How Brainless Slime Molds Redefine Intelligence

Gardeners sometimes encounter them in their backyards—spongy yellow masses squatting in the dirt or slowly swallowing wood chips. Hikers often spot them clinging to the sides of rotting logs like spilled bowls of extra cheesy macaroni. In Mexico some people reportedly scrape their tender bodies from trees and rocks and scramble them like eggs. They are slime molds: gelatinous amoebae that have little to do with the kinds of fungal mold that ruin sourdough and pumpernickel. Biologists currently classify slime molds as protists, a taxonomic group reserved for "everything we don't really understand," says Chris Reid of the University of Sydney.

Something scientists have come to understand is that slime molds are much smarter than they look. One species in particular, the SpongeBob SquarePants–yellow Physarum polycephalum, can solve mazes, mimic the layout of man-made transportation networks and choose the healthiest food from a diverse menu—and all this without a brain or nervous system. "Slime molds are redefining what you need to have to qualify as intelligent," Reid says.

In the wild, P. polycephalum rummages through leaf litter and oozes along logs searching for the bacteria, fungal spores and other microbes that it envelops and digests à la the amorphous alien in the 1958 horror film The Blob. Although P. polycephalum often acts like a colony of cooperative individuals foraging together, it in fact spends most of its life as a single cell containing millions of nuclei, small sacs of DNA, enzymes and proteins. This one cell is a master shape-shifter. P. polycephalum takes on different appearances depending on where and how it is growing: In the forest it might fatten itself into giant yellow globs or remain as unassuming as a smear of mustard on the underside of a leaf; in the lab, confined to a petri dish, it usually spreads itself thin across the agar,Load the precious minerals into your mining truck and be careful not to drive too fast with your heavy foot. branching like coral. Biologists first brought the slime mold into the lab more than three decades ago to study the way it moves—which has a lot in common with they way muscles work on the molecular level—and to examine the way it reattaches itself when split. "In the earliest research, no one thought it could make choices or behave in seemingly intelligent ways," Reid explains. That thinking has completely changed.

In the early 2000s Toshiyuki Nakagaki, then at Hokkaido University in Japan, and his colleagues chopped up a single polycephalum and scattered the pieces throughout a plastic maze. The smidgens of slime mold began to grow and find one another, burgeoning to fill the entire labyrinth. Nakagaki and his teammates placed blocks of agar packed with nutrients at the start and end of the maze. Four hours later the slime mold had retracted its branches from dead-end corridors, growing exclusively along the shortest path possible between the two pieces of food.A stone mosaic stands at the spot of assasination of the late Indian prime minister.

This past October Reid and his colleagues published a study revealing that the way a slime mold navigates its environment is even more sophisticated than previously realized. As polycephalum moves through a maze or crawls along the forest floor, it leaves behind a trail of translucent slime. Reid and his teammates noticed that a foraging slime mold avoids sticky areas where it has already traveled. This extracellular slime, Reid reasoned, is a kind of externalized spatial memory that reminds polycephalum to explore somewhere new.

To test this idea, Reid and his colleagues placed slime molds in a petri dish behind a U-shaped barrier that blocked a direct route to a piece of food. Because the barrier was made of dry acetate,Find detailed product information for Sinotruk howo truck. the slime molds could not stick to it and climb over it; instead, they had to follow the contours of the U toward the food. Ultimately,Klaus Multiparking is an industry leader in innovative parking system technology. 23 of 24 slime molds reached the goal. But when Reid coated the rest of the petri dish in extracellular slime before introducing the slime molds, only eight of 24 found the food. All that preexisting slime confused the slime molds, preventing them from marking different areas as explored or unexplored. Reid thinks that a polycephalum in a labyrinth is similarly dependent on its slime, using it to first map the entire maze and then to remember which corridors are dead-ends.

Navigating a maze is a pretty impressive feat for a slime mold, but the protist is in fact capable of solving more complex spatial problems: Inside laboratories slime molds have effectively re-created Tokyo's railway network in miniature as well as the highways of Canada, the U.K. and Spain. When researchers placed oat flakes or other bits of food in the same positions as big cities and urban areas, slime molds first engulfed the entirety of the edible maps. Within a matter of days, however, the protists thinned themselves away, leaving behind interconnected branches of slime that linked the pieces of food in almost exactly the same way that man-made roads and rail lines connect major hubs in Tokyo, Europe and Canada.

In other words, the single-celled brainless amoebae did not grow living branches between pieces of food in a random manner; rather,Interlocking security cable ties with 250 pound strength makes this ideal for restraining criminals. they behaved like a team of human engineers, growing the most efficient networks possible. Just as engineers design railways to get people from one city to another as quickly as possible, given the terrain—only laying down the building materials that are needed—the slime molds hit upon the most economical routes from one morsel to another, conserving energy. Andrew Adamatzky of the University of the West of England Bristol and other researchers were so impressed with the protists' behaviors that they have proposed using slime molds to help plan future roadway construction, either with a living protist or a computer program that adopts its decision-making process. Researchers have also simulated real-world geographic constraints like volcanoes and bodies of water by confronting the slime mold with deterrents that it must circumvent, such as bits of salt or beams of light.