Intro scene questions

I see it the way that it is Earth, before the time of animals and humans, and his DNA that ends up in the water gives birth to the life on our planet. The engineer does look surprised when he starts falling apart, so I think drinking the liquid is some sort of experiment. They do this on different planets and see what happens. That's why the spacecraft is hovering above him and checking what's going to happen. Or do they go to habitable planets (remember the engineers need air as well), one of them sacrifices themselves to start life on the planet. But in that case, why do they have to drink the liquid? Wouldn't the DNA spread into the water if they just drowned themselves and let their bodies "get bad" and their cells would go all over the place with the water.

I think the black goo is a catalyst for DNA transformation. Whatever gets in that goo is getting transformed, mutated in some way. And it also does so really fast (worms turned into snake things, Fifield got zombified, Holloway got infected)

Unfortunately, the DNA is like one of the first organic body things to go. I would think. Even if it lasted it would quickly break down into amino acids and not have the desired result. I haven't seen it yet but from a strictly biology/chariots of the gods fan I would think this is how they introduce life/DNA onto a hospitable planet.

not seen the film... but was wondering why would the engineers want to spawn humanoid life - if thats what they are doing by leaving their DNA. does this mean the ultimate culmination of DNA evolutionary process is the human with supreme intellect?

The way I see the scene is that the Engineer in the beginning is being cast out from their society and kills himself by drinking the poison. Little did they know that he would fall into the water and that his DNA would create the life of planet Earth. He himself looked surprised as he started to disintegrate. Thus all life on the planet was a mistake! We are a mistake!!! And thats why the engineers are going to Earth to fix their mistake. It also didn't help that their mistake was able to track them down and actually talked to them. Remember the Engineer didn't become aggressive until David started to talk to him in a language he understood! As for what killed all the Engineers 2000 years ago? More giant worms perhaps?

why did the engineers visit us in the past as the cave paintings suggested?

Thats a valid question. But i believe that they were keeping an eye on us. Something happened 2000 years ago on Earth that they felt was justifiable to killing us! Was it that Jesus came about and claimed to be the son of God? In retrospect everyone is the child of God if God is the Engineers. But that probably pissed them off. Also the sleeping Engineer didn't get aggressive until David started to talk to him. Perhaps he figured out that he wasn't human (thats why he pulled his head off) and was mad that humans had created artificial life. Oh hell, I don't know! Go watch the movie red5:) Its a MASTERPIECE. And i wish people would stop comparing it to Alien. Two totally different kids of films. Also Damon Lindelof said that part 2 would explain why the Engineers wanted to kill us after they created us.