The origin of the state: grain, tax and writing

The invention of agriculture has been seen as the spur for the emergence of large-scale human societies. However, the long gap between the development of agriculture and the emergence of states suggests that it was only intensive agriculture that provided enough surplus for emerging states. Alternatively, it was the taxation potential of cereal grains that enabled the formation of states and writing became crucial for keeping records of those taxes. We test these hypotheses by combining trait data on 868 cultures worldwide with a global supertree representing their genealogical relationships. Our results suggest that intensive agriculture was as likely the result of state formation as its cause. On the other hand, grain cultivation always preceded state emergence, while non-grain agriculture was lost. Grain cultivation also predicts the emergence of taxation, and writing is never lost once states are formed and only adopted in tax-raising societies likely to record those taxes.