Diatoms and Diatomaceous Earth, Part 1

This is an iHeart podcast. Guaranteed human. Rural Britain. Gigaclear goes further to bring you fast, reliable, whole home coverage. 100% full fiber, affirmative. Free Wi-Fi installation. Engineers ready to go. Amazon Eero RUNER next level. All from only 16 pounds a month. Cosmic Quasars. Switch to Gigaclear. Faster broadband for rural Britain. 18 month contract. Prices may vary. Verify at gigaclear.com. Welcome to Scuffed to Blow Your Mind, a production of iHeart Radio. Hey, welcome to Scuffed to Blow Your Mind. My name is Robert Lamb. And I am Joe McCormick. And today on Stuffed to Blow Your Mind, we're going to begin a series of episodes talking about microbial organisms called diatoms, focusing both on their living biology and on the way that their fossilized remains in mineral form have pervaded human techno history and culture. Rob, I don't remember if I told you this, but I actually got the idea to do this episode jumping off of a sort of research tangent that I ended up not going down when we did an episode on sand a few weeks back. I was looking at weird different kinds of, you know, sand and soil on earth. And I started thinking, actually, diatomaceous earth is so much weirder than people think about when they go buy a canister of food grade, diatomaceous earth, or get some for their garden. Yeah, you know, and I don't think I'd really ever encountered it on the commercial end of things before. Like, I don't think I've ever purchased a canister of this stuff before or anything like that. But I do find it, I think it's great that it's a spin off of our sand episode, which I think everyone was excited for. And so were we. It is also in a weird way, kind of a continuation of our dust series from years back. A series that some people were like, how are they doing? Why are they doing episodes on dust? Makes me so angry. But people love those episodes as well. We loved researching them and recording them. We're getting into that same area. And I think it's a fascinating world, especially when we leave behind the human perspective and we start really zeroing in on what's going on at a much smaller scale. So I thought we should start with the organisms. Before we get to diatomaceous earth, we talk about diatoms themselves. So diatoms are microscopic single celled photosynthetic algae that are notable for living inside strange, beautiful geometric cell walls that they manufacture for themselves out of what's called opaline silica. So essentially, these are microscopic algal life forms, photosynthesizing single celled organisms that live in transparent or translucent silicon based solids, these little houses made out of a substance very similar to glass. And these glass like shells they make are called frustules. The weird and sometimes dazzling shapes of these frustules are a major reason historically that diatoms have been so interesting to people since they were first observed through microscopes over 300 years ago. But diatoms are not just some obscure biological curiosity that's pretty to look at. Diatoms are everywhere and in a sense they are tied up in the life of everything on earth. So diatoms are found in nearly every aquatic habitat on the planet. Sea water, freshwater, icy oceans, lakes and rivers, puddles, even damp soil. You can find them stuck between layers of seasonal ice that accumulates in Antarctica. Like anywhere there's water, you're going to find them. So if you put a drop of water from any natural water source under a microscope, there'll be some exceptions, but very likely very high odds you're going to find diatoms in that water. Yeah, to a certain depth. That's worth noting as well. Yes, exactly. Yeah. So some of them live as free floating plankton. So they'll be floating in the water carried about by currents in the water. And others live by attaching themselves to surfaces in the water, like the outer surface of aquatic plant tissues. Some of the earliest images of diatoms people ever recorded seeing up close through microscopes were attached to plant roots. Or sometimes they will just stick to inorganic surfaces, the surfaces of rocks or even the surface of ice. That's a strange place to find things living, but there is interesting research about thriving diatom communities that live on the surface of ice or even in between layers of ice. Oh, wow. So individually, most diatoms, I'll mention a couple of exceptions, but most diatoms are too small to see with the naked eye. They live on the scale of micrometers, with the smallest being only a few micrometers wide, which is much too small to see without magnification. And the largest growing to a few hundred micrometers, which is roughly the width of a human hair. There appears to be one extreme outlier, a species I came across called ethmodiscous Rex, which can grow up to two or three millimeters in width, while still being only a single cell, which is pretty crazy to think about. Obviously that one is visible with the naked eye, but most of them are not. And while almost all of them are too small to see without a microscope, together they have a massive impact on the planet. So in satellite photography, you can see them as blooms of color in the ocean from orbit, and they are major atmospheric engineers. Diatoms by themselves are responsible