Dogs May Have Been Domesticated Twice

A pooch that lived in Newgrange, Ireland, some 4,800 years ago has become a canine Rosetta Stone for researchers seeking to reconstruct the timeline of dog domestication. According to new research published in the journal Science, the animal's especially well-preserved inner ear bone enabled scientists to sequence and publish its complete genome, which is a first for ancient dog specimens.

When the specimen was compared against DNA samples from 605 modern dogs and wolves, a tale of two doggy cities emerged. The study's authors, led by University of Oxford evolutionary geneticist Laurent Frantz, discovered that there is a deep genetic divide between East Asian and Western European ancient dog populations. This comprehensive new family tree suggests that dogs were independently domesticated in two locations from distinct wolf populations separated by thousands of miles.

"What we have now is what we believe to be the first evidence, both genetically and archaeologically, that dogs were domesticated two times," said Greger Larson, an Oxford evolutionary biologist and co-author on the study, in a video about the results.

Though there is little doubt that the bond between dogs and humans predates all other domestication efforts, there has been longstanding debate over the exact origins of this productive and adorable partnership. Archaeological evidence suggests that dogs emerged as early as 16,000 years ago in Western Europe, and around 14,000 years ago in China, and that most dogs today are descendents of the latter East Asian branch.

The relationships between these populations is still unclear, but with the help of the Bronze Age Newgrange dog's genome, Frantz's team has shown that they likely did not significantly intermingle until many millennia after their unique domestications. At some point between 14,000 to 6,400 years ago, the East Asian population migrated west and assumed genetic dominance across Eurasia, possibly aided by a bottleneck in the European population.

This effectively wiped out the genetic legacy of the western dogs, though some modern breeds, like huskies and Greenland sledge dogs, have mixed heritage from both groups.

The research is far from conclusive, and work is already being done to create even larger genomic analyses to corroborate these findings. But it would be fascinating to discover that creating loyal companions like dogs out of fierce predators like wolves was not a one-time-only brainwave, but rather an idea that might have emerged naturally in places where the two species closely co-habited.

Of course, regardless of what future studies say about their complicated history, our canine sidekicks are undoubtedly the best, and they deserve lots of treats, walks, and belly rubs because they have been good dogs.