Reply #31: Actually, those people probably made them extinct.

[Xithras]

It's fairly well understood today that the first Native American's probably drove a lot of species to extinction when they first arrived, because those species weren't adapted to human predators. Examinations of bones indicates that the first people here ate and killed off the Giant Ground Sloth, the horses, and several other slow breeding species. Horse numbers were already down significantly as North American grasslands vanished beneath the growing forests at the end of the last ice age, but there's little question that humans were the final nail in their coffins. Bison are the only large bodied herbivore that survived the introduction of humans into North America, and it was only their extreme numbers and aggressive demeanor that kept them from extinction.