The ivory hunters knew they had found something special. It was 2020 and they were tunnelling into the banks of the Badyarikha river in Siberia. The permanently frozen soil of the river basin is a rich hunting ground for woolly mammoth tusks, which fetch a pretty price on the Chinese ivory market. Occasionally, however, rarer treasures turn up – more complete remains of mammoths and other long-dead animals.
This, however, was on a different planet. Inside a block of ice, the prospectors spotted a furry carcass unlike anything they had seen before. They alerted scientists, and eventually the ice block reached at the Borissiak Paleontological Institute in Moscow for analysis. Last year, he and his team concluded that the remains were those of a , an animal only distantly related to living cats, and one that hunted like no predator does today.
“For the first time in the history of palaeontology, the appearance of an extinct mammal that has no analogues in the modern fauna has been studied,” says Lopatin. “It’s a fantastic feeling.”
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And it is one that might become more familiar to palaeontologists in the years ahead. Although frozen mummies have been emerging from the permafrost of Russia and North America for two centuries, we entered a golden age of discovery about 15 years ago. In that time, some of the finest known woolly mammoth mummies have come to light, as well as the first mummies of predators including wolves and cave lions. There are high hopes of more – potentially even the first frozen mummies of Stone Age humans.
Peter the Great’s museum of curiosities
Knowledge of permafrost mummies stretches deep into the frozen mists of time. In the late 1690s, Danish merchant-adventurer Evert Ysbrants Ides, who had somehow been appointed Russia’s envoy to China by Peter the Great, spent three years schlepping overland from Moscow to Beijing via Siberia. His reports that many of the region’s people knew of – and feared – huge corpses emerging from river banks. Folklore had it that they were gigantic subterranean beasts that expired when exposed to light, and that people who encountered them fell ill and died.
His book also contains the first contemporary description of a permafrost mummy, a rotting carcass of a “mammut” discovered in 1692 on the banks of the Yenisey river. A local man told him that the animal’s forefoot had the girth of a man’s waist.
In 1722, perhaps inspired by his envoy’s account, Peter the Great issued a decree for the collection of natural curiosities, including the remains of mammoths, to fill his Kunstkamera (museum of curiosities), then under construction in St Petersburg. But he died in 1725 with his mammoth ambition unfulfilled.
In fact, the collection and study of permafrost mummies would remain a frustratingly difficult task for another 200 years, partly because the ancient remains typically occur in locations that aren’t easily accessible to scientists. For instance, in 1799, a mammoth mummy – the first known to science – was spotted on the banks of the Lena river in Siberia. Early reports suggested it was nearly intact, but by the time biologist Mikhail Adams got there in 1806, it was in poor condition. The tusks had been removed and much of the soft tissue, including the trunk, had rotted away or been eaten by scavengers. Nevertheless, Adams recovered a portion of skin, bundles of wool and the rest of the skeleton, then dispatched them to St. Petersburg.
The Berezovka mammoth
According to a 1929 paper by biologist Innokenty Tolmachoff, around 30 more mammoth and rhino mummies were reported in the century after the Adams mammoth, but . Many more mummies were probably kept secret or destroyed, Tolmachoff speculated. An exception is the Berezovka mammoth, which was found in a sitting position in 1900, excavated in 1901 and sent (in parts) to the Zoological Museum in St. Petersburg. It still had vegetation in its mouth and an erect penis, indicating a sudden death, possibly by asphyxiation.
But money talks, and in 1938 the president of the USSR Academy of Sciences offered a reward of up to 1000 roubles – roughly £20,000 in today’s money – to any citizen who reported the remains of a mammoth, rhino or other animal to him, either by radio or mail. Gold mining arrived in the far north of Russia and North America at this time, too, and together these initiatives ““, according to a recent publication by at the Pleistocene Park Foundation and at Bryn Athyn College, both in Pennsylvania. Thus began the first golden age of mummy discovery.
A near-complete steppe bison was found in an Alaskan gold mine in Alaska in 1979
Up to that point, mummies of only three species that had lived during the last glacial period more than 10,000 years ago were known: mammoths, rhinos and a small, rabbit-like animal called a pika. But over the following decades, eight more were added, including wild horses, musk oxen, stag-moose and steppe bison.
