Did you know that you have 86 billion neurons in your brain, making you part of the most intelligent species on Earth? But what if you were a pulsating mass of yellow goo? Let’s dive into the fascinating world of slime molds with some help from Amy at Deep Look.
Physarum polycephalum is a slime mold that might look like the mold you find on old bread, but it’s not a fungus. It’s a jelly-like protist, which is like one big cell containing millions of nuclei. Despite its simple appearance, this slime mold is surprisingly smart. Let’s see how.
This slime mold can solve mazes! It explores every path, and when it finds food at either end, it retracts the paths that don’t connect the points. To solve a maze, it needs to remember where it’s been. So, how does a single-celled blob remember? Physarum leaves chemical trails to mark dead ends, helping it “remember” its path. When faced with a maze with multiple solutions, it can even find the shortest one. This is impressive because mapping efficient networks is a complex problem that usually requires big computers and complex math. Yet, this living organism does it naturally. It has even mapped the rail system of Tokyo and the major highways of the UK!
Dictyostelium is another type of slime mold that shows a different kind of intelligence. Unlike Physarum, it lives most of its life as single, free-living amoebae, eating bacteria. But when food runs out, something amazing happens.
One cell starts releasing a chemical that attracts other cells. As they join, they emit their own chemical signals. This process, called chemotaxis, strengthens the signal until tens or hundreds of thousands of cells work together. These cells, once independent, now cooperate like a multicellular organism, moving as one. This “slug” travels farther and faster than any single cell could alone. It’s about to undergo an incredible transformation.
After migrating, the slug flattens and begins to sprout. A thin stalk grows, lifting a fruiting body into the air. Spores are released from here, carried by insects to new food sources. Remarkably, the cells forming the stalk die, sacrificing themselves so others can continue. This is similar to how a wheat plant grows, dies, and releases seeds. But unlike plants, these amoebae are separate individuals acting for the benefit of others. This is called “altruism.”
Altruism challenges the idea that every individual wants to succeed and pass on its own genes. It suggests that helping the group we’re related to can benefit the entire species. We see this in animals hunting together, worker bees caring for the queen, meerkats guarding their dens, and chimpanzees sharing food. Slime molds challenge our ideas of intelligence, showing that nature’s intelligence is more complex than we often think.
Anthropologist Jeremy Narby notes that our concepts don’t always fit the data when we see slime molds solving problems. It’s not that nature lacks intelligence, but that our understanding is limited. If something as simple as a slime mold can solve problems and cooperate for the group’s good, it’s a reminder that we can too.
If you’re curious to see how slime molds move and how scientists are using them to inspire future robots, check out Deep Look. And remember, always stay curious!
Design your own maze on paper or using a digital tool. Imagine you are a slime mold trying to find the shortest path to food. Draw or simulate the paths you would take, marking dead ends with a different color. This will help you understand how slime molds solve complex problems naturally.
Use an online simulation tool to observe how slime molds navigate mazes. Pay attention to how they leave chemical trails and retract paths. Discuss with your classmates how this behavior compares to human problem-solving techniques.
In groups, simulate the chemotaxis process. One student starts as a signal cell, and others join by following the signal. Move together as a “slug” to a designated area in the classroom. Reflect on how cooperation enhances movement and problem-solving.
Research another example of altruism in the animal kingdom. Prepare a short presentation for the class, explaining how this behavior benefits the species. Compare it to the altruistic behavior of slime molds.
Write a short story from the perspective of a slime mold. Describe your journey through a maze, your interactions with other cells, and your transformation into a fruiting body. Use this exercise to explore the intelligence and cooperation of slime molds creatively.
Here’s a sanitized version of the provided YouTube transcript:
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You’ve got 86 billion neurons at your disposal, and you’re a member of the most intelligent species on the planet. But what if you were a pulsating mass of yellow goo? Let my friend Amy from Deep Look introduce you.
[AMY VO]
This is Physarum polycephalum, a slime mold. It might look similar to the mold you find on stale bread, but it’s not a fungus; it’s a jelly-like protist. You can think of it like one big cell, holding millions of nuclei. And while they might not seem like much, slime molds are smarter than they look. Just watch.
