This Ice Age wolf pup does not look much like a fearsome predator, with its tiny teeth and tiny, fluffy ears. However, according to her DNA, the mummified pup, called Zhr, came from a group of ancestors of all modern wolves. The permafrost in Canada dried its remnants shortly after its death around 57,000 years ago.
“It’s the most complete wolf mummy that has ever been found.” Julie Mitch, a paleontologist at Des Moines University, said it’s 100 percent healthy – all it’s missing is her eyes.
In July 2016, miner Neil Loveless of Favron Enterprises was searching for gold in the famous Klondike Goldfields, Alaska. He was spewing frozen mud along the banks of Last Chance Creek. It is a process called “hydraulic thawing,” and it aims to thaw and soften permafrost so miners can search for gold in flowing sediments, a method called alluvial mining. But Loveless found something much stranger and more interesting than Klondike Gold: a frozen, mummified wolf pup.
We thank [Loveless] Because of her keen eyes, she spotted flowers thawing from permafrost, ensuring they remained safe in the fridge, and then reported the discovery to Yukon Fossils, Mitch and her colleagues wrote in a recent paper in Current Biology. Studying the Yukon’s Pleistocene wilderness means working with gold mining companies, whose workers may be the first to discover something like Zhr. Scientists like Meachen also work closely with people who have called this area home for thousands of years, such as Tr’ondëk Hwëch’in First Nation.
Members of the group gave the puppy its name, Zhr, which means “wolf” in the Han language. Zhùr is a culturally important discovery by Tr’ondëk Hwëch’in, but they were also interested in how the Frozen Pup could teach us about Ice Age wolves. The First Nation agreed to display the mummy at the Yukon Beringia Interpretive Center in Whitehorse, where it was cleaned, preserved, and studied.
“We are grateful for the partnership with Tr’ondëk Hwëch’in in our joint role in protecting and preserving Klondike’s heritage resources,” Meachen and her colleagues wrote.
Taking small samples from a handful of Zhiblyr’s incredibly well-preserved hair follicles, Meachen and her colleagues radiocarbonate dating a frozen pup and studying chemical isotopes in her body, providing clues about what she ate and the climate she lived in. They also sequenced mitochondrial DNA, which is the genetic material that is passed on directly from mother to offspring.
Ancestors of modern wolves
Zor may have lived around 57,000 years ago, but it took three different ways of dating to find out.
Radiocarbon dating can only tell Mitch and her colleagues that the mummy was more than 50,000 years old. The pup’s genome suggested that it lived between 75,000 and 56,000 years, based on the rate at which wolf DNA collects mutations over time. Her body’s oxygen isotopes indicate that she lived during the relatively warm period of marine isotope stage 3, when warmer conditions reduced oxygen-18 isotope ratios in the core of the marine sediments – and in Zour’s body. MIS 3 spanned a period of 57,000 to 29,000 years ago.
All of these possible dates overlapped at some point: 57,000 to 56,000 years ago. At that time, sea levels were much lower than they are today, and a land area called Beringia connected Siberia and Canada. Animals were moving freely back and forth between continents, which is why the Ice Age wolves discovered across Eurasia and North America are closely related. The Zhr mitochondrial DNA fits perfectly into that closely related group of animals, or clade, with a common ancestor that lived between 86,000 and 67,500 years ago.
Zur and Kiddha are the ancestors of every wolf in the world (except for the possibility Himalayan soaring wolves, Who appears to have been doing their own things for hundreds of thousands of years, according to a study conducted earlier in 2020).
But since mitochondrial DNA passes directly from mother to pup, Mitchin and her colleagues can tell that Zhùr was not a direct ancestor of the wolves that roam the Klondike today. At some point in the past 56,000 years or so, the inhabitants of Klondike have died from wolves or have left the area, and another group of wolves has replaced them – one less associated with flowers. Currently, there isn’t enough data to know if the newcomers have left the car, outdid the competition, or absorbed Zhr’s relatives, but the puppy’s DNA hints at an exciting yet unexplored story.
Wolves also eat fish
If Zhr can’t tell Meachen and her pals exactly what happened to a whole group of Klondike wolves, she could at least tell a large part of her own story. Depending on how her bones developed, the puppy was around 7 weeks old when she died. Since modern wolves in the area usually give birth in early summer, this means that Zur may have died in July or early August, around the same time Lovelace washed it out of permafrost after 57,000 years.
By that time, Zohoor’s mother may have weaned her pups from milk and started bringing real food for them. Modern wolves begin eating solid food at around 5 or 6 weeks of age. In Zur’s case, this appears to have included a lot of fish, according to the amount of the nitrogen-15 isotope in its body. Nitrogen isotopes provide clues about how far the animal will move up the food chain and whether more of its food comes from land or water.
Looking at all the fish, the puppy’s breathing must be terrible. “Usually, when you think of wolves in the Ice Age, you think of them eating bison or musk ox or other large animals on Earth,” Michin said. “The only thing that surprised us was that she was eating water resources, especially salmon.”
Modern wolves in inland Alaska have been known to feast on fish, at least in seasons when they are readily available. And the Zh farr’s den was not far from the Klondike River, where Chinook salmon spawn today. Fish swim over the Yukon River to the Klondike River, where it would have been a veritable buffet for a wolf mother looking to feed her young.
How to freeze and dry an ice age predator
Obviously, things didn’t turn out well for Zhr, or we wouldn’t have a ridiculously gorgeous ice mummy to study today. Her burial could provide some clues about its abrupt end and its supernatural preservation over thousands of years. She must have died under the right conditions and was buried quickly – a rare combination. “The animal must die in the permafrost site, where the ground freezes all the time, and it must be buried very quickly, like any other fossilisation process,” Mitch said.
Animals killed by predators do not tend to form perfectly preserved ice mummies, and animals that die from disease or exposure also do not tend to be buried quickly enough to freeze and embalm. The isotopic analysis indicates that the pup was feeding well, so whatever happened, she probably wasn’t sick and definitely wasn’t starving.
Mitch and her colleagues believe a den collapsed, killing her instantly and burying the remains in the frozen ground. “We feel a little better because we know the poor little girl hasn’t suffered for a long time,” Mitch said.
Another question that Zohoor will never be able to answer is: Why was she alone in the den? Wolves’ mothers usually have four to six dogs at a time, but Zhr’s is buried next to Last Chance Creek; She showed no sign of her mother or her littermates. “You could be a lonely puppy, or the other wolves were not in the den during the crash,” Mitch said. “Unfortunately, we’ll never know.”
The permafrost mummies of large mammals, such as mammoths, bears, and even wolves, are rare discoveries by paleontologists. But smaller ones, like ground squirrels and rodents, often appear in places like Siberia and Yukon. Mitch and her colleagues speculate that animals that lived in burrows or dens, including wolf pups, may have had better odds of keeping them in permafrost, especially if they died in caves.
Even large permafrost mummies are becoming more and more popular. a A cave bear emerged from the permafrost of Siberia Earlier this year, it was one of several recent discoveries. “One of the small positive aspects of climate change is that we’re going to find more of these mummies as the permafrost thaws,” Michin said. “This is a good way for science to better reconstruct that time, but it also shows us how warm our planet is.”