What kind of evidence did Diamond rely on in Guns, Germs and Steel?

One of
the reasons that Guns, Germs and Steel byhas been such a successful and
influential book is the way it deploys multiple types of evidence to support its central
thesis. 

Guns, Germs and Steel begins with a personal
anecdote, telling of Diamond's interactions with Yali and how those set Diamond on the path of
writing the book to investigate why Europeans possess so much more "cargo" (material
wealth and advanced technology) than the natives of Papua New Guinea. His own experiences
interacting with people of differing cultures add personal credibility or what rhetoricians call
"argument from ethos" to the book. 

Next, he uses scientific
evidence, especially from biology, geology, geography, and archaeology to make arguments about
the prevalence of different types of domesticable plants and animals in different regions and
how local climates and geography affected the development of civilizations. 

He also uses historical evidence from various texts to describe how people...