:| Well evolution of that kind can take place but the main reason why i dont believe it did happened is because that would take billions upon billions of years.

As far as why we arent as far as our length of existence would dictate we should be..well maybe the last dominant civilization was just as intelligent, but just as dumb as we are, and they blew themselves back to the stoneage; the stoneage that we know.

I always believed that if you dont learn from your mistakes and you just keep trying to make them work, then history will just repeat itself. I think that there once was an advanced human civilization, or several that got further up the development ladder than us.. but still hadnt learned enough wisdom to make it last.