Ancient humans made dogs their best friend not once but twice, by domesticating two separate populations of wolves thousands of miles apart in Europe and Asia.
That is the conclusion of scientists who said on Thursday they had used modern genetics to unravel canine evolutionary history, revealing a deep internal split between dogs from opposite ends of the Eurasian continent.
People and hounds go way back – they were living together at least 15,000 years ago, or 5,000 years before cows, goats and pigs arrived – but how, why, when and where the two species got friendly has been a mystery.
It was widely believed dogs were tamed just once, with some experts claiming this happened in Europe and others favoring central Asia or China.
But a new story emerged when researchers used the inner ear bone from a 4,800-year-old dog unearthed in Ireland to sequence its full genome, and then compared it to both modern animals and DNA traces from 59 ancient dogs.
“Our data suggests that dogs were domesticated twice, on both sides of the Old World,” said Laurent Frantz, a geneticist at the University of Oxford, whose work was published in the journal Science.
“This suggests that at least two group of humans independently came to the same conclusion: dogs can be domesticated. It also suggests that the process of domestication, while mostly rare, may be replicated more often than we think.”
After constructing a family tree for dogs based on the genetic data, the scientists concluded there were very old domesticated animals in both the east and west of Eurasia but not in the middle.