The only time that Jared Diamond talks much about social class is in Chapter 14. There, he tells us that social classes come to exist as societies reach the last two stages of development. At that point, interactions between social classes tend to become exploitative. In chiefdoms and states, there are social classes. The upper classes, Diamond says, exploit the lower classes. Diamond says that this can get to be bad enough that the governments can be called "kleptocracies" that take resources from the lower classes and give them to the elites.