Alien Astronauts Visited Mankind in its Distant Past

Erich von Däniken's theory that alien astronauts visited primitive man and "jumpstarted" technology and civilization is the clear controlling idea in the book, and the idea most likely to jar the scientific community and cause a stir in the general populace. To be specific, the author imagines a race of giants (for so many ancient texts speak of "giants"), with technology sufficiently advanced from our own that would allow long-distance space travel. These beings, for a reason the author refrains from guessing upon, arrive on Earth sometime in the Early Paleolithic Age, literally at the dawn of civilization. They teach mankind basic laws (e.g. Moses bringing down commandments from an unseen God on high), masonry techniques (for what else could explain the marvelous Egyptian pyramids?), astronomy (e.g. the uncanny accuracy of the Mayan calendar) and agriculture, sewing the...