[JOE VO]
This slime mold can solve mazes. It does so by first exploring every path, and when it finds food at either end, it retracts any paths that don’t connect the points. Solving a maze involves remembering where you’ve been. So, where does a single-celled mass of goo hold memories? Physarum does this by leaving chemical trails to mark dead ends, allowing it to “remember” where it has already explored. When slime molds are presented with a maze that has multiple solutions, they can even figure out the shortest one. No matter the shape, they’ll almost always connect distributed food sources by the shortest path. If that doesn’t impress you, consider that once you start adding points, mapping efficient networks becomes an incredibly complex problem that humans need big computers and complex math to solve. This living organism is redefining what it means to be intelligent. They’ve even been able to map the rail system of Tokyo and the major highways of the UK.
Another kind of slime mold shows a different kind of intelligence. This is Dictyostelium, a cellular slime mold. Instead of a creeping blob, this slime mold lives most of its life as single, free-living amoebae, consuming bacteria. But when it runs out of food, something amazing happens.
[AMY VO]
One cell starts emitting a chemical that attracts other cells. Once they join up, those cells begin emitting chemical pulses of their own. This is called chemotaxis, and as the mass grows, the signal strengthens until there are tens or hundreds of thousands of cells working together. These once free-living cells now cooperate like a multicellular organism, moving in unison. This “slug” travels farther and faster than any single cell could on its own. It’s about to undergo a remarkable transformation.
[AMY VO]
After the slug migrates away, it flattens itself and begins to sprout. A thin stalk grows out, lifting a fruiting body into the air. From here, spores will be released to be collected by passing insects and carried to new food sources. What’s remarkable is that the cells making up the stalk die, sacrificing themselves so other cells can continue. It’s not that different from what a wheat plant does—growing, dying off, and releasing the next generation to the wind. But a plant lives its whole life as a multicellular organism, while these amoebae are separate individuals acting for the benefit of others. This principle is called “altruism.” It challenges our expectations from natural selection, which suggests that every individual wants to succeed and pass on its own genes. Altruism suggests that helping the group we’re genetically related to can benefit the entire species.
We see this in animals hunting together, worker bees tending to the queen, meerkats standing guard over their dens, and chimpanzees sharing food. These slime mold species especially challenge our notions of intelligence, as many of our preconceived ideas don’t fit what we observe. Anthropologist Jeremy Narby writes, “We struggle over words when the slime mold solves the maze because our concepts don’t fit the data. It is not that nature lacks intelligence, but that our own concepts do.” What he means is that any view of nature that puts humans in a separate category isn’t a very good view of nature at all. If something as simple as a slime mold can solve problems and cooperate for the good of the group, it’s a nice reminder…
[AMY VO]
That if the goo can do it, so can we. If you want to get an up-close look at how slime molds move and how scientists are using that as inspiration for future robots, follow me over to Deep Look. And as always, stay curious.
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This version maintains the essence of the original transcript while ensuring it is appropriate for all audiences.
Slime – A slippery substance produced by certain organisms, often used for protection or movement. – The slime on the frog’s skin helps it stay moist and protects it from predators.
Mold – A type of fungus that grows in the form of multicellular filaments called hyphae. – The mold on the bread was a result of leaving it out in a damp environment.
Intelligence – The ability to learn, understand, and apply knowledge to adapt to new situations. – In psychology, intelligence is often measured through various cognitive tests.
Chemotaxis – The movement of an organism in response to a chemical stimulus. – Bacteria use chemotaxis to move toward nutrients or away from harmful substances.
Altruism – The behavior of an organism that benefits another at its own expense. – In biology, altruism can be observed when a meerkat stands guard to protect its group from predators.
Neurons – Specialized cells in the nervous system that transmit information through electrical and chemical signals. – Neurons communicate with each other to process information in the brain.
Amoebae – Single-celled organisms that move and feed by extending their cytoplasm to form pseudopods. – Amoebae can change their shape to engulf food particles in their environment.
Paths – Routes or courses taken by organisms or signals, often referring to neural pathways in biology. – The brain’s neural paths are essential for transmitting information quickly and efficiently.
Spores – Reproductive cells capable of developing into a new individual without fusion with another cell. – Fungi release spores into the air to reproduce and spread to new areas.
Networks – Interconnected systems or structures, such as neural networks in the brain. – The brain’s networks allow for complex processing and integration of sensory information.