for producing somewhere between 20 and 30 percent of the oxygen we breathe. They are also a major primary producer of organic material and thus a base of the food web in the ocean. According to a 2018 paper by Agira et al. in scientific reports, which I'll come back to later, diatoms by themselves account for, quote, 45 percent of total primary production of organic material in the sea. So diatoms are just going to be making up a huge portion of the base layer of the food web in the world's oceans with other major primary producers in the oceans, including cyanobacteria and dinoflagellates. According to Agira and co-authors, there are actually there are more than 100,000 species of diatoms. I think those are not all documented. I think those would be there. There's some estimation involved in there because I've seen other estimates saying that there are somewhere between tens of thousands and millions of species of diatoms. I think we don't really know exactly how many species there are. And they tend to be classified according to the shapes of their frustules, these glass cases that they build for themselves and live within. So some of these frustules, and we'll do much more intricate description as we move on, because that's a big part of the series, is just looking at these shells, looking at the frustules. But some of them are roughly shaped like zigzagging chains of squares and rectangles. Some of them kind of look like pistons, like piston cylinders or tubes with these perforations in them. Some look like little coin purses or glass lips. Others look like coliseums, weird little Roman coliseums. Yeah, it's amazing how they can feel like this weird mix of organic and technological and psychedelic. And it really feels at times when you're looking at images of these, like the machine elves have opened up the walls and allowed you to see inside reality. Absolutely. There's one micrograph image I saw that looked like a stone hairbrush. And that shook me. I don't know. I was like, what's going on with this hairbrush? But anyway, one of the really interesting things is that these hard silicon based cell walls have a life beyond the algal organism that lives inside them. So when diatoms die, their frustules do not just disappear. They usually sink down to the sediment layer below the body of water where they live. And in some cases, before they can be broken apart and dissolved, they pile up and accumulate and form a kind of silica based ooze, which can become fossilized together to create a porous low density sediment sedimentary material called diatomite. Which you can think of as a soft, sponge like sort of chalky fossil rock made out of compressed layers of these microscopic glass shells. And if millions of years later, you dig up layers of this mineral diatomite and you grind it up into a powder, you get a well known and extremely common utility material called diatomaceous earth, which is a misleading name, I think, like I think so. I think we can already say just this far into the episode, you could more readily call this like necro dust or something. Like it's a lot grislier. You know, this is like the mass graves of a billion billion prehistoric creatures or life forms, rather. This is so fascinating. Again, you take it for granted and you're just like, oh yeah, I bought that sprinkle that don't inhale it. That's the most people think about it usually. The trillions of razor hippodromes of death. Yeah. But this stuff, diatomaceous earth, despite having this strange, organic fossil history, has all kinds of mundane, industrial and practical uses throughout history and still today. And we'll definitely come back and discuss some of these uses, both historical and today in more detail later. But just to run through a few of them, diatomaceous earth is commonly used as a filtration medium for liquids like oils and oil water emulsions. Like it's used in food filtration, food and beverage filtration. It's used in pool cleaning devices for filtration and making beverages like beer and wine. It's used as a toiletry product in like some shampoos and toothpaste. I think sometimes just generally used as an abrasive. It's used in some types of cat litter. I think you've got something about that, Rob. And worth noting too, at this point, that broadly you'll find there are different classifications of it, including food grade, diatomaceous earth. Which I don't know if we're going to vouch for that yet. I don't want to cast too much doubt on it either. I just, I haven't made up my mind what I think about so-called food grade, diatomaceous earth. Well, I mean, that's the technical classification, I believe, the industry classification for it. I don't know, yeah, I don't know how much we're going to go into some of the more human-bodied, centered uses and proposed uses for this stuff. As always, we'll just refer to a standard caveat of check with your doctor, check with an actual doctor on any questions like that. Yeah, I have not researched for this episode a lot of these so-called these medical claims about diatomaceous earth. But just be aware that out there, there are some health and wellness claims about diatomaceous earth that appear at first glance to me to be not super well-founded. But maybe we can come back and look at that in more detail later. Because