To clarify, when I say that "nature left to itself is perfect", don't confuse that with me saying everything would be alive & well & unchanging. "Perfect Nature" includes extinction, survival, non survival, disease, predators, etc. That IS a perfect balanced system actually.
I was referring to the ways humans interfere with that balance by doing unnatural harm and interference. Take this Gulf oil leak for example. Of course turtles, fish and other sea life die in nature. But I think we would all agree that it should NOT be this way, right? Their life spans, or whether they get filtered down through predators, etc is natural and not comparable to the mass destruction to the ecosystem we may cause with this.