摘要
Are humans part of nature？ Clearly humans are, or they wouldn＇t be able to interact with it. The real question is what part are they？ Most texts define an exotic species as one translocated by humans to an area where it had not previously existed. （This would seem to make humans, throughout most of their range, an exotic species, although this fact is never mentioned）. But the effect that the species has on its new surroundings has little to do with how it got there, and more to do with its being a newcomer. What is a native species？ It is basically one that has been around a long time, i.e., not a newcomer. The question is, how long？ A length of time that makes sense is the length of time that it takes for the other species in the area to evolve to adapt to the newcomer-on the order of a million years. That would make humans native only to Africa, and everywhere else a rank newcomer （exotic species）. This is not a value judgment, just biological fact, but maybe also a good indication of how we should behave： with restraint, with the manners of a guest.
