Modern sled dogs — Arctic-adapted breeds like the Greenland dog, the Alaskan Malamute and the Husky — share ancient Siberian roots and represent a largely continuous genetic lineage that likely emerged as the glacial remnants of the last ice age subsided nearly 10,000 years ago.
In a new genetic study of modern and ancient Arctic sled dogs, researchers unveiled the antiquity and origin of this small, yet unique, canine group and its integral bond to the lives of Arctic peoples and their survival since the dawn of the Holocene about 12,000 years ago.
According to the findings published in the June 26 issue of Science, present-day sled dog breeds and their cold-climate adaptations stem from a common ancient Arctic ancestor that diverged from other dog lineages more than 9,500 years ago in Northeast Asia.
These ancient dogs co-adapted with their human counterparts to the cold, northern regions, where they were used much in the same way as they have by Arctic peoples over the thousands of years since — as important hunting companions and for pulling sleds great distances across the harsh, frozen and often unforgiving landscape.
The tradition of dog sledding is worldwide and has been practiced by Arctic peoples and the same group of dogs for millennia. However, the Arctic is rapidly changing environmentally and culturally, threatening traditional dogsledding cultures with extinction. What's more, increased interbreeding between sled dogs and other non-Arctic dogs is putting the Arctic breeds at risk of disappearing as well.
Despite being one of the most unique and culturally important groups of dogs, very little is known about the sled dog's genetic origin and evolutionary past.
"Given the great diversity of dogs in the world, sled dogs represent such a small part, with only a few breeds and individuals, however they have been paramount for the Arctic side of human history and are truly genetically unique," said the study's lead author, Mikkel-Holger Sinding, a researcher at the University of Copenhagen's GLOBE Institute.
Sinding is one of the founders of the QIMMEQ, a Greenlandic-Danish interdisciplinary research project dedicated to conserving Arctic sled dog culture and exploring the genetic history of the sled dog.
"Their history, evolution and bond to Arctic cultures is more than 9,500 years old. It would be such a shame to see this going extinct due to a lack of care and knowledge and I really hope our research makes a difference here," Sinding said.
While it's thought that domesticated dogs and dog sledding played an important role in the lives of Arctic peoples for at least 15,000 years, some of the earliest archaeological evidence for sled dog use in the Arctic stems from a 9,500-year old site located on what is now Zhokhov Island in the East Siberian Sea. When humans and their sled dogs roamed the region, post-ice age sea levels were lower and the Zhokhov site was part of the mainland.
Sinding and the team used ancient DNA extracted from the jawbone of a canine recovered from the site to explore the earliest-yet example of the sled dog genome. The authors also sequenced the genomes of 10 modern Greenland sled dogs – an indigenous breed used for hunting and sledding by Inuit — as well as that of a 33,000-year-old extinct Pleistocene Siberian Wolf.
While genetic analyses of domestic dogs are not new, Sinding said, most have focused on Eurasian or Asian dogs and genomic data for Arctic sled dogs are sparse.
The results of the study show that the Zhokhov dog is a common ancestor to present-day sled dog breeds, particularly the Greenlandic sled dog. While all modern sled dogs are closely related and share common ancestors, other sled dog breeds have interbred significantly with Eurasian dog breeds. However, due to their isolated populations, the Greenlandic dog has largely avoided contact with other dog breeds, and as a result can trace a more direct genomic ancestry to the ancient sled dog from Siberia.
While Sinding and the researchers found evidence of gene flow from Siberian Pleistocene wolves, unlike many other American dog breeds, they found no evidence of significant genetic mixing between any sled dog and American-Arctic wolves, despite ethnographic accounts indicating that dog-wolf matings were common, at least historically. If true, Sinding said that the surprising finding implies that ancient people actively avoided the propagation of wolf-dog hybrids in Greenland sled dog populations.
The analysis also demonstrated several convergent genetic adaptations related to the unique harshness of Arctic environments that sled dogs share with other Arctic animals like mammoths and polar bears, including one which allowed dogs to eat the fat-rich and starch-poor diets of their human handlers.
"Pre-industrialization, I think that dogs were one of our most precious tools, in the Arctic especially, where long distance transportation with speed and ability to transport heavy loads is priceless," said Sinding. Their senses, far keener than our own, are invaluable in Arctic environments and capable of navigating through blizzards and knowing their way home, even when their handler does not.
"And they can fight a polar bear," Sinding said. "No snowmobile can do that."