The number of isolated ecosystems that had a massive extinction event shortly after humans arrived is quite amazing: Australia, New Zealand, Madagascar, etc.
The Americas would of course be by far the largest, and it’s always seemed a little illogical to me that pre-technological humans could accomplish such a massive extinction, but there is considerable evidence of a connection.
http://en.wikipedia.org/wiki/Quaternary_extinction_event
Most of these megafauna had been around for one or two million years, including multiple glacial/interglacial cycles, then all disappeared within a short time after humans appeared in the area.
Obviously there are other explanations put forward, and the chronology might not be as tight as sometimes portrayed, but it is an amazing coincidence.
A fascinating conundrum.
My personal favorite part of the notion is that it makes the Indians responsible for a very large mass extinction.
I don’t believe any of that. You’re saying the paltry amount of humans then overcame the extensive population of Dire wolves, Short faced bears (a running bear 5 foot at the shoulder), American lions and saber tooth tigers. As a hunter I don’t think so. more likely a sudden deep freeze or heat wave killed them all off because it happened suddenly.
There are some suggestions too that the short face bear was so formidable it kept humans out of North America for many years. There is a skull on display in the natural history museum in Cincinnati, Ohio. Imagine being on the plains and having one of these creatures after you, an enormous running bear, very much different then the bears today.