DNA reveals the true identity of the prehistoric cave lion

Ancient DNA is helping scientists to unravel the mysteries of the enigmatic cave lion. A new study has revealed the prehistoric feline's place in the lion family tree, and it's also shown us that these big cats are even more ancient than we realised.

The cave lion, Panthera spelaea, is a species of big cat that lived during the Ice Age in Europe, Asia and the Arctic. Despite the name, the cats probably didn't live in caves, although their remains are often found in them (there's also evidence suggesting they may have had a habit of preying on young cave bears). When they disappeared some 14,000 years ago, the lions left behind a palaeontological puzzle.

A replica of prehistoric cave lion paintings from the Chauvet Cave in southern France. Prehistoric art like this tells us that unlike today's lions, male cave lions probably didn't have manes. Image: Claude Valette, Flickr

For decades, scientists have recognised how similar cave lions were to the big cats that still roam Africa today today – Panthera leo – and they've debated over this relationship: were cave lions and African lions truly different enough to call them separate species?

Many palaeontologists have argued that they were, pointing out the interesting differences between the two. From their bones, for example, we can see that cave lions were larger than their African cousins, and from some incredible prehistoric cave art, we know that cave lion males did not have manes.

But not everyone agreed these differences were enough, and just recently, a team of experts led by palaeogeneticist Ross Barnett turned to DNA for some answers.

Not all fossils contain DNA, but if you manage to find samples from the right place (usually cold, dry areas) and the right time period (late Ice Age), ancient genetic material can reveal all sorts of information that bones cannot.

For the cave lion study, palaeontologists extracted DNA from an upper arm bone found in the Yukon, and from a frozen clump of fur from Russia. Both specimens were dated at about 30,000 years old.

Image: Cave lion hair recovered from the Malyi Anyui River in Chukotka, Russia. Barnett et al., 2016

Four views of the cave lion arm bone specimen recovered from the Yukon Territory in Canada. Image: Barnett et al., 2016

The team compared the mitochondrial DNA of the cave lion to several species of living cats, including the African lion. And sure enough, their analysis showed that the two lion species are closely related, but the genetic differences between them are what you'd expect to see between two different species – indicating that the cave lion was indeed unique enough to stand on its own.

And there was another surprise. By comparing DNA, researchers can estimate how much time has passed since two species split from their common ancestor. The oldest fossil evidence of lions is just under 1.5 million years old, but Barnett's study indicated that Panthera spelaea and Panthera leo had an ancestor almost two million years ago! This means there's half a million years' worth of lion evolution we haven't yet found in the fossil record.

What was this two million-year-old ancestral lion like? What other differences existed between these two ferocious felines? And will scientists be satisfied by these new conclusions, or will the debate about the cave lion continue? To answer all of these questions, we'd better get digging!