Mold May Help Design Future Transportation Routes

tokyo mold railway photo
The tendril network of a slime mold is a near match to Japan's railway sytem. Photo via Science/AAAS

In 2000, Toshiyuki Nakagaki won an Ig Nobel Prize for demonstrating the 'problem solving' ability of mold. His experiment tested a slime mold, Physarum polycephalum, usually found inside decaying logs, to see how effectively it could run a maze. It all revolves around the way the mold finds food, sending out thin tendrils in all directions like a web. When food is found, the tendril with the most efficient path to the source expands while all the others slowly disappear. Well, the mold was successful in 'running' the maze, from one food source to the next--but researchers now believe the special skill of the mold could be used to make roadway designs more efficient as well.But running a maze with one possible solution is different than the complex network of roadways required for large transportation system.

Mold Built Tokyo's Railway
In order to see just how plausible the idea of a mold-designed roadway would be, researchers though to first compare it with a preexisting example: Tokyo's train network. On a map of Japan, bits of food (in this case, oat flakes) were placed in a pattern mimicking where major cities would be. Researchers then impregnated the P. Polycephalum at the point representing Tokyo, and waited 23 hours as the mold built its tendrils to each city.

The result? A striking similarity to Tokyo's railway system.

Will Mold be on the Job?
Researchers are eager to come up with a computer simulation that models the mold's unique ability. Designing traffic routes connecting urban centers can pose quite a challenge for engineers who must weigh cost with efficiency when deciding on whether to connect cities directly or by networks of smaller paths.

The report, which will appear soon in the journal Science, it yet another fascinating example of how mankind can learn from even nature's humblest organisms. After all, the mold has been at this much longer than we have.

UPDATE: The original story incorrectly identified Toshiyuki Nakagaki as a recipient of a Nobel Prize. Instead, Mr. Nakagaki was awarded an Ig Nobel Prize for his work studying the behavior of mold. Ig Nobel Prizes are an American parody of the Nobel Prize, meant to award scientific achievements that are primarily amusing.

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