Let’s face it, the Indians did not have repeating rifles like the European invaders of Australia, New Zealand and Madagascar. Also I do not have the impression that the Clovis population was very numerous.
The megafauna of Oz, NZ and Madagascar were not wiped out by European settlers, but respectively by the Aborigines, Maori and Malagasy.
The Aborigines arrived in Oz sometime between 40,000 and 80,000 years ago. They were at a stone-age level and remained there till Euros showed up.
The Maoris arrived in NZ around 1200 to 1300 AD. They were also stone age.
The Malagasy arrive in Madagascar sometime between 500 BC and 500 AD. They came from Indonesia, not the nearby Africa. I don’t know whether they were using metals yet, but they probably were. Indonesia, then as now, was home to a wild variety of cultures and levels of civilization, but there were certainly fairly advanced cultures around. They quite obviously had fairly advanced boat-building capabilities, or they’d never have survived their voyage.
None of these peoples needed guns, or, in the case of at least two of them even metals, to wipe out the native megafauna. Assuming that’s what happened, which it’s pretty clear it did in at least NZ and Madagascar, they being so much more recent.
Extrapolating this to the Americas is, I agree, a big jump due to sheer acreage. But the example of Oz seems to indicate that a continent-sized population of megafauna might indeed be vulnerable to extinction by stone-age human hunters.
All somewhat speculative, but the dates and other history are certainly interesting. The biggest flaw in the “American mega-slaughter” theory, IMO, is the increasing evidence humans were in the Americas for many thousands of years before the extinctions started.
Any such extinction would also seem to imply a rather large human population across North America, the physical evidence for which is darn thin, as you point out. A small band reproducing enough in a relatively short time to create that level of population seems unlikely.
OTOH, the Maoris apparently managed to overpopulate their islands and start fighting over the suddenly scarce resources in just two or three centuries, from just a few canoe-loads at the start. Extrapolating that to the American continent might take just one or two centuries more.
gleeakin, I think what we’ve got here is a “hunted to extinction” crusader. I sent him/her to some links that are pretty compelling re a catastrophic end to the Pleistocene and I’m guessing he/she got a painful whiplash turning away from it. Not only that but evidence of simultaneous megafauna extinctions in other parts of the world besides the Americas which he/she also ignored. I’m also wondering if he/she has read there has been few, if any, human artifacts found dating to within a thousand years or so AFTER the events that took out the megafauna. Indicating of course that whatever snuffed the megafauna likely also snuffed most of the peoples of at least North America. Don’t know about the rest of the world.