A 14,400-year-old wolf puppy’s last meal is shedding light on the last days of one of the Ice Age’s most iconic megafauna species, the woolly rhinoceros.
When researchers dissected the frozen mummified remains of an Ice Age wolf puppy, they found a partially digested chunk of meat in its stomach: the remnants of the puppy’s last meal 14,400 years ago. DNA testing revealed that the meat was a prime cut of woolly rhinoceros, a now-extinct 2-metric-ton behemoth that once stomped across the tundras of Europe and Asia. Stockholm University paleogeneticist Sólveig Guðjónsdóttir and her colleagues recently sequenced a full genome from the piece of meat, which reveals some secrets about woolly rhino populations in the centuries before their extinction.
One bad day for a rhino, one giant leap for paleogenomics
“Sequencing the entire genome of an Ice Age animal found in the stomach of another animal has never been done before,” said Uppsala University paleogeneticist Camilo Chacón-Duque, a co-author of the study, in a recent press release.
Scientists found the freeze-dried corpse of the wolf puppy—and her sister—eroding out of the permafrost near the Siberian village of Tumat in 2011 and 2015. When the team brought the puppy to a lab for dissection in 2022, they found small pieces of her last meal still in her stomach. DNA sequencing identified the meat as woolly rhino (or Coelodonta antiquitatis, if you’re fancy) and the puppies as wolves, not dogs.
But extracting a full genome’s worth of DNA from the rhino meat was a challenge. After 14,400 years in the permafrost, DNA molecules break down, leaving genomicists only small, degraded strings. Sorting the rhino’s DNA from the wolf’s was also no small feat.
The rhino’s DNA suggests that it came from a genetically healthy population that was large enough to avoid inbreeding. Inbreeding leaves its mark in descendants’ genomes in the form of long strings of homozygous genes, in which the individual inherits the same version, or allele, of a gene from both parents. It’s normal to have some homozygous genes, but a genome laden with lots of long stretches of homozygosity could be a sign of inbreeding over several generations. The Tumat rhino (or what was left of it) showed no such signs.
That came as a surprise, since woolly rhinos disappear from the fossil record about 400 years later. Already, the species was making its last stand in northeastern Siberia; its range had been shrinking eastward since around 35,000 years ago. But apparently, on the cusp of extinction, the species was still doing pretty well in northeastern Siberia (except for this particular rhino, who got eaten by a wolf after what one can only assume was a bad day).
Woolly rhino population was small but healthy
So what counts as a stable population?
In the genome of a 49,000-year-old woolly rhino from a few hundred miles east in Rakvachan, Siberia, Guðjónsdóttir and her colleagues found clues about the species’ even more ancient history. Big changes in population size, among other events, can leave traces in the genome, and the researchers used those to estimate that between 114,000 and 63,000 years ago, the woolly rhino population dropped sharply, from about 15,600 to about 1,600.
Those numbers refer to what ecologists call the “effective population,” which means the number of rhinos breeding and contributing to the group’s gene pool (so there would have been more than 1,600 running around, but not all of them were reproducing). After 63,000 years ago, the woolly rhino population seems to have leveled out.
According to ecologists, an effective population of 1,600 rhinos would have been more than enough to keep the species thriving. Smaller populations, especially with shrinking ranges, are more vulnerable to being wiped out by events like environmental change, natural disasters, or disease outbreaks. And small populations are also more likely to face the genetic consequences of inbreeding, a loss of genetic diversity, and genetic drift (in which potentially harmful mutations can pile up), leaving the species even more vulnerable. The whole thing can turn into a vicious cycle.
For most species, the threshold for avoiding those genetic pitfalls is an effective population of around 1,000.
The end came suddenly for woolly rhinos
Researchers had expected to find woolly rhinos in dire straits by 14,400 years ago. Prior to discovering the Tumat genome inside a wolf’s stomach, the most recently sequenced woolly rhino genome dated to 18,400 years ago (and it was found just a few miles from the Rakvachan rhino). That genome showed all the signs of a healthy, stable population. But by 14,000 years ago, woolly rhinos disappeared from the fossil record—so it looked like their population must have started its death spiral shortly after 18,400 years ago.
But it turns out that the last woolly rhinos in the world probably died off in just a few hundred years, starting sometime after 14,400 years ago. And the culprit was probably a period of rapid climate warming called the Bølling–Allerød interstadial. An interstadial is a warmer period between the deepest freezes of an Ice Age, and the Bølling–Allerød lasted from 14,700 years ago to 12,800 years ago. Across the northern hemisphere, temperatures rose sharply; ice sheets collapsed, sea levels rose, and the woolly rhinos’ world changed too fast.
When Guðjónsdóttir and her colleagues compared the Tumat rhino’s genome to the one from 18,400 years ago, they found the same very low level of inbreeding and genetic load (a buildup of harmful genes, often from inbreeding or genetic drift). Whatever happened to the woolly rhino gene pool in the end, it hadn’t happened yet when Tumat got eaten by wolves.
In fact, the end of the woolly rhinos may have come so swiftly that it didn’t have time to leave a trace in the genome. The only way to answer that would, of course, be to sequence the genomes of woolly rhinos who lived even closer to the species extinction. And we have to find them first.
Insights for modern climate change
The fate of the woolly rhino may eventually shed some light on what’s happening to modern species facing extinction.
“In the current biodiversity crisis driven by anthropogenic climate change, it becomes increasingly important to understand the underlying drivers of population declines and the propensity of species going extinct,” wrote Guðjónsdóttir and her colleagues in their recent paper.
Genome Biology and Evolution, 2026. DOI: 10.1093/gbe/evaf239 (About DOIs).
The Wolfbox Mega Flow 100 Is the Best Cordless Electric Air Duster Under $50