at the same time, again, it is everywhere and in all sorts of products. Right. And not in a way that should alarm you. Totally. I don't want to be alarmist about it either. I just don't want to say that all alleged uses of it are legitimate, obviously. So anyway, so it's in all that stuff, but also it's commonly used as an insecticide. I think we'll have some stuff on this later, like a crawling insect repellent. It's used as an additive in paints and varnishes. And it even played a key role in the invention of dynamite. Strange story there. So I think it's so interesting that this stuff that you can buy in bulk at the tractor supply store and like has all of these mundane roles in human industry. If you zoom in on the particles of this stuff with a high powered microscope, you can still see fragments of these insane xenomorphic geometric structures. Like it's like you go to the tractor supply and you buy a bag of smashed up microbial cathedrals and these gears of alien machines. It's kind of wild. Yeah, absolutely. I was looking at various images of these things. And again, I encourage everyone out there, just do your standard image search. Bring up some images of these different diatoms and diatomaceous earth closeups. And you're going to be astounded. I was thinking like, what do these look like? What are the different vibes that I'm getting off of these? And so this is just a short list. I would say I definitely get a sense of uncooked romulan pasta of exploded components of a high end Swiss watch. Totally. Defective components from a mechanical pencil factory. OK. Some of them, especially the more colorful presentations of different diatoms that you'll find, I get a 1970s bathroom tile mosaic at your Aunt Helen's house sort of feeling. In just a minute, I want to get into some reasons for some of these different colorful versus more machine looking ones. But yeah, totally. I see that too. I get a sense of checks, mix prototypes for the International Space Station. And did I'm not being deployed? They sent ramen instead or something. And then also, especially with some of the colorful images, rejected dead can dance album covers. Yeah. OK. I like all of those descriptions. I think they're all valid. One of the things I noticed is that two different descriptions of yours mentioned sort of printed or human made, but like mass manufactured food products. So one, I think when you said like Romulan pasta, uncooked pasta, you're thinking of like cut pasta shapes like those curly cues or tubes. You get rigatoni and things. And then you also mentioned checks, like checks mix. And I do see both of those things. I don't know what's significant about that, but maybe it's because you get these at once kind of organic looking. So it's kind of food, but also mass manufactured and tool and component looking. So it's like printed foods, these kind of like mass made foods that are all the same. Yeah. Yeah. Definitely. I mean, definitely you're looking at something that is like a lattice work. Yeah. Yeah. And we can't help but compare it to some of these various food products. So one thing that is interesting if you look up micrograph images of diatoms and of diatomaceous earth, even the ones that are similarly shaped will look pretty different depending on whether the image is produced using visible light microscopy or by a scanning electron microscope. And I didn't put this together until I read it mentioned in one of the explainer pages by an ecologist and diatom researcher named Sarah Spalding on diatoms.org, which is actually that's a great website maintained by a group called diatoms of North America. It seems like most of the articles on here by this researcher, Sarah Spalding. But the author here points out that under light microscopy, most diatom frustules, the glass like shells on the outside of the diatom, most of these are going to be transparent under light microscopes. They're going to be like glass. So this gives them the appearance of fine crystal glassware and jewelry. Diatoms are often compared to jewels. And so that's like one sort of genre of diatom imagery. Whereas under a scanning electron microscope, the frustule is not transparent but opaque. And I think there could be different reasons for this. This may be wholly or partially do not to inherent properties of the frustule, but to how samples are pretreated for the electron microscope. I think they might get some sort of metallic coating to make them visible under this method. I'm not totally sure about that. But whatever the cause, the result is that the electron microscope highlights the shape and the texture of the frustule itself, producing these images that look less elegant and subtle and transparent. There's less light and color about them. So you don't get that glowing gem appearance you get with the light microscope images. These are the ones that look more like the gray alien gears and machinery. And so I think it's interesting that you, of course, have different kinds of diatoms that on their own, you know, because of their natural biodiversity contribute to all these different types of shapes and colors and structures you get. But also the different microscope methods give you very different feelings when you look at them. Yeah, yeah. So I know we want to talk about a couple of