You can’t outfox natural selection for billions of years without some rudimentary smarts. Now scientists in Europe and Japan are showing that primordial slime molds are clever enough to reveal how animal cells glom together to form intelligent creatures.
In slime molds, individual amoeba cells stitch themselves together into a coagulated mass, often a foot wide. The mass’s cytoplasm sloshes back and forth, allowing it to move forward and digest whatever lies in its path.
However, amoebae don’t lurch ahead indiscriminately. They pick efficient routes, as a Japanese-Hungarian team proved by urging one through a maze. At first the mold expanded in all directions, exploring all possible paths. After a few hours, it began to withdraw its tendrils from dead ends and roundabout routes, conserving energy and lessening its exposure to danger. Another team in Japan proved that slime molds can anticipate and steer clear of painful burns if the burns come at regular intervals. In the most impressive exercise of all, computer scientists in England taught a slime mold to pilot a crablike robot to sidle away from strong light and toward dark recesses.
This research helps show how sophisticated behaviors can emerge from collections of feeble cells—a mysterious process. Within humans, for instance, scientists know how individual neurons work but not how thoughts arise in networks of neurons. Slime molds provide a nice model for scientists to deconstruct before they move on to the harder problem of how volition and consciousness emerge in our own wet, slimy brains.
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