This ice wolf puppy does not look much like a scary predator, which with its small puppy teeth and soft soft ears. According to her DNA, however, the mummified puppy, named Zhùr, comes from a population that is among the ancestors of all modern wolves. The Canadian permafrost lyophilized it remains shortly after its death, about 57,000 years ago.
“She is the most complete wolf mummy ever found. It’s practically 100 percent intact – all that’s missing are her eyes, “said Julie Meachen, a paleontologist at Des Moines University.
Puppy surprise
In July 2016, miner Neil Loveless of Favron Enterprises was searching for gold in the famous Klondike gold fields in Alaska. Sprinkle the frozen mud along the banks of the Last Chance creek. It is a process called “hydraulic thawing”, meant to thaw and soften frozen permafrost so that miners can look for gold in river deposits, an approach called pleasure extraction. But Loveless found something much stranger and even more interesting than Klondike gold: a frozen, mummified wolf puppy.
“Thank you [Loveless] for his eager eye to see Zhùr melting from the permafrost, making sure it was kept safe in a freezer and then reporting the discovery to the Yukon paleontology, ”wrote Meachen and her colleagues in a recent paper in the journal Current Biology. Studying Pleistocene wildlife in the Yukon means working with gold mining companies, whose workers may be the first to notice something like Zhùr. Scientists like Meachen are also working very closely with people who have called this region home for thousands of years, such as Tr’ondëk Hwëch’in First Nation.
The members of the group gave the puppy her name, Zhùr, which means “wolf” in the Hän language. Zhùr is a culturally significant discovery for Tr’ondëk Hwëch’in, but they were also interested in how much the frozen puppy could teach us about Pleistocene wolves. The first nation agreed to display the mummy at the Yukon Beringia Interpretation Center in Whitehorse, where it was cleaned, preserved, and studied.
“We are grateful for the partnership with Tr’ondëk Hwëch’in in our common role in protecting and conserving Klondike’s heritage resources,” wrote Meachen and her colleagues.
Taking tiny samples from some of Zhùr’s incredibly well-preserved hair follicles, Meachen and her colleagues radiocarbonated with the frozen puppy and studied the chemical isotopes in her body, which gave clues about what she ate and the climate in which she ate. he lived. They also sequenced her mitochondrial DNA, the genetic material passed directly from mother to offspring.
The ancestors of modern wolves
Zhùr probably lived about 57,000 years ago, but it took three different methods of meeting to figure it out.
The radiocarbon meetings could only tell Meachen and her colleagues that the mummy was more than 50,000 years old. The puppy’s genome suggested that he once lived between 75,000 and 56,000 years ago, based on the rate at which the wolf’s DNA collects mutations over time. And the oxygen isotopes in her body suggested that she lived in the relatively warm period of marine isotope stage 3, when warmer conditions led to lower ratios of the oxygen-18 isotope in marine sediment nuclei – and in Zhùr’s body. MIS 3 spanned 57,000-29,000 years ago.
All of these possible data overlapped at one point: 57,000 to 56,000 years ago. At that time, sea levels were much lower than they are today, and a land region called Beringia connected Siberia to Canada. The animals moved freely back and forth between the continents, which is why Pleistocene wolves dug up in Eurasia and North America are all so closely related. Zhùr’s mitochondrial DNA falls into that very group of closely related or clad animals, with a common ancestor that lived between 86,000 and 67,500 years ago.
Zhùr and its clade are the ancestors of every wolf in the world (with the possible exception of high-altitude Himalayan wolves, which apparently do their own thing for hundreds of thousands of years, according to a study earlier in 2020).
But because mitochondrial DNA is passed directly from mother to puppy, Meachen and her colleagues might say that Zhùr was not a direct ancestor of the wolves that roam the Klondike today. Sometime in the last 56,000 years, the population of Klondike wolves died or left the area and was replaced by another group of wolves – one less related to Zhùr. At this time, there is not enough data to say whether the newcomers left, overtook or absorbed Zhùr’s relatives, but the puppy’s DNA suggests an interesting story yet to be explored.
