July 6, 2009
Three Thoughts On Early Cities
Cities may be engines of innovation, but not everyone thinks they are beautiful, particularly the megalopolises of today, with their sprawling rapacious appetites. They seem like machines eating the wilderness, and many wonder if they are eating us as well. Is the recent large-scale relocation to cities a choice or a necessity? Are people pulled by the lure of opportunities, or are they pushed against their will by desperation? Why would anyone willingly choose to leave the balm of a village and squat in a smelly, leaky hut in a city slum unless they were forced to?
Image via Wikipedia
Well, every city begins as a slum. First it’s a seasonal camp, with the usual free-wheeling make-shift expediency. Creature comforts are scarce, squalor the norm. Hunters, scouts, traders, pioneers find a good place to stay for the night, or two, and then if their camp is a desirable spot it grows into an untidy village, or uncomfortable fort, or dismal official outpost, with permanent buildings surrounded by temporary huts. If the location of the village favors growth, concentric rings of squatters aggregate around the core until the village swells to a town. When a town prospers it acquires a center — civic or religious — and the edges of the city continue to expand in unplanned, ungovernable messiness. It doesn’t matter in what century or in which country, the teaming guts of a city will shock and disturb the established residents. The eternal disdain for newcomers is as old as the first city. Romans complained of the tenements, shacks and huts at the edges of their town that “were putrid, sodden and sagging.” Every so often Roman soldiers would raze a settlement of squatters, only to find it rebuilt or moved within weeks.
The origins of modern human behavior are marked by increased symbolic and technological complexity in the archaeological record. In western Eurasia this transition, the Upper Paleolithic, occurred about 45,000 years ago, but many of its features appear transiently in southern Africa about 45,000 years earlier. We show that demography is a major determinant in the maintenance of cultural complexity and that variation in regional subpopulation density and/or migratory activity results in spatial structuring of cultural skill accumulation. Genetic estimates of regional population size over time show that densities in early Upper Paleolithic Europe were similar to those in sub-Saharan Africa when modern behavior first appeared. Demographic factors can thus explain geographic variation in the timing of the first appearance of modern behavior without invoking increased cognitive capacity.
While it’s very nice to have some statistical evidence for this idea (even if I can’t pretend to understand the “Bayesian coalescent inference” method used by the scientists to calculate the population densities in the late Pleistocene), it’s worth pointing out that the density explanation isn’t particularly new. In The Economy of Cities, Jane Jacobs forcefully argued against the “dogma of agricultural primacy,” which assumed that farmers and agricultural innovations made civilization possible. Jacobs argued that the dogma was exactly backwards, and that it was the density of urbanesque clusters which generated the innovations that made farming possible. As Jacobs writes: “It was not agriculture then, for all its importance, that was the salient invention…Rather it was the fact of sustained, interdependent, creative city economies that made possible many new kinds of work.” After all, you can’t learn how to grow food until you’ve got a system for transmitting knowledge, which is why population density is so essential.