This trope is used all the time. It’s incredibly rare for it not to be used, in fact. And I must say, it’s one thing which I frequently find disappointing about sci fi. I am, of course, talking about the depictions of aliens. Specifically the fact that those aliens are, more often than not, humanoid.
Don’t get me wrong, I mean… Some of my best friends are humanoid. But from an astrobiological perspective, it seems rather unlikely that our template (by which I mean, a head, two arms, and two legs) should be the definitive one for intelligent technological species. In fact, PZ Myers of Pharyngula is quoted as saying, of the Na’vi in Avatar, “If I saw that situation for real, I’d be an intelligent design creationist, because it’s obvious that the intelligent aliens did not evolve from the animal stock on that world.”
I have to say, he has a point. Because consider what you see in the film (and if you haven’t seen it, there are no spoilers here so don’t worry). Most of the animal species you see on the planet Pandora have six limbs, and appear to breathe from large nostrils in their chests. The Na’vi, however, are essentially tall blue humanoids with tails. It’s easy to suspend your disbelief for the sake of a good story, of course, but they just don’t match.
The reasons why this are the case are pretty obvious. Firstly (and more mundanely), traditionally it needs to be a human actor portraying said alien. Obviously, at least on TV, it’s a lot easier to have a human in a mask. It’s unfortunate that a few of the TV shows which attempted to show non-humanoid aliens ended up somewhat laughable.
More deeply though, the obvious fact is that the writers and audience are human too. It’s just easier to empathise with the characters when they’re obviously people. Which is probably the reason why I’m having trouble thinking of any sci fi with a non-humanoid alien which wasn’t the bad guy. Which would concern me if we ever found ourselves making contact with non-humanoid extraterrestrials in real life!
Of course, there are varying levels of humanoid alien. At the extreme, Time Lords in Doctor Who are a good example of aliens who are visibly indistinguishable from humans. Then you get the “rubber forehead” aliens such as the Klingons from Star Trek or the Minbari from Babylon 5. Finally, you have the clearly-not-very-human humanoids such as the Yautja (Predator).
But the thing is, even these creatures follow the same basic humanoid design. Two legs, two arms, torso, and head. I mean whether you’re talking about the Predator, the Prawns from District 9, or the Vortigaunts from Half Life… Yes it’s true that they’re a lot more alien looking than Mr Spock. But they still follow the same humanoid template. With movies, video games, and even mainstream TV using CG at increasingly higher rates, it has to be asked – isn’t it about time the writers started really letting their imaginations go wild? Just for once I would love to to see anything in sci fi showing us an intelligent alien species which is both drastically non-humanoid and not evil★.
I’ll freely hold my hands up and admit that we know nothing of evolution on other planets, or convergent evolution of technological species… But somehow, I have my doubts that any alien species humanity will encounter are very likely to be cut from the same cloth as us.
★ Note, incidentally, that our old friend the Horta was neither humanoid nor evil. Though it did go on a killing spree and murder a lot of redshirts…
A trope is a recurring theme in any narrative which conveys information to the audience. These are snippets of information which have somehow ended up in our collective subconscious as ways in which storytellers have gotten their points across. Overused tropes end up as clichés.