I find the whole "ancient astronaut" theories insulting/racist. Why couldn't different cultures develop their own technology to build pyramids etc, without the help of aliens?
http://www.skepdic.com/vondanik.html
The term 'ancient astronauts' designates the speculative notion that aliens are responsible for the most ancient civilizations on earth. The most notorious proponent of this idea is Erich von Däniken, author of several popular books on the subject. His Chariots of the Gods? Unsolved Mysteries of the Past, for example, is a sweeping attack on the memories and abilities of ancient peoples. Von Däniken claims that the myths, arts, social organizations, etc., of ancient cultures were introduced by astronauts from another world. He questions not just the capacity for memory, but the capacity for culture and civilization itself, in ancient peoples. Prehistoric humans did not develop their own arts and technologies, but rather were taught art and science by visitors from outer space.
Where is the proof for von Däniken's claims? Some of it was fraudulent.
However, most of von Däniken's evidence is in the form of specious and fallacious arguments.
There have been many critics of von Däniken's notions, but Ronald Story stands out as the most thorough. Most critics of von Däniken's theory point out that prehistoric peoples were not the helpless, incompetent, forgetful savages he makes them out to be