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A scrap of tissue, preserved for thousands of years inside an ancient wolf, has given scientists a rare look at a woolly rhinoceros that lived right near the species’ end.
What they found is not the slow, sad genetic unraveling you might expect. Instead, the animal’s DNA suggests woolly rhinos stayed surprisingly healthy until very late, hinting that extinction came fast – more like a sudden crash than a long decline.
The work comes from researchers at the Center for Palaeogenetics, a collaboration between Stockholm University and the Swedish Museum of Natural History.
The findings suggest that woolly rhinos didn’t show the classic genetic warning signs of a population dwindling for ages.
That pushes the spotlight toward a rapid, external shock – most likely the big warming at the end of the last Ice Age.
An unprecedented genetic find
The story starts with a detail that feels almost too strange to be real: the rhino sample wasn’t taken from a bone in a museum drawer, or even from a frozen carcass. It came from the stomach of a wolf.
“Sequencing the entire genome of an Ice Age animal found in the stomach of another animal has never been done before,” said senior author Camilo Chacón-Duque, a former researcher at the Center for Palaeogenetics.
That matters for more than bragging rights. Genomes from animals that lived close to extinction are hard to get.
Yet, they can tell you whether a species was already genetically cornered or whether it still had plenty of diversity and simply got wiped out by circumstances it couldn’t outrun.
“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,” Chacón-Duque said.
Tissue hidden in permafrost
The wolf itself was found in permafrost near the village of Tumat in northeastern Siberia.
When scientists examined the frozen remains, they discovered a small piece of preserved tissue in the stomach. It was like finding a sealed envelope in a time capsule.
Radiocarbon dating placed the tissue at about 14,400 years old. DNA sequencing then showed it belonged to a woolly rhinoceros, Coelodonta antiquitatis.
That makes it one of the youngest woolly rhino samples ever identified, and that timing is the whole point: it sits close enough to the end to help answer what the end actually looked like.
The challenges of ancient DNA
Ancient DNA is rarely neat. It breaks into tiny fragments, degrades over time, and can be swamped by contamination. This sample had all the usual problems, plus an extra one: it was literally mixed into predator stomach contents.
That means the wolf’s own DNA is everywhere and so is microbial DNA. The rhino tissue itself is just a small fragment – hardly the dream sample you’d pick if you were trying to rebuild an entire genome.
“It was really exciting, but also very challenging, to extract a complete genome from such an unusual sample,” said study lead author Sólveig Guðjónsdóttir, who carried out the work as part of her master’s thesis at Stockholm University.
Still, the team managed to reconstruct the rhino genome at high-quality, which is why the study can make stronger claims than many “ancient DNA” stories that rely on smaller snippets.
A stable genome until the end
To see whether woolly rhinos were fading slowly over time, the researchers didn’t treat this one animal as a standalone curiosity.
They compared its genome to two other high-quality woolly rhino genomes from older individuals, dated to around 18,000 and 49,000 years ago.
That comparison lets you look for trends. If a species is shrinking for millennia, you often see rising inbreeding, falling genetic diversity, and an accumulation of harmful mutations. Think of it like a population slowly losing options.
But that’s not what they saw. Instead, the genetic signals were steady. No obvious deterioration. No clear sign that the species had been limping along for ages.
“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, a former postdoctoral researcher at the Center for Palaeogenetics.
This is the kind of result that changes the shape of the extinction story. It suggests that woolly rhinos weren’t doomed because they became too inbred or genetically fragile over a long period. They may have been doing fine, until something big changed quickly.
Climate versus humans
Whenever an Ice Age giant disappears, the same argument comes up: was it climate, or was it humans? The new genome doesn’t magically settle everything, but it does put weight on one side.
If the population stayed viable for a long time after humans arrived, then it’s harder to blame extinction purely on hunting pressure. The researchers point out that woolly rhinos seem to have held on for thousands of years alongside people in northeastern Siberia.
“Our 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,” said Love Dalén, a professor of evolutionary genomics.
The logic is pretty simple. If a species persists for that long after humans arrive and then disappears as the climate shifts sharply, warming begins to look like the more plausible trigger.
This is especially true when the genetics show no sign of a slow population squeeze.
Looking beyond one species
It’s easy to get distracted by the headline weirdness – “rhino genome from wolf stomach” – but the deeper message is about timing.
Extinction doesn’t always look like a long, gradual slide. Sometimes it looks like stability and then, suddenly, nothing.
This also hints at something useful for modern conservation. A population can appear genetically healthy and still be vulnerable if the environment changes faster than it can adapt.
Genetics can tell you part of the story, but it can’t protect a species from a rapidly collapsing habitat.
And finally, there’s a quiet methodological lesson here. If you can pull a full genome from stomach tissue in permafrost, it widens the kinds of samples scientists might dare to try in the future.
Sometimes the last clues aren’t in the bones. Sometimes they’re in the belly of a predator that ate the evidence and then froze in time.
The study was published in the journal Genome Biology and Evolution.
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