Hollywood has gotten into prequels, obviously. Explaining how things came about never stops being interesting ... in theory. In some cases a prequel works out okay> I actually mostly enjoyed X-Men: First Class and it was because Michael Fassbender is a great entertainer (more on this, inevitably). This mutant prequel worked because it got back to the core conflict between Magneto and Professor X and showed how their paths diverged despite a sincere friendship.
But prequels like Star Wars Episodes I-III didn't even deliver on a fan hope for a depiction of the actual clone wars. For that fans would have to wait for the titular Clone Wars cartoon (and not necessarily the slight but eminently watchable Tartakovsky version). I will have a great deal I'd like to say about the distinction between "mythos" and actually mythic narrative function down the road but I am saving that stuff for the sequel and this is not a prequel.
The week before the film came out I wrote this:
Spoiler alert--the Engineer DNA and the human DNA are the same. Ergo, we made ourselves. ;-) There are a variety of ways of explaining this and some people explain it one way and others explain it in another way. The white Engineers and the black goo are curiously blank slates that don't invite a lot of explanation of motive. To be sure some have provided lengthy and detailed explanations of motive but I propose, in an admittedly uncharitable perspective, that one of the problems of Prometheus is that it merely poses questions that it is not particularly interested in answering. Rather, the answer is summed up in "because we could" at the start of the film when Charlie explains to David why David was created. David replies, "Imagine how disappointed you will feel when your creators tell you the same thing."
One of the mysteries of the film Prometheus is the question of motive. "Why?" is a question that abounds in the film. Unfortunately as this is a horror film the question "why?" permeates the actions of characters in ways that can be sent up readily. As Dana Stevens wrote over at Slate "I think they want us to go and meet them" is the first of many lines uttered in such a genre film that telegraph that bad ideas are about to be implemented with disastrous consequences. Elizabeth Shaw, who is some manner of at least nominal Christian, at least has a self-explanatory motive. Her boyfriend Charlie Holloway's motives are to find answers but perhaps in the vein of guys who go along on quests because of the women they want to be with Holloway's motives often seem remarkably secondary or unfocused. It's Charlie who tells David the android "we made you because we could". Charlie's disdain for artificial life is about the only thing vaguely hinted at from the actor's performance.
The other being that when he upsets Elizabeth by saying it takes no real effort to create life, just a bit of DNA and some dirt Elizabeth takes offense. Elizabeth is infertile and can't have children. Charlie explains that he didn't mean it like that, it might be worth noting that he never actually says sorry. Perhaps like overly lenient girlfriends in other genre films Elizabeth decides to not hold this against him.
The most memorable scene in the film is where David explains that Elizabeth is three months pregnant. This can't be, Elizabeth says with some alarm, because she is infertile. David politely and calmly remarks that he didn't say it was a human baby. Thus begins Elizabeth's frantic effort to get the thing out of her. She has a machine cut the infant creature out of her and "gives birth" to a kind of starfish squid (whose resemblence to the face-hugger alien from Ridley Scott's seminal sci-fi horror film is more than just passing). This face-hugging squid seems to absorb nutrients from the air itself and increases to twenty times its original size by the end of the movie in which it is locked in combat with the last Engineer (or so it would seem).
You see the moon with life on it is an abandoned moon, a derelict weapons storage center the Engineers gave up eons ago.
That the Engineers created human life is all too telegraphed in a scene where a lone Engineer commits some kind of ritual suicide and his disintegrating DNA becomes a foundation for humans to discover evidence via pictograms of the Engineers' role in the creation of human life. The film plays a lot with questions that are not necessarily answered or are answered with answers that can be met with"That's it?" Because we could? In other words the answer is based on possibility and practicality (in sci-fi genre senses of the term) and not in terms of motive, which is precisely the sense in which the big questions are almost only ever asked. In a sense the horror at the heart of Prometheus is that the questions get asked and the answers are violence without an answer (what, prcisely, was David's motive for infecting Charlie with some kind of grub who gave Charlie the ability to impregnate Elizabeth with a monster that eventually kills the final Engineer who plans to go wipe out humanity?) or answers that can be met with "Uh ... that's it?"
"Yes" Michael Fassbender's android David would appear to reply, "that's it. I'm terribly sorry. You know I don't really feel sorry but I know humans like to hear those words when something disappointing happens to them."
Why, yes, David, that's right. Thank you.