Civilization is a series of techniques in which the hunter-gatherer brain teaches itself to rewire itself. And the sad proof that civilization is a composite of the higher and lower brain functions is seen when civilization breaks down in civil wars, and brutal instincts emerge full-force, and theft, rape, destruction, and murder become commonplace. Because the plastic brain can always allow brain functions that it has brought together to separate, a regression to barbarism is always possible, and civilization will always be a tenuous affair that must be taught in each generation and is always, at most, one generation deep.