Most animals gnaw at a bone, or rip it open with slicing molars, but a hyena just crushes it. Even a bear can't do that. The bones found in the cave, Turner says, were clearly there because of the hyenas.
But one set of bones especially intrigues Turner.
"We found a true dog skull," he says. "We've dated the skull to about 14,000 years ago, and it's a domesticated dog," so much smaller than a wolf that it would not have survived if it had not been domesticated. The dog, he adds, was dragged into the cave, where it was devoured by hyenas.
It's the oldest dog ever found in Siberia, Turner says, and it was domesticated just before humans started their migration north, leading them eventually to the Americas.
"The coincidence is so remarkable," he says. "Once we get the dog, then we get people in the new world almost immediately."
Dogs Save the Day
Although at this point it's largely guesswork, Turner thinks it's quite possible that those early Siberians domesticated the dog in an effort to protect themselves from hyenas. A dog will bark at anything that approaches its territory, so barking dogs might have helped keep hyenas away from hunting camps.
At the very least, it would have alerted humans to an approaching horde of bone-crushing beasts.
That, Turner theorizes, might have finally given humans the edge, allowing them to encroach further into land thick with hyenas.
Eventually, the humans found the bridge across the Bering Sea, about 2,000 years before the hyenas themselves, along with many other larger animals, died out.
There are many uncertainties and gaps in the archaeological record, because the hyena has been largely ignored by anthropologists, Turner says.
But if he's right, those nasty critters kept us out of here for thousands of years, and dogs finally let us in.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.