Intelligent? Brainless slime can 'learn': study

April 27, 2016
Physarum polycephalum. Credit: frankenstoen/Wikipedia

What is intelligence? The definitions vary, but all infer the use of grey matter, whether in a cat or a human, to learn from experience.

On Wednesday, scientists announced a discovery that turns this basic assumption on its head.

A slime made up of independent, , they found, can "learn" to avoid irritants despite having no central nervous system.

"Tantalizing results suggest that the hallmarks for learning can occur at the level of single cells," the team wrote in a paper published in the journal Proceedings of the Royal Society B.

For the study, researchers from Belgium and France sought to demonstrate "habituation learning" in a brainless organism.

Habituation learning is when original behaviour changes in response to repeated stimulus—think of a human losing their fear of needles after being repeatedly exposed to them in phobia therapy.

The team wanted to see whether an organism without a nervous system could similarly "learn" from experience and change its behaviour accordingly.

They chose a very humble life form indeed—Physarum polycephalum, also known as "many-headed slime".

A handout picture released by the French National Centre for Scientific Research on April 27, 2016 shows a single-celled protist Physarum polycephalum

Single P. polycephalum cells meld into a single, yellow blob—specimens of which can be found on decaying leaves and tree trunks in cool, moist spots.

The slime moves from place to place, albeit very slowly, by extending finger-like protrusions called pseudopods.

The scientists grew slime samples in petri dishes containing a gel made of agar, a jelly-like substance derived from algae.

They then placed each sample near another containing a meal of oats, also in agar gel.

The two dishes were separated by an agar gel "bridge" for the slime to "crawl" across, which it generally did within about two hours.

For the experiment, the team then polluted a part of the "bridge" with quinine or caffeine in concentrations that were bitter, but not harmful, to the slime.

Scientists have found that a slime made up of independent, single cells can "learn" to avoid irritants despite having no central nervous system

The slime "showed a clear aversive behaviour" at first, they observed. It hesitated, then took more than three times as long to cross the bridge by a very narrow path as it sought to avoid touching the offensive substance.

In the days that followed, the crossings became quicker—evidence that the became "habituated" to the quinine or caffeine, said the team.

These findings in an organism that preceded humans on Earth by some 500 million years, suggests that "learning" may predate the emergence of nervous systems, said the researchers.

"Our results point to the diversity of organisms lacking neurons," they wrote, "which likely display a hitherto unrecognized capacity for learning."

The discovery may boost understanding of the behaviour of other simple organisms like viruses and bacteria.

Explore further: Slime mold prefers sleeping pills

More information: Habituation in non-neural organisms: Evidence from slime moulds, Proceedings of the Royal Society B: Biological Sciences, rspb.royalsocietypublishing.or … .1098/rspb.2016.0446

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21 comments

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dirk_bruere
5 / 5 (4) Apr 27, 2016
Intelligence is generalized problem solving ability
Guy_Underbridge
4.3 / 5 (11) Apr 27, 2016
My roommates girl makes $65 an hour on the internet....
I figured web-porn paid better...
Brainless slime can 'learn'...
Does this mean there's hope for climate-change deniers?
antigoracle
1.6 / 5 (7) Apr 27, 2016
Does this mean there's hope for climate-change deniers?

Does this mean there's still NO hope for you.
Guy_Underbridge
4.2 / 5 (10) Apr 27, 2016
Does this mean there's hope for climate-change deniers?

Does this mean there's still NO hope for you.

Well, maybe not all of them...
antigoracle
1.6 / 5 (7) Apr 27, 2016
Does this mean there's hope for climate-change deniers?

Does this mean there's still NO hope for you.

Well, maybe not all of them...

So, that's a yes.

Thanks for confirming. LOL
antialias_physorg
5 / 5 (5) Apr 27, 2016
Related to the article: one could turn this around and say that neurons habituate based on activation (connections are strengthened on activation and weakened on disuse). So this is not really a different kind of mechanism but just evident in less specialized cells.
kochevnik
2.7 / 5 (7) Apr 27, 2016
Infinite fractal compression enables learning on the cellular and atomic level. I suspect even DNA has some intelligence
antialias_physorg
4.6 / 5 (9) Apr 27, 2016
Infinite fractal compression enables learning on the cellular and atomic level.

What does that even mean?

You're just stringing meaningless sciency words together again.

(Hint: That doesn't make you look smart. It makes you look exceptionally dumb, because it makes you look like you think no one notices.)
RhoidSlayer
not rated yet Apr 27, 2016
why does learning always seem to be included as a trait/qualification for intelligence ?
anterograde amnesia inhibits learning but the afflicted are still intelligent.
intelligence is a measure of function, IQ an assessment of a melding of capabilities originally measured by psychologists.
the general notion of intelligence led to it's deconstruction via myriads of fields of study, each providing data on their part of the elephant.
a simple thermostat instantiates the intelligence to fulfill it's function, some thermostats use fuzzy logic and learning to provide predictive environmental control. (shades of spock's brain)
yada yada yada /rant
RhoidSlayer
not rated yet Apr 27, 2016
splitting the baby: learning, itself, appears to be the quality enabling intelligence,
but if the slime mold stopped learning, for as long as what it had learned remained, that is intelligence embodied
MrVibrating
5 / 5 (1) Apr 27, 2016
From the headline i was half-expecting a report of associative learning - ie. like a slime avoiding something usually unoffensive after associating it with a stressor.. But it seems a stretch to ascribe intelligence to stress avoidance itself.

