Recent research provides a better understanding of urban populations throughout history, digitising almost 6,000 years of data for the first time (Published in the Guardian, 27 June, 2016)
Urbanisation is one of the defining processes of modern times, with more than half of the world’s population now living in cities, and new mega-metropolises mushrooming in Asia, Latin America and Africa. But a comprehensive, digitised database of city populations through world history has been lacking, with the United Nations’ dataset only extending as far back as 1950.
That was until recent research, published in the journal Scientific Data, transcribed and geocoded nearly 6,000 years of data (from 3700BC to AD2000). The report produced a gargantuan resource for scholars hoping to better understand how and why cities rise and fall – and allowed blogger Max Galka to produce a striking visualisation on his site Metrocosm.
“In general, it helps us see human interaction with the environment,” says lead author Meredith Reba of the Yale School of Forestry and Environmental Sciences. “It helps us to understand why settlements grew at the times they did.”
Mining tabular data from two tomes only available in print (the works of historian Tertius Chandler and political scientist George Modelski), Reba and her team mapped how city populations developed around the world over the millennia. The resulting dataset – available for free online – bills itself as “a first step towards understanding the geographic distribution of urban populations throughout history and around the world”.
The Sumerian city of Eridu marks the dawn of urbanisation in 3700BC, which trickles around Mesopotamia, Iran, India and China before eventually coming west to the Mediterranean. Mapping the data makes certain trends and patterns quite clear. For instance, it’s notable that the earliest cities from China to Mesoamerica can all be found in a similar latitudinal belt, suggesting a possible link between early phases of urbanisation and climate.
Many more urban centres sprang up around the world thereafter but, as late as 1800, only 3% of the world’s population lived in cities. Global urbanisation accelerated from the middle of the 19th century onwards. This precipitous rise is palpable in Galka’s visualisation of the data (and in this one by Quartz), with a burst of cities clotting the map around 1875 and then again during the 20th century.
The last entries in the database date to 2000AD; if updated to the present day, the database would include the stratospheric 21st-century growth in urban populations in Asia. Reba admits that the data “is not final in any sense. Our aim was to pull together a richer, global urban population database, and to get this data into a usable format so it can be tested and improved.”
Though the report offers no theories of its own, Reba and her team hope that the results of their work will help researchers better explore a range of subjects that have long troubled scholars of urbanisation. Reba’s initial motivation for the study was her frustration at the lack of data relating to her own field of interest – the relationship between the growth of cities and their proximity to agricultural land. But combined with other data and lines of inquiry, the database can be used to trace deeper ecological and climatic trends, as well as to study the effect of transport, trade routes, and shifting political boundaries on urban growth.
Reba didn’t try to reconcile the multiple definitions of a city in Chandler and Modelski’s works, which vary significantly by region and period. Chandler, for instance, generally considered any locality of greater than 20,000 people between AD800-1850 to be worthy of recording, but only counted places in Asia with a population of over 40,000 in that same period. Modelski’s minimum thresholds changed over time: at least 10,000 inhabitants until 1000BC, 100,000 until AD1000, and one million people thereafter. They amassed their figures for urban populations from a plethora of sources, including censuses, traveller’s accounts, tax rolls, gazetteers, disaster records, public bath rolls and archaeological records.
Though there is thorough data for a handful of Chinese localities, the new database is much more comprehensive in how it charts European urban development than the waxing and waning of cities in South Asia, Africa, and pre-Columbian America. “There’s definitely a Eurocentric view,” Reba says, but she hopes new archeological and archival discoveries will help expand the database, and begin to fill in the more glaring geographic and temporal gaps.