Researchers at the Swedish Centre for Palaeogenetics have analyzed DNA from an extinct woolly rhinoceros found in the stomach of a frozen wolf pup. The discovery, the first of its kind from the Ice Age, provides new clues about the species' extinction. The analysis suggests climate change likely caused the rhinoceros's disappearance rather than human hunting.
About 14,400 years ago, woolly rhinoceroses roamed Siberia, three meters long with thick fur, sturdy horns, and substantial fat deposits for protection against the cold. One such rhinoceros ended up in the stomach of a wolf pup in Yakutia, which soon after died in a landslide and froze into the permafrost, preserved until today.
Researchers at the Stockholm-based Centre for Palaeogenetics, led by Love Dalén, professor of evolutionary genetics at Stockholm University, have now mapped the rhinoceros's genome—a world first noted by CNN. "It is the first time ever that the genome of an animal—found inside another animal—from the Ice Age has been mapped," says Dalén.
The analysis was challenging as stomachs normally break down tissue, but the sample was barely digested. "We were very lucky because it had hardly started digesting at all," says Camilo Chacón-Duque, one of the researchers. They compared the DNA with samples from rhinoceroses that lived 18,000 and 49,000 years ago. The results show no signs of inbreeding, indicating a large population just before extinction around 14,000 years ago.
The rhinoceroses likely went extinct due to climate changes as the Ice Age ended and landscapes shifted. "They were well adapted to the cold and a certain type of landscape. When the landscapes changed, it could have put a lot of pressure on them," says Dalén. Human impact, such as hunting, seems unlikely as the main cause.