Chances are, you’re already quite familiar with the notion the ancient astronauts visited the earth and gave humans the tech support they needed to climb the ladder of civilization. There's no true proof to back it up, yet ancient astronaut speculation is a 20th century invention -- and one tied closely to a single bestselling author. In this episode of Stuff to Blow Your Mind, Robert and Joe discuss Erich von Däniken and Carl Sagan's thoughts on ancient aliens. (Originally published June 28, 2018)