A Question of Scale
I'm in the midst of reading Jared Diamond's The Third Chimpanzee : The Evolution and Future of the Human Animal which is, in itself an interesting book and raises the valid questions about how different we are from other animals on the planet, and where those differences might be taking us.

The latest research on the genetic differences goes even further, suggesting that chimps and people should be classified as homo, the same genus, indistinguishable on 99.4% of the DNA that matters and 98.4, even in other areas of the genome.

What interests me even more than that is this: if so little difference can make such an enormous difference once the process is fully expressed, why on earth do we assume that the significant differences that we are making to the ecosystem should not be important? The question is not how much we can do without "harming" the system and rather how little we might need to do to change it irrevocably, and to our detriment.

The answer is, we don't know, OUR answer is, "we'll risk it anyway"