Termites shape and are shaped by their mounds

February 11, 2019, Harvard John A. Paulson School of Engineering and Applied Sciences

Termite construction projects have no architects, engineers or foremen, and 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, drive internal airflows in the mound. As air moves through the mound, pheromones carried in these flows trigger building behavior in individual termites, who respond by modifying the mound architecture. Those modifications, in turn, alter the internal flows in a continuous feedback cycle.

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 framework breaks down the artificial barrier between living and non-living systems 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, 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."

While they might look like apartment complexes, termite mounds actually function as a ventilation system for the colony that lives deep underground. In previous research, Mahadevan and his team found that changes in external temperatures throughout the day drive changes in airflow, temperature and humidity inside the termite mound.

Read more at: