For decades, scientists have studied the DNA of long-extinct animals found frozen in permafrost. However, researchers from the Centre for Palaeogenetics in Stockholm, Sweden, have just completed a world first and sequenced the entire genome of an Ice Age animal found in the stomach of another.
The study, published today in Genome Biology and Evolution, analysed a tissue sample from a woolly rhinoceros (Coelodonta antiquitatis) recovered from the stomach contents of an ancient wolf (Canis lupus).
This ‘Russian doll’ of Ice Age remains was discovered in permafrost near the village of Tumat in the remote, northeastern corner of Siberia.
During an autopsy of the frozen wolf, researchers found a small, 4x3 cm fragment of tissue that, after a series of DNA analyses, was identified as belonging to a woolly rhinoceros.
Both the woolly rhinoceros tissue and the wolf remains were radiocarbon dated and found to be 14,400 years old, making the former one of the youngest specimens of its kind ever discovered.
“Recovering genomes from individuals that lived right before extinction is challenging, but it can provide important clues on what caused the species to disappear, which may also be relevant for the conservation of endangered species today,” said one of the study’s authors, Camilo Chacón-Duque, in an associated press release.
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The DNA analyses conducted by this study were made particularly challenging by the peculiar style of preservation. While animal remains found in permafrost can preserve DNA, it’s typically degraded and only occurs in very small amounts. The fact that the fragment of tissue was found inside a predator’s stomach further complicated analyses, introducing the potential risk of wolf contamination.
Nevertheless, researchers were able to parse the two animals’ genomes and reveal secrets hidden in their DNA. “It was really exciting, but also very challenging, to extract a complete genome from such an unusual sample,” said the study’s lead author, student Sólveig Guðjónsdóttir, who carried out the work as part of her master’s thesis at Stockholm University.
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The genome sequenced from the woolly rhinoceros tissue sample was later compared with two other genomes recovered from older woolly rhinoceros remains, dated to 18,000 and 49,000 years ago. These comparisons revealed no signs of genetic deterioration as the species approached extinction 14,000 years ago. Instead, they suggested woolly rhinoceroses maintained a stable and relatively large population until a sudden collapse just prior to their disappearance.
“Our analyses showed a surprisingly stable genetic pattern with no change in inbreeding levels through tens of thousands of years prior to the extinction of woolly rhinos,” said Edana Lord, another researcher from the Centre for Palaeogenetics.
Love Dalén, also from the Centre for Palaeogenetics, added, “[the] results show that the woolly rhinos had a viable population for 15,000 years after the first humans arrived in northeastern Siberia, which suggests that climate warming rather than human hunting caused the extinction.”
Interestingly, the wolf the woolly rhinoceros tissue was recovered from was a puppy, not an adult. This puppy is one of two, now-famous ‘Tumat Puppies’ found in 2011 and 2015, respectively.
These puppies are believed to have been littermates, and their presence near mammoth bones showing signs of butchering by humans previously led some researchers to suggest they were early domesticated dogs.
A study published in June, 2025, put a pin in that particular theory, suggesting they were most likely wolf cubs on the basis of several chemical ‘fingerprints’ found in their bones, teeth and tissue.
It’s likely the puppies died shortly after one of them dined out on the remains of a woolly rhinoceros, as the tissue sample analysed by this latest study had not been fully digested. This hints at a rather sombre end for the ‘Tumat Puppies’, but it also suggests they were being cared for by their packmates who may have brought them scraps from a recent hunt.
Top image: Tumat-1 wolf puppy. Credit: Mietje Germonpré
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