Many of the discoveries became famous worldwide, such as Effie the baby mammoth, found in 1948; the Selerikan horse in 1968; another baby mammoth, Dima, in 1977; and a near-complete steppe bison found in a gold mine in Alaska in 1979, dubbed Blue Babe because it was coated in vivianite, a blue iron phosphate mineral.
Most permafrost mummies date from the latest part of the Pleistocene Epoch, which lasted from around 2.58 million years ago to 11,700 years ago and is commonly called the Great Ice Age. The earliest known exceed 50,000 years old, right on the edge of the range of radiocarbon dating. The latest are from the Holocene Epoch, which followed the Pleistocene. But the majority are from the period before the last glacial maximum, which occurred around 26,000 years ago.
During that time window, much of the northern hemisphere was buried under ice sheets, but to the south lay a ribbon of land called the mammoth steppe, a cold, dry, treeless grassland stretching around the globe between present-day Siberia and the territory of Yukon in Canada.
Megaherbivores
This ecosystem was dominated by megaherbivores, such as mammoths, woolly rhinos, musk oxen, bison and moose, as well as the carnivores that preyed on them: cave lions, wolves, bears, cave hyenas and scimitar-toothed cats. There were plenty of smaller creatures in this landscape too, such as wolverines, hares, ferrets, lemmings, ground squirrels, pikas and birds.
Occasionally, these animals met a suffocating end, trapped in mud, water, crevices or collapsed burrows from which they couldn’t escape. Even more rarely, their whole or partial bodies were frozen, entombing them in ice or permafrost (defined as ground that stays below 0°C (32°F) for at least two consecutive years). Such frozen mummies can survive for thousands of years until they re-emerge from their frigid tombs, perhaps when a river cuts through the permafrost or when prospectors excavate the sediments in search of ivory or gold.
Some of the species preserved as permafrost mummies still exist, and most of the extinct ones have modern analogues. Mammoths, for instance, are closely related to Asian elephants and are anatomically similar in many ways. Even so, the mummies of extinct species contain information that can’t be obtained from skeletal remains or living relatives.
“The big value is to actually see the real morphology,” says , an evolutionary geneticist at the Swedish Museum of Natural History in Stockholm. “For all these frozen mammoths that we found, there are many things we would never have known about, for example that they have this kind of finger-like protrusion on the trunk, the size of the ears and stuff like how short the tail was.”
That information is useful for Colossal Biosciences, a US biotechnology company attempting to de-extinct the woolly mammoth. “It tells you what phenotypes you should look for,” says Beth Shapiro, the company’s chief science officer. “It sure is nice to have some actual hair to look at and see the shape and the texture and how it was distributed around the body.” The mummies are also a source of ancient DNA that is often in better condition than any that can be extracted from bones and teeth, says Dalén.
By the end of the 20th century, permafrost mummies belonging to 12 species, all herbivores, had been recovered from permafrost. But most were in quite poor condition. Of 38 specimens in total, only eight were complete – meaning that 90 per cent or more of the animal was intact – and four of those were ground squirrels or voles. The larger intact specimens were two mammoths (Dima and Masha), a woolly rhino (Starunia 2) and Blue Babe.
The second golden age of mummy discovery
In the past 15 years, the species count has jumped to 19 and now includes five mammalian predators and the first non-mammal, a lark. The number of complete specimens has leapt too. It now stands at 22, and the number of mammoth specimens has more than doubled.
This second golden age of mummy discovery is largely down to increased levels of ivory hunting in Siberia and gold mining in the Klondike region of Yukon, says Dalén. The former is driven by demand from China, which banned the sale of elephant ivory in 2017. Although there is , prospectors can also operate legally if they allow local scientists to join their expeditions.
The first groundbreaking discovery of the 21st century was the Tumat wolf in 2011, the first predator to be found mummified. The grey wolf – the same species as the living Canis lupus – was around 3 months old when it died some 12,500 years ago. Four other grey wolf pups, one of them more than 50,000 years old, have since been found in Yukon (pictured on page 30) and in the region of Yakutia in Russia. In 2019, the severed but intact head of an adult wolf, complete with fur and teeth, was found in Yakutia.
