Urban Planet Weird Wednesday: Slime mold maps out Tokyo’s rail system


Weird Wednesdays on Urban Planet takes a look at obscure, absurd, and curious things about cities around the world.

In one of the weirdest Weird Wednesdays yet, we look at Japan where researchers have been finding out that some very simple organisms are capable of some very complicated urban planning.

Over the past decade, Japanese scientists sutdying slime mold, Physarum polycephalum, have been discovering that the organism is extremely adept at creating efficiencies within itself. In order to reach new sources of nutrients, the mold expands in a series “tendrils” which explore its surrounding areas. Once they reach more food, these tendrils start to ferry the nutrients throughout the rest of the organism, reinforcing and growing stronger, while the ones that aren’t successful disappear. In 2000, the researchers discovered that, when placed in a maze, the mold will eventually reach the food piece at the end through the shortest route possible.

A decade later, these researchers put the mold to the ultimate city building test. They dispersed oat flakes in the same pattern as Japanese cities and unleashed the mold on the flake representing Tokyo. Over 26 hours, as the multiple plates of mold expanded and began to streamline its network of tubes, many of the results were very closely mirroring the Tokyo rail system.

Similar tests have subsequently been done for the UK and the Iberian Penninsula with similar results.

While it’s an interesting notion, unless the mold learns to also navigate issues like funding and politics, cities won’t likely be replacing their planning departments just yet. However, these tests could help scientists design networks that can adapt an reroute itself efficiently when certain points are removed, or even shed light on similar network-building systems like tumors.

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