In Guns, Germs, and Steel what is the relationship between food production and complex societies-does one lead to the other?Guns, Germs, and Steel...

In Chapter 14, Diamond tells us that there is not an
either-or answer to the question of which of these things leads to the other.  Complex
societies do not lead to food production or vice versa.  Instead, Diamond tells us (on
page 285 in the paperback edition) that these two things "stimulate each
other."

Of course, food production is needed to get a more
complex society.  There is no way to get a large and complex society without it. 
Diamond says that very few societies make it to the level of chiefdoms without food
production.  However, complex societies also make it easier to have food production. 
The existence of an organized government can make it possible for there to be public
works like irrigation systems that make food production more
possible.

So, the causation goes both ways.  Food
production and complex societies lead to one another.