In the last few years, there has been increasing interest in the potential of using ‘big data’ for a wide range of historical and archaeological issues. The advantage of this approach is that it relies on combining multiple sets of data and using them to explore much wider patterns and trends than has traditionally been possible. A recent classic is M. H. Hansen’s The Shotgun Method, which uses the catalogue that was compiled by a preceding project to offer new estimates of the size of the urban population, urbanization rate, and total population of the Greek world at or around the fourth century B.C. The unusual title is unashamedly based on method. As Hansen explains, studying ancient history or classical archaeology can be a bit like hunting hares. The smart hunter uses a shotgun instead of a rifle because it is more effective against smaller, faster creatures, given the way the pellets spread out to cover a larger area. His point, of course, is that it is sometimes necessary to use more sweeping methods than have normally been used to answer certain questions about the ancient world, especially when it comes to settlement and demography.
Over the last few years, I have been using a similar approach to provide a more comprehensive account of the urbanism of the Roman world in the imperial period (as part of my D.Phil. at the University of Oxford). I’ve used a mixture of textual and archaeological evidence to come up with a new catalogue of sites that conform to certain criteria, as well as locating and dating them to explore how they were distributed in space and changed over time. I’ve used maps and plans to estimate the sizes of as many of these sites as possible and to examine the available information for their population densities. This has allowed me not only to estimate the populations of individual cities, but also assess the urban population and urbanization rate, reconstruct the urban hierarchy, and examine the extent to which it conformed to concepts like urban primacy and the rank-size rule. In addition, I’ve also examined the monumentality of each site, explored their different civic statuses, and investigated the sizes of their hinterlands and the connections between them by sea, river, and road routes.
I’d like to suggest that this kind of work now places us in a unique position, in that it allows us to compare the urbanism of different areas and times for the first time, allowing us to get to the heart of fundamental questions about the development of urbanism. In particular, it sheds light on whether the development of urbanism has followed a single, continuous arc, or been made up of a series of intermittent bursts (known as efflorescences). This has implications for one of the more uncomfortable questions that specialists on modern urbanism have been asking over the last few years; namely whether or not the degree of urbanism that is experienced in the modern world can be sustained.
The kind of work I’ve been discussing, however, also raises another challenge for historians and archaeologists, which is how to make sense of the similarities and differences that can be found between the urbanism of individual civilizations. How should we react if we get unexpected results? What theoretical frameworks are there that allow us to conceptualise and think about problems? For example, what does it mean if there were more cities in one period than another, or if the numbers grew or contracted faster or slower at different times or spread more or less quickly through different regions? What should we do if the size of the urban population was lower or higher in ancient times than modern times? What does it mean if the size of the urban population increased more or less than the size of the rural population in some areas or at some times? And, most importantly, what is the link between urbanism and economic growth? Is urbanism normally associated with sustainable or unstainable economic growth, or aren’t they related?
I’m extremely fortunate to have recently joined a project that is working on some of these questions. As one of my colleagues has explained elsewhere, The Social Reactors Project: Human Settlements and Networks in History is made up of a number of scholars from various disciplines, including history and archaeology, but also economics and physics, who hail from various institutions (the University of Colorado at Boulder, Arizona State University, and the Santa Fe Institute). It’s important to stress, though, that my colleagues don’t just see themselves as collaborators who should remain within their own provinces, but have a real (and really infectious) drive to learn as much about each other’s fields as possible, even becoming specialists in their own right. The aim of this project is to build a more general theory of settlements, focusing on their common properties, which can then be used to understand or explain a host of communities across a wide range of areas and times. This has stemmed out of previous work, which suggests that the population of cities scales with infrastructure and various social, political, and economic measures (such as wealth, innovation and invention, as well as poverty, crime, pollution, and disease) according to a few simple rules. This has been explained by the role of cities as ‘social reactors’ that increase the number of opportunities for interactions between individuals, thus increasing the likelihood that they will generate either positive and negative outputs.
This research suggests an explanation for the development of urbanism that is not necessarily reliant on the specific characteristics of different places or periods. If this is true, it might be possible to make sense of the similarities and differences between the urbanism of individual civilisations by referring to a much more general theory of how settlements work across space and time. This means it could be an exciting time to be thinking about the implications of urbanism for the overall course of human history, but only time will tell.
 Hansen and Nielsen 2004; Hansen 2006.
 Jebwab 2015.
 Bettencourt et al. 2007; Bettencourt et al. 2010; Bettencourt 2013.
Bettencourt, L. M. A., (2013), ‘The orgins of scaling in cities’, Science, 340: 1438-1441.
Bettencourt, L. M. A., Lobo, J., Helbing, D., Kuhnert, C., and West, G. B., (2007), ‘Growth, innovation, scaling, and the pace of life in cities’, Proceedings of the National Academy of Sciences, 104: 7301-7306.
Bettencourt, L. M. A., Lobo, J., Strumsky, D., and West, G. B., (2010), ‘Urban scaling and its deviations: Revealing the structure of wealth, innovation, and crime across cities’, PLoS One, 5.11.
Hansen, M. H., (2006), The Shotgun Method: The demography of the ancient Greek city-state culture, (Columbia and London: University of Missouri Press).
Hansen, M. H., and Nielsen, T. H., (2004), An Inventory of Archaic and Classical Poleis: An investigation conducted by The Copenhagen Polis Centre for the Danish National Research Foundation, (Oxford: Oxford University Press).
Jedwab, R., and Vollrath, D., (2015), ‘Urbanization without Growth in historical perspective’, (working paper).