The Ancient Astronaut Theorists say so. Aliens have always been here, and helped to shape our history.
I'm home sick today and for several hours I've been watching Ancient Aliens on the History channel. Sounds like an odd place for this type of programing, but not really. Projected theories, past, present and future abound in this show. It's the perfect show for someone like me.
For instance, the moon is hollow. Aliens placed it in Earth's orbit for us. Yeah it's true. So the rhythmic motion of the moon on the Earth could have caused life to evolve here. Is the moon artificial-- is it a satellite and somewhat like the Death Star in Star Wars?
Here's another-- the missing link-- is it possible that an advanced culture from some distant solar system intervened in human evolution? Wild concepts, right? But not so much if you have a Science Fiction brain! Here's one-- Are Angels (translated messengers) really ET extraterrestrial beings? Travelers from distant planets? For sure this stuff is fodder for a SF author