As I've said, it's hard to say whether or not he is serious about this. He is the type that will enter into any family occassion by declaring that some close unwed cousin or brother has "big news" and is going to be a mommy or daddy...In fact, when he called to tell his mother about me being pregnant with our daughter--she didn't believe him! I had to get on the phone and tell her that yes, I was indeed pregnant.
So, whether or not he's playing on my "grr" factor by saying that aliens used pyramids as docking stations a la Stargate, is up to question. He sees Von Daniken as a bit of a nutter. However, he has grown up in "UFO country" and seen some pretty weird things with his family while driving on deep reservation areas. So, all of his joking aside, I think I can say that he doesn't rule out aliens or UFOs as a possible reason for the switch to cliffdwelling based on local lore and some of his experiences.
Stephanie
In every man there is something wherein I may learn of him, and in that I am his pupil.--Ralph Waldo Emerson