He has already identified the selection process by which civilizations evolve: war. War is, historically, where your surplus goes. Surplus elites, surplus laborers, surplus resources, surplus manufacturing capabilities, all of these things are expended in war, and all of them have the same potential to cause the problems Turchin is describing. Surpluses threaten the distribution of power, precisely because they can be used to engage in war. Civilizations are always under the threat of internal warfare, and without external warfare, which nuclear weapons have essentially made impossible, the threat only increases with surplus.
