Dogs Found To Have Been Domesticated Twice Separately

For a long time, researchers have argued as to the origin of dogs. We now know through evolutionary fossil records and DNA testing that the modern dog is the descendent of the wolf. But many questions remained unanswered. Was it in Europe or Asia that dogs formed their partnership with humans?

A newly released study has made some interesting findings that it could have been both – entirely separately from each other. Via genetic analysis of many hundreds of dogs, it has been found that the common dog was domesticated actually two times – once in Asia and once in Europe, solving the mystery once and for all, and resolving the many contradictions that indicated both these regions to be where the once believed single domestication took place.

Nevertheless, this isn’t to close the case on the matter just yet. According to Robert Wayne, evolutionary biologist from University of California – the original researcher many years ago who discovered the fact that dogs evolved in Europe – says the results are still too early to confirm. Like with many things in science, peer review is a normal part of the scientific method, and confirmation by colleagues must take place before any new research becomes widely accepted.

An intriguing piece of anatomy centers around the mystery – an ear bone belonging to a 5000 year old canine that was discovered in Newgrange, a large but man-made pile of dirt in an area of Ireland that has been dated back to the period of Stonehenge. This ear bone was sequenced by genomic researchers from the University of Oxford – the first genome of an ancient dog to be sequenced – and compared with the DNA of hundreds of modern dogs from different regions in the world.

Using this DNA comparison, a genomic “family tree” of sorts was created. It was found that there was a sharp divide between European dogs and Asian dogs when both were compared to the DNA of this ancient dog. In order to investigate the reason behind the divide, the ancient Newgrange specimen was crucial to solving the riddle. The researchers were able to calculate an average rate of genetic mutation over a 5000 year period for canines in order to calculate how different dog breeds around the world could have evolved from the ancient dog. The results were staggering: it was found there was no conceivable way the Asian dogs could have mutated into their current breeds from the ancient dog – suggesting that they weren’t as closely related as previously believed. The data suggested that the ancestral split between the Asian and European dogs was more likely to have occurred up to 14,000 years ago.

Also noted was a “genetic bottleneck” of sorts in the European dog – a decrease in its genetic diversity tied to a radical decline in its population. This sort of phenomenon is observed when groups split off from their main group (similar such behaviour has been noted in ancient human migration records). Thus, these two pieces of evidence; the stark genetic differences and lack of genetic diversity in European dogs, indicate that dogs in Asia were domesticated more than 14,000 years ago. Furthermore, a small portion of these Asian dogs are now believed to have migrated to Eurasia, most likely with humans. At some point, additional domestication would have taken place in Europe.

Nevertheless, there is a little catch. Previous archaeological research found dog remains in Germany believed to be over 16,000 years old. If true, this would indicate that dogs were already in Europe to begin with, before the Asian migration.

Scientists are still less than certain about the results. If the mutation rates were found to be inaccurate even just slightly, then the ancient dog bone found in Newgrange could have belonged to an ancestor of both European and Asian dogs. And the genetic mutation rates aren’t as certain as researchers behind this study may think – as interbreeding between dog species could have muddled the mutation predictions according to at least one archaeologist.

The end result is that further research is needed to confirm these new findings. But at least for now, this new theory is at the forefront of discussion. If the dual-domestication hypothesis ends up to be true, it will explain many unresolved questions in dog domestication research.

Study Source: Science

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