We’re living in an age of rapid urbanization. Increasingly, our planet is being covered in massive metropolises, so densely packed and brightly lit, they can be seen from space. Since 1960, the number of people living in cities has increased from 34 to 54 percent, with more people moving from rural peripheries to urban centers each day. But how did this process of urbanization start? When were the first cities built? Who built them and how did they spread?

These are the questions data enthusiast Max Galka sought to answer in the short video above (shared by Gizmodo). Using data from a recent study published in the journal Scientific Data, Galka has traced the evolution of the world’s major cities over the course of 6000 years, starting with the beginning of Sumerian civilization.

The study, written by Yale University researcher Meredith Reba and several colleagues, digitized two earlier historical texts—Four Thousand Years of Urban Growth: An Historical Census (1987) by historian Tertius Chandler and World Cities: -3,000 to 2,000 (2003) by political scientist George Modelski—in order to make their dense data sets more accessible. Both Chandler and Modelski used an array of historical sources to identify or estimate the populations of historical cities around the world. Chandler, for instance, calculated urban populations using everything from how many public bathhouses a city had to the amount of bread its merchants sold. Reba and her team, in turn, united Chandler's and Modelski’s data in order to provide a more comprehensive picture of the history of urbanization over thousands of years.

The goal, according to the study, was to provide information to researchers and history enthusiasts about how cities and cultures around the world have changed and evolved.

“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,” the study explains. “The dataset provides the first spatially explicit archive of the location and size of urban populations over the last 6000 years and can contribute to an improved understanding of contemporary and historical urbanization trends.”

Galka took that data set and turned it into the video above, which shows when cities around the world came to be, and reveals how urbanization spread to encompass the globe.

[h/t Gizmodo]

Banner Image Credit: Max, YouTube

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