So here's the theory: In the far future, we will probably have exhausted Earth of almost all its resources, and in order to survive, we will have to move away, to a different planet. And once we get to said planet, we will probably eventually use all of its resources, and have to move again. Well my theory is, what if Earth is not the planet where we have originated? What if it's like the 26th planet our species has moved to? What if at first, we came to Earth as octopi with eight legs and eventually evolved into humans to adapt to this planet? And if we were so intelligent enough to move to different planets, then why don't we know this? How come we aren't aware of the previous intellectual life that came to Earth before us? Well, maybe there are three reasons: Number one: we just lost eventually forgot after the millions of years we spent on Earth. Number two: our previous terrestrial life decided to hide the fact that we came here from a different planet.

Number three: some catastrophic event occurred after our previous terrestrial life descended here on Earth that completely wiped out said life and altered the conditions on Earth, but humans then came to evolve out of microorganisms. Okay, this is a completely wack theory but I said it. So there.