" In a way, it’s odd that the greatest sympathy for evolutionism is found among scholars who study the distant past. For events of this century, and especially of the last few decades, suggest that the arrow of history identified by some social scientists of the nineteenth century is roughly on target. Lewis Morgan’s essential point was right: the endless impetus of cultural evolution has pushed society through several thresholds over the past 20,000 years. And now it is pushing society through another one. A magnificent new social structure—our future home—is being built before our eyes. "

― Robert Wright , Nonzero: The Logic of Human Destiny