I'm a grad student who reads the list-serve to look for job opportunities, but these threads on agroecosystems and climate change bring up a question I have never really gotten a satisfactory answer to, namely: Are humans to be considered a part of the natural world? On the one hand, humans are clearly a species of mammal living on the planet. Science in general follows the Copernican Principle: don't assume there is anything particularly unique about your place in the world. I doubt many of you would consider us to have been specifically placed on the planet and set apart from other forms of life. And yet, when it comes to the things humans do, a clear distinction is made between human causes and natural ones, human modified ecosystems and wild ones. And it is definitely useful to make distictions between human effects and natural ones when studying many ecosystems-I've certainly done it in my own research.
So why is this true? How can natural humans cause unnatural effects (or is one assumption false, despite both seeming reasonable)? Can only humans harm the environment? What's the difference between an invasive species being introduced to an island by humans, or the same one arriving on the foot of a bird? What does harming the environment mean, anyway? Somewhat like the two perspectives above, I have seen it defined as: (A) changing the environment from it's original natural or pre-human state (which natural state? how do you define your baseline?), and (B) Making the environment less capable of supporting human life (supporting human life now or indefinietely? at what standard of living?). Those two goals aren't always compatable. So, comments? Thoughts? How do you resolve this? Adam