interesting and surprising uses of diatomaceous earth made from these fossil diatoms today. But before we do that, I wanted to talk a bit more about the biology of diatom frustules and in these glass like structures that the diatoms live inside. So to picture a diatom as a living organism, I think it's a very different kind of diatom. So if you picture a diatom as a living organism, you have to think about a soft inner cell that looks in some ways like a typical cell of algae. Though if you think algae, you may be thinking green. Your brain just naturally goes there because masses of algae we see, especially in like freshwater sources are often green. A lot of diatoms, I think, are going to be more like they vary, but a lot of them tend to be more gold or golden brown in color. And technically, historically, diatoms have been thought of as what were were called protists. So that was kind of a cash-all group for single-celled eukaryotic organisms with a cell nucleus housing their main genetic material, but which were not plants and were not animals and were not fungi. And it's like that. It is not any of those things. It is a photosynthesizing and makes its energy from the sunlight. Photosynthesizing single-celled organism. It does have a cell nucleus, but it's not a plant. It's not an animal, not a fungus. And as we've been talking about, one of the main things that really makes a diatom unique as an organism is that this soft inner cell is protected by the fortified cell wall, this rigid glass-like material made out of silica that goes all the way around the frustule. Frustules are often compared to pill boxes in design. And I was trying to make sure I understood this right. I think I finally landed on an analogy that makes sense of it for me. So Rob, we'll see if this gets you there. So they're often described as pill boxes because diatom shells are typically made of two interlocking halves, which are known as the epitheka and the hypotheca. So think of a box or a container with two differently sized halves, a base and a lid where you close them together by sliding the lid down over the top of the base. A common comparison used in a lot of sources to describe this is a Petri dish, but I think that's probably an easier point of reference for people who work in labs a lot. So the best comparison I could think of for just regular people would be the boxes that board games come in. So you've got two halves, one is slightly bigger than the other, and the lid fits over the base by closing over it tightly. Yeah, yeah, that makes sense to me. OK, so there's an interesting fact about the interaction between the rigid frustule, which exists in these two halves and diatom reproduction. And shout out that again, I came across this, I think, originally by reading explainers by the researcher, Sarah Spalding, on diatoms.org. But I was reading about this in a few other places. So the way it works is like this. Diatoms reproduce both sexually and asexually, but a lot of the reproduction is asexual reproduction. Asexual reproduction happens when a single diatom parent cell divides in two and makes a copy of itself. So each new cell, now you've got two cells where there once was one, each new cell gets to take one half of the frustule. So each new diatom then treats its half frustule as the big half and makes a smaller half of a frustule to close inside of it. So to follow from the board game box analogy, imagine that the board game clones itself. You know, you've got your your monopoly game inside that makes a copy of itself. And each copy of the monopoly game takes one half of the original box with it. So one new one game takes the lid, one game takes the base. Might this also be like if a human were to spontaneously clone and then one clone got to keep like the shirt and the other clone got to keep the pants, right? Sure, yes. Putting aside structural differences between the rigid case and the clothes. Yeah, it's much like that. If a human reproduced by just splitting in two and making two humans, one would take the shirt, one would take the pants. Yeah. And it's a long shirt in my mind. So, you know, it's still functional. They're fine. OK, but now imagine following that analogy, I was going to say that for the board game now you've got the two new monopoly games and each one takes the half of the box that it took as the lid and it makes a new base. OK. In your analogy, I think it would be that you've got the two humans and one takes the shirt, one takes the pants, but they both use that article of clothing as the shirt. And so now they both need to make a new pair of pants. OK. But let's just stick with the board game analogy for a second. So I don't get confused. So since the lid of the box always has to fit over the base of the box, you know, and they each took half. So one of them took away a base to make into a new lid. This means that the diatom that originally took the base and treated it as the lid will have a smaller shell overall than the original parent. And if that diatom divides again, one of its offspring will have to be even smaller and so on and so on. Now, obviously this cannot go on forever. Over the course of a few months, diatom reproduction can result in generations dramatically smaller than the original ancestor. I think this varies somewhat by