Robert Leonard Carneiro (June 4, 1927 - June 24, 2020) was an American anthropologist and curator of the American Museum of Natural History. His Circumscription Theory explains how early political states may have formed as a result of interactions between environmental constraints, population pressures, and warfare.
Carneiro took his first course in anthropology as an undergraduate at the University of Michigan, while studying Political Science with the goal of becoming a lawyer. As a graduation gift, his father (who hoped his son would run the family business someday) arranged for a trip around the globe on an ocean liner. After the trip, Carneiro began work at his father's company, manufacturing presses used to print magazines and newspapers.
Travelling the world, however, had fueled his interest in anthropology; so, Carneiro returned to the University of Michigan. His graduate research took him to Brazil where fieldwork with an indigenous people, the Kuikuro, revealed large earthworks and ancient trenches. Based on those observations, he earned a Ph.D. in 1957, and went on to teach at several universities.
Carneiro was an influential cultural evolutionist. He worked toward a general theory, to explain the emergence of political culture, strongly opposed to humanistic and non-scientific tendencies in anthropology. His work remains influential, but also has its critics.