An Ice-Age Squirrel Found by Gulag Prisoners Gets Its Scientific Due

“We should be very thankful to those unnamed prisoners who saved those carcasses.”

A 30,00-year-old mummified squirrel carcass
One of the three squirrels that was found by Gulag prisoners, whose DNA has now been analyzed  (Zoological Institute of the Russian Academy of Sciences)

I’ve never read a scientific paper that so thoroughly gripped me in the first paragraph, so I will let the authors of a new paper from the journal Scientific Reports speak for themselves.

Readers of “The Gulag Archipelago” by Aleksandr I. Solzhenitsyn might remember how the book starts: “In 1949 some friends and I came upon a noteworthy news item in Nature, a magazine of the Academy of Sciences. It reported in tiny type that in the course of excavations on the Kolyma River a subterranean ice lens had been discovered which was actually a frozen stream - and in it were found frozen specimens of prehistoric fauna some tens of thousands of years old” (p. ix). That very same news item in Nature (‘Priroda’) continued by reporting what Solzhenitsyn did not: that in May 1946 unnamed prisoners of GULAG recovered a nest with three complete mummified carcasses of arctic ground squirrels at a depth of 12.5 meters of the permafrost sediments of the El’ga river (the upper Indigirka river basin, Yakutia). The carcasses were extremely well preserved and “smelled of dampness immediately upon their recovery but lost the smell after having air-dried and remained in a stable condition resembling that of the mummies” (p. 76). It was suggested that they had lain in the permafrost for at least 10–12 thousand years.

It turned out to be even longer, 30,000 years, according to new radiocarbon dating.

The paper goes on to describe how the team, led by Nikolai Formozov at Lomonosov Moscow State University, sequenced DNA from one of the mummified carcasses, along with DNA from four fossils found recently in Siberian permafrost and modern day Arctic ground squirrels. It was all a long time coming. Formozov first suggested studying the squirrels 25 years ago—a small blip of time when you’re talking about creatures that have laid in the ground for millennia but still, a long time in the span of a single scientist’s career.

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The hard part was not, actually, getting access to the famous specimens, whose modern provenance is well documented. The unknown prisoners had turned the squirrels over to the Gulag camp’s geologist, Yuriy Popov, who gave two of them to the Zoological Museum in what is now St. Petersburg. The third, preserved in alcohol, is at the Magadan Regional Museum of Local Lore, closer to the camp where it was originally found.

Years ago, Formozov and his colleagues took some mummified squirrel tissue and extracted their DNA. They did it three or four times, only to end up with three or four different results. The problem, it turned out, was their lab, which was contaminated with DNA from modern day ground squirrels they also studied. The results always matched whatever modern squirrel species happened to be in the lab recently.

Ancient DNA is tricky like this. Over time, long coiled strands of DNA fragment into shorter pieces. The older, the more fragmented, leaving few intact strands for the scientists to sequence. Meanwhile, the cells of present-day ground squirrels are bursting with fresh DNA that can easily drown out the bits of intact ancient DNA. “It is impossible to study ancient and modern DNA of the same group at the same time in a lab,” Formozov wrote to me in an email. “So we stopped.”

Then, a reunion with an old university classmate, Marina Faerman, set things back on course. At a mutual friend’s apartment in 2010, Formozov remet Faerman, who like many Russians of Jewish descent, had moved to Israel in the 1980s. She now had a lab at the Hebrew University of Jerusalem studying ancient human DNA, which meant 1) she was an expert in handling ancient DNA and 2) her lab was uncontaminated by modern squirrels. “It took about a minute to convince her to take part in this project,” said Formozov.

An ancient Arctic ground squirrel nest found in permafrost in the Yukon
An ancient Arctic ground squirrel nest found in permafrost in the Yukon. Grant Zazula

Around this time, Formozov remembered the preface to The Gulag Archipelago, which he, like many in the then Soviet Union, vividly recalls reading. Alexander Solzhenitsyn’s book was the first historical account of what happened in the Gulag camps, and it circulated in samizdat in the Soviet Union. Formozov’s family owned the first volume, he says, smuggled in from the west. The second volume was passed among friends, who had it for a few days at a time. The third volume was “extremely rare,” and he recalls having only three hours to read it in a friend’s home. If he could find the scientific paper referenced by Solzhenitsyn, Formozov thought, perhaps he could learn more about the origin of these mummified squirrels. In half an hour of scanning old copies of the journal Priroda, he found the original note by Yuriy Popov, the Gulag camp geologist.*

For Formozov, this wasn’t just an interesting bit of trivia, but the meeting of two long-time interests. About twenty-five years earlier, he learned that two of his teachers had taken part in the bloody uprising at Kengir, another Soviet labor camp, that is described in detail in The Gulag Archipelago. He became interested in the Kengir uprising and helped organize international conferences about Gulag uprisings in the early 1990s. It is with the weight of all this history in mind that he took to studying the squirrels originally found by Gulag prisoners.

