How Hibernating Bears Beat Bone Loss

Human hibernation

That's a great question, Fred. There's no direct proof I know of that our ancestors could hibernate, but there's strong circumstantial evidence that the first mammal--which was a distant ancestor of ours, of course--could: Physiologists who study hibernation have pointed out to me that diverse kinds of mammals, including at least one primate, are able to hibernate. That suggests our lineage lost the ability somewhere along their evolutionary path.

Interestingly, some experts speculate that we haven't completely lost the capacity to lower metabolism during periods of cold, which is a hallmark of hibernation. There are anecdotal reports of young children falling into icy waters and being pulled out alive long after an adult in the same situation would have perished. Are kids somehow able to ratchet down metabolism when their lives depend on it? If so, it could provide a window into how the adult body could be coaxed into hibernation.

Ben Harder of DC @ Jan 31, 2008 12:46:21 PM