57,000-year-old wolf puppy found frozen in Yukon permafrost

In the summer of 2016, a gold miner in the Yukon Territory of Canada discovered unexpected treasure. While blasting a wall of permafrost with a water cannon to find the riches inside, Neil Loveless saw something melt from the ice. He was not a valuable miner, but the oldest and most complete wolf mummy ever discovered.

Loveless quickly put the frozen puppy in a freezer for paleontologists to check. The animal was discovered to be a well-preserved young woman, part of an extinct ecosystem dating back to the time when northwestern Canada was home for American mastodons and other Pleistocene megafauna. Locals Tr’ondëk Hwëch’in named the 57,000-year-old Zhur puppy a “wolf” in the language of their community.

Specific mammals were recovered from the Siberian tundra which also dates back to the Pleistocene, a period from about 2.6 million to 11,700 years ago also known as the Ice Age, because the poles had ice caps much bigger than today. However, finding a wolf so intact in the Yukon is unparalleled.

“In Siberia, conservation like this is very common because of the way the permafrost preserves things there, which is less common in the Yukon, Alaska, and elsewhere in North America, ”says Julie Meachen, a paleontologist expert at Des Moines University, the lead study author describing Zhur published today in the journal Conventional biology. Much of Zhur has survived intact after tens of thousands of years, from the fur of her coat to the delicate papillae on her tongue.

“The conservation looks amazing,” said Ross Barnett, a University of Copenhagen paleontologist, who was not involved in the study. But there is more to Zhur than meets the eye. “She tells us a lot,” Meachen says, from her age at death – seven weeks – to what she ate. The research provides a glimpse into a time of relief between frozen races of Earth’s history.

Zhur lived at an interspecific time, when the Arctic glaciers were eroding for some time, and the forest passed over the colder grasslands. These were the times of mastodons, camels, giant beavers, and, as Zhur documents, gray wolves.

“Preserving carnivores is such an amazing situation to look into Ice Age ecosystems from a predator’s perspective,” says Tyler Murchie, a McMaster University paleogenetic expert , who were not involved in the study.

While they are iconic parts of the North American desert today, gray wolves did not enter the Americans. These canals first appeared in Eurasia and crossed the Bering land bridge in the late second century Pleistocene, more than 500,000 years ago.

“Zhur is from a time when the Yukon is not very well known for mummification,” Barnett says. And by examining the remains of the wolf puppy’s DNA, Meachen and colleagues found that this animal records a group of wolves that no longer exist in the area.

Zhur belonged to a population that had genetic links to wolves in both Alaska and Eurasia, but wolves living in the Yukon today have a different genetic name. The results show that the first gray wolves in the Yukon were wiped out followed by other numbers that had made their way further south.

“Ancient DNA shows time and time again how far the history of evolution and paleoecology is than we could come from a study of bones and fossils,” Murchie says. Without Zhur genes, this extraction and repositioning would be invisible to scientists.

Zhur’s body also tells us about her life. Just about seven weeks old when she died, the puppy had just passed a tired age, when she would have started eating harder food. The geochemical names of the teeth indicate that it was fed from rivers and streams, possibly fish such as Chinook salmon that still spawned in the rivers near where it was found. Diets are similar to many modern-day wolves in the interior of Alaska, hitting fish more often than a big game.

Sadly, Zhur’s life was cut short. She apparently died in such a fall, the rapid burial allowing for the special preservation of her body. Other mammals from this period – such as Arctic ground squirrels and black-footed squirrels – have been similarly preserved.

Zhur existed at ancient crosses, not only between glacial cold spells, but between now separated numbers of wolves. By studying the pups’ genes, scientists can gain a better understanding of its place in the ancient world and what has changed since then. “Ancient DNA gives the Late Pleistocene animation that was virtually invisible from just the bones,” Barnett says.

How animal numbers moved around during the Pleistocene this is a story that is still being extracted from tattoos of ancient DNA left in preserved samples, but the remains of Zhur offer important clues. Where bones and genes meet, researchers find a new window into the lost world of the Ice Age.