Monday, May 21, 2012

The Wisdom of Slime

From an op-ed in the New York Times, recently entitled "The Wisdom of Slime." 

An interesting fact about this slime mold is that it is highly intelligent — or at least it behaves as if it is. In locating food in its environment, it builds networks that have been shown to be optimally efficient in transporting the nutrients over the area in question. If placed in a maze, for instance, with a source of food outside the maze, the slime mold will discover the shortest path out. 

The Japanese researcher Toshiyuki Nakagaki and his colleagues have demonstrated that the slime mold’s foraging behavior can be used to perform sophisticated computations, as long as the problems are represented spatially. Problems solved by the slime mold include not only the shortest path out of a maze, but also other complex mathematical challenges (like creating a Voronoi diagram and a Delaunay triangulation). 

Despite its ability to solve an array of problems, the slime mold was designed by evolution to solve just one problem: how to build an optimal transport network (for its nutrients). So we decided to investigate how the slime mold, when presented with the task of connecting the major urban areas of the United States, would design a transport system. Would its design resemble that of the United States highway system, or would the slime mold propose a superior one? 

Here’s how our experiment worked. As we detail in a forthcoming article in the journal Complex Systems, we took a large dish in the shape of the United States and placed rolled oats (a food for the slime mold) in the locations of 20 major urban areas. Then we put the slime mold on the rolled oats representing the New York area. The slime mold propagated out from New York toward the other urban areas and eventually spanned them all with its network of protoplasmic tubes. We performed this experiment a number of times.

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