" The city thus at an early date recaptured the polymorphism of the insect hive: by social means it achieved the equivalent of the physiological differentiations that accompany the integration of insect societies. True, thus division of labor allowed for far greater internal mobility than insect communities know. Even prostitution, though it condemned a whole class to the drudgeries of sexual intercourse, never reached the point of creating a single class of sexual breeders, segregated for childbearing. (That horror possibly awaits the triumph of Post-historic Man.) Nevertheless, the parallel between human and insect societies applies even to the working life; for within a single lifetime the differences between vocations still cause characteristic diseases and disabilities, even changes in bodily structure. These differences still affect the death rate and the span of life of each major occupation. "

― Lewis Mumford , The City in History: Its Origins, Its Transformations, and Its Prospects