Who knows? Ridley knows.

I'd say it was not a sacrificial act. This scene with a flying saucer and a Hell Raiser character that eats some bad caviar and dies in a waterfall turning into cells that divide has no real meaning. If that was all the information you have, it is not enough.If you show this scene in a film class no one would understand it.It should have been a desolate planet with no water or plant life so when the bald alien died we could see his cells generating life on a dead planet. As it played in the film it looked like there was already life on that planet. As for the engineers caring about their creations after they are made who is to know? the life process shown in this film seems to be automatic and not need watching over.For parents to be disappointed at their children's actions they must be present no? There wasn't one scene in the film that showed that these bald albinos were in fact engineers at all, it was just a line a character said that you are supposed to swallow as the truth.They really needed the scene with the re-animated jockey head to be the exposition where the engineers motives are hinted at . For me that scene was just a harbinger of what a mediocre film I would be sitting through as I thought about how great the original Alien is.

It's good to guess what the meanings are working forward from what you've seen. But be sure of what you've seen first! the Engineer seeded a Planet. It may be Earth, and we are tempted to think so for several reasons, including the star of scene two (the standing rock resembling the disc ship) but they may be leading us up the garden path. We can guess away at why the act was done. It was probably not a selfless act of an engineer sacrificing himself. I doubt we've SEEN an engineer, and they are using these grey things as clones to do their unpleasant tasks like 'seeding' primordial planets, and being hosts for xenomorphs. Ina further way of developing this slave idea,... imagine if they've kidnapped their slaves? Alien abduction from Earth, would explain WHY the grey dudes share our DNA. (some genes are activated and others deactivated to make them more single minded and muscular) That would reflect on how on Earth we had mass slavery (Egypt, US, S. America, Nazi Germany) and treated others as untermeschen with no right to find their own purpose in the world.

[i]I'd say it was not a sacrificial act. This scene with a flying saucer and a Hell Raiser character that eats some bad caviar and dies in a waterfall turning into cells that divide has no real meaning.[/i] It has many possible meanings and is deliberately ambiguous. [i]If that was all the information you have, it is not enough.If you show this scene in a film class no one would understand it.It should have been a desolate planet with no water or plant life so when the bald alien died we could see his cells generating life on a dead planet. As it played in the film it looked like there was already life on that planet.[/i] Water is a prerequisite for the chemisty of life. DNA on open rock will be destroyed by solar radiation. This is a barren planet ... there was water before there was a any single cell life. I think we saw some green patches of the shots (of Iceland)... but not necessarily chlorophyl. There are only two trees in this film, both artificial.