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Slime molds

At Nautilus: Slime molds show intelligence without a brain

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In a recent mailing, Nautilus‘s managing editor Liz Greene introduces an article by environment journalist Sarah Gilman:

What living creature can be shaped like a disco ball, scrambled eggs, or even a pretzel? Behold the humble slime mold. Despite their somewhat unappealing name, slime molds are pretty darn cool. They assume incredible shapes to spread their spores into the world, and a single one can cover an area more than 108 square feet. But that’s not all. These blobbish wee creatures aren’t just going with the slime flows. There’s evidence that they can solve problems and make choices, even though they don’t have so much as a single neuron—or even a central nervous system. How do they do it? We don’t really know yet. But that’s part of what makes these creatures so intriguing. They add one more slimy layer to the puzzle of what consciousness is, and how other animalsplants, even electrons, might experience the world.

In her article, Gilman notes,

At minimum, unconventional life forms like slime molds should warn us against false certainties that we have, for example, “found the secret” of animal intelligence or that we “know how it evolved.”

In her article, Gilman notes,

These remarkable creatures do more than rack up nicknames. They also challenge the conventional scientific wisdom that an organism must have a central nervous system to learn and to show intelligent behaviors. One well-studied species, the yellow Physarum polycephalum, can find the most efficient path to food through a maze. Various researchers have also placed little piles of food on flat maps of Tokyo, Canada, the U.K., and Spain and shown how Physarum navigate between hubs in ways that mirror those regions’ modern transportation networks or follow routes of comparable efficiency.

In another experiment, researchers presented the species with various food mixtures. The Physarum specimens first explored each mixture, then consistently chose the one with the most ideal nutrient balance. In still other experiments, the organism used its own slime paths to remember where it had been. Physarum can also habituate to stimuli, such as a novel chemical, proceeding more cautiously and slowly across a surface where the chemical is present but learning to ignore it over time if repeated encounters lead to no ill effect. A habituated slime mold can even pass on what it has learned to another plasmodium by fusing with it.

The Sublime Smarts of Slime Molds,” June 23, 2025

At minimum, unconventional life forms like slime molds should warn us against false certainties that we have, for example, “found the secret” of animal intelligence or that we “know how it evolved.” Great certainties can close off paths to profound realizations.


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At Nautilus: Slime molds show intelligence without a brain