A 4,800-year-old dog bone dug out of the Newgrange monument in Co Meath has helped to explain how the canine came to be man’s best friend.
New research has shown that the domestication of dogs from wolves occurred twice and on opposite sides of the planet, proving that the relationship between dogs and humans was meant to be.
The dual domestication of dogs was revealed for the first time in a research study led by Oxford University and involving Trinity College Dublin.
It shows that wolves were turned into pets more than 12,000 years ago in both Europe and the Far East.
Details of the research were published on Thursday evening in the journal Science.
"Whenever you delve into the past you always find something new," said Prof Dan Bradley, professor of population genetics in the Smurfit Institute at Trinity.
Prof Bradley had already used ancient DNA to map the history of cattle domestication and was looking to build on this with researchers from Belfast.
To this end they were looking through bones originally excavated from the Newgrange passage graves decades ago.
“We were actually primarily looking for cattle bones, but we came across a dog bone,” he said. “It occurred to me, ‘Why don’t we look at the genetics of this dog?’”
It turned out the sample was pristine and his PhD researcher and joint first-author of the paper Victoria Mullin was able to sequence the dog's whole genome despite its age.
Prof Bradley said he knew Oxford had a project running on dog ancestry and his group joined them, bringing their Newgrange dog data with them.
“We found that the [Newgrange] dog was like European dogs and shared modern dog ancestry, but there was something extra. It was like a ghost ancestry with something else.”
The Oxford group, led by Prof Greger Larson and lead author Dr Laurent Frantz, were able to deliver that ghost.
A large research team at the university had recovered DNA from 59 ancient dogs living between 3,000 and 14,000 years ago.
The team also looked at the DNA of 2,500 previously studied modern dogs.
“The theory that fitted best was you had a European domestication in parallel as an Asian domestication,” Prof Bradley said.
This would have happened more than 12,000 years ago.
"But then subsequently there was a migration of these Asian dogs into Europe, where they mixed with the European dogs to bring what we have today."
Prof Bradley’s human and animal DNA studies convinced him these dogs were brought into the West by the first farmers who migrated into Europe from the Near East.
Clearly neither man nor dog has looked back and the bond established 12,000 years ago persists to this day.