Pillars of Theoretical Biology: Airway stability and heterogeneity in the constricted lung

•I briefly summarize the contributions of Anafi & Wilson’s model of the terminal airway unit.•Anafi & Wilson introduced an instability at the level of a single airway.•This gave rise to interest in dynamic self-organization and pattern formation at whole-lung scale.•I discuss developments following on from Anafi & Wilson, and scope for future development.