"Funny you should say that because in that world, they don't call themselves humans or Earthlings, they call themselves Gaians. I don't know if they even count as humans... They sure look like humans - or at least the one that I've met does - but all of them have psychic abilities. They were able to come to our Earth through these... dimensional doorways, I'd guess you'd call them, and had been doing it for thousands of years. That's why there's psychic people on Earth - we're all descendants from Gaians who, uh, hooked up with regular humans."