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Humans domesticated dogs twice, says study

New research suggests that dogs were domesticated not once, but twice, in different parts of the world.

A new study suggests that dogs arose from two separate – possibly now extinct – wolf populations on opposite sides of the Eurasian continent.

While some researchers have argued dogs were first domesticated in Central Asia or China, others claim that humans first domesticated wolves in Europe. The new paper, published in the journal Science on June 3, 2016, suggests that both claims might be right. Dogs may have been domesticated not once, as widely believed, but twice.

An international team of researchers, led by the University of Oxford, reconstructed the dog’s evolutionary history by first sequencing the genome of a 4,800-year old medium-sized dog from bone excavated at the Neolithic Passage Tomb of Newgrange, Ireland. The team also studied mitochondrial DNA from 59 ancient dogs living between 14,000 to 3,000 years ago and compared them with the genetic signatures of more than 2,500 modern dogs.

The results of their analyses show that there’s a genetic separation between modern dog populations currently living in East Asia and Europe. What’s odd is that this population split appears to have happened after the earliest archaeological evidence for dogs in Europe. According to a statement from the University of Oxford:

The new genetic evidence also shows a population turnover in Europe that appears to have mostly replaced the earliest domestic dog population there, which supports the evidence that there was a later arrival of dogs from elsewhere. Lastly, a review of the archaeological record shows that early dogs appear in both the East and West more than 12,000 years ago, but in Central Asia no earlier than 8,000 years ago.

Combined, these new findings suggest that dogs were first domesticated from separate wolf populations that lived on on opposite sides of the Eurasian continent. At some point after their domestication, the eastern dogs moved with migrating humans into Europe where they mixed with and mostly replaced the earliest European dogs. Most dogs today are a mixture of both eastern and western dogs – one reason why previous genetic studies have been difficult to interpret.

Oxford University’s Greger Larson is the study senior author. He 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.

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Ollie the dog. Image Credit: Chris Parfitt via Flickr.

Bottom line: A new study published in the journal Science on June 3, 2016, suggests that dogs may have been domesticated not once, as widely believed, but twice.

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Eleanor Imster

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