True on one, but we're also the only animal able to clean up the "ecosystem" to suit us if we think it's too dirty.
False on two. We could probably wipe ourselves out with an out-all nuclear exchange, but even that's not certain. We're damn resilient species. We could probably wipe out all of the other land vertebrates with a nuclear war, and do a number on the sea vertebrates, but the invertebrates have survived far worse than what we can dish out, and I doubt we could do much more than annoy the microbes for a while.






