Tanvi Misra is a staff writer for CityLab covering immigrant communities, housing, economic inequality, and culture. She also authors Navigator, a weekly newsletter for urban explorers (subscribe here). Her work also appears in The Atlantic, NPR, and BBC.
A new study by researchers at Yale University maps urban centers from 3700 B.C. to 2000 A.D.
How did cities emerge? Where were they located? How did they change over the course of human civilization? How did they change their surroundings?
The answers to these questions are available, but hard to access. The United Nations World Urbanization Prospects, for example, only tracks urban populations and their locations from 1950 on, and so offers only a small, relatively recent snapshot of urbanization. The work of the historian Tertius Chandler and the political scientist George Modelski is much more extensive. The two painstakingly gathered population and archeological records from as far back as 2250 B.C. The problem, however, is that their data exist in the form of tables that are stuffed with hard-to-decipher numbers and notes.
A new paper published in Scientific Data takes a stab at mapping the information Chandler and Modelski gathered. Yale University researcher Meredith Reba and her colleagues digitized, transcribed, and geocoded over 6,000 years of urban data. She and her colleagues write in their paper about the significance of their effort:
Whether it is for timely response to catastrophes, the delivery of disaster relief, assessing human impacts on the environment, or estimating populations vulnerable to hazards, it is essential to know where people and cities are geographically distributed. Additionally, the ability to geolocate the size and location of human populations over time helps us understand the evolving characteristics of the human species, especially human interactions with the environment.
Their map, pictured below, plots the first recorded populations for all urban settlements between 3700 B.C. and 2000 A.D. The earliest records available are in the warmest colors, and are clustered around Ancient Mesopotamia. The latest ones on record are in blue. (To be clear, the map shows when the populations of cities started being documented, not when and where these cities were actually “born.”):
One application of making this dataset more usable is that it helps illustrate how urbanization spreads. The researchers found, for example, that the centers of urbanization shifted westward from Mesopotamia. Reba, a research associate at the Yale School of Forestry & Environmental Studies, told ResearchGate:
In grade school we are taught that Mesopotamia is the cradle of civilization, and this study shows that the center of urban development shifted geographically over time. It also suggests that the geographic center of “urban civilization” doesn’t remain constant. We need to keep this in mind as we enter a century where we will experience large-scale urbanization: the urban center of power will continue to shift.
The dataset this paper is based on is not comprehensive by any means. But it’s a “first step,” the researchers write, toward really understanding how cities were born, multiplied, grew—and how they took over the world.