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This 18,000-year-old puppy, preserved in the Siberian permafrost, still has its nose, fur, teeth and whiskers – but DNA tests to determine whether it is a dog or a wolf have come up blank, suggesting it may represent a common ancestor of both.

The puppy’s remains were identified by researchers at a site near Yakutsk in eastern Siberia, last year. Since then, a team at the , a joint venture between Stockholm University and the Swedish Museum of Natural History, has been analysing a piece of the animal’s rib bone.

So far, the researchers have determined that the animal is male. Team members estimate that he was 2 months old and lived around 18,000 years ago. The puppy is now named Dogor, a .

But the researchers can’t tell if the puppy was a dog or a wolf. If the animal is a dog, it may be the oldest ever found. But a researcher on the team thinks it may represent a common ancestor of both dogs and wolves.

“It’s normally relatively easy to tell the difference between the two,” team member David Stanton . “We have a lot of data from it already, and with that amount of data, you’d expect to tell if it was one or the other. The fact that we can’t might suggest that it’s from a population that was ancestral to both – to dogs and wolves.”

Research from the same team suggests that dogs and wolves may have diverged from a common ancestor around 40,000 years ago, although some dog breeds may have bred with wolves after that point.

However, this doesn’t tell us anything about when dogs became domesticated, and why. There is some evidence that the ancestors of domestic dogs may have carried genetic variants that made them “hypersociable”, and so more willing to interact with humans.