Can Creatures Think Without a Brain?

Slime molds, although formerly classified as fungi, are in fact the sticky cousin of eukaryotic organisms. They are single-celled organisms with neither neurons nor brains. However, for the past ten years, scientists have been arguing whether slime mold has the ability to learn about the surrounding environment and adjust its behavior accordingly.

When the slime mold is in a new environment, it slowly extends its fractal mesh tendril to explore the surroundings and encodes the information of the discovered location by changing the diameters of tentacles. Previous research work has seen that the biological signals inside the slime mold and even the network structure itself are capable of storing information about what has happened. But since the ability to remember information is not necessarily equivalent to the learning behavior, researchers want to see the direct connection between the behavior of slime molds and habituation -- the simplest way of learning that is powered by neurons typically in humans and animals.

A recent study by Audrey Dussutour and her team proved that slime molds still remember their previously learned behavior after being physiologically and destructively dormant for one year, which means that slime mold has the ability to learn from experience to some extent. Despite continued arguments about the definition of “primitive recognition” and “learning,” it’s safe to say that this new finding challenges the traditional view that only neuronal organisms have the ability to learn.