What are aliens, really?

As I said here, one reason I reject alien-abduction stories is that the aliens they describe -- "greys" and suchlike -- are just unimaginative modifications of the human form.  It's very unlikely that evolution on another planet would produce anything so closely resembling us or any other Earthly species.  Aliens with a technological civilization would probably have sophisticated sense organs and organs of manipulation (like hands or tentacles), but that's all we can assume.

Such visions are clearly products of the human mind.  But why do human minds even come up with such fantasies at all?  Does the fact that reports of alien encounters are limited to the last eighty or so years mean anything?

During the Dark Ages, reports of personal encounters with angels and demons were very common.  If angels and demons actually existed -- and people at that time certainly believed they did -- then there's no reason to think that such encounters would be any less common today than back then.  Yet such reports are pretty rare today, and generally heard only from people with intensely-religious backgrounds.

Humans seem to have an occasional tendency to hallucinate vivid encounters with human-like but often grotesquely distorted beings, who may be either benevolent or menacing.  It could be a sporadic survival into adulthood of the "imaginary friend" phenomenon seen in children.  Such hallucinated entities are interpreted according to (and perhaps derive their visual form from) the library of concepts and images available to the person having the hallucination.  In a time and place where most people's thinking was dominated by Christianity, they manifested themselves as angels and demons.  Since rocketry and space travel got going, and beings from other worlds using such technology to visit Earth became a common theme of science fiction, they've manifested themselves as aliens.

In both cases, the encounters often include sexual elements (succubi and incubi, alien "probing" and even impregnation), and sometimes feature the superior beings delivering statements which are received as profound wisdom, but in fact are usually just trite platitudes drawn from the trash culture of the day.

It also seems that aliens are taking on some of the functions humans formerly assigned to gods.  There are claims that aliens created the human race (by interbreeding with apes, or something equally silly) or that they will be coming here soon to save humanity, or some favored subset thereof, from the various intractable problems we've created for ourselves.  The quasi-religious quality of such ideas is obvious, and given time and more coherent "doctrines", such ideas could even evolve into religions.  Scientology already involves ancient aliens in roles similar to those given to gods or devils in other religions.

In case you were wondering, by the way, there is no substance to such claims.  The human genome and that of our closest relative, the chimpanzee, have been exhaustively mapped -- since the differences are of obvious interest to anthropology.  None of those differences (which are surprisingly small) look like anything other than ordinary results of mutation and natural selection.

There's a more niche cult which oddly parallels the "God of the gaps" concept -- the argument that if there's no obvious explanation for some phenomenon seen in nature, God must have done it.  I'm referring to the "ancient astronauts" cult fomented by writers like Erich von Däniken, which claims that various pre-modern structures like the Egyptian pyramids or the fortifications of pre-Columbian Peru could not have been built by people at the time, therefore aliens must have helped.  As with scientifically-unexplained natural phenomena, the sensible response -- that we simply don't yet know the explanation -- is ignored to promote a favored claim.

And, as with the natural phenomena, in most cases there is actually no mystery.  It's pretty well understood how the pyramids were built, for example.  The Egyptians of 2600 BC were not grunting primitives -- they had a literate civilization with agriculture, cities, and a total population of about four million.  The pyramids could have been built by a few tens of thousands of workers in a couple of decades using ordinary techniques known to have been available at the time.  Ancient Egypt was an absolute monarchy, so the pharaoh could easily have assembled a workforce that size for a project he considered important.

James Randi and others have done a thorough job of documenting the idiocy and dishonesty of von Däniken's claims -- he even found it amazing that early Peruvians knew what human skeletons looked like when they didn't have X-rays, for example.  And no archaeological site anywhere on Earth has ever yielded any unambiguous trace of the advanced technology aliens would have had and were supposedly using to help build these structures -- not one dropped screw or wire or discarded food wrapper or anything showing signs of precision manufacture or made of a material unavailable to people at the time.  There's also an odd element of racism involved.  No one has ever claimed that aliens must have helped build the Parthenon or the Köln cathedral -- because those were built by Europeans, who were presumptively smart enough to have done it themselves.  It's only non-Europeans who must have needed alien help to build great works.  Sorry, no -- early humans were surprisingly ingenious, all over the world.

There certainly might be other technological civilizations elsewhere in the universe, perhaps even within this galaxy.  My own assessment is that there probably are not, but we just know far too little right now to come to firm conclusions one way or the other.  But the tales of aliens, UFOs, ancient astronauts, and the like which entertain credulous modern people have nothing to do with any such possibility.  They're just new manifestations of the same old visions, scams, and errors of logic which have plagued us in various forms for thousands of years.