TehDog
5 / 5 (1) Apr 27, 2016
I wondered if this behavior could be some form of generational reinforcement, doesn't look like it.

https://en.wikipe...cephalum

Clever little critters :)
sascoflame
not rated yet Apr 27, 2016
I am sure slime is much smarter than people. My question is it at smart as a chimp.
obama_socks
2 / 5 (4) Apr 28, 2016
Infinite fractal compression enables learning on the cellular and atomic level.

What does that even mean?

You're just stringing meaningless sciency words together again.

(Hint: That doesn't make you look smart. It makes you look exceptionally dumb, because it makes you look like you think no one notices.)
- antialias_P
I believe that kochevnik may be referring to this:

"Fractal compression is a lossy compression method for digital images, based on fractals. The method is best suited for textures and natural images, relying on the fact that parts of an image often resemble other parts of the same image. Fractal algorithms convert these parts into mathematical data called "fractal codes" which are used to recreate the encoded image." from Wikipedia.
Infinite fractal compression should refer to intelligence at the Quantum level, if I'm reading kochevnik correctly. Perhaps even proton, neutrons, etc. have an ability to react and interact?
obama_socks
1 / 5 (2) Apr 28, 2016
(con'd)
Maybe subatomic particles have the ability to "learn" also, but without intelligence as we know it. Instinctive actions, reactions, and interactions are all a part of cellular activities. We are composed of trillions of cells. And perhaps kochevnik may have stumbled onto the idea that such processes are also inherent in "objects" at the Quantum level. That possibility has never been investigated, I'm sure. Larger life forms may be at the intermediate level and b/c of larger size, humans/animals developed brain CELLS - thus, intelligence. Infinite fractal compression on a 2D or 3D graphics scale is one thing, but if it were possible on a scale that involves life forms and other matter/energy on many different levels....Could it mean that existence in and of itself is subjected to existence in many "dimensions" all at once? Like infinite fractal compression?
HOOYII - as uncle Ira would say.
LMAO
Where is Einstein when you need him?
ogg_ogg
5 / 5 (2) Apr 28, 2016
There seems to be an assumption that a slime mold, after 4 billion years of adaptation, must necessarily be too "primitive" to be able to habituate. And that habituation is necessarily linked with intelligence. There is some process behind its habituation, & defining it doesn't magically make the slime mold's behavior "intelligent". My scenario for an intelligent slime mold includes its refusal to cross the bridge at all, as well as it forming the outline of the letters "F.U." Although, I am also drawn to the definition of "intelligence" which includes the characterization of a rock as intelligent, as its behavior is - in its niche - perfectly rock-like in response to any stimulus. More seriously, intelligence requires memory and the ability to make a different and more appropriate choice when new information becomes available. The slime mold doesn't seem up to that. There's no a priori reason that intelligence requires a nervous system.
antialias_physorg
5 / 5 (3) Apr 28, 2016
Why is everyone talking about "intelligence", here? The article has nothing to do with intelligence. It talks about habituation learning.
axemaster
5 / 5 (2) Apr 28, 2016
Infinite fractal compression should refer to intelligence at the Quantum level, if I'm reading kochevnik correctly. Perhaps even proton, neutrons, etc. have an ability to react and interact?

No... This reminds me of homeopathy... You're triggering me!!!!

I am very disappoint.

As for the article, I would be very interested to see how long the learned behavior persists. What could be the storage mechanism?

Also, does the entire slime "remember" the behavior? Or just the arm it originally extended? Do the cells somehow teach each other?
axemaster
5 / 5 (3) Apr 28, 2016
OK, I read the paper, which is here:

http://rspb.royal...full.pdf

Apparently the learned behavior was partially unlearned if they stopped exposing the slime mould to the aversive chemical for a few days. They think that the behavior occurs due to temporary epigenetic changes. As a signaling pathway is repeatedly stimulated, the number of chemoreceptors for that signal start to decrease, until the cell doesn't respond very much anymore.

This sounds pretty similar to the usual high-pass filtering effect that seems to happen in most sensory systems. The organism slowly adjusts the sensory receptors until the received signal is at some neutral level. So, if you input a high signal all the time, eventually it gets adjusted down to zero.
Lex Talonis
not rated yet May 02, 2016
This only proves that it's not only possible, but that fact of Jesus the Jewish Zombie, did actually blast off into low earth orbit, and lives in outer space without oxygen, but it was achieved 2000 years before space grade rockets were developed, and the story about rising on a fiery cloud was true.

Isn't science wonderful.
kochevnik
not rated yet May 02, 2016
Infinite fractal compression should refer to intelligence at the Quantum level, if I'm reading kochevnik correctly. Perhaps even proton, neutrons, etc. have an ability to react and interact?

No... This reminds me of homeopathy... You're triggering me!!!!
Actually the basis of emotion

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