Complex adaptive urban systems change by evolution: a first phylogeny of city form types in the UK

What is it about?

The physical form of cities is perceived as mainly static, but it actually change continuously in time and space. Cities, in this respect, complex adaptive systems of a spatial nature. This paper provides a first investigation of urban form evolution in cases taken from 45 UK cities. For this task, we propose an innovative approach that uses concepts and methods derived from biological evolution and systems ecology, which we name "Urban Morphometrics". We find that urban forms originated in different historical periods share identifiable typical characters, that a very limited number (three) of urban form features explain most of such characters, and that with all their diversity, all pre WWII urban form types belong to the same "species" while all those originated after WWII belong to another. That means that WWII can be assumed to have witnessed the first "bifurcation" in urban form evolution.

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Why is it important?

Cities have always been misrepresented and as a consequence misunderstood up to a few years ago. By re-conducing physical cities in their appropriate phenomenological class, that of complex adaptive systems generated by the continuous evolution of human culture, we set the stage for an entirely new approach to urban planning, and open the way to focusing the analysis on cities as they are, rather than as they ought to be. The proposed Urban Morphometrics method opens the way for the rigorous and systematic characterisation of urban form, and the accurate identification of the physical structure that drives the character of cities (the "DNA" of places).

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