The Memory of Slime

is also very slimy but also a little stabby. And then finally we are discussing the slime mold, which is uh, taking it in a in a different direction, but a really really deceptively mind blowing direction, because when you just talk about the word mold itself is kind of boring. Mold is something that grows somewhere that you don't think about, you know, It's like it's it's that's the stuff that grows in the tub, it grows in the corner, grows under the house maybe and unless you think about it

the better. Yeah. Um, but slime mold is actually something that is helping is to redefine intelligence and we'll talk a bit more about that in a moment. Um. But when we talk about slime mold and we say mold, we actually are not talking about any sort of fungus here, right, We're talking about mainly when we talk about slime old is something called phi serum polycephalum, and that that name actually means many headed slime mold. Slime is not a slime mold is not a plant or an animal. It's

not a fungus, though it sometimes resembles one structurally. Yeah, it's a single, single celled creature, brainless, brainless, No, no brain and that's important here, no nervous system to speak of. And yet it's intelligence. It's what fascinates us. Yeah, I mean it ultimately makes us really think hard and deep about what intelligence is and what it can be, especially when we're trying to think about what what life could

be like elsewhere in the in the universe. Um. And when you say in the universe, you should consider that, Uh, these guys go back in evolutionary history history about a billion years. And according to Dr Baldolph, who is a Swedish biologist studying the DNA of slime mold species, she says that they might be tightly linked to the development of soil on land, which is very cool to think

about when you think about slime mold. Yeah, it's kind of triggy to to to really look at our history of fly mold because it's not something that really lends itself well to the fossil record. Yeah, exactly. We do know that there are nine hundred known species of slime mold, but they're really only about two that are studied in earnest.

Slime mold's live in moist terrestrial habitats like decaying wood or fresh captung nice and once the mold has found food, such as a piece of decaying vegetation or a micro organism, it grows over it and it secretes digestive enzymes. So something like polycephalum then construct an elaborate network of interconnections between foods sources which allow it to shuttle nutrients around

and get the full form of the organism fully fed. Um. Slime molds then devour many parts of bacteria, and then this releases those nutrients for other organisms to grow on. So it's a huge part of the ecosystem. So what does it look like, Um, it does not really so much look like slime per se like, it doesn't look like Nickelodeon bucket of slime falling on someone's head. And it has more of a yellowy consistency to it. It It doesn't particularly look viscous. Yeah, a lot of people have

lined it to dog vomit. Um. That's a that's the usual thing that people spot. UM. But it actually comes in nearly every color of the rainbow except green because it lacks chlorophyll um. Some resemble honeycomb lattice structures, others kind of look like BlackBerry configurations. UM. And then of course there's the dog vomit, which is the classic thing. UM. Some remain microscopic to the eye, but others grow large, and you can form boldest masses as long as ten

to thirteen feet long. So in the second we're gonna we're gonna get into the idea of what happens when you put slimold in a maze. But but imagine you have a slime mold working its way down a corridor and what happens when it encounters another slime mold coming down the corridor from the opposite direction. You probably want to do they do they fight each other? Do they is there a war of slime mold that takes place here? Well, if food is scarce is what's interesting is they do

essentially team up into it like a single communicating mass. Yeah, it's really cool. Um. This is from a New York Times article, Can answers to evolution be found in slime mold? Yeah? The organisms do respond to starvation by rushing together by the thousands into a single blob. And the blob stretches out into a slug shaped mass about one millimeter long, which is about one inch, and then it begins to crawl along like a worm toward light. Wow, like like

a caravan of line. Really yep yep. And then once it reaches the surface surface of the soil, the slug, this the slug configuration undergoes another transformation. Some of the cells turn into a stiff stock, while the others crawl to the top inform a sticky ball of spores and they stick to the foot of an animal and travel to a hospitable place. So inside the slug. And this again is according to the article, about one percent of

the miba's turn into police. This is really cool. They crawl through the slug in search of infectious bacteria and then they vanquish it. Really, they find this pathogen and they devour it. And then these sentinels drop away from this slug configuration of slime mold, taking the pathogen with it, and then they die of the infection, while the slug itself remains healthy, the colony of it remains healthy. So um, this is so amazing to me. This is all going

on at this microscopic level. This these acts of altruism. Really. Yeah, all right, we're gonna take a quick break and when we come back, we will enter the maze with the slime mold and discuss exactly how it finds its way out. All right, we're back. So the maze. We we did a whole episode on mazes, and we discussed what they

