How do you define natural non-human intelligence? I thought about this as I watched a PBS-Nova’s episode, the Secret Mind of Slime.
I love slime because it’s one of those living beings that don’t fit the mold, if you’ll pardon the pun. It might look like a mold, but it’s not. It belongs to a kingdom of unique living beings: Protista. These singled-celled lifeforms often display some traits common to fungi. They also may display traits found in some plants and animals. But though they may share traits with those in other kingdoms, they’re not similar enough to any of them to belong there. It’s tempting to think of them as living beings who don’t fit. But I prefer to think of them as unique. This short MooMoo Math and Science video provides a good overview of the inhabitants of this amazing, often overlooked kingdom.
In our sometimes anthropocentric way, we may feel tempted to perceive these tiny mysteries as rejects. Ancient beings who played no role in the evolution of higher beings like plants and animals and left precious few traces of themselves in the fossil record. But studies of slime increasingly reveal that dismissing their importance both then and now would be a grave mistake. In addition to causing us to expand our awareness of life on this planet beyond plants and animals, these single-celled beings with their multiple nuclei cause us to rethink how we think about intelligence.
Older folks interested in cat and dog behaviors and that of other animals may recall that it’s been an uphill struggle just to get some people to accept that those animals display intelligence. In some academic disciplines, even hinting that such was possible could have doomed once-promising careers.
According to the anti-animal intelligence group, only humans are capable of intelligence. But once sufficient evidence made it clear this wasn’t the case, some of the nay-sayers grudgingly accepted this. However, more resistant folks then maintained that only animals with a brain and nervous system were capable of intelligence. Then scientists proved that some plants also were capable of displaying behaviors that fulfill the intelligence definition, something Charles Darwin had determined in his own research more than a century earlier. Given this background, it’s understandable why those who saw their definitions of intelligence eroding weren’t pleased when some contemporary scientists started suggesting that slime were capable of displaying intelligence!
Part of the problem is that there’s little agreement on what the word “intelligence” means. It’s one of those words most of us think we know the meaning of, but couldn’t define if our lives depended on it. When this occurs, our responses tend to be dominated by emotions instead of facts. Meanwhile, most formal definitions of intelligence mention the ability to solve problems, plan, comprehend complex ideas, learn, learn from experience, and pass learning on to others. This is based on the word’s Latin roots which mean to perceive or comprehend.
Given this human track record, it’s no surprise that suggestions—let alone evidence—that at least one slime mold possesses intelligence shocked many. Depending on your personal intellectual orientation, the hero or culprit is Physarum polycephalum. Like many brilliant discoveries in science, a small group of scientists saw fascinating behaviors where others saw, well, just slime.
Physarom polycephalum
Among the first to discover Physarum’s problem-solving ability was Japanese researcher Toshiyuki Nakagaki. He demonstrated how it could find its way out of a maze to reach a food supply. In a more challenging experiment designed to determine Physarum’s problem-solving efficiency, his team laid food in a pattern that mimicked the routes and stations of the complex Tokyo metro-system. They chose it because it already was known how much computer-enhanced human data analysis preceded the pattern placement to ensure maximum service and efficiency.
As it had demonstrated in previous successful escapes from mazes, Physarum initially sent out multiple pulsating tendrils toward the scent of the food, abandoned those that didn’t pan out, and strengthened those that did. Ultimately, the single-celled slime lacking a brain and nervous system and—most would say—intelligence, created an optimal path that mimicked that of the metro system.
What else can this brainless single-celled slime being do?
Physarum in Nature
After spending time in the same research environment as Nakagaki, entomologist Tanya Letty decided to bring Physarum back to Australia as a lab pet. There, the slime’s behavior gained the attention of post-doc entomologist Audrey Dussutour. She requested a piece of Physarum from her colleague and named it Blob.
Finding slime more intriguing than ants, the researchers then attempted to determine a more natural and complete diet than the rolled oats most researchers fed Physarum at the time. After they developed a variety of more nutritionally sound samples, they then let Physarum choose the one that best fits its needs. Though the slime initially grew toward the entire dietary line-up, once again it soon abandoned those routes that didn’t lead to the best option. Instead, it and focused its energy on moving toward the perceived goal.
