I've been thinking a lot lately about aliens taking human form (whatever they may be, beings from other planets or other dimensions, let us use the word "alien" here to mean "sufficiently advanced nonhuman intelligence"). Let us suppose that it is at least possible that aliens exist and that they may be able to disguise themselves as humans. For what purpose would an alien disguise itself as a human, who knows? Maybe they want to learn more about humans as an anthropological study, or to prepare the way for an invasion. Maybe they want to vacation on Earth undetected, or immigrate to the planet because they are unhappy with their home world for some reason. Maybe they just want to cause trouble with an inferior species for their own amusement.
How would you tell whether someone was a human or an alien disguised as a human? If these aliens are sufficiently advanced then their disguises would be perfect. Even at a molecular level there would be no way to distinguish their bodies from those of humans. The only possible way to tell them apart that I can think of is their behaviour (possibly). A sufficiently alien lifeform would have a sufficiently alien psychology to make it possible to distinguish it from a human*. No matter how good an actor, it is always possible for an infiltrator to be found out. Now, it is possible that an alien impersonating a human would be hypnotised before being dropped (or beamed) on Earth so as to forget that it is only pretending to be a human, however, if it is sufficiently alien then it should give itself away eventually.
With this as our metric, looking for humans with sufficiently alien behaviour, we can begin to assess whether someone is 1. a normal human, 2. a human with deviant behaviour, or 3. an alien disguised as a human. Please take note that I am putting emphasis on the term sufficiently alien, because I do not have any specific objective standards for which to assess whether someone is necessarily a deviant human or an alien in disguise. Right now I am merely dealing with possibilities, not actualities. This does raise an interesting question, namely: how do we distinguish between someone who has some mental illness but is otherwise human and someone who is an alien disguised as a human? If, as indicated above, these aliens are advanced enough to make human disguises that are indistinguishable from real human bodies on a molecular level, and all we have to go on is behaviour, how can we make the distinction between a genuine alien and a deviant human? Is someone, say a schizophrenic or serial killer, crazy or are they an alien?
In this series I will be trying to answer those questions.
One place to start is, interestingly enough, an episode of Ancient Aliens (no, I did not get the idea from the series). While the series pretty much uses aliens as their deus ex solution to absolutely everything, they do, on rare occasion, raise interesting points. The pyramids absolutely were not made by guys hauling stones up a ramp because the ramp would require more material than the pyramid itself and would represent an even more fantastic engineering feat. The "Baghdad Battery" was a source of electricity in ancient times used for purposes unknown, and it does fit nicely with the lightbulb carvings in Dendera in explaining how people worked in the pyramids when there are no signs of soot from oil lamps or torches and there is no other means of getting light inside than with electric lighting. The Stone of the Pregnant Woman at Baalbek in Lebanon is so massive that it does not have enough surface area to attach enough ropes to it in order to move it, yet it was clearly carved with the intent of moving it somewhere. This episode also raises the question of whether certain serial killers, such as David Berkowitz, who claimed to be hearing voices, were really hearing alien voices who wanted them to kill just to cause trouble with humans. Maybe some people so easily labled as crazy were perfectly sane, they were just aliens, or brainwashed by aliens. I will be analysing details from this episode in the next part in this series. For now it will suffice for you just to watch the program.
*There is an article titled "Xenopsychology" that I will be disgussing in a future part of this series that looks at how aliens might think differently from humans. There is also a book called Solaris by Stanislaw Lem (that was made into two films) that basically says it would be impossible for humans to communicate with a sufficiently alien lifeform because its way of thinking would be incomprehensible to humans. I never read the book, but it's short so you can breeze through it pretty quickly, unless it's boring.