Hey man - I don't feel like posting in that damn thread anymore, but I wanted to point something out...
Although we live in a perfect set of circumstances, it has been proven that any given set of conditions is not required for any given species to live. Fish need water to breathe due to their respiratory systems - but over thousands of millions of years, some fish evolved to be able to breath air without water, therefore changing the "perfect" surroundings they needed. We evolved to breathe oxygen because it is most plentiful in our atmosphere - but if, say, nitrogen were more prevalent, who's to say our evolution wouldn't have made it more neccessary?