Androids and aliens are creepy because they're almost human

Check out the creepy human hands on this guy.

Did you ever wonder why androids and aliens are so popular in sci fi? I mean, they're as close to standards as the genre has, true, but they aren't required for a show or movie or story to be considered sci fi-- for that, all you need is some sort of seemingly-plausible extrapolation of what science can or should do, and a decent explanation for your world (as opposed to fantasy, where all you need is magic, and the less it can be explained, the more fantastic it is). Something set in the exact present, without aliens or rockets or robots or anything like that could be sci fi if it has, say, a shiny new weapon that changes how people interact with the world and their history, or a device that alters the course of what would be our usual future.

So why all the A&As?

It's because they're almost like us. Almost, but not. There's an idea that things that are close to what we are, but obviously different, cause a sort of psychological disconnect, a fear that might be the same thing as a fascination. It lets them do things we can't or won't do, like when the Cylons are created to work and fight wars while humans bask in the leisure life that creates, but it also makes them like strange, sentient mirrors to who and what we, as a people, are, like when Data spends a decade and a half trying to be more human, or when the Newcomers settle in the suburbs in Alien Nation and try to blend into normal life. By watching shows about people who might look like us, but aren't like us, we can learn about ourselves-- the plots involving A&As usually wind up being about how we, humans, react to them: stories about discrimination bring up the spectre of racism that still haunts our cultures and elevate it to a world perspective, and point out the reasons for racism, the flaw in it's argument, the ways it can and should be overcome; stories about obsession bring up ideas of betrayal to the species or family, and mix them with ideas of acceptance and even love, because if Sykes can come to think of George as more than a partner, something like a brother, and can come to marry Susan, if Data can be a member of the erstwhile family of the Enterprise's command system, if John Connor can care so much about the various Terminators he's worked and lived with that he'd risk his ridiculously-important self to save them, maybe there's hope for our species.

But there's also the idea of threat. Aliens and Androids are always Other, always outside, and anything from the outside is strange, Uncanny, and holds the potential to destroy the world, or at least the world as we know it. Hence, the Cylons and Terminators and even Data's brother Lor try to Kill All Humans (something Futurama makes fun of, but humor is how we show our fears and prejudices, really), and some of the Newcomers wants to take over Earth, and the aliens in V (or Stargate, or Invasion America, or, like, every Doctor Who episode) pretend to be like humans, to help us, and really want us all dead. It's what we're most terrified of-- annihilation. By our own creations, by those we thought were friends, by anything external to ourselves, and if there's one thing sci fi is good at doing, it's good at making all people one united body: which leaves Androids and Aliens as the new Other, the new projection of what we don't trust, the new mirror to show us who we are, the new Uncanny. And as our own real-life tech starts leading toward self-aware robots that can pass as people, starts leading us out into space where we might meet real aliens if they're there to meet, we'd better start paying attention to what they tell us.