First Cities. Mesopotamia (ancient Iraq) was the setting for humankind's earliest complex civilization. Among the many ways by which social scientists measure civilization are the presence of political and social organizations such as government and religious hierarchies, specialization of labor, markets for the exchange of goods, achievements in the arts and sciences, and long-distance trade. These aspects of civilization are interdependent, and evidence for all of them is centered in the most significant development of complex civilization: the city. For many people to inhabit densely a small area—one mark of an urban center—there must be mechanisms that enable them to acquire the means of survival (food and water) and to live together peaceably (laws), as well as a system that maintains those mechanisms (government and bureaucracy). With some of the inhabitants producing enough basic foodstuffs for the whole population, primarily through farming and herding...