Strange evolution

Okay, some random ideas from reading The Death and Life of Great American Cities. Natural selection works by a constant succession of generations, where some survive and others don’t. Species co-evolve, meaning that every generation of a species by itself is more likely to survive than the species contemporary to its ancestors. But since this is true for all species in the ecosystem, the environment is in constant flux, and thus the features that had survival value in the past might not have survival value now or in the future.

Cities, on the other hand, don’t seem to be subject to natural selection. They do evolve, but differently. I’m not sure you can say that neighborhoods have generations, and that some generations survive while others die. There are other mechanisms involved in the adaptation of neighborhoods. Neighborhoods in cities are, it seems, most often planned to some extent. I recall that Steven Johnson writes about Manchester in Emergence as an example of a city that has evolved pretty much on its own, but I can’t remember exactly what he said.

In Death and Life, Jane Jacobs criticizes bad city planning theory, that has little to do with reality, and shows that good intentions actually worsen the situations that were to be remedied. One such thing is the idea that large, open spaces almost automatically would turn a bad neighborhood into a good one. Jacobs shows that what’s important is that the neighborhood provides a balanced mix of residences, offices, and restaurants and bars, such that there’s a steady flow of people during the larger part of the day. There are several other factors, of course, which she describes in full detail, but what’s relevant in this context is that guided evolution based on the wrong theory will cause totally unexpected results.

Jacobs has several examples of neighborhoods that were dismissed as slums, but that upon closer examination actually are functioning very well. I guess that these neighborhoods have essentially been left to themselves. Obviously there is much room for improvement in the slums, but it still begs the question: Where’s the balance between guided and unguided evolution?

Recently, I read Robert Topley’s article Evolutionary Development, which didn’t feel right to me; the generation metaphor doesn’t quite hold up. Software systems are more equivalent to cities in the sense that they lack distinct generations, while indeed evolving over the course of time. Evolutionary development would then have much to do with finding the balance between guiding the evolution at the macro scale, and letting it evolve more freely at the micro scale.

The above was posted to my personal weblog on March 25, 2003. My name is Peter Lindberg and I am a thirtysomething software developer and dad living in Stockholm, Sweden. Here, you’ll find posts in English and Swedish about whatever happens to interest me for the moment.

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