Urban characteristics attributable to density-driven tie formation

TL;DR

This paper presents a generative model linking city density to social tie formation, accurately predicting various urban metrics and their super-linear scaling with city size.

Contribution

It introduces a novel analytical and simulation-based model that explains urban social structures and their scaling laws without relying on modularity or hierarchy.

Findings

Predicts super-linear scaling of social ties and information flow with city population.

Accurately fits data on communication, disease, innovation, and crime across cities.

Provides a unified framework for understanding urban social dynamics.

Abstract

Motivated by empirical evidence on the interplay between geography, population density and societal interaction, we propose a generative process for the evolution of social structure in cities. Our analytical and simulation results predict both super-linear scaling of social tie density and information flow as a function of the population. We demonstrate that our model provides a robust and accurate fit for the dependency of city characteristics with city size, ranging from individual-level dyadic interactions (number of acquaintances, volume of communication) to population-level variables (contagious disease rates, patenting activity, economic productivity and crime) without the need to appeal to modularity, specialization, or hierarchy.