I agree Pygmys have been known to skewer an Elephant. But they came no where near to making them extinct. And there's a big difference between a 500 pound chicken and a Woolly Mammoth or a Smilodon or a Megatherium or a Cave Bear. I will concede that prehistorric Hunters may have "harrassed" a few Mammoths into Death-By-Chasing, but what about the population of Pygmy Mammoths on Wrangel Island? It's estimated that they survived as recently as 1700 BC. The Inuits there harpooned whales using primitive weapons, but, apparently, they left the Mammoths alone, dispite being far smaller than a regular Mammoth.
I gotta think that it was a reduction in food, caused by all that ice, that was the demise of the Megafauna. Man, opportunistic even back then, just happened to be in the right place at the right time.
