Modern dogs may have 'dual origins.'iStock

Trinity College scientists have used DNA from a 4,800-year-old dog bone excavated at the ancient passage tomb at Newgrange in County Meath to test a new theory that dogs may have been domesticated twice.

The study, ‘Genomic and archaeological evidence suggest a dual origin of domestic dogs,’ has been published in the international journal 'Science.’

It was previously claimed that humans first domesticated wolves in Europe, while other researchers believed they were domesticated in Central Asia or China. Now scientists believe that both claims may be right and that dogs may have come from two separate, and now extinct, wolf populations.

The Irish Independent reports that at some point eastern dogs mixed with and replaced the early dogs from Europe. Today's dogs are a mixture of both, which has made earlier studies difficult to interpret.

Newgrange. Credit: Tourism Ireland

Newgrange. Credit: Tourism Ireland

Daniel Bradley, professor of Population Genetics at Trinity College in Dublin and the senior author of the new body of research, said the discovery was an important milestone in using ancient DNA to study dogs.

"Modern dogs are affected by processes like cross-breeding and mutations which affect their type, colour and illnesses, but this bone was from an original kind of dog," he said.

"It is 4,800 years old, which means it was around at the time of the first farmers at Newgrange."

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"The Newgrange dog bone had the best preserved ancient DNA we have ever encountered, giving us prehistoric genome of rare high quality," said Bradley. 

"It is not just a postcard from the past, rather a full package special delivery. We were able to sequence every gene.

"It will now be used in subsequent studies so we hope it has made a huge contribution to the field."

* Originally published in June 2016.