Also see John Horgan's response to this piece, “No, War Is Not Inevitable.”
“History is a bath of blood,” wrote William James, whose 1906 antiwar essay is arguably the best ever written on the subject. “Modern man inherits all the innate pugnacity and all the love of glory of his ancestors. Showing war’s irrationality and horror is of no effect on him. The horrors make the fascination. War is the strong life; it is life in extremis; war taxes are the only ones men never hesitate to pay, as the budgets of all nations show us.”
Our bloody nature, it can now be argued in the context of modern biology, is ingrained because group-versus-group competition was a principal driving force that made us what we are. In prehistory, group selection (that is, the competition between tribes instead of between individuals) lifted the hominids that became territorial carnivores to heights of solidarity, to genius, to enterprise—and to fear. Each tribe knew with justification that if it was not armed and ready, its very existence was imperiled. Throughout history, the escalation of a large part of technology has had combat as its central purpose. Today the calendars of nations are punctuated by holidays to celebrate wars won and to perform memorial services for those who died waging them. Public support is best fired up by appeal to the emotions of deadly combat, over which the amygdala—a center for primary emotion in the brain—is grandmaster. We find ourselves in the “battle” to stem an oil spill, the “fight” to tame inflation, the “war” against cancer. Wherever there is an enemy, animate or inanimate, there must be a victory. You must prevail at the front, no matter how high the cost at home.