So now scientists knew that a single-cell lacking a brain and nervous system could escape from a trap, devise strategies, detect differences in potential food sources, and make choices. But could it habituate? Could it learn to ignore a repeated negative stimulus like humans and other animals did?
To answer these questions, the team created an experiment involving Physarum’s preferred food—a food with more sugar—and one with more salt that it didn’t like. They placed a disk of the preferred food at the end of a connecting “bridge” covered with just enough salt to bother, but not harm the slime. The first day it took the slime 10 hours to cross the bridge. But each day they repeated the experiment, the transit time shortened. By Day 5, it took the experimental group no longer to cross the bridge than those in a control group who crossed a salt-free bridge. This added the ability to habituate to Physarum’s growing list of intelligent behaviors.
Next, the researchers wondered whether the salt-habituated slime could pass on its knowledge/memory to those lacking it. To determine this, they divided the nuclei of habituated and naïve Physarum and placed them together. The resultant combined Physarum accepted salt. The salt-tolerant Physarum somehow had shared its acceptance to the naïve.
But for as amazing as this is, Michael Levin’s work on bioelectricy elevates the concept of intelligence to a whole new level. In short, Physarum produces measurable bioelectric waves that flow through it. In more complex, multi-celled organisms these waves are carried to specialized cells that then process their messages. In those systems, the cells function as the microprocessors and bioelectricity is the software the cells run. A record of the bioelectric activity in specialized cells in the heart and brain is what we see in electrocardiograms (ECGs or EKGs) or electroencephalograms (EEGs).
But the much more primitive and elegant single-celled Physarum’s changes in bioelectricity’s attracting and repulsing signals are capable of supporting the same complex behaviors we commonly associate with higher organisms: regeneration, problem-solving, memory, learning, habituation, and sharing learning with others.
Complex organisms like these:
When I work with clients whose animals are displaying problem behavior, I remind them that it’s all about energy. No matter how maddening or self-defeating the problem behavior superficially may appear, it represents the most energy-efficient way for that animal to achieve the maximum stability in that environment. But I had no idea this elegant energy-based system that affects all living beings predated us by thousands, if not millions of years.
How do you define natural non-human intelligence? I thought about this as I watched a PBS-Nova’s episode, the Secret Mind of Slime.
I love slime because it’s one of those living beings that don’t fit the mold, if you’ll pardon the pun. It might look like a mold, but it’s not. It belongs to a kingdom of unique living beings: Protista. These singled-celled lifeforms often display some traits common to fungi. They also may display traits found in some plants and animals. But though they may share traits with those in other kingdoms, they’re not similar enough to any of them to belong there. It’s tempting to think of them as living beings who don’t fit. But I prefer to think of them as unique. This short MooMoo Math and Science video provides a good overview of the inhabitants of this amazing, often overlooked kingdom.
In our sometimes anthropocentric way, we may feel tempted to perceive these tiny mysteries as rejects. Ancient beings who played no role in the evolution of higher beings like plants and animals and left precious few traces of themselves in the fossil record. But studies of slime increasingly reveal that dismissing their importance both then and now would be a grave mistake. In addition to causing us to expand our awareness of life on this planet beyond plants and animals, these single-celled beings with their multiple nuclei cause us to rethink how we think about intelligence.
Older folks interested in cat and dog behaviors and that of other animals may recall that it’s been an uphill struggle just to get some people to accept that those animals display intelligence. In some academic disciplines, even hinting that such was possible could have doomed once-promising careers.
According to the anti-animal intelligence group, only humans are capable of intelligence. But once sufficient evidence made it clear this wasn’t the case, some of the nay-sayers grudgingly accepted this. However, more resistant folks then maintained that only animals with a brain and nervous system were capable of intelligence. Then scientists proved that some plants also were capable of displaying behaviors that fulfill the intelligence definition, something Charles Darwin had determined in his own research more than a century earlier. Given this background, it’s understandable why those who saw their definitions of intelligence eroding weren’t pleased when some contemporary scientists started suggesting that slime were capable of displaying intelligence!