are and what they symbolize for us humans. Essentially, you're talking about uh binding, confusing pathway corridors that end in dead ends while other corridors take you ever closer to freedom. So we often use these in science experiments. Put a mouse inside of a maze. See what happens when it gets stressed out? See if it can find its way out? What happens when you put a slime mold into a maze is really fascinating because now, for one thing, you

do have to sort of um. You have to create a situation where the slime old quote unquote wants out, the slime mold wants to find its way to food. So that becomes the the idea here um for a dead end. To be a true dead end, it needs to not have something that the slime old can eat at the end of it, whereas they dad end with food at the end of it is essentially kind of

an exit. So they found that if you put a Researchers have found it that if you put a slime mold inside of this maze, it will start off by mapping its environment out. It will send out these uh, these tendrils, and they will follow every course in the

maze to its end. And if they find a true dead end where everything just ends and there's no food there, then it will retract, but it will leave a trail of slime that kind of works as an external memory of where it has been, and that is a that is a hallway that it need not go down again because there's no food down there, and then it will concentrate its efforts on the pathways that do lead to food. Yeah, it's really cool. As you say, it's like this externalized

spatial memory and um. And again no brain. Creature does not have a brain, and it is not intelligent in the larger sense of the word. But it is is using a certain amount of matt making intelligence. It's using that chemical scent to figure out where it's been and then not expend the effort on searches that won't pay off. Right, So it's saying, I've been down that hallway, there's no no reason I need to redouble my efforts on this. Another cool thing is that the five serum slime mold

sends these tendrils of protoplasum out search for food. And it's but but it's not just hey, wholesale everybody find food. What they do is they say, okay, this one over here to the left has found some food. These guys over here on the right have not. All right, everybody reconfigure and now let's bolsh for our efforts to that food to the left. So they reorganize themselves to then sort of go in and effectively cover that food spectrum

that they did find, which is amazing. So not only are they making sure that they're not going into areas they've already been, but when they do find food, they're able to to sort of say, all right, troops, here we go, We're now going to some trade on this. All right. All of this is really amazing when you look at it in the context of engineering problems that

we humans try to solve every single day. Yeah, particularly um it's it's interesting when you take the slime mold and you put it over a major city, and then you distribute the food in a way that resembles uh, major population points, major points of interest, places that you

need to say, a public transportation system to reach. So if it were a map of Atlanta, for instance, you would have like central Atlanta, Midtown, you'd have the Bucket area where we are, and and various other important places. Um well, several of those in both places are probably not gonna reach by public transportation down here as far as the train goes. But that's a whole another story.

But you put the slime mold in there and you let it figure out the best ways to get to its food sources, and researchers have found that the paths that the slime mold creates are comparable to the major public transportation system in those cities. You know, we've seen this again and again. It's not just Okay, there's just one set of researchers doing this. But I think the standout in this is the Tokyo railway system. Um, it's

a two excuse me. In two thousand and ten, mathematical biologists toshi Yuki naga Aki and his colleagues observed how this networking behavior could translate into efficient city planning. So they drew a map of Japan. They put oat flakes on the map to represent cities, and then they let the five serum loose on the area that represented Tokyo, Okay.

So key to this is that they're obviously going to be obstacles in city planning, like waterways that you can't you have to make sure that you didn't try to transverse long standing buildings and areas that you're just not going to bulldoze to build your right. So what they did is they took bright lights in these areas and which slim olds will avoid they do not like, and so those represented those areas that they knew that you

couldn't do any sort of public transportation around. And then what bloomed in front of the researcher with the FI serum network that produced interconnections just that were strikingly similar to the layout of the Tokyo railway system and um in the ways that they differed from the actual Tokyo railway system. It turns out that their methods of reaching uh net networked UM places was much more effective that than what was already in place. So what we're saying

here is that slime molds are solving engineering problems. I mean, this is amazing. This is stuff that we spend a lot of time on. This is these are computer programs, are modeling that's going on, and you just let a sly old loose and they can help. It'll equal or exceed human production on those of those same trade routes are same public transportation routes. Because another one that I ran across what was they were actually able to get up of the serum to um to reproduce the silk

road in various other global trading routes. Put it on a map of the Earth and you'll see, oh, it's well, there's a silk road right there. It's thinking along the same lines as uh as as as humans did when they were trying figure out how to get from a point A to point B in the most effective manner possible, right, And when they took that globe to they configured it so that again there were certain places that that mold couldn't try to transfer because of the configuration of the