More predatory species have emerged too. One of the Pleistocene’s apex carnivores was the now-extinct cave lion, a robust big cat closely related to today’s lions, at first known only from sporadic discoveries of teeth and isolated bones. In 2015, were found side by side in a collapsed den in Yakutia. Named Dina and Uyan, they were just a week old when they died 30,000 years ago. Two more cave lion cubs, , turned up in a different location in 2017 and 2018, though they lived tens of thousands of years apart. The , later identified as a horned lark that lived around 45,000 years ago, were found in the same location in 2020. Other recent complete specimens include the Anyuy steppe bison, a 48,000-year-old adult male found in a river in Yakutia; the Batagai foal, a young Lena horse; and three infant mammoths.
Scimitar-toothed cat cub
The jewel in the crown, however, is the scimitar-toothed cat cub unveiled last year (pictured, left). The rear end of the animal is missing, but the chest, front legs and head are preserved in exquisite detail, including the stubs of its whiskers.
From an anatomical examination, Lopatin and his colleagues identified the cub as a juvenile Homotherium latidens. Radiocarbon dating suggests that it died roughly 37,000 years ago. “We don’t know the cause of its death, but we can assume that it quickly became covered with sediment and froze into the ground,” says Lopatin.
H. latidens is an extinct relative of the more famous (and also extinct) sabre-toothed cat Smilodon. The former lived across Eurasia, North America and Africa during the Pleistocene, dying out around 12,000 years ago. Skeletal remains aren’t uncommon, but the discovery of a mummy – even half a juvenile one with unerupted teeth – adds a great deal to our knowledge of these charismatic and fearsome carnivores. “The muscles, skin and fur of the mummy were well preserved,” says Lopatin.
The team showed that the ancient cub had an unusually large upper lip – twice the height of those of similarly aged lion cubs – presumably so that adult H. latidens could cover and protect their large canines. This is in line with a 2022 study that inferred from fossils that H. latidens .
The permafrost mummy also had unusually wide paws, perhaps an adaptation to walking in snow. Its fur, a chocolatey brown, lacked the spotted or striped camouflage often seen in young cats today. It is unclear why. Had the cub lived, it would have grown into a robust lion-sized cat with , both thought to be adaptations for bringing down large prey. “It’s pretty cool,” says Dalén.
Permafrost humans
Despite the recent advances, there are holes the mummy hunters would dearly love to fill. Cave bears remain stubbornly elusive. And Lopatin says he is hoping for a specimen of the “super huge” Elasmotherium, an elephant-sized, long-legged rhino. Dalén thinks that we can go much further back in time: he and his colleagues recently found a lemming mummy in the , suggesting there is a possibility of finding larger-bodied species from around that time. He would also love to see the mummy of an adult cave lion, to test his hypothesis that they turned white in winter.
But the icing on the cake would be a permafrost mummy of an ancient human. Ötzi, a frozen mummy discovered in the Alps in 1991, continues to be a rich source of information on ancient human life. But it is “only” 5300 years old, a resident of the European Copper Age. Permafrost human mummies could be much older. “We know that modern humans were up there [in Siberia] already 30,000 years ago,” says Dalén. A human mummy of such antiquity would provide us with an unprecedented glimpse into the Eurasian Stone Age – and potentially offer important data on a human population that included the ancestors of the first Americans. More speculatively, it is even possible that there are permafrost Neanderthal or Denisovan mummies out there, although there is no evidence that these ancient humans lived so far north.
“To me, it is surprising that some sort of frozen hominin hasn’t been found yet,” says Dalén. “I’ve talked to the Russians about this, and the answer I get is actually a bit mysterious. What they say is, well, we are also surprised. But for the locals up there, finding a human is a huge taboo. It’s quite possible that they have found humans, but they will not tell anyone about it. The rumours I’m hearing is that maybe they have been found…”
Neanderthals, ancient humans and cave art: France
Embark on a captivating journey through time as you explore key Neanderthal and Upper Palaeolithic sites of southern France, from Bordeaux to Montpellier, with New Scientist’s Kate Douglas. Visit iconic archaeological sites and deepen your knowledge of Neanderthals and early human ancestors, all while journeying from Bordeaux across the picturesque south of France. Traverse through charming medieval towns and breathtaking countryside, culminating in the vibrant city of Montpellier.
