“People are becoming more interested in Physarum because it doesn’t have a brain but it can still perform a lot of the behaviors that we associate with thinking, like solving mazes, learning new things, and predicting events,” said first author Nirosha Murugan, a former member of the Allen Discovery Center who is now an Assistant Professor at Algoma University in Ontario, Canada. “Figuring out how proto-intelligent life manages to do this type of computation gives us more insight into the underpinnings of animal cognition and behavior, including our own.”
‘Studies in brainless slime molds reveal that they use physical cues to decide where to grow, thereby thinking without an actual brain.
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Slimy action at a distance
Slime molds are amoeba-like organisms that can grow to be up to several feet long, and help break down decomposing matter in the environment like rotting logs, mulch, and dead leaves.
The researchers experimented with several variables to see how they impacted Physarum’s growth decisions, and noticed something unusual: when they stacked the same three discs on top of each other, the organism seemed to lose its ability to distinguish between the three discs and the single disc. It grew toward both sides of the dish at roughly equal rates, despite the fact that the three stacked discs still had greater mass. Clearly, Physarum was using another factor beyond mass to decide where to grow.
The team’s research demonstrated that this brainless creature was not simply growing toward the heaviest thing it could sense – it was making a calculated decision about where to grow based on the relative patterns of strain it detected in its environment.
“Our discovery of this slime mold’s use of biomechanics to probe and react to its surrounding environment underscores how early this ability evolved in living organisms, and how closely related intelligence, behavior, and morphogenesis are. In this organism, which grows out to interact with the world, its shape change is its behavior. Other research has shown that similar strategies are used by cells in more complex animals, including neurons, stem cells, and cancer cells. This work in Physarum offers a new model in which to explore the ways in which evolution uses physics to implement primitive cognition that drives form and function,” says corresponding author Mike Levin, Ph.D., a Wyss Associate Faculty member who is also the Vannevar Bush Chair and serves and Director of the Allen Discovery Center at Tufts University.
Source: Medindia
