New genomic research on a 14,400-year-old woolly rhinoceros specimen challenges the assumption that rapid inbreeding drove the species to extinction. The analysis, published in Genome Biology and Evolution, suggests the rhino population remained genetically stable for millennia before its disappearance, with no clear signs of decline in genetic diversity right before extinction. This finding is significant because it points to climate change rather than human hunting or internal genetic weakness as the primary cause of the woolly rhino’s demise.
The Last Rhino Genome
The genome was extracted from muscle tissue found inside the stomach of a remarkably preserved wolf puppy discovered in the Siberian permafrost. Radiocarbon dating confirms both remains are approximately 14,400 years old, making this one of the most recent woolly rhino specimens ever analyzed. This is the first time a complete ancient genome has been recovered from an animal inside another animal’s remains, a unique and challenging feat.
Stable Population, Sudden Extinction
Researchers compared the new genome to two previously published Late Pleistocene woolly rhino genomes. The results revealed surprisingly few segments of homozygous DNA – areas where genes are identical due to recent inbreeding. This suggests that the population did not suffer a rapid genetic bottleneck before extinction, as seen in many endangered species today.
Instead, the researchers found no evidence of shrinking population size during the Bølling-Allerød interstadial, a period of rapid warming around 14,700 years ago. This implies that the extinction may have happened either very quickly – too fast to leave a detectable genomic signature – or as a result of sudden environmental shifts.
Climate, Not Humans?
The study supports the hypothesis that climate warming, rather than human hunting, was the primary driver of the woolly rhino’s extinction. The species survived for at least 15,000 years alongside early human populations in northeastern Siberia without showing genetic collapse, suggesting humans did not significantly impact the rhino’s population size until the very end.
“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,” says Professor Love Dalén, a co-author of the study.
The findings highlight the importance of examining genomic data from near-extinction individuals to understand the true causes of species loss, offering valuable insights for modern conservation efforts. The woolly rhino’s story suggests that even stable populations can vanish rapidly under extreme environmental pressure.
