Urbanisation and the Division of Labour in the Roman Empire

One of the main hallmarks of human agglomeration is task specialization and an expanded division of labour and this relationship has been a long-standing topic of inquiry among archaeologists, anthropologists, sociologists, and economists. Recently, researchers investigating contemporary urban systems have proposed a novel explanation for this relationship grounded in a view of human settlements as fundamentally social, informational, and infrastructural networks embedded in physical space. This construal does not incorporate the particular socio-economic conditions and market economies of the modern world, and this leads to the question of whether the relationships between population size and productive diversity observed in contemporary systems also characterized pre-modern and even ancient systems. Here, we present a general model for the relationship between the population size and functional diversity of individual settlements within a settlement system in which functional (or skills) diversity is interpreted as an indicator of the division of labour. Using a novel dataset on occupational associations in ancient Roman cities, we develop an index of urban functional diversity to analyse the relationship between population size and skills diversity. Our empirical results are consistent with theoretical expectations and with patterns of professional diversity in contemporary cities. These results add further support to the view that urban systems throughout history have emerged through a common set of generative social processes.