species. Like I think there are some species, maybe that don't really shrink like this and others that do and they might shrink to different extents. But anyway, some sources, at least talking about some species, said that you can get more than 50 or 60 percent reductions in size in just a few months. Oh, wow. Yeah. So I think the board game box analogy actually works really well here because yeah, if the top of the box becomes the new bottom of the box and this process keeps going, eventually normal monopoly becomes travel monopoly. And then eventually you have a monopoly set inside of a matchbox or something. It's too small to play with eventually. Yeah, exactly. So this brings us to a question. How does a diatom reproductive line get big again? Well, according to Spalding, diatoms get back to their original size by entering a specialized life phase where they create a structure called an oxo spore. So instead of a rigid silica shell surrounding the entire cell like you get with regular diatoms, the oxo spore only has these bands of silica, which go around it. These bands are called parisonia. And because the oxo spore lacks the full shell, the oxo spore can grow to its ideal size before kicking off the reproductive line again through cell division, which results in full size diatoms with full size frustules. So diatom species that shrink like this usually use sexual reproduction to reach the oxo spore phase. Highly shrunken diatoms are triggered to produce gametes and these gametes combine to become the full sized oxo spore. So it's like the shrinking process that triggers the sexual reproduction. Once they get shrunken down enough, it's like time to reproduce sexually. So you could say that in some cases, diatoms are sexually frustrated. Hey, I think I'm probably not the first person to make that. Now, there are some other really interesting things about diatom biology that I want to get into. But I think I want to save them for the next episode because I also want us to talk today about some of the bizarre properties of diatomaceous earth, the fossil remnants of these organisms as they are often sold in bags and places all around the world. That's right. Yeah. So we're going to get into some of these topics concerning diatomaceous earth here. And we're going to start talking a bit about diatomaceous earth as an insecticide, as a mechanical insecticide, or as a component in other insecticides. And in order to get into this, I thought we might sci-fi it up a little bit. Which is an exercise we sometimes do on the podcast and also often what happens in my own mind when I'm trying to understand something or picture it. So bear with me here. It is the year 1060 A.E.E. OK. You are part of the human exploration mission to the exoplanet, let's see, Blout 1606B. It's a dry world, not altogether lifeless, but no longer harboring intelligent life as you know it. Initial scans reveal vast deserts and gaping canyons, but also isolated valleys that could provide protection for landed modules. So you descend into just such a valley where ancient black pyramids whisper of a bygone age when the world's last civilization sought refuge in these valleys, probably during some sort of impending cataclysm that eventually destroyed them. But whatever lived here once your bioscans indicate are no longer present. This valley is now lifeless. And tech scans also show no evidence of the machines that your civilization purged itself off, nor the machine descendants of other alien civilizations. So everything seems good to go. Time to land. You're going to keep your suit on, of course, but you're going to land and check it out. So that's what you do. You set out on foot, you and your team. You're clad in your protective armored spacesuits, complete with powered exoskeletons and all the human enhancing technology that is currently permitted by the ecclesiastical authority. You scan again for pathogens and the scans read negative emboldened you and the team descend into the largest of the black pyramids. The inscriptions on the walls are indecipherable, composed in an alien text and then on top of that degraded by untold eons of neglect. But you can't help but try. You're staring at them. And as you're staring at these inscriptions, you hardly notice that the finely etched floor of black stone has steadily given away to some sort of fine sand or dust. And as you encounter various statues and are captivated by these hauntingly humanoid, yet drastically super, numerary figures with various limbs and appendages, you also fail to notice how your footfalls are stirring up all of this fine dust around you. In no time, this dust adheres to your suit and each grain of the strange dust simultaneously slices into your armor and also somehow begins to absorb it. Suddenly a whole host of warning lights are blinking in your helmet's heads up display. You get you have indicators of multiple suit apertures. You have failures going on throughout the system. Your powered exoskeletal movement is completely down. Biocontainment is breached and then you begin to lose moisture and an alarming rate to the dry environment outside of your suit and to the dust particles themselves. So life drains from each of you, leaving behind only desiccated corpses within perforated technological shells, which soon