Wayne wrote:

"But five hundred years later the descendants of the survivors would be living practically in paradise."

I think five hundred years would be long enough for them to stuff it up again. From a small founding population Maoris destroyed most pre-existing ecological systems in NZ within two hundred years. The first Americans may have taken five hundred years to achieve the same there, but achieve it they certainly did. Certainly both groups developed a conservation conciousness eventually but it was through necessity.