Termite construction projects have no architects, engineers, or foremen, yet these centimeter-sized insects build complex, long-standing, meter-sized structures all over the world. How they do it has long puzzled scientists.

Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences and the Department of Organismic and Evolutionary Biology have developed a simple model that shows how external environmental factors, such as daytime temperature variations, cause internal flows in the mound, which move pheromone-like cues around, triggering building behavior in individual termites. Those modifications change the internal environment, triggering new behaviors and the cycle continues.

The model explains how differences in the environment lead to the distinct morphologies of termite mounds in Asia, Australia, Africa, and South America.

This new framework demonstrates how simple rules linking environmental physics and animal behavior can give rise to complex structures in nature. It sheds light on broader questions of swarm intelligence and may serve as inspiration for designing more sustainable human architecture.

The research is published in the Proceedings of the National Academy of Sciences.

“Our theoretical framework shows how living systems can create micro-environments that harness matter and flow into complex architectures using simple rules, by focusing on perhaps the best known example of animal architecture — termite mounds,” said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, professor of organismic and evolutionary biology and of physics, and senior author of the study. “As Winston Churchill once said ‘We shape our buildings and thereafter they shape us.’ We can quantify this statement by showing how complex structures arise by coupling environmental physics to simple collective behaviors on scales much larger than an organism.”