Systems Complexification from Cells to Urban Infrastructure

Abstract: Our intuition tells us that cities are wasteful and less efficient than nature—but is that true? By mapping mass distributions across 3,000+ cities and 34,000+ urban neighborhoods, we uncover some intriguing stats and regularities. I will show how economies of scale in built structure act as glue, enabling the emergence of ever more complex nested urban systems. Moving beyond mass alone, we extract energy consumption data from hundreds of cities in the US and China and discover that as urban systems grow, an increasing fraction of their mass shifts to long-lived infrastructure—roads, buildings, pipes—that persists across generations of human activity. This shift toward "inert" mass correlates with sublinear energy scaling, an urban analog of Kleiber's law in biology. I propose that this scaffold fraction is not merely correlated but causal: metabolically inert structures provide the integration required for higher-level organization. The same principle may extend to plants and animals. If time permits, I will sketch a computational approach—evolutionary algorithms and agent-based models—exploring how hierarchical scaffold structures might emerge from simple dynamics.