If you think dire wolves (Canis dirus) are closely related to other wolves then you know nothing, Jon Snow.
A new study, published in the journal Nature, shows that extinct dire wolves were only a distant relative of today’s wolves, splitting off from other wolf types nearly six million years ago.
Key research points:
- Dire wolves are a distant relative of today’s wolves
- The species are so different from coyotes and grey wolves they were not able to interbreed
- Dire wolves evolved solely in North America
- There are three primary Canis lineages: dire wolves, African jackals, and a group comprising all other existing wolf-like species
“Dire wolves are sometimes portrayed as mythical creatures – giant wolves prowling bleak frozen landscapes – but in reality turns out to be even more interesting,” says co-lead author Kieren Mitchell, from the University of Adelaide.
An international team of researchers from the UK, Germany, the US and Australia found that dire wolves were so different from other canine species, such as coyotes and the grey wolf, that they were likely unable to interbreed with each other.
“Despite anatomic similarities between grey wolves and dire wolves – suggesting that they could perhaps be related in the same way as modern humans and Neanderthals – our genetic results show these two species of wolf are much more like distant cousins, like humans and chimpanzees,” says Mitchell.
After analysing five dire wolf genomes from fossil bones dating back 13,000 to 50,000 years ago, the team was able to reconstruct the evolutionary history of the dire wolf for the first time.
They found no evidence of gene flow between dire wolves and grey wolves or coyotes, an absence of genetic transference that indicates dire wolves evolved in isolation from the ice-age ancestors of these other species.
While the different species did overlap, the researchers suggest the deep evolutionary differences meant that dire wolves were likely ill-equipped to adapt to changing conditions at the end of the ice age.
“While ancient humans and Neanderthals appear to have interbred, as do modern grey wolves and coyotes, our genetic data provided no evidence that dire wolves interbred with any living canine species,” says Mitchell.
“All our data point to the dire wolf being the last surviving member of an ancient lineage distinct from all living canines.”
Spotlight: the dire wolf
- Dire wolves are considered one of the most famous prehistoric carnivores from Pleistocene America; they became extinct around 13,000 years ago; the cause is a mystery
- Their scientific name Canis dirus means “fearsome dog”
- They were approximately 1.5 m long and weighed about 60 kg – making them 25% bigger than grey wolves
- The teeth of a dire wolf were strong enough to bite through bone and were designed for tearing, not chewing – making it likely they tore large chunks of meat and swallowed them whole
The researchers suggest that unlike many canid species that are believed to migrate repeatedly between North America and Eurasia over time, dire wolves evolved solely in North America.
“Hybridisation across Canis species is thought to be very common – this must mean that dire wolves were isolated in North America for a very long time to become so genetically different,” says senior author Laurent Frantz, from the Ludwig Maximilian University of Munich, Germany.
Instead, based on the genomic analysis, the researchers conclude that three primary lineages descend from the shared ancestry: dire wolves, African jackals and a group comprising all other existing wolf-like species – including the grey wolf.
As for potential explanations of why the dire wolf went extinct, one hypothesis is that because of its body size, the dire wolf was more specialised for hunting larger prey. When that larger prey went extinct, the dire wolf was unable to survive.
However, with genetic analysis showing dire wolves were genetically very different, co-lead author Alice Mouton from the University of California, Los Angeles, suggests a lack of interbreeding may have also added to its demise.
“Perhaps the dire wolf’s inability to interbreed did not provide necessary new traits that might have allowed them to survive,” she explains.
While researchers get closer to understanding these mysterious creatures, fossil remains, DNA analysis and a little help from Game of Thrones helps their legend live on.
Amelia Nichele is a science journalist at The Royal Institution of Australia.
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