Indians? Man, it would pre date the Nazca Lines or even ancient Egypt. The Predators could have seen the rise and fall of Atlantis, Lemuria, Thule. Beacuse of the focus on the Hunt, they must have originated from a large homeworld rich in biodiversity and life forms. I think they were at some point evolved into a barbaric tribe civilization that over a period of time became spacefaring; which I only believe was possible through some kind of first contact with a more advanced species. If you want to stay in cannon with the films and books, then there is a great possibilty that it was the Space Jockeys (I like this). For a character so loved there is so little that is known about it's history, legends, and folklore. Maybe that is one facet of the Predator's appeal. Mystery. It won't exist until you create it; and thats how it should be - history written by those that cherish it.
Movies don't keep this alive, we do.
haha the evolution of pred pic is cool!