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The team ultimately sequenced one of the mummified squirrels found near the camp as long with four mummified squirrels more recently pulled out of the ground in Siberia. Because ancient DNA is so degraded, they sequenced only one gene. Yet that was enough to sketch out the relationships between these ancient Arctic ground squirrels and present day ones. The Ice Age was not a period of constant cold, but a period of fluctuations, when it warmed and cooled. Where the squirrels could live changed, too. So the squirrels that once lived in eastern Russia had actually gone extinct, the DNA analysis suggested. The squirrels that live in Siberia today are descendants of a later group that crossed the Bering land bridge from Alaska to colonize the area. The only known exception are squirrels on the Kamchatka peninsula that juts out of Russia’s east coast, which appear to be descended from the Ice Age squirrels. (Formozov also wrote me a magnificent email about how they collected the Kamchatka squirrels. It involves a fox.)

Gold mine where ancient Arctic ground squirrel nests are found
A gold mine in the Yukon, where ancient Arctic ground squirrel nests are found. Tim Rabanus-Wallace

“I love this paper. It’s really cool,” said Tim Rabanus-Wallace, who works with ancient DNA at the University of Adelaide. “The science behind it is very solid.” At least as solid as any ancient DNA work can be, as Rabanus-Wallace knows, because he has done preliminary work sequencing ancient Arctic ground squirrels in the Yukon in Canada.

Here might be a good place to dwell on the fact that these ancient squirrels nests are also found in North America—often, in fact. The region comprising Siberia and western North America is known as Beringia, and it was of course once a contiguous region when the Bering land bridge existed.  In the Yukon today, gold miners shoot water cannons to melt permafrost, which occasionally exposes the nests that ancient Arctic ground squirrels made to hibernate through winter.** And even more occasionally, some of those squirrels never made it out of hibernation. Bad for the squirrel, but very good for Arctic ground squirrel researchers because underground lockers are the safest place to store a fossil. “They make the perfect kind of fossils,” said Grant Zazula, a paleontologist with the government of Yukon.

Ancient Arctic ground squirrels are also interesting, scientifically, because these little creatures build nests. In other words, they go out and do the work of collecting Ice Age flora and saving it in an underground deep freeze for you. “They’re quite a neat little record,” said Zazula. He went on, “Most paleontologists who study the Ice Age, especially men, study these big wooly mammoths and saber-toothed tigers. When I’m at the conferences, I get up and say I study ground squirrels. But that’s okay.”

Sequencing ancient Arctic ground squirrels in North America would help confirm the findings in this study. Zazula and Formozov both say they’re open to collaboration, and they’ve corresponded with each other in the past. It’s gotten harder to collaborate with scientists in Russia recently, says Zazula, given the political winds. But as the shared lineage of Arctic ground squirrels reminds us, it’s really just a short hop across the Bering Sea.

* The opening of The Gulag Archipelago goes on to describe what Popov reported, that the prisoners who found the prehistoric fauna in ice “immediately broke open the ice encasing the specimens and devoured them with relish on the spot.” In an article in the Russian literary journal Novy Mir, Formozov wrote that this was unlikely, given that animals encased in permafrost lose moisture over time and become hard like wood. It’s likely those creatures were just fish stuck in a frozen river. But did he consider, I asked, even briefly when first reading the account that specimens might have been eaten? “Who knows what truly hungry people are capable of eating or trying to eat,” he replied, “The year 1946 was a very hungry one in Kolyma [the Gulag camp]. So we should be very thankful to those unnamed prisoners who saved those carcasses because they found the time and strength to do it in those terrible conditions.”

** You might be wondering how these little creatures dug nests in the permafrost, and the answer is they didn’t. The Ice Age was colder, which also meant there was less moisture around. With less moisture, there wasn’t enough liquid water in the ground to freeze into permafrost. These areas only later became permafrost, which had the effect of preserving the nests.