On destroying Tokyo, plasmobots, and making decisions without a brain

By Ed Yong | September 8, 2010 8:53 am


To tie in with the launch of the Guardian’s new science blog network, Alok Jha – a veritable dervish of commissioning – has been asking various science bloggers and writers to contribute to a Science Blog Festival. It’s meant to be a “celebration of the best writing on the web” and Alok hopes that it will “give [readers] a glimpse of the gems out there.” It’s a great idea. The Guardian gets cool content, bloggers get more exposure to a vast audience, and readers get a miscellany of great stories.

Today, my first contribution is up and it’s a whirlwind tour through the incredible biology of Physarum, the decision-making, robot-inspiring, town-planning slime mould that manages to be surprisingly intelligent without a brain. Here’s the intro:

In 2009, scientists unleashed an amoeba-like blob on to Tokyo, and watched as it consumed everything in sight. In less than a day, the blob had spread throughout the entire city, concentrating itself along major transport routes.

Fortunately for the citizens of the great Japanese metropolis, the blob did its work on a model. Flakes of oats stood in for the major urban zones and the scientists involved were no B-movie villains. Rather, they were biologists studying the sophisticated behaviour of a slime mould, an oozing blob of goo that performs feats of apparent intelligence despite being completely brainless…

Without a brain, Physarum makes decisions by committee. The plasmodium is a single sac but it behaves like a colony. Every part rhythmically expands and contracts, pushing around the fluid inside. If one part of the plasmodium touches something attractive, like food, it pulses more quickly and widens. If another part meets something repulsive, like light, it pulses more slowly and shrinks. By adding up all of these effects, the plasmodium flows in the best possible direction without a single conscious thought. It is the ultimate in crowdsourcing.

Click across to read the whole thing. I wanted to push myself a bit for this so rather than covering a single paper (and there is a new one out today), I wanted to see if I could write a mini-feature about the entire field, in less than a weekend. I hope people enjoy the result.

And to any new readers who have come over from the Guardian: hello! Hang up your coats and have a look around.


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Comments (1)

  1. Heteromeles

    Glad to see this happening. Back when I took mycology, I jokingly proposed using Physarum for solving “traveling salesman-type” problems and other mapping issues. My professor told me it would never work. Glad you and others are having so much fun with it.


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