> This does not mean humans have not also participated in numerous extinctions, ancient and modern. It only means we cannot be responsible for the sudden American extinctions.
This is a may, not a can: a trivially fitting hypothesis is that the clovis culture was based around that megafauna, and when it finally went through everything it ended with them.
This also explains the synchronicity of the disappearance, because any megafauna hunted to extinction would lead the hunters to fall back on the next genera, increasing hunting pressure on it and thus accelerating its disappearance.
> Given more time, we would no doubt have wiped out many of the species. But horses and camels survive on other continents, exposed to humans. Why would Americans have, uniquely, chosen them to wipe out?
Either coevolution (meaning the megafauna would have had the time to adapt its reaction pattern to the rise of humanity), or environments which allow them to evade hunters and avoid extinction which may not have been available in the americas.
