Synthesized answer
The provided passages do not contain information about unanswered questions in *Guns, Germs, and Steel*. They only offer a title and a category for the book [1]. Therefore, I cannot answer what questions remain unanswered.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Guns, Germs, and Steel by Jared M. Diamond Categories: Civilization