. It comes partly from the enormous number of ancestors each one of us have,” said University of Leicester professor of genetics Mark Jobling, who was not involved in the study.
Since the number of ancestors each person has roughly doubles with each generation, “we don’t have to go too far back to find someone who features in all of our family trees,” he said.
Jobling cited a scientific paper published in 2004 that went so far as to predict that every person on the planet shares ancestors who lived just 4,000 years ago.
“Although, as the authors note, the approach is inherently ‘noisy’ [ie, error-prone], it still does give results for European populations that are in reasonable agreement with historical expectations,” said Mark Stoneking, a professor of evolutionary anthropology at the University of Leipzig, Germany, who also was not involved in the study.
Coop and Ralph said the findings might change the way Europeans think about their neighbors.
“The basic idea that we’re all related much more recently than one might think has been around for a while, but it is not widely appreciated, and still quite surprising to many people, even scientists working in population genetics, including ourselves,” they said in an e-mail.
“The fact that we share all our ancestors from a time period where we recognize various ethnic identities also points at how we are like a family — we have our differences, but are all closely related,” they said.