According to Guns, Germs, and Steel, what major elements separate the world's "haves" from the "have-nots"?

To Diamond, the "ultimate factor" that determines which
societies become "haves" and which become "have nots" is geography.  Societies that
developed in places that had many domesticable plants and animals had an advantage,
particularly if it was easy for those species to spread across a large area.  So
geography is the major cause of the fact that some societies became richer and more
powerful than others.

More proximate causes are technology,
epidemic diseases, and political organization.  The political organization allowed some
societies to extract taxes from their people and then to create centralized governments
with militaries and bureaucracies.  Such societies had an advantage over less organized
ones.  The impact of technology and diseases are more obvious.  Technology allowed some
societies to be more powerful economically and militarily.  Diseases allowed some
societies to decimate the populations of others without even
trying.