io9 editor Annalee Newitz leads a tour of two mathematical relationships scientists have used to describe the relative quantitative properties of cities: Zipf's Law and Kleiber's Law.

In describing Kleiber's Law, a relationship between body mass and metabolic rate in mammals as well as the relationships among city population sizes and dozens of quantities, she quotes mathematician Steven Strogatz: "Geoffrey West of the Santa Fe Institute and his colleagues Jim Brown and Brian Enquist have argued that a 3/4-power law is exactly what you'd expect if natural selection has evolved a transport system for conveying energy and nutrients as efficiently and rapidly as possible to all points of a three-dimensional body, using a fractal network built from a series of branching tubes — precisely the architecture seen in the circulatory system and the airways of the lung, and not too different from the roads and cables and pipes that keep a city alive."

Read the post in io9 (December 9, 2013)