I guess all Sci-fi tries to go to social engineering one way or another because society is what changes the most with time and space, do remind how quickly human society changed when electricity was created and the changes that came with the cellphone to work habits, in this film there was a severe population reduction due massive earthquakes so pollution stopped being a mayor problem, as there were not much of people alive to contaminate at all, in fact there is a small segment when in the museum, Phoenix is finding out about "future weapons" and a great ww3 is mentioned slightly as the origin of powerful new weapons and how it accounted for massive losses and used no ammo at all but a rechargeable battery instead. So there are severe evidences of these issues, also with the whole "changeroo" of characters from gender to personality, in my eyes the last big female character was Ripley, but heck, there have been a couple good characters after her so who knows, maybe I'm wrong :)