Superlinear scaling in cities, which appears in sociological quantities such as economic productivity and creative output relative to urban population size, has been observed, but not been given a satisfactory theoretical explanation. Here we provide a network model for the superlinear relationship between population size and innovation found in cities, with a reasonable range for the exponent
Arbesman, Kleinberg, and Strogatz – Superlinear scaling for innovation in cities
From 2009, work related to what Geoffrey West discusses in his book Scale.
no straight lines 