It looks like dogs might well have been man's (and woman's) best friend for a lot longer than once thought.
The long-held conventional wisdom is that canis lupus familiaris split from wolves 11,000 to 16,000 years ago and that the divergence was helped along by Stone Age humans who wanted a fellow hunter, a sentry and a companion.
Now, DNA evidence suggests that the split between dogs and their wild ancestors occurred closer to 30,000 years ago.
Publishing in Thursday's edition of Current Biology, the authors of a new study looked at the genome of a 35,000-year-old wolf from the Taimyr Peninsula in northern Siberia. "We find that this individual belonged to a population that diverged from the common ancestor of present-day wolves and dogs very close in time to the appearance of the domestic dog lineage," they wrote in the abstract.
The team, led by Pontus Skoglun, a research fellow at Harvard, concluded that the mutation rate for canines is "substantially slower than assumed by most previous studies, suggesting that the ancestors of dogs were separated from present-day wolves before the Last Glacial Maximum."
In other words, there may have been a faithful Fido walking with a human before the end of the last Ice Age (and before agriculture).
As The New York Times writes: "Based on the differences between the genome of the new species, called the Taimyr wolf, and the genomes of modern wolves and dogs, the researchers built a family tree that shows wolves and dogs splitting much earlier than the 11,000 to 16,000 years ago that a study in 2014 concluded."
However, a study reported in 2013 places the date of the canine split closer to the study published on Thursday. As NPR's Nell Greenfieldboyce reported then, a team headed by Robert Wayne, a biologist at the University of California, Los Angeles, and publishing in Science, used DNA analysis to peg the date at somewhere between 18,800 to 32,100 years ago.
In the new study, an author of the report was quoted by the Times as saying the simplest explanation for the new data is that dogs were domesticated as much as 30,000 years ago, but he cautions that the study does not prove it. "We can't just look at the DNA and say whether a canid was living with modern humans," he was quoted by the newspaper as saying.
"One scenario is that wolves started following humans around and domesticated themselves," Dalen told BBC. "Another is that early humans simply caught wolf cubs and kept them as pets and this gradually led to these wild wolves being domesticated. If this model is correct then dogs were domesticated by hunter gatherers that led a fairly nomadic lifestyle."