Did aliens visit Earth in ancient times? It’s possible.

The late Carl Sagan once argued that there was a “statistical likelihood that Earth was visited by an advanced extraterrestrial civilization at least once during historical times.”

A statistical likelihood is one thing. Is there any reliable evidence that any such thing ever actually happened?

None whatsoever.

So why do 3 out of 4 Americans believe there are signs that aliens have visited Earth in the past? I think there are two reasons. First and most fundamentally, when most people see a wonder of the ancient world, such as the Egyptian pyramids, they can’t imagine how our so-called primitive ancestors possibly could have built it....