War necessary evil, science suggests

War drove the formation of complex social institutions such as religions and bureaucracies, a study suggests. The institutions would have helped to maintain stability in large and ethnically diverse early societies. The study authors, who tested their theories in simulations and compared the results with historical data, found that empires arise in response to the pressure of warfare between small states. Peter Turchin, a population dynamicist at the University of Connecticut in Storrs, and his colleagues set out to understand why social institutions came about when they were costly for individuals to build and maintain. “Our model says they spread because they helped societies compete against each other,” says Turchin. 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 was fierce: Africa and Eurasia between 1500 bc and ad 1500. In the first millennium bc, nomads on the Eurasian steppe invented mounted archery, the most effective projectile weaponry technique until gunpowder. As that technology spread, evolving into chariot and cavalry warfare, conflict intensified.