splinter and collapse into shards as well. Sounds rough. Don't want to go to that planet. And actually, it kind of reminds me. I don't know. I haven't read recently to what extent this is still a concern. But I remember years ago reading about proposed, you know, crude missions for longer habitation on the moon or maybe in other places as well. Particularly, this was with reference to the moon, the idea that the that the lunar regolith had some abrasive qualities that actually would make it rather hard to deal with that. It's like sticky and abrasive at the same time and would be harmful to to space suits. And, you know, oh, yeah, yeah. There's certainly a lot of dust related concerns in space exploration, including things like, you know, dark, what happens of dark matter? Oh, not dark matter, but, you know, dark dust of some sort, adheres to your suit and then is hit with solar energy. You know, is it heat up and so forth? So yeah, there's a there's a lot we could discuss on that matter. But for this, for our purposes here, yeah, this is a little sci-fi indulgence. But this is also somewhat how Diatomaceous Earth acts on insects and arachnids as a mechanical pesticide, which is to say it's not a poison. It's not a toxin. It's not a pathogen. It kills insects via largely physical interaction with them. For starters, what's going on here is as we've been discussing, Diatomaceous Earth is abrasive and at the scale of insects and arachnids, the particles slice into exoskeletal plates, like I've seen various comparisons online, like the teeth of a roaring chainsaw, like shards of glass in a tornado. I mean, you pick the comparison that sounds the grisliest to you. And this is the this is all caused by the edges, the sharp edges of the fossilized diatoms. Well, actually, I was about to think about what is it like crawling through? And I was thinking, is it like razor blades or whatever? But I wonder to what extent it sort of would be like crawling through glass, because in the sense this material is kind of like glass. Yeah, I mean, coming back to sand a little bit, one of that we talked about different types of sand, different smoothness levels of sand in our episode on sand. And there are certain beaches that I always dig in the sand of a metabeech. And some of the rougher beaches I've been to, the ones that are where the sand is composed of like hard and visible pieces of shells. Like some of those, your hands definitely begin to feel raw after a certain amount of digging, you know? Yeah. So, you know, I can't help but compare it to that. But yeah, that's what's going on here. On one level, yes, the little particles of the diatomaceous earth, the fossilized diatoms are like cutting into the exoskeletal layer of the insects and arachnids. But on top of that, the particles are also absorptive and they are leaching away lipids from the waxy outer layer of the creature's exoskeleton. And this essentially unseals the containment suit of the insect, allowing its inner moisture to be drawn out of the body as well, killing the organism via dehydration, sometimes referred to as enhanced dehydration. And so this also works to varying degrees on snail slugs and other creatures, but it's particularly hard on exoskeleton bound arthropods. And as such, diatomaceous earth is widely used as an insecticide, the one that functions in a different way compared to what we might think of concerning like more chemical insecticides. So again, it requires external contact with the organism to work. So it has to be applied in a way that will coat the organism, cause it to be coated or work as a barrier to prevent the organism from crossing it, like almost like a magical magic circle spelled out in salt to keep a demon at bay. And indeed, salt is also used as a mechanical pesticide. You know, it draws the moisture out of bodies of certain pests or perceived pests. And also, again, it's mechanical and therefore widely regarded as safe for humans and animals that don't have exoskeletons. Again, even coming in food grade forms. So, you know, it can be used. It's often used in agricultural settings and so forth. Yeah. Now, that's not to say diatomaceous earth can't hurt you. It, you know, certainly can be harmful if inhaled. It can irritate the eyes and other tissues. Obviously, the large quantities rule is in place for this as well. But it's not going to eat through your skin and turn you into a money. Right. And so, yeah, on one level, diatomaceous earth can work like this is an insecticide on its own, but it also is apparently sometimes added to pesticide mixtures as well. And I've also read that it's it's very versatile in the ways you can use it as an insecticide or an insect barrier, you know, sprinkling it here, putting it in hard to reach places and so forth. Trying to imagine up close the magnified view of it working as a mechanical insecticide, I think is made especially grisly if you're looking at the like scanning electron microscope images of it. And you're seeing all these little sharp looking shards of these fossil shells. You know, it just looks like shrapnel. Exactly. Yeah. These pieces of the coliseums, these pieces of the old fences and all this mechanical looking. It's like the world the terminators come from. It's just like piled up scraps of things that look mechanical