Bears of the Pleistocene

[brotherbear]

In the Shadow of the Sabertooth by Doug Peacock.
The abundance of gigantic Pleistocene predators means a lot of killing was going on. There must have been intense competition and interaction around the carcasses of big herbivores. Short-faced bears would have challenged lions and sabertooth cats, with dire and Beringian wolves close behind, shadowed by flocks of ravens, magpies, mobs of buzzards and condors. Grizzlies were around too.
With humans in Pleistocene America, what was the pecking order? Even if people managed to kill a mammoth or sloth, those other scavenging animals would be close on the scene, especially short-faced bears. And the other bears might be in chase, though not as aggressively as the short-faced variety. Brown bears, over millennia, learned to defer to humans even before European firearms arrived, as told in the ethnologies of Western tribes. Early people hunted in groups, growling or roaring when advantageous; grizzlies have never been known to attack a group of four or more people.
The Eurasian brown bear and the American grizzly may look alike but their aggression levels are sufficiently dissimilar to earn the grizzly the subspecies name, Ursus arctos horribilis. When the brown bear crossed over the Bering Strait some 70,000 years ago to the American side, the theory goes, mothers had to protect their cubs from American lions, short-faced bears, wolves and other Alaskan predators on the open tundra. The best defense was a good offense. Grizzlies charged and, when necessary, attacked threats to their young.
Corridor routes were closed off roughly 22,000 years ago ( there's a spectrum of opinions here ). At any rate, that seems to be the range of possible pre-Max-dates - 30,000 to 23,000 years ago - for people to have made it southward to mid-latitude North America. Going south was definitely possible. We know it was possible because the grizzly did it.
In 2002, a cranial fragment of a brown bear was located in a museum collection of fossils from fluvial gravels near Edmonton, Alberta. This well-preserved bone was subsequently dated, based on two "accelerator radiocarbon dates on collagen," at 26,000 years old ( this is the average of two radiocarbon dates; a recalibrated date would be several thousand years older. The salient point is that it is decidedly before the LGM.

Grizzlies came down from Beringia before the two great ice sheets collided, the pre-Max-route. ( We don't know how much earlier. The first grizzly crossed over from Northeast Asia 70,000 to 50,000 years ago. So grizzlies roamed Alberta by 26,000 years ago.
Evidence of a grizzly in Alberta 26,000 years ago strongly suggests that a route that humans - if they were in Beringia that long ago - could have used was open for several thousand years and that the habitat along that particular migratory corridor was rich and fully revegetated after prior glaciations. Reply