Explaining the Avatar Ecosystem, Part II

Peter Watts noticed the same problem with the Avatar ecosystem that Tam did (earlier discussed here) and has a theory to explain it:

About a planet sheathed in deep forest, and the six-legged fauna that lived there, and the ruthless Human industrialists who come to exploit its riches only to be fought by the gone-native descendents of an earlier expedition that had learned to live in harmony with nature?

………

Someone put a lot of thought into Pandora’s wildlife; it was beautiful to behold, it was amazingly diverse, it even seemed (for the most part) phylogenetically consistent. Across a wide range of species, everything from nostril placement to jaw structure was nicely suggestive of common ancestry. Except for the Na’vi, which are ridiculously anthropomorphic: tetrapod bipeds where everything else on the planet seems to have six limbs; binocular vision on a world where four eyes is the vertebrate norm. Evidently Cameron felt that his hero could not plausibly fall in love with a four-eyed banana-slug, but that a blue-skinned cat-woman just might pass muster. (I agree that the former premise would result in a much more challenging film, conceptually— but then, I like conceptually challenging films.)

The ultimate example of such a plot (in which the “natives” turn out to be descendants of earlier explorers) can be found in The Gray Prince by Jack Vance in which the oppressed natives on an alien planet revolt, followed by another revolt by the even-more oppressed ETs they grabbed the planet from. Then it gets even more entangled …