A study into bone remains at Newgrange has shed new light on how dogs were domesticated by humans, with it likely to have happened separately, and concurrently, across the continents.
There’s a wonderful new DNA retrieval technique that Trinity College Dublin’s Dan Bradley is pioneering, which has achieved some remarkable discoveries in the past 12 months.
Bradley and his team can sequence almost the entire DNA genome of something that died thousands of years ago by simply using its ear – the petrous bone, to be precise.
Press your finger behind your ear and you will feel a part of dense bone, the petrous. After the tissue and other DNA wastes away from other parts of the body – human or otherwise – the petrous keeps valuable doses for centuries.
Previously, Bradley teamed up with colleagues in York to successfully sequence 80 skeletons found in the UK that had been decapitated – a landmark discovery.
A similar story emerged in Africa last year, when a 4,500-year-old skeleton was sequenced by a different team of scientists – this was an even greater landmark, as Africa’s often arid environment makes DNA retrieval remarkably hard.
Now, the petrous is playing a central role in finding out where and when humans first domesticated wolves into dogs, thanks to bone remains found at Newgrange.
The true genesis of domesticated dogs is often debated, with Asia and Europe both argued as the starting point – hunter-gatherers working alongside wolves to hunt and eat, then gradually raising wolves themselves, domesticating them into what we see today chasing frisbees in TV commercials.
Comparisons are key
So, Bradley and an international team of scientists looked at a 4,800-year-old ‘medium-sized dog’ that was excavated from the Neolithic passage tomb. They compared it with DNA from 59 ancient dogs living between 14,000 and 3,000 years ago.
What they found was a distinct deviation, demonstrating a separation between modern dog populations currently living in east Asia and Europe.
“It’s only in the last two years or so that we’ve really started to look at genomics in pre-history,” Bradley said recently. “Up until then we were looking at modern genetics, how events in the past would have given us modern genetic patterns.”
Bradley and his team now suggest that dogs were first domesticated from geographically separated (now extinct) wolf populations on opposite sides of the Eurasian continent.
At some point after their domestication, the eastern dogs dispersed with migrating humans into Europe, where they mixed with and mostly replaced the earliest European dogs.
Victoria Mullin, a researcher at Trinity who was joint first-author on the paper, said: “The role of the Newgrange dog in its neolithic community is a mystery. However, now in the 21st century it is playing a vital role in understanding the process of domesticating man’s best friend.”