I will elaborate here a little bit about the previous post regarding the battle between the Spanish Pizarro and the Inca leader Atahuallpa. The question is why guns, germs and steel were in favor of Pizarro's side and ultimately led him to destroy the Inca civilization.
Why did Pizarro come to America rather than Atahuallpa try to conquer Spain? Pizarro had better technology (ships+guns) and also the necessary political organization of Spain that helped finance and build the ships. Atahuallpa was a godlike leader; by capturing and killing him the whole of Inca empire shattered. Had the King of Spain been killed, it would have been replaced since the government does not rely so much on a monarch.
As Diamond says, this is the easy part of the answer. The hard part is to figure out why it came to be in such a way. His answer is: food production.
Farmer-based societies were advantaged as opposed to nomadic hunters. Initially all people were hunters, moving from place to place wherever food and animals was available. At some point all tribes (at different times) switched to food production which allowed them to stick to a place, store food and develop people other than farmers (e.g. soldiers, craftsmen, politicians). Also, staying because of the crops there favors population expansion. Just imagine a nomadic mother that has to carry her child around until it can walk on its own. She won't make another child for an average of another 4 years. There is no such issue in settled-down tribes.
Therefore a cause for Pizarro's conquest was the fact that his civilization developed earlier and more efficiently food production, which then led to all the other advantages that ultimately led him to win. Of course now we have to go deeper and ask: why was food production developed better in Eurasia and not in the Americas or Africa?
