[Question] Reference request: human as “backup”

I remember reading some paper that suggests humans to take a specialized role inside super AI, like mitochondria, or like a biological “backup”. The argument was that humans might have specialized functions that they can do well, like mitochondria is good at making energy. And humans might be good at surviving, so might be a good “biological backup”.

I feel like it’s by Vernor Vinge, but I just checked and he didn’t write that. I googled around and couldn’t find it either. Can you find from which paper this might have come from?