Part of the problem is that there’s little agreement on what the word “intelligence” means. It’s one of those words most of us think we know the meaning of, but couldn’t define if our lives depended on it. When this occurs, our responses tend to be dominated by emotions instead of facts. Meanwhile, most formal definitions of intelligence mention the ability to solve problems, plan, comprehend complex ideas, learn, learn from experience, and pass learning on to others. This is based on the word’s Latin roots which mean to perceive or comprehend.
Given this human track record, it’s no surprise that suggestions—let alone evidence—that at least one slime mold possesses intelligence shocked many. Depending on your personal intellectual orientation, the hero or culprit is Physarum polycephalum. Like many brilliant discoveries in science, a small group of scientists saw fascinating behaviors where others saw, well, just slime.
Physarom polycephalum
Among the first to discover Physarum’s problem-solving ability was Japanese researcher Toshiyuki Nakagaki. He demonstrated how it could find its way out of a maze to reach a food supply. In a more challenging experiment designed to determine Physarum’s problem-solving efficiency, his team laid food in a pattern that mimicked the routes and stations of the complex Tokyo metro-system. They chose it because it already was known how much computer-enhanced human data analysis preceded the pattern placement to ensure maximum service and efficiency.
As it had demonstrated in previous successful escapes from mazes, Physarum initially sent out multiple pulsating tendrils toward the scent of the food, abandoned those that didn’t pan out, and strengthened those that did. Ultimately, the single-celled slime lacking a brain and nervous system and—most would say—intelligence, created an optimal path that mimicked that of the metro system.
What else can this brainless single-celled slime being do?
Physarum in Nature
After spending time in the same research environment as Nakagaki, entomologist Tanya Letty decided to bring Physarum back to Australia as a lab pet. There, the slime’s behavior gained the attention of post-doc entomologist Audrey Dussutour. She requested a piece of Physarum from her colleague and named it Blob.
Finding slime more intriguing than ants, the researchers then attempted to determine a more natural and complete diet than the rolled oats most researchers fed Physarum at the time. After they developed a variety of more nutritionally sound samples, they then let Physarum choose the one that best fits its needs. Though the slime initially grew toward the entire dietary line-up, once again it soon abandoned those routes that didn’t lead to the best option. Instead, it and focused its energy on moving toward the perceived goal.
So now scientists knew that a single-cell lacking a brain and nervous system could escape from a trap, devise strategies, detect differences in potential food sources, and make choices. But could it habituate? Could it learn to ignore a repeated negative stimulus like humans and other animals did?
To answer these questions, the team created an experiment involving Physarum’s preferred food—a food with more sugar—and one with more salt that it didn’t like. They placed a disk of the preferred food at the end of a connecting “bridge” covered with just enough salt to bother, but not harm the slime. The first day it took the slime 10 hours to cross the bridge. But each day they repeated the experiment, the transit time shortened. By Day 5, it took the experimental group no longer to cross the bridge than those in a control group who crossed a salt-free bridge. This added the ability to habituate to Physarum’s growing list of intelligent behaviors.
Next, the researchers wondered whether the salt-habituated slime could pass on its knowledge/memory to those lacking it. To determine this, they divided the nuclei of habituated and naïve Physarum and placed them together. The resultant combined Physarum accepted salt. The salt-tolerant Physarum somehow had shared its acceptance to the naïve.
But for as amazing as this is, Michael Levin’s work on bioelectricy elevates the concept of intelligence to a whole new level. In short, Physarum produces measurable bioelectric waves that flow through it. In more complex, multi-celled organisms these waves are carried to specialized cells that then process their messages. In those systems, the cells function as the microprocessors and bioelectricity is the software the cells run. A record of the bioelectric activity in specialized cells in the heart and brain is what we see in electrocardiograms (ECGs or EKGs) or electroencephalograms (EEGs).
But the much more primitive and elegant single-celled Physarum’s changes in bioelectricity’s attracting and repulsing signals are capable of supporting the same complex behaviors we commonly associate with higher organisms: regeneration, problem-solving, memory, learning, habituation, and sharing learning with others.
Complex organisms like these:
When I work with clients whose animals are displaying problem behavior, I remind them that it’s all about energy. No matter how maddening or self-defeating the problem behavior superficially may appear, it represents the most energy-efficient way for that animal to achieve the maximum stability in that environment. But I had no idea this elegant energy-based system that affects all living beings predated us by thousands, if not millions of years.