Ancient Japanese Wolves May Be the Closest Wild Relative of Modern Dogs

The Japanese wolf (Canis lupus hodophilax) is a smaller subspecies of grey wolf distinctly known for its small, border collie–like stature, Science’s David Grimm reports. The canids were endemic to Honshū, Shikoku, and Kyūshū in the Japanese archipelago and were revered as a guardian of farmers and travelers. They went extinct in the early 20th century about 100 to 120 years ago following a rabies epidemic in the 17th century that caused a purge of the species.

Because living wolves are not very closely related to today's dogs, scientists suspect modern dogs evolved from a single population of extinct grey wolves, reports Michael Le Page for New Scientist. Now, researchers comparing genetic data of preserved Japanese wolf specimens found that the canid may be more closely related to dogs than any other wolf found so far. The results challenge other proposed regions where dog domestication may have occurred, like the Middle East and Western Europe, according to a new study published on the preprint server bioRxiv on October 11.

Earlier this year, a study published in iScience in January 2021 found that the Japanese wolf was closely related to Siberian wolves previously thought to be extinct in the late Pleistocene era, and more recent evidence found that modern pups may have come from Siberia, Science reports.

To see if Japanese wolves are related to modern dogs, scientists sequenced nine genomes of Japanese wolves from museum specimens, Science reports. Lead author Yohey Terai, an evolutionary biologist at the Graduate University for Advanced Studies in Hayama, Japan, and his team also sequenced 11 genomes from modern Japanese dogs, including the Shiba Inu. All the sequences were then compared to genomes from foxes, coyotes, dingoes, and other modern wolves and dogs from around the globe.  

After comparing all genomes, the researchers found the Japanese wolf is part of an evolutionary branch of wolves that arose 20,000 to 40,000 years ago. Some of the wolves from this branch evolved into the Japanese wolves while others branched off and gave rise to modern dogs, New Scientist reports. The split between the Japanese wolves and today's dogs may have occurred in East Asia.

“If true, this is very important,” says Laurent Frantz, an evolutionary geneticist from the Ludwig Maximilian University of Munich who was not involved with the study, to Science. “It’s the first time we’ve seen a wolf population that’s close to dogs.”

However, not all dogs have a genetic overlap with the Japanese wolf. Eastern dogs, like the dingo, New Guinea singing dog and other Japanese breeds, shared five percent of their DNA with the Japanese wolves. Western dogs, like Labrador retrievers and German shepherds, shared much less genetic material. Scientists suspect that Japanese wolves may have bred with dogs migrating East, and later, those dogs bred with Western dogs, leaving the Japanese wolves’ genetic signature, per Science.

To confirm if dogs arose from East Asia, Terai hopes to extract DNA from ancient wolf bones found in the region, New Scientist reports. More data is needed to know if modern dogs and Japanese wolves share a common ancestor, but the find is a paw in the right direction.

“This is a really good step forward,” Frantz tells Science. “Wolves are the key to understanding dogs, so it’s going to be really exciting to see where this goes.”

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.