No. We are not natural in that we are the only species of animal on this planet that consistently seeks and manages to live outside the normal capacity of the planet's ecosystem. And we know it. And we know the risks too - we just ignore those.
Benefit = $$$ and convenience Emotion is equivalent to ethics, imo. As emotions dictate what we feel is right and wrong.
We are the only species capable of prolonged overpopulation. Of course, as you said earlier, "biology has a funny way of compensating for these things". Compensation is inevitable.
Honestly, I'm not sure I even understand what overpopulation means in this context. We're here because there's enough food/water/etc. to sustain us in our current abundance. Whether that continues to be the case is yet to be seen, but I certainly see how the loss of biodiversity could threaten our survival going forward. My beef is with the idea that humans uniquely have the ability to upset the balance of nature, or act in "unnatural" ways. We are not outside of nature--we are a part of it.
We do have a unique ability to upset the balance of nature. I think it would be very difficult to give evidence to the contrary. "Unnatural" is a tricky word, as we are natural products of this environment. Our patterns as a species show a specific disregard for maintaining a working relationship with the very same "nature" that we originated from, and must survive within. In that regard, I would agree with your last statement - albeit with an important caveat: We are not outside of nature--we are a part of it. We've just forgotten. The thing is that, unlike any other animal, we have the capacity to understand the consequences of our expansion. But we don't take advantage of this knowledge. I'd argue that unnatural, in as much as the natural environment degrades at our expense while we still aimlessly struggle against the very same ecology we depend upon. If a pack of wolves kills off all the sheep available to it, and dies off due to starvation, I'd call that natural. When humans do that, it's folly.
