War caused the formation of social institutions such as religions and bureaucracies, a study says. The institutions would help to maintain stability in large and ethnically diverse societies early in history. The study authors, who tested the theories in simulations and compared the results with historical data, found that empires arise in response to the pressures of warfare between smaller states.
, a population dynamicist at the University of Connecticut and his colleagues set out to understand why these social institutions came about when they were costly for individuals to build and maintain it. “Our model says they spread because they helped societies compete against each other,” he said. The results are published in the Proceedings of the National Academy of Sciences.
The team looked at a part of world history in which competition between nations and societies were fierce. As technology like arrows and spears spread, conflict intensified in these places.
The researchers developed a model in which the continents of Africa and Eurasia were divided into a grid of cells with 100 kilometres on each side. Each cell was characterized according to the kind of landscape, its elevation about sea level, and whether or not it had agriculture, an important point for early societies. At the start of that simulation, each farming cell was inhabited by an independent state, and states on the border between agrarian societies and the steppe were seeded with military technology. The team simulated this diffusion of that technology and looked for effects on the intensity of warfare and the development of social institutions.
Turchin recognized that states compete in more ways than just warfare, but says that although the model was simple, it predicted the historical rise of empires in the region with about 65% accuracy. That figure dropped to 16% if the diffusion of military technology was omitted from this model. The disintegration of empires led to the dismantling of institutions. “When the Roman Empire broke up, literacy effectively went extinct, because the smaller fragment states did not need a literate bureaucracy,” Turchin says.
Turchin is pioneering a systematic approach to history
that tests the hypotheses against big data. Kenneth Pomeranz, a historian of modern day China at the University of Chicago in Illinois and president of the American Historical Association, says that Turchin’s claims are reasonable given the “very rough granularity” of the data. Turchin wants “to explain why big states form in some places more often than others, not why the Greeks defeat the Persians at Salamis or why Qin rather than Chu becomes the core state of the early Chinese empire” says Pomeranz. Pomeranz adds that this model of early empire building is a “real contribution”.