Dr. Paula Cushing: It's hard to say if they brought in any scientists as advisors to design the aliens. The biology and form of the aliens (at least the worm-like form) is fairly close to several different types of real-life parasites, so they certainly may have gotten ideas for the form from a parasitologist or from books about parasites.
WW: What animal would you say most closely resembles the alien in the real world?
PC: The general life history of the movie alien is that lays its eggs inside a host, then changes the behavior of the host so that its own progeny have a better chance at dispersal and survival. It's actually very close to the life history of a myriad of parasites found on Earth. Before the event, I'll describe some of the more bizarre parasites whose behavior is as horrific, if not more so, as the behavior and life history of the aliens in the movie.
WW: Since the aliens use humans as hosts, would they pick up new DNA every time they were in a new host?
PC: The facehugger form of the alien is just hugging the face in order to lay its eggs inside the body of the "host" (the poor sap). Thus, it is just using the host for its own reproduction and is not picking up any DNA or genetic material from the host.
WW: If you had to guess, what do you think they'd smell like?
PC: Guessing what the alien might smell like sort of creeps me out so I'm just not gonna go there!
WW: Since we only see the aliens in the human environments in the films, what's your best guess for their natural environment?PC: It is intriguing to imagine the natural environment of the alien. Since its eggs are laid en masse in a relatively dry area, I suspect the natural environment is a relatively dry habitat. But it is equally clear that at least one of their life stages must be passed inside the body of some large host (e.g., a human or another alien). That primary host must be bigger than a cat because, at one point in the movie, the alien has an opportunity to infect the cat but does not do so. So their natural habitat and the planet where they originate must be inhabited by relatively large creatures that can serve as hosts for the alien.
Alien screens at Phipps Theater at the Denver Museum of Nature & Science on Wednesday, July 20. Order tickets here.