"Complex societies are problem-solving organizations, in which more parts, different kinds of parts, more social differentiation, more inequality, and more kinds of centralization and control emerge as circumstances require. Growth of complexity has involved a change from small, internally homogeneous, minimally differentiated groups characterized by equal access to resources, shifting, ephemeral leadership,and unstable political formations, to large, heterogeneous, internally differentiated, class structured, controlled societies in which the resources that sustain life are not equally available to all. This latter kind of society, with which we today are most familiar, is an anomaly of history, and where present requires constant legitimization and reinforcement."
Joseph A. Tainter, The Collapse of Complex Societies