In 1959, my final year as an undergraduate at the University of Toronto, I produced a paper entitled ‘A Definition of Urbanism’ for a course in which Ronald Cohen, then a young assistant professor, sought to introduce his students to the most recent trends in ecological and neoevolutionary analysis. I compared the ecological, demographic, economic, social, political, and cultural characteristics of five urban centres: Tenochtitlan, Akhetaton, Rome, and an ancient Mesopotamian and a medieval Western European city. I concluded that the eclectic range of features exhibited by these urban centres did not support Gideon Sjoberg's (1955, 1960) general construct of the ‘preindustrial city’ and that the early development of cities must have been multilinear rather than unilinear. My recent rediscovery of this early work in a dusty filing cabinet reminded me of how long I have been interested in comparative studies of early civilizations.

In the autumn of 1959, as a graduate student at Yale University, I had the opportunity to study the theory and methods of cross-cultural comparison under the expert guidance of George Peter Murdock and Clellan Ford. In 1963–64, I learned still more about this subject from Raoul Naroll, a senior colleague at Northwestern University. To these anthropologists, none still living, the present work owes a great debt.

After that time, my interest in comparative studies was in abeyance while I worked on settlement archaeology, historical archaeology, and the history of archaeology.