It seems to me that Crake believes that in order for the human race to survive, it has to become essentially non-human. He is doing what he believes is necessary to save what he considers to be the best parts of humanity. Barring the methods by which he achieves it, I think that it is interesting to examine this motivation as it stands, outside of the context. Personally, I do not agree with what Crake considers to be the best parts of humanity, just as I don’t agree with Butler’s argument that the “hierarchical impulse” is entirely bad.