Saturday 29 September 2018

Lions in the Carpathians

When I last talked about Eurasian cave lions, back in 2013, I said that there was some debate as to whether they were a distinct species, or just an unusual subspecies of the modern, living, lion. Although the issue is, perhaps, still not entirely resolved, it's probably fair to say that the clear majority opinion these days is that they were a separate species (Panthera spelaea).

This swing in opinion has been helped by new genetic data, something that we can obtain because the animals died out so recently - around 12,000 BC by most estimates. Specifically, an analysis published in 2016 was able to obtain the full mitochondrial genome of a pair of cave lions, allowing a more detailed genetic analysis than ever before. This showed that, as expected based on earlier studies, cave lions really were "lions" in the sense that they were more closely related to modern lions than thy were to, say, leopards.

More significantly, they indicated that cave lions and their modern relatives diverged 1.9 million years ago, which is long before the split between the African and Asian subspecies of modern lion. Indeed, it's quite a way before the last known split between any living species of living big cat - the two modern species of clouded leopard diverged only 1.4 million years ago. While there's still some wiggle room, depending in part on the precise definition of "species" used, this is strongly suggestive that we should consider the two to be distinct.

Cave lions were first described by Georg Goldfuss in 1810, based on a fossil he had discovered in, appropriately enough, a cave, in southern Germany. Since then, it has become apparent that they lived across large swathes of Europe and northern Asia, and even reached Alaska, at a time when the sea level was low enough to get there by walking from Siberia. Not all the fossils come from caves, and those that are found there were probably from carcasses dragged there by scavengers. But they seem to lived alongside such other Ice Age animals as cave bears, cave hyenas, and, yes, "cave men". The latter thoughtfully provided us with eye-witness paintings on their cave walls, which show, among other things, that the males appear not to have had manes.

Cave lion fossils have been known from the Carpathian Mountains since at least 1913. This tells us that, while cave lions also lived in the lowlands, on grassy steppes and open woodland, they also lived at quite high altitudes - something that modern lions do not, even where the climate is warm enough to make this a more reasonable prospect than it must have been in Ice Age Europe. But how high could they reach?

In 1953, a cave was discovered (at least, officially... it's hard to prove that nobody else had noticed it previously) in the mountainous slopes of northern Slovakia, less than two miles from the Polish border. Part of a much larger cave system formed by erosion of limestone deposits within sedimentary rock, it proved to consist of two chambers with a narrow passage leading yet deeper into the rock. The entrance was at 1,133 metres (3,717 feet) altitude, but at first it seemed no more significant than any other cave.

In the late '60s, however, archaeologists looking for signs of human habitation instead found fossils... of cave bears. In 1979, however, that narrow passage turned out to lead to a third chamber, a good 160 metres (525 feet) from the entrance, and this contained, along with some partial remains, an unusually complete skeleton of a cave lion.

Worried that curious spelunkers might damage the site, and without the resources to do much themselves at the time, the original discoverers kept this fact secret, and the fossil could not actually be removed until 2007. It's taken another ten years to get around to fully describing it. These things take time to get right, and the budgets aren't exactly extensive.

So what does this new fossil tell us that we didn't already know? Well, for one, it's big, even by the standards of cave lions, which were noticeably larger than the modern sort. It's usually hard to get an estimate of the weight of an animal based on the size of its skeleton alone, but, in this case, we have a pretty good idea of the exact shape and muscular proportions of a lion, so we our best guess is likely more reliable than it is for stranger-looking animals. And what we get is a touch over 300 kg (660 lbs).

This is about 50% heavier than the typical male lion today, and, in fact, is roughly the weight of the largest tiger ever reliably recorded - tigers being noticeably larger than lions. This is significant for a couple of reasons. For one thing, since the skeleton is 'only' around 46,000 years old this rather seems to quash a theory that cave lions became smaller over time. For another, one of the partial fossils found alongside the more complete one was the skull of an adult cave lioness, and from its size, we'd guess that she only weighed around 165 kg (365 lbs).

We already knew that male cave lions were larger than their lionesses, but that's a pretty significant difference.

This disparity in size has been used in the past to argue for cave lions living in prides, where males have to compete for and defend a number of females. And that cave lions would live in prides when their closest modern relatives do the same does seem plausible anyway. But one does have to question just how much food is going to available for a cat that size on a mountain slope 1,100 metres above sea level during the Ice Ages.

It's not a remarkable altitude for big cats in general, with leopards and even tigers, being found at even greater elevations. But those, of course, are solitary animals, and its notable that when modern lions are found on high slopes (on Mount Kenya, for example), they tend to hunt alone. It has often been argued that cave lions were solitary, or, at best lived in groups much smaller than modern lion prides, and this find would provide at least circumstantial evidence in favour of that. On the other hand, it doesn't mean that they couldn't have lived in prides where food was more plentiful - and some contemporary cave paintings do seem suggest that at least some of them did. (Assuming it wasn't just artistic licence, of course, which is hard to know).

One other question about the find remains, however: what was the lion doing in the cave in the first place? The usual explanation, as I said above, is that such remains were dragged there by hyenas or other scavengers. But, in this case, the animal does not appear to have been attacked or eaten, so that doesn't fit.

It's possible that this particular cave lion really did den in the cave. Modern lions don't do that, but, since they mainly live in prides, that might be difficult for them, and tigers and leopards do sometimes use caves as dens, so it's not unreasonable. Another possibility, however, especially given the lack of other cave lion fossils that seem to fit the pattern, was that this particular lion was searching for food when it died.

We know that cave lions ate a variety of hoofed animals, with a particular focus on reindeer. But that's likely not all they ate. It has, for instance, been suggested that some cave lions attacked and ate cave bear cubs, perhaps while their mothers were hibernating. In this case, one thing we do know is that cave bears regularly used the cave, and raised cubs there. Might this cat have been hunting when it met its fate? It might seem extreme, but tigers have been reported to eat black and brown bear cubs (although not very often, it has to be said).

In evolutionary terms, cave lions were undeniably "lions". But in their habits, at least when they lived in marginal habitats such as high mountains, they may have behaved more like tigers.

[Photo by "Tommy", from Wikimedia Commons.]


  1. Living in prides being a lion idiosyncrasy, I guess it's likely to habit arose only after cave lions split off?

    Also, Eurasian cave lions? Is there another sort?

    1. Yes, the term "American cave lion" is sometimes used for P. atrox, which lived in America, and may or may not be a subspecies of P. leo. (Opinion still seems pretty divided on this, from what I can tell).

    2. Ah, thanks.

      (Still unable to post from home, for whatever reason.)

  2. Ah, so posting from work works. For some reason, I couldn't post from home earlier this week, logging into the google account seemingly worked - and other sites where I log in with it worked unexceptionally - but when I submitted a comment i simply disappeared into thin air, and the "Comment as" field kept saying "Google account" despite the login seemingly having worked.