Today Science Daily has a report about a new study, recently published in the Proceedings of the National Academy of Sciences, that examined isotopes found in the remains of ancient cave bears (Ursus spelaeus). Apparently the nitrogen isotopes indicate that the bears were "largely vegetarian." (see here for a great explanation of how nitrogen can be used to determine diet).
These were not completely "gentle giants" that spent all of their time browsing on plants, however:
"Although many of these cave bears appear to have been largely vegetarian, the Oase bears and scattered individuals from other cave sites show that they were sometimes as omnivorous as modern brown bears, including North American Kodiak and grizzly bears."
Order Carnivora is fascinating, because although the name defines the group with a description of a specific diet, the taxon actually includes animals with a wide spectrum of feeding habits, from the almost exclusively meat eaters such as many felid species to the infamously herbivorous giant pandas, and everything in between. Everyone's favorite canid, the maned wolf, subsists on a diet that is around 68% plant material (almost 40% of that from a single species: Solanum lycocarpum, the "wolf apple"). Few things are absolute in biology, and nature almost always finds a way to humble us when we attempt to impose our own categories on the biological world. Case in point: possibly carnivorous members of the Diprotodontia a marsupial order often characterized by its largely (although apparently not exclusively, we are discovering) herbivorous habits.
Personal anecdote: this ferocious carnivore, which which I have extensive field experience, happens to love green beans and watermelon mixed in with his kibble. I am still trying to elucidate what food item that ridiculously long tongue is adapted to take advantage of, it's like a canine tongue version of the ultra proboscis found in the hawk moth:
Cases like these (although the last example has yet to go through the peer-review process) and nature in general never fail to amaze me: even when you are "just" dealing with bones and fossil fragments of long-dead critters, there is always something new and interesting to discover that can make you look at the traditional classification in a whole new way.Ref:
Richards, M.P., Pacher, M., Stiller, M., Quilès, J., Hofreiter, M., Constantin, S., Zilhão, J., Trinkaus, E. (2008) Isotopic evidence for omnivory among European cave bears: Late Pleistocene Ursus spelaeus from the Petera cu Oase, Romania. Proceedings of the National Academy of Sciences USA, online January 7.
(Bear image credit)
3 comments:
To be fair, Alaskan bears eat nothing but berries except during the salmon run, when they'll gorge themselves on fish. And sure, there's the occassional moose kill. But overall, this finding doesn't surprise me in the least.
"I am still trying to elucidate what food item that ridiculously long tongue is adapted to take advantage of"
My guess is viscera, brains, maybe marrow...or in the case of my dog peanut butter packed inside a Kong.
I agree, Zach, that it isn't at all surprising that they had similar feeding ecologies to today's bears, learning about the nitrogen isotopes was what I felt was most interesting about the story. One of the talks I attended at SICB had a fascinating way to identify what classes of prey an animal had consumed during its life based on characterizing isotope profiles for browsers vs grazers, I need to post about that soon!
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