It is the deep rooted fear that other creatures would be smarter than us. The other day, I was watching Smallville and saw that Kara's spaceship was being opened by earthlings. Why was not the spaceship had AI yet there was an AI creature running around? And the ship piloted itself to Earth and could not protect itself? I have rarely seen an AI ship doing things like a humanoid except Vorlon ships, then again Babylon 5 is a whole new level of entertainment.