Of course, in the End of Eternity context that's not a hole. Where are the aliens? Humans happened to be first out and crowded out or pre-empted the others, without the need for robotic xenocide.I actually loved the prequel books that were were written after his death, because they fill in some holes. Where are the aliens? Daneel killed them, because the laws don't apply to them, and we need their soil.