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Dog remains are often ‘just’ a wolf

Researchers have spent years looking for the ‘missing link’ between wolves and dogs. But many of the domesticated dogs that had been found prove to have been wolves after all. This is what vet and archaeologist Luc Janssens says in his dissertation. PhD defence on 27 June.

Genetic research has shown that it must have happened somewhere in East Asia, around 25,000 to 20,000 years ago: an early human managed to rear and domesticate a wolf pup. In the millennia that followed, this wolf transformed into the different forms of ‘man’s best friend’ that keep us company today, from the dachshund to the Pekingese and chihuahua. 

But the remains of an early breed of dog have never been found. The earliest finds date from around 15,000 years ago, leaving a gap of around 5,000 to 10,000 years. No wonder, therefore, that archaeologists are desperate to find an even older dog. Every now and then, a researcher will claim to have found one of these ‘missing links’ between wolf and dog, whipping up a storm of publicity. Unwarranted, Luc Janssens now concludes. He researched the ten claims that have been made and showed that all of these supposed dogs were, in fact, common or garden wolves, and far from domesticated.

Unreliable criteria

‘Many of the morphological criteria used to differentiate between dogs and wolves have proven to be unreliable,’ says Janssens. ‘Small changes in the skull shape prove to be very unreliable, for instance. Wolves and dogs are both known for their enormous variability in skull shape and body size. A somewhat smaller or broader skull therefore falls within this variability and is not a good indicator for differentiating between dogs and wolves.

Janssens compared the ten ‘dodgy dogs’ with several hundred present-day and archaeological skeletons of wolves and dogs. He found that these were wolves rather than early dogs. ‘For each individual claim, I showed that, based on the morphology, there is no way you can say that these are dogs.’

According to Janssens, there are only two reliable morphological characteristics that can be used to distinguish between prehistoric dogs and wolves. The first is that early dogs are about a third smaller than wolves and that their skulls and some teeth are obviously smaller too. The second is that a dog’s head differs significantly from wolf’s one, with eye sockets protruding more to the side and top of the head. All the other criteria failed to pass muster.

Archaeologists lack veterinary knowledge

Janssens suspects that as archaeologists lack veterinary knowledge, they sometimes jump to conclusions. This Belgian external PhD candidate’s regular job is as an orthopaedic surgeon for pets in a specialised animal hospital in the Netherlands, where he operates on dogs every day. ‘The combination of orthopaedic dog surgeon and archaeologist has proven really useful. I could show that a very old archaeological dog suffered from a serious disease that had not been noticed before, and I could also refute the claim that certain vertebral conditions correlated to carrying burdens.

And so the hunt for an older ‘missing link’ between wolf and dog will go on. ‘Everyone in the field is looking for this transitional form,’ says Janssens. ‘Genetic research has shown that the dog is a descendant of the Eurasian wolf, so we will probably be able to find older dogs in Asia or even in Europe. But that is such a large area that it is largely uncharted territory for archaeologists, particularly because extensive archaeology is still at an embryonic stage in many Asian countries.

Text: Merijn van Nuland
Photo: A wolf in Yellowstone National Park, United States
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