Thanks to a slime mold called Physarum polycephalum, scientists no longer totally believe learning needs a brain, neurons and a nervous system.

The "brainless" P. polycephalum feeds on bacteria and other microbes and is easy to grow in culture, making it a favorite among scientists. It's typically yellow in color.

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As the subject of a study published in the journal Proceedings of the Royal Society B, the single-celled P. polycephalum showed it can learn and remember. This finding suggests learning predates the development of brains and a nervous system in higher animals since P. polycephalum evolved before neurons and brains existed. Plants can also learn and remember despite being "brainless."

Study lead author Romain Boisseau noted that what's interesting about slime molds is "they appear to be simple, because there is only one cell, but they are capable of amazing stuff, things that we thought were only possible with nervous systems or brains. These guys are very cool."

Researchers developed experiments to find out if P. polycephalum is truly capable of learning. In one experiment, they erected bridges made of agar between P. polycephalum and an oatmeal dish. Normally, P. polycephalum came together and moved across the bridges to get to the food.

Researchers then coated the bridges with caffeine or quinine, substances P. polycephalum generally avoid but which aren't toxic to them in small quantities. The slime mold first avoided the coated bridges.

It then did something extraordinary: it extended one of its long tendrils across and moved the rest of its body over the bitter bridge. Equally incredible, P. polycephalum later learned the caffeine and quinine weren't really deadly to it and so boldly crossed the bridges.

Boisseau and other scientists are at a loss to explain how P. polycephalum managed these feats. More studies are needed but the experiments do indicate scientists need to start thinking more deeply about the nature of this particular aspect of intelligence.

The study, however, runs counter to the idea learning always requires neurons. It might also reveal more information about the early evolution of learning in living things.

TagsPhysarum polycephalum, slime mold, Romain Boisseau, P. polycephalum