Self-organized biotectonics of termite nests

Significance Termite nests are a remarkable example of functional self-organization that show how structure and function emerge on multiple length and time scales in ecophysiology. To understand the process by which this arises, we document the labyrinthine architecture within the subterranean nests of the African termite Apicotermes lamani and develop a simple mathematical model that relies on the physical and biological interactions between termites, pheromones, and mud in the nest. Our model explains the formation of parallel floors connected by linear and helical ramps, consistent with observations of real nests. In describing this multiagent system, we elucidate principles of physical and behavioral coupling with relevance to swarm intelligence and architectural design. The termite nest is one of the architectural wonders of the living world, built by the collective action of workers in a colony. Each nest has several characteristic structural motifs that allow for efficient ventilation, cooling, and traversal. We use tomography to quantify the nest architecture of the African termite Apicotermes lamani, consisting of regularly spaced floors connected by scattered linear and helicoidal ramps. To understand how these elaborate structures are built and arranged, we formulate a minimal model for the spatiotemporal evolution of three hydrodynamic fields—mud, termites, and pheromones—linking environmental physics to collective building behavior using simple local rules based on experimental observations. We find that floors and ramps emerge as solutions of the governing equations, with statistics consistent with observations of A. lamani nests. Our study demonstrates how a local self-reinforcing biotectonic scheme is capable of generating an architecture that is simultaneously adaptable and functional, and likely to be relevant for a range of other animal-built structures.