and things that look organic all mixed together. But it all looks sharp. It all looks like it would hurt. Yeah. Dell PCs with Intel inside are built for the moments you plan and the ones you don't. For the time you forgot your charger at the gate. Passengers, we are now on our initial ascent. Or when you're bouncing between projects like a ping-pong ball. We build PCs with long lasting battery life so you're not scrambling for a charger and built in intelligence so you can stay focused on whatever you're doing. Dell Technologies built for you. Dell.co.uk forward slash Dell PCs. Now we've already touched a little bit on the history of diatoms and anti-diatomaceous earth in terms of our understanding of diatoms. And we're going to come back to that in the next episode as well. But I was curious about just how far back the use of diatomaceous earth, particularly as a pesticide really goes. And one source I was looking at is diatomaceous earth for pest control by William Quarles. This was published in the IPM practitioner back in 1992. And citing a 1972 work by one F. Allen, the author here mentions the possibility that the use of diatomaceous earth as an insecticide might date back some 4,000 years to late Neolithic or early Bronze Age China. Wow, I had no idea. I didn't read anything about this. Yeah. Yeah. And I wasn't able to uncover a ton here. So I definitely take this with a grain of fossilized diatom. Because this is not, I don't know that this is something one can really put any hard numbers behind. But supposedly humans may have picked up on this. Ancient humans may have picked up on this practice by observing birds engaging in dust baths. So I believe we've all observed birds taking a dust bath before. Certainly if you have chickens or you just do a lot of bird watching, you may have observed this. I don't know if you've seen this, Joe. There used to be a dusty place in my backyard and I would sometimes catch birds in there. I'd see movement flapping. I'm like, what's going on? And it's just a bird in there just flapping around in the dust, just flinging dust everywhere and then flying away when I get too close. Interesting. Well, I mean, I would immediately start thinking, what's that for? What's it? Why is it doing that? Yeah, because it seems ridiculous, right? Like a bath, you don't take it in dust. You take a bath to get rid of dust. What possible good comes of taking a bath in dust? And basically it comes down to individual pest control. And it's interesting because it does seem to play a little bit. It seems like diatomaceous earth and the function of diatomaceous earth does play a little bit into what's happening with particularly avian dust baths. There are non-birds that do something like a dust bath, but for our purposes here, we're going to be looking at the birds. I looked to a paper, and this is a really recent one. This came out March of 2026 in proceedings of the National Academy of Sciences, USA, by Kuo et al., titled Mechanics of Dust Bathing in Birds. One of the things that they point out is that this is an area, the actual mechanics of what's going on here has long been kind of poorly understood. Like we see birds doing it, but do we really know like what's actually happening? I've read elsewhere that dust baths may actually mechanically impact parasites, such as mites via dehydration along the same lines as what we're talking about with the diatomaceous earth. But Kuo et al. focused mostly on wing flapping powered substrate interaction. Now, what does that mean? I'm just going to read a quote from the paper here because I think this sums it up nicely. Collision modeling indicates that the impact force from sand particles exceeds mite adhesion forces. Thus, collision is the dominant removal mechanism. Mites are removed within seconds when sand is present, suggesting that sand plays an active mechanical role in parasite dislodgements. So a bird gets in the dust, starts just whipping that dust all around themselves. And what is happening is those little particles, particularly if it's sand-like, apparently, they're like boulders smashing into mites and knocking them physically, mechanically knocking them off of the feathers of the birds. So that's pretty crazy. Now, did humans use diatomaceous earth in ancient times based on the observation of avian dust baths? Again, I don't know that we really know an answer to this. I suppose it's possible, maybe even likely. But as the researchers point out, again, the mechanics of what's going on have been at best poorly understood. But there's all sorts of things about the natural world that humans picked up on because we observed our animal relatives doing something. And on some level, we understood that they had developed those methods and those acts and those practices and those habits because they did something that was useful. I mean, I guess one thing to think about is that diatomaceous earth has a different anti-insect, anti-arachnid mechanism than the sand in this example does. Right. Like this thing, it's knocking off the external parasites. Whereas if it was diatomaceous earth, what you would probably be thinking it was doing was like eventually killing them so that they die and fall off. Right. And I think it's possible given different components in different dust or sands that