Searching for the DNA of urbanisation. A material perspective.

Broadly accepted categorical differentiations of urbanisation understand cities as well-defined objects containing urban spaces in contrast to their hinterlands. However, urbanisation's multidimensional complexity challenges these approaches in the context of increasing social issues marked by rapid urban expansion, uneven development, ways of life, inequality, commodification, etc., that require fresh scientific answers grounded in innovative empirical evidence. Here, we analysed the population-based and the land-use/land cover-based categorical understandings of urbanisation, looking at their origins and main shortcomings. Our analysis makes a generalised description of urbanisation's spatial complexity, with an emphasis on the problematic spatial delimitation of urban boundaries; urbanisation occurring in remote wild areas; and the missing third spatial dimension. We discuss these shortcomings based on recent scientific developments, providing reasons why the categorical approach needs to be changed and how. We propose a continuous indicator of urbanisation which is based on the accumulation of anthropogenic materials, a physical, rather than a spatial or demographic characteristic. Our proposal allows the analysis of socio-ecological systems' spatial organisation, pursuing comparative studies across geographies and times, informing globally generalisable patterns of urbanisation processes and giving a material body to address claims for sustainable urban development. • Demographic and land use-based urbanisation approaches separate space into urban and rural producing several shortcomings; • Urbanisation produces material structures, purposive objects like buildings and infrastructures that we call technomass; • Technomass describes the continuous spatial structure of urbanisation based on a physical property; • Technomass is measured by weight and/or volume per unit of space and time (Ton/km2, m3/hectare/year); • This operational conceptualisation places the process of material accumulation as the urbanisation's DNA. [ABSTRACT FROM AUTHOR]