Give examples from Guns, Germs, and Steel that support Diamond's argument as to why some civilizations are much more advanced than others.

There are many examples from the book that are meant to
prove Diamond's point.  Let me briefly discuss two of
them.

First, there is the example of the Polynesia
societies that is discussed in Chapter 2.  In that chapter, Diamond establishes that
some Polynesian cultures were more advanced than others.  He also shows that the more
advanced societies were those that were on islands that could support more agriculture. 
This proves that environmental conditions lead to agriculture (or lack thereof) which
determines which societies become advanced.

Second, there
is the example of the Aboriginal Australians, discussed in Chapter 15.  There, Diamond
notes that the Aborigines were one of the most primitive societies in the world.  He
goes on to prove that this was due to their isolation and the lack of resources that
were native to their homeland.  This, too, works to defend Diamond's overall
thesis.