Urban Fabric and Human Nature
As different as the individual buildings are, this picture of a modern city is slightly reminiscent of a vernacular Mediterranean town. Here, too, buildings are similar in overall massing but different in detail. This is necessarily the way that traditional vernacular urbanism was built. There were only a few available materials and there was a local tradition of how to build, but each family built its own house, so there was individual variation within general consistency of design.
Settlements among the earliest humans who built shelters must have been similar. Our earliest human ancestors were nomadic, and family groups hunted and gathered individually, so they had a large area of land to support themselves. But the entire tribe came together periodically so children could marry outside of their families, because a minimum of 3000 people is needed to create enough genetic diversity to avoid inbreeding and genetic disease. The sort of temporary settlements that people built when tribes came together must have had this combination of individual variation with general consistency, because each family built its own shelter but all used the same materials and the same tradition of how to build, like the people who built the traditional Mediterranean town.
Evolutionary psychology provides an obvious reason for why people find urban fabric attractive: During the period of evolutionary adaptation, if people were attracted to the temporary settlements that had the genetic diversity to allow mating, they had a better chance of finding mates and producing healthy children. Thus, evolution hard-wired us genetically to like settlements whose buildings have individual variation within general consistency.
This sort of urban fabric remained common during most of human history, in traditional cities and villages and into the twentieth century. One of my favorite examples is the upper west side of Manhattan, which has three types of fabric buildings: On Riverside Drive and West End Ave., there are 12 to 14-story apartment buildings; on Broadway, there are 12 to 14 story apartment buildings with shopping on the first floor; and on the cross streets, there are 5-story row houses. In each case, the fabric buildings have similar heights, footprints, and orientation to the adjoining sidewalk, but they are different in detailing, and the buildings were obviously designed and build individually. The apartment buildings date from the first decade of the twentieth century, and the row houses are left over from the nineteenth century.
During the twentieth century, though, we lost this timeless way of building (as Christopher Alexander calls it), for two reasons. First, larger scale development let us create mass-produced settlements in the style of Levittown, where each building is identical with surrounding buildings, with no individuality at all. Second, new technologies let us create modernist buildings that broke completely with the surrounding context, with no consistency at all.
The New Urbanists have shown that it is possible to avoid both these errors by using form-based codes, which create an urban fabric with the same combination of individuality and general consistency that we find in traditional cities and towns.
The most famous examples are walkable suburbs such as Andres Duany's Seaside, only because there have been more opportunities to develop new suburbs than to develop other types of neighborhoods. But Duany's Transect makes it clear that the same principles apply to neighborhoods at all densities, from small rural towns to dense cities.
Consistent but varied urban fabric is not the only thing needed to create attractive cities. The typical strip mall is an obvious example: the McDonalds, Burger King, and KFC all have buildings that differ in detail but have similar size, are located similarly on their lots, and are surrounded by similar parking lots, and the strip is ugly despite this varied, consistent fabric.
Though it is not sufficient in itself, urban fabric is one necessary element of attractive cities. If you think about your favorite urban places, you will probably find that virtually all of them have a this varied but consistent fabric, sometimes with major public buildings that stand out from the fabric buildings.
Some people will disagree, because they have been indoctrinated in modernist architecture and urbanism. But ordinary people show their preference when they flock to Europe as tourists so they can sit in sidewalk cafes and enjoy the traditional urban fabric.
I develop this idea further in my essay, "Architecture and Evolutionary Psychology," which was published on the INTBAU Web site and also here.