Scientists have discovered that almost all dogs are "a bit of a wolf"

A new study by scientists from the American Museum of Natural History and the Smithsonian Institution's National Museum of Natural History has found that most modern dogs have a small but detectable proportion of "wolf" genes that emerged after domestication and affect body size, sense of smell and even behavioural traits.

The work is published in the journal Proceedings of the National Academy of Sciences and shows that later interbreeding with wolves helped dogs better adapt to a wide range of environments near humans. Wolf admixture is found in both large breeds like the Shiloh shepherd and miniature dogs - including the Chihuahua.

"Modern dogs, especially pet dogs, seem very far removed from the wolves that are often demonised," said Audrey Lin, lead author of the paper. - But some of the traits we really appreciate in dogs may be just as wolf-like in origin. Technically, this study is about dogs, but in many ways it's also about wolves."

How the genes of dogs and wolves are related

Dogs are thought to have descended from an extinct population of grey wolves in the late Pleistocene, about 20,000 years ago. Wolves and dogs can still produce viable offspring today, but such hybridisation is thought to be rare in nature, and after domestication it was long assumed that there was little or no genetic exchange.

"Before this study, it was thought that to be a 'real dog,' there should be almost no wolf DNA in the genome," Lin says. - But if you look closely at the genome of modern dogs, the wolf is there. "It seems that the dog genome can 'tolerate' some amount of wolf DNA and still be the dogs we love."

What the genome analysis revealed

The scientists used more than 2,700 complete genomes of wolves, purebred dogs, village (free-living) dogs and other canine species - from the late Pleistocene to the present day - from public databases.

Results:

• nearly two-thirds of purebred dogs have evidence in their nuclear genome of interbreeding with wolves that occurred about a thousand generations ago;

• all stray dogs studied carry a detectable proportion of wolf heritage;

• in purpose-bred Czechoslovakian and Sarloos Wolfdogs the share of wolf genes is expectedly the highest - 23-40%;

• among common breeds, the Great Anglo-French Tricolor Hound (about 4.7-5.7 per cent of wolf DNA) and the Shiloh shepherd (about 2.7 per cent) are the most "wolfish".

The Shiloh shepherd is the result of crossing dogs with Wolfdogs for the sake of healthier and more "family orientated" shepherds. But the pronounced wolf admixture in the French hound is a surprise: there is no data on conscious crossbreeding with wolves in the breed.

Interestingly, the Tamaskan breed, specially created in the 1980s in Britain as a "wolf-like" breed (based on huskies, malamutes and other northern breeds), has about 3.7 per cent of wolf genes.

Who has more wolf - and who has almost none

The researchers noticed several patterns:

• more wolf admixture in large dogs and in breeds bred for specific jobs:

  • arctic sled dogs,

  • stray dogs,

  • hunting breeds;

• the least wolf blood on average in terriers, dogs and hounds.

That said, there are exceptions: some large guard breeds have a high proportion of wolf DNA, while others have no traces of wolf, such as:

• neapolitan Mastiff,

• bullmastiff,

• st Bernard.

Wolf genes were also found where it's hardest to expect - in Chihuahuas, which have about 0.2 per cent wolf admixture.

"Any Chihuahua owner would say that makes sense," Lin jokes. - "And, as our research shows, it's the norm: most dogs are a little 'wolfish'."

Character and "wolf blood"

The scientists compared what character descriptions canine clubs use for breeds with a high and low proportion of wolf heritage.

The most common descriptions for dogs with low levels of wolf admixture were:

• "friendly",

• "eager to please,"

• "easy to train,"

• "lively,"

• "affectionate."

For breeds with a high proportion of wolf were more commonly used:

• "distrustful of strangers",

• "independent,"

• "vigilant,"

• "loyal/committed,"

• "reserved,"

• "territorial."

Words such as "intelligent", "obedient", "good with children", "calm" were found about equally in both groups. The authors stress: these are subjective breed descriptions and it has not been proven that wolf genes are directly responsible for such traits, but the links found open up an interesting field for further research into dog behaviour.

Wolf genes as an evolutionary "tool" for dogs

The study also found examples where wolf genes helped dogs better adapt to living near humans:

• stray dogs have an increased proportion of wolf DNA in their olfactory receptor genes - this may help them find human food waste more efficiently;

• tibetan mastiffs have been found to have a gene similar to that of Tibetan wolves that helps them tolerate low oxygen levels in the highlands of the Tibetan Plateau and the Himalayas.

"Dogs are our friends, but as it turns out, wolves have greatly helped make them as we know them," says study co-author Logan Kistler. - "Living alongside humans presents dogs with many challenges, from surviving at altitude to finding food around villages or guarding the herd, and they seem to have utilised wolf genes as part of the 'toolkit' for evolutionary success."