  Prevailing hypotheses recognize cities as 'super-organisms' which both
provides organizing principles for cities and fills the scalar gap in the
hierarchical living system between ecosystems and the entire planet. However,
most analogies between the traits of organisms and cities are inappropriate
making the super-organism model impractical as a means to acquire new
knowledge. Using a cluster analysis of 15 traits of cities and other living
systems, we found that modern cities are more similar to eukaryotic cells than
to multicellular organisms. Enclosed industrial systems, such as factories and
greenhouses, dominate modern cities and are analogous to organelles as hotspots
that provide high-flux goods and services. Therefore, we propose a 'super-cell
city model' as more appropriate than the super-organism model. In addition to
the theoretical significance, our model also recognizes enclosed industrial
systems as functional components that improve the vitality and sustainability
of cities.
