The brainless slime mould that can solve problems and teach what it has learnt to other slimes
France-based scientists continue to study a slime mould that can “learn” from experience
By Marcus Strom
It doesn’t have a brain or any neurons, it is just one single cell but somehow by fusing with others of its kind this slime mould can pass on learnt behaviour.
France-based scientists David Vogel and Audrey Dussutour have previously shown that the slime mould Physarum polycephalum can learn from experience.
Now, in a study published this month, they have shown that the slime mould can pass on what it learns to “naive” members of its own species by fusing with them.
In April, the French team at the Research Centre on Animal Cognition found that by creating bitter tasting, yet harmless, barriers between the mould and its food source, the species quickly learnt to ignore the harmless substances, such as quinine or caffeine.
This method of “learning” is called habituation.
In the latest study, the scientists have shown that this acquired behaviour can be passed on to other organisms by fusing with them.
Dr Dussutour and Dr Vogel created a salt barrier between a food source and the organism for 2000 slime moulds. Another 2000 moulds had to cross a bridge to reach food that had no salt barrier.
Paired habituated and “naive” slime moulds fused and the knowledge to ignore the salt was immediately absorbed by the naive moulds.
“Most people thought that it was impossible for a cell to learn,” Dr Dussutour told The Atlantic. “But we’ve tried this now with more than 2000 slime moulds. It can’t be an accident.”
The slime mould has already been shown to have the ability to solve simple puzzles, such as finding the fastest way through mazes to reach food sources.
It has even been able to create efficient networks, mimicking the railway infrastructure of the Tokyo underground, Australian highways or the British rail network.
Biologist Andrew Adamatzky has shown this many times. He places food as representative of population centres or transport hubs. The slime mould travels across the terrain, creating an efficient network between food sources.
A University of Sydney biologist, Tanya Latty, spoke to The Atlantic about the findings. She said: “I think we’re beginning to realise that brains are not prerequisites for complex and interesting behaviour.”
Dr Latty said: “The majority of life forms on Earth are brainless, but we know very little about how this brainless majority are able to adapt their behaviour in changing environments. I really hope studies like this one encourage other researchers to investigate that.”
So could studying these slime moulds help us learn about how neural intelligence developed?
This is still a mystery. The slime mould in the study is not a plant, it’s not an animal and it’s not a fungus: it’s a single-cell organism known as a eukaryote. It’s name means “many-headed slime” and it prefers cool, moist terrains such as in the decaying logs and trees of forests.
The researchers write: “Slime moulds are capable of habituation, a simple form of learning, when repeatedly exposed to an innocuous repellent, despite lacking neurons and comprising only a single cell.”
They’ve now shown they can pass this information on.
How do they do this? Dr Dussutour told The Atlantic: “We’ve talked to a lot of neuroscientists and they have no idea.”
The study was published in the Proceedings of the Royal Society B.