A few years ago, several of us banded together and proposed to write a text on urban ecosystems for a major academic publisher. For various reasons, it fell to me to draft a rough-out of the manuscript for my co-authors to build their material into. For various reasons, having largely to do with sloth, procrastination, and the need to earn an actual living, I failed to do so. For various reasons, we have revived our own and the publisher’s interest in this manuscript.
However, it turns out that in the interim, a number of nominally competing books on urban ecosystems have been published. I bought ‘em all. They are uniformly expensive, intensely academic, and generally dull. In other words, intended to serve primarily as texts for classes taught by the authors. Since we don’t have such constraints, and would far prefer to render the fascinating field of urban ecology in a form digestible by a more general audience, we’ve revised our target readership. In keeping with the zeitgeist, we thought to write it so it can be read in small bites by people who spend too much time dealing with too many bytes. In fact, we’re drafting it as brief, weblog-like chapters. Which yields a perfect motivation for finishing up this damned draft. I’ll start posting chapters weekly here until the book is complete. First installation—the Prologue—is below. We’ll go chapter-by-chapter from here.
Prologue
Years ago, one of us—Ludwig—had business in the seaside city of Aqaba on the Gulf coast of southern Jordan. It took most of a day for my colleague and me to be driven down the ancient King’s Highway from Amman. We arrived late in the afternoon and gave our drivers the evening off. After checking in to our hotel, we wandered the town, keeping to the seaside road.
We came upon what seemed to be a vacant lot tucked into a shoreline corner between the beach and a canal that ran back into the city. On closer inspection, it turned out to be an archaeological site. Under excavation was a street from an ancient town, with the foundations of small, rectangular buildings built wall to wall. Informative signs identified the town’s souk (market), and explained the architecture of the buildings. Most were combinations of commercial space—shops or storehouses—with residences. With the quiet waters of the Gulf of Aqaba meters away, and the sun setting behind some date palms, it was easy to imagine life in the trading town of Ayla around 600 AD.
Older ruins—dating to Roman times and beyond, possibly to the middle of the first millennium BC—were reputed to be nearby on the shore. Within Ayla itself, the narrow street with open building fronts didn’t seem that different from a modern souk in the crowded alleys of any Middle Eastern city. You could feel the heat of the day slipping away as the markets opened, smell the dates and lemons for sale, hear the calls of the cloth-sellers and metal workers. Ayla was one of the first conquests of the Islamic Caliphate rising from Arabia. Its part on the world stage didn’t change much, only the place taxes were sent. Ayla remained a busy trading crossroads where land and water transportation met. Small industry prospered. The population supported itself on the combination of local produce and import/export business.
It immediately occurred to us to seek the sources of fresh water and agricultural production that kept Ayla going. Alas, these hinterlands—except for the waters of the Gulf itself, which undoubtedly provided fish and shellfish--are now buried beneath infrastructure of the modern city. But it occurred to us that, at least in pre-Roman times when trade was likely a smaller proportion of the city’s life support system, it must have been a tough place to support a sizeable population.
And what was that population size? Well, it fluctuated, depending on whether Ayla was in the trading route mainstream or sidelined by alternatives. It may have fluctuated with climate, as well, which varied over the life of the town which extended from at least 1500 BC to near 1500 AD. Absolute population figures are not available. The infrastructure as I saw it could probably support no more than a few thousand individuals, including local providers of food, water, raw materials, and products. But the fact remains: this was a city on a body of salt water backed against a desert. Not the most propitious place for a city.
Consider the problems such a location entails. Fresh water is hard to come by. Pasture land is sparse. Trash doesn’t decompose in the salty soils. The air may be humid, at least spot-on the coast, but it carries the constant winds and grinding sands of the desert. And the location is exposed, from both land and sea, to invaders.
We were struck by the oddity of the location, and shocked at how much like a modern city Ayla looked. Many of our questions—why this particular place? How did they provision? What did it cost someone—in time, money, effort, risk—to live here? What benefits made the investments worthwhile?—were similar to the questions systems ecologist ask all the time.
Until that warm sunset on the Aqaba shoreline, it hadn’t occurred to us to think of cities as ecosystems. After that, we never thought of them any other way.
Notes
[1] a briefing-level history of Ayla is available at http://www.unesco.org/csi/act/jordan/preproject.htm
[2] a more detailed account built from a report of sequential archeological excavations is at http://oi.uchicago.edu/research/pubs/ar/91-92/aqaba.html
[3] a detailed discussion of population characteristics, but not size, is “Scholars and Society at Early Islamic Ayla.” Journal of the Economic and Social History of the Orient 38 (1995): 417-428. Presently available at http://upenn.academia.edu/PaulMCobb/Papers/445308/Scholars_and_Society_at_Early_Islamic_Ayla
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