Brainless Blob Can Learn And Even Teach Other Brainless Blobs

Brainless blobs of slime mold are able to learn and even teach other slime molds, according to new research out of Toulouse University.

“Recently, we discovered that non-neural organisms are able to learn to ignore an innocuous stimulus when this stimulus is repeated,” Toulouse researchers David Vogel and Audrey Dussutour wrote in a paper recently published by Proceedings of the Royal Society B. “This result raised the exciting possibility that mechanisms for learning might pre-date the evolution of nervous systems and could be emulated through physiological adaptation in non-neuronal organisms.”

Proceedings of the Royal Society B is the “the Royal Society’s flagship biological research journal, dedicated to the fast publication and worldwide dissemination of high-quality research.” The “B” in the title of the publication simply stands for “Biology.”

Stephanie Pappas at Live Science offers an accessible breakdown of Vogel and Dussutour’s findings.

“Vogel and Dussutour reported in April 2016 that P. polycephalum can learn. They cultured the slime mold in dishes filled with a mix of agar cell and Quaker Oats and then put the molds next to a patch of food, accessible only by an agar bridge. Half of the time, the researchers coated the bridges with bitter-but-harmless quinine water or caffeine. They found that the slime molds were initially reluctant to cross these bitter bridges, and took twice as long as the slime molds that got to cross bridges free of repellent. Over the course of a few days, though, the slime molds ‘learned’ that the quinine and caffeine were harmless, and sped their passage across the bridges. This demonstrated habituation, or a diminished response to a repeated stimulus.”

More recently, Vogel and Dussutour repeated the same basic experiment, but changed the stimuli and added another twist to see if the slime molds’ acquired knowledge could somehow be communicated to other slime molds that could then integrate that knowledge, as Pappas explains.

“For the current study, the researchers repeated this experiment with another harmless deterrent, sodium chloride — table salt. After confirming that the slime molds responded to the salted bridges first with aversion and then with habituation, Vogel and Dussutour added a twist. After habituation, they exposed slime molds that had experienced the salted bridges to slime molds that had crossed only plain bridges, and allowed those molds to fuse. In the process of fusion, the individual molds kept their nuclei but lost their cell membranes to become one blob-like cell.”

The researchers discovered that after the slime molds had been fused, the fused molds would cross the salted bridge without hesitation. This occurred regardless of how many habituated slime molds had been introduced to the fused groups. As long as there was at least one habituated slime mold within the group, the entire fused slime mold would act collectively as a habituated slime mold.

For instance, if one habituated slime mold was fused with three unhabituated slime molds, the four fused slime molds would then act collectively as a habituated slime mold. This suggests that the slime molds could learn from each other while connected.

The most stunning find, however, came when the researchers separated the fused molds so that the previously unhabituated molds no longer had any connection with the habituated molds. Even after the separation, the unhabituated slime molds continued to respond to the salt bridge in the same manner as the habituated slime molds. This indicates that they had acquired and retained knowledge from the habituated slime molds by being temporarily fused to them.

The results should lead to further research and greater understanding of the “transfer of adaptive behavioral responses in other types of cells,” Pappas notes.

In the meantime, we’re stuck with the knowledge that even some of the most basic life forms, like slime molds, may be able to demonstrate one of the most significant functions of more advanced life, the ability to learn.

[Featured Image by Richard Mayne and Andrew Adamatzky | Wikimedia Commons | Cropped and Resized | CC BY 4.0]