Chris Doss
I see my main point has not really been addressed. If human beings are some kind of large-animal-bane, how come there are all these huge critters stomping around Africa, where human beings and hominids in general are from? It can't be that it's because these beasties are all terribly afraid of people, because they're not. One obvious reason I can think of is that because Africa is pretty balmy and has lots of game, unlike Ice Age Europe, so people would have no need to go after big critters. However, that does not work in the case of tropical Central and South America. Moreover, this speciesocide seems highly selective. They got all the horses, but for some reason left the buffalo alone? What about moose? Caribou? Cave bears are marked for death, but not grizzlies?
In the case of South America specifically, I suggest extremely tentatively that the sloth extinction may be part of the general replacement of indigenous animal species (like almost all the marsupials) by more efficient animals who migrated down the landbridge.
^^^ CB: Looking at the whole thing in hindsight, it may just be that African cultures developed smarter ecological sense. It is fundamental that a predator's existence and species perpetuation depends on the perpetuation of its typical and critical prey species. If your prey, your main food, goes extinct, you go instinct. Self-limitation of your own hunting is a necessity in the struggle for existence. Of course , as you say, there was lots of other stuff to eat in Africa, but maybe not so much further north. On the other hand, the human groups in the north didn't _all_ go extinct , so all's well that ends well.
Charles
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