continents and the continents of that time. And so they tried to reproduce that and that is amazing that the silk road came up. That popped up. Another example I think it's really cool is this is by Andrew Adamatzki, and he's a researcher at the University of West England. He wanted to figure out what would happen in the nuclear disaster. In other words, if a reactor melted down, what would be the best course of action for citizens

to flee from it. So he took those ice eilier modes that um that are used for highway like patterns, and they grew a slime mold network of highways for Canada. And then they placed a crystal of salt which repels slime molds on the map where the Bruce nuclear power plants located in Canada. And then what they found is that the slime mold abandoned its tendrils near the salt and then grew a new highway pattern that efficiently re routed food across Canada and also showed different paths that

you could leave obviously this area. So it sheds some sort of light on what can happen in disaster situations. Yeah, that's it's just amazing to think about slime mold is that is, being capable of doing this um and again it ultimately makes us rethink what intelligence is, um is as we we look at possible models for extraterrestrial life. Yeah. Adam Rogers, he's a senior editor at Wired. He has a really interesting riff on this, so if you want to see his video, check that out on Wired dot com.

I believe the column is observation Deck Intelligent slime Molds and the applications here with slime molds, I mean, aside from possible shooting scenarios that were in addition to UH their biophysicist in Germany and Singapore who think that the mathematical models that they were agam based on sly mold behavior might lead to new ways to starve tumors of blood and essentially to a fight cancer, Yeah, which is because what they found is that again there's this mathematical

similarity in the ways that a tumor tries to gain nutrients from the body and the way that slim mold grows. So taking those those two um examples, they can actually try to figure out ways that they could try to starve that tumor. As you say, yeah, I mean it all comes down I think to the idea you think about, Okay, what is what is mathematics? What is our what is

our spatial understanding? What is what is the the ability to create a map on a piece of paper as a as an intelligent human like, it all comes down to our ability to navigate the physical world. Um, it's just kind of a an ability that has grown, uh for more robust with the passage of time, with our evolution and then with our the building of our culture. But at it's at the very like base level, something even without a brain, has to be able to do this to some level. And the and the slime mold

does a fantastic job. So if you ever find yourself lost wandering about, think about, yeah, I think about the serum polysphal um, and take take heart in saying that this uh, this organism that goes back a billion years can find a way and so too can you. All Right, well, there's slime Mold for you, and that finishes out our three episodes on slime. If you missed it any of the other two, do check them out. There's a lot of cool data in there, and it really really made

me rethink what slime is. And really, as I mentioned before, a long time fan of slime loved slimy monsters, slimy things even as I hated slugs, and uh, and there's just so much more there, uh, not only understanding how slime works, but but slugs as well. I mean, they're I think, to slug like monsters that have appeared in various uh forms of fiction and even once where they do a pretty good job of making the creature monstrous, like, they really don't dive into all of the just weird

and fascinating biology of a slug. So just putting that out there, are there any potential filmmakers and fiction weavers in the audience, Well, let's call the robot over and do one quick listener mail this when it comes to us from Catherine and she has a book recommendation for us, She says, Robert and Julie, your most recent podcast made me think of one of my favorite books by my

favorite author. For a great book about pretending to be someone you're not, I recommend Mother Night by Kurt Vonnegut. The main character is an American playwright who has spent most of his life in Germany. As an adult, during World War Two, he was recruited by the US government to help transmit messages to the Allies. He does this via code inserted into his Nazi propaganda radio show. He is so good at pretending to be a Nazi that he has respected as a leader within the Nazi Party.

He also managed to get on the list of wanted war criminals. The problem is that he entered this knowing that the U s would never recognize his work, nor would they come to his defense. So really, the only people invested in keeping him alive or the nazis a group he does not truly want to be a part of. There's a movie made of the book starring Nicknolty. Read the book. Thanks as always for the entertainment and education. I hate the term entertainment. Yeah, I don't think we

really use entertainment either. But let's got a bit of a musty ring to it. Yeah, but we hit the idea. But we're we're glad that we're providing some interesting tidbits for you guys. That's an awesome book recommendation, something I definitely want to follow up on. Yeah, I've I've only read a couple of Vonnegut stories of read Slaughterhouse Five and The Sirens of Titan. Good stuff, especially Slaughterhouse Five,

one of my all time favorites. So hey, if you want to reach out to us, you want to share some stuff with us, you want to see what we're up to, what we're blogging about, what links we're looking at, maybe get an idea of what future episodes will consist of. Then you can find us on Facebook, you can find us on tumbler. We are stuff to blow your mind on both of those, and you can also find us

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