With the recent History Channel series on ancient astronauts, many of the UFO and mystery related forums have been filled with debate on this subject.
Besides the "Chariots of the Gods" book, there is Zechariah Sitchin's theory that ancient Sumerian writings tell the story of how the Annunaki came to earth to use mankind to mine gold for their atmosphere.
To accomplish their goal, DNA manipulation was used, which supposedly raised mankind to a higher level being. You can see a basic overview of this theory at Ancient Aliens Involved in our Evolution?. Do you buy into this theory?