I can remember reading more than one article where the author argued that the human shape was so inevitable and perfectly adapted that any intelligent aliens that we might meet would look exactly like us.
That is so stupid. Our human form is the product of an incredibly long chain of circumstance, that at any point could have gone in a different direction entirely. The only way to get to humanoids on another planet would be to re-run our history exactly for four billion years, with the head-or-tails choice identical at every throw.
Yeah, I know the thing about ichthyosaurs looking like sharks looking like dolphins, but that’s due to the strong adaptive pressures of movement in a dense fluid. And anyway, they all had a common ancestor. Which was a fish.
(People are still arguing — even NASA exobiologists, for heaven’s sake — that life “must” require water, or be based on carbon, or will inevitably use DNA as its basis for replication. They will look so foolish in a hundred years.)
But I don’t really blame science fiction on the screen for always having humanoid aliens. That’s the only way you can fit an actor into the rubber suit. Though even written science fiction, supposedly more intellectual than the movies, still almost always makes its aliens, whatever their external form, think and act like humans. I admit that it’s difficult to come up with something really alien, but I’m convinced that if we do ever encounter intelligent life, we’ll find it very, very strange and hard to understand.
Think about this: men and women have almost identical brain structure, and the bio-chemistry differs only in small ways too. It would be a brave man who would deny that women are intelligent, rational creatures. Yet men often have real problems understanding women’s thoughts, desires, and motivations. Imagine what it would be like if they did come from another planet