you could have some combination of things going on in a dust bath. But again, I don't know that we really have everything completely squared away on what's going on with an avian dust bath. But when it comes to, say, chickens, chicken farmers, I was reading online, I saw some various threads about this. Chicken farmers seem to go back and forth on whether you should add diatomaceous earth to the dust bath portion of a chicken's living area. Some people are like, yeah, do it. Others are like, no, no, no, don't do it. They go back and forth on it. But there are some people argue that it helps them get rid of their own mites. But we're not making a call on that. I'm not making a call on that. I'm just saying there is discussion out there on this topic. Now, coming back to that paper by Quarles, he also points to some of the more recent history in the US regarding the use of diatomaceous earth and things like it. Points out that road dust was observed killing cotton worms as early as 1880. Points out that until the 1950s, clay dust, sand, and silica gel were more popular test materials than diatomite. And then insects he lists controlled by different dusts up to 1950 included the oriental fruit moth, the coddling moth larva, flea beetles, cucumber beetles, cockroaches, Mexican bean beetle larva, and stored grain pests. So there is a, even before targeted use by diatomaceous earth, there was a more general practice of using various types of dust or other mineral grains, even sand in some cases, to repel or harm insects that were considered pests. Right. Right. He writes that, quote, dust in general are repellent to insects. And he provides an overview of some of the different findings that existed at this time. Basically, different experimentations entailed different types of diatomaceous earth. For instance, looking at diatomaceous earth of marine origin and freshwater origin. Also different experiments with silica gel, grain size, sometimes factors into how effective or ineffective it seemed to be, but also different insects seem to have different vulnerability levels to diatomaceous earth. Oh, okay. And this makes sense because, again, we're talking about a physical interaction here between these little tiny shards and some sort of surface. So more vulnerable include large surface area to volume ratio insects. And this generally means smaller insects. Right. Because as you scale up, your volume increases cubically. Yeah. Right. Right. Plus insects that have lots of, he calls it body hair. We know it's not quite here. But you know, if an insect has lots of little things on it like hair that can pick up particles that can grab onto particles, that also makes them more vulnerable. Thinner layers as well can play into this. You know, again, we're talking about physical interaction. The thinner the armor, the more susceptible, the easier it's going to be for something to breach it. Yeah. And he also writes, quote, insects such as the cockroach that is protected by a low melting grease are more susceptible than insects with hardened waxy cuticles. Hmm. Now less vulnerable include smoother beetles like the confused flower beetle. When sex, that's a that's a type of beetle. Yeah. Yeah. I didn't I didn't do a deep dive on this, but that is at least the common name for it. Insects with thick cuticles. And they are also less vulnerable, likewise. And then also sucking insects that are constantly obtaining water by feeding on vegetation. They're just going to be, my understanding, their moisture, compared to, say, dry, grain feeding insects. Okay. Again, these are going to be less vulnerable. So, yeah, you're going to have a lot of variability in exactly what kind of diatomaceous earth you're you're using. And then what kind of insect is on the receiving end of it? What kind of insect or arachnid exoskeleton bound organism is on the receiving end of your sand? There is such a honey, I shrunk the kids quality to this of the, you know, the horrors that you don't even really think about because of the scale on which you exist and trying to imagine all of the different ways the world is threatening. This reminds me of, I feel like I've mentioned it on the show a million times at this point. I'm always thinking about it, but the classic JBS Hall Day in SA on being the right size, which has to do in part with the different physical forces that act on you most and represent the most threat to you when you are different sizes. So that like we at the size we are do not really have to worry that much about the surface tension of water as a physical force that can destroy us. But like, you know, small insects that can get overwhelmed by a droplet of water is like the surface tension of water is a much more threatening physical force to very small creatures. Whereas we really have to worry about gravity and tiny insects don't have to, you know, like falling for a tiny insect is not nearly as threatening. And that SA also includes, I think the part about how, you know, if a mouse falls down a mine shaft, it bounces, a human is broken, a horse splashes. Yeah. But, you know, the counterpoint to that is like, diatomaceous earth could maybe be like a lung or eye irritant to us. Like you wouldn't want to get it on your sensitive mucous membranes in certain ways. And, you know, it's not