New evidence suggests that the first domestic dogs appeared on opposite sides of the Eurasian continent more than 12,000 years ago. Two separate populations of wolves thousands of miles apart may have befriended humans and given rise to the domestic dog.
Later, the eastern dogs dispersed with migrating humans and bred with those from the west. Today, most dogs are a mixture of these ancient and once separate descendants of wolves, scientists believe.
The origins of man’s best friend is a hotly debated topic, with experts disagreeing about where and when wolves were first domesticated.
Some have pointed to Europe and others to central Asia or China, but up until now it was thought the transformation of wolves into domestic dogs only happened once.
For the new study, a team led by scientists from Oxford University analysed DNA from 59 ancient dogs that lived between 3,000 and 14,000 years ago.
Researchers also sequenced the full genome, or genetic code, of a 4,800-old-dog from Newgrange, Ireland, using one of the animal’s bones.
Comparing the data with DNA signatures from more than 2,500 previously studied modern dogs, as well as archaeological evidence, revealed a genetic split between modern dog populations from eastern Asia and Europe.
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The findings are reported in the current issue of the journal Science.
Professor Greger Larson, from Oxford University, said: “Animal domestication is a rare thing and a lot of evidence is required to overturn the assumption that it happened just once in any species.
“Our ancient DNA evidence, combined with the archaeological record of early dogs, suggests that we need to reconsider the number of times dogs were domesticated independently. Maybe the reason there hasn’t yet been a consensus about where dogs were domesticated is because everyone has been a little bit right.”
Colleague Professor Dan Bradley, from Trinity College Dublin, who led analysis of the Newgrange bone, said: “The Newgrange dog bone had the best preserved ancient DNA we have ever encountered, giving us prehistoric genome of rare high quality.
“It is not just a postcard from the past, rather a full package special delivery.”
Co-author Professor Keith Dobney, who co-directs the dog domestication project at the University of Liverpool, said a “new coherent story” of the origins of the domestic dog was now beginning to emerge.
He added: “With so much new and exciting data to come, we will finally be able to uncover the true history of man’s best friend.”
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