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A gold miner found the mummified puppy and kept it in a freezer until paleontologists were able to collect it.
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Conservatives cleaned the mummified chicken and even brushed its fur carefully.
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The puppy’s remains are dry, but mostly intact due to burial in permafrost.
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X-rays showed how completely the puppy’s bones had developed, which paleontologists used to estimate his age.
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The puppy’s teeth are largely intact, as are the details of his lips and gums.
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Permafrost mummies are very fragile and you should not throw your snout.
Wolves also eat fish
If Zhùr couldn’t tell Meachen and her colleagues exactly what happened to a whole population of Klondike wolves, she could at least tell quite a bit of her own story. Based on the evolution of her bones, the puppy was about 7 weeks old when she died. Since modern wolves in the area usually give birth in early summer, this means that Zhùr probably died in July or early August, at about the same time Loveless washed it of permafrost 57,000 years later.
By then, Zhùr’s mother had weaned her chicks from the milk and started bringing them real food. Modern wolf chicks start eating solid foods at about 5 or 6 weeks of age. In Zhùr’s case, he seems to have included a lot of fish, depending on the amount of nitrogen-15 isotope in her body. Nitrogen isotopes provide clues as to how far the animal could have been and whether more of its food came from land or water.
Given all the fish, the puppy’s breathing must have been atrocious. “Normally, when you think of wolves in the ice age, you think of them eating bison or musk oxen or other large animals on land,” Meachen said. “One thing that surprised us was that they eat aquatic resources, especially salmon.”
Modern wolves in northern Alaska have been known to throw fish, at least in seasons when they are readily available. And Zhùr’s lair is not far from the Klondike River, where the Chinook salmon comes out today. The fish swim on the Yukon River to the Klondike, where it would have been a real buffet for a mother wolf looking to feed her cubs.
How a predator of the ice age dries by freezing
Obviously, things didn’t end well for Zhùr, or we wouldn’t have a ridiculously adorable canid ice mummy to study today. Her burial may provide some clues about her premature end and her extraordinarily good preservation in the millennia that followed. She probably died in the right conditions and was quickly buried – a rare combination. “The animal must die in a permafrost location, where the soil is frozen all the time and must be buried very quickly, like any other fossilization process,” Meachen said.
Animals that are 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 fast enough to freeze and mummify. And the isotopic analysis suggests that the puppy was well fed, so no matter what happened, she probably wasn’t sick and certainly wasn’t starving.
Meachen and her colleagues believe that Zhùr’s lair collapsed, instantly killing her and burying the remains in the frozen earth. “We feel a little better knowing that the poor girl didn’t suffer too long,” Meachen said.
However, there is another question that Zhùr will never be able to answer: why was she alone in the lair? The wolf’s mothers usually have four to six puppies at a time, but only Zhùr was buried next to Last Chance Creek; no sign of mother or bedding colleagues appeared. “She may have been a single cub, or the other wolves may not have been in the den during the crash,” Meachen said. “Unfortunately, we will never know.”
A warning queue
The permafrost mummies of large mammals, such as mammoths, bears and even wolves, are rare discoveries for paleontologists. But smaller ones, such as squirrels and ferrets, occur more often in places like Siberia and the Yukon. Meachen and colleagues speculate that animals that lived in burrows or burrows, including wolf cubs, may have been more likely to be kept in permafrost, especially if they died in pits.
Even the great discoveries of the permafrost mummy are becoming more frequent. A cave bear came out of Siberian permafrost earlier this year and is one of many recent discoveries. “A small advantage of climate change is that we will find more of these mummies as the permafrost melts,” Meachen said. “This is a good way for science to better reconstruct that period, but it also shows us how much our planet is warming.”
Current Biology, DOI 2020: 10.1016 / j.cub.2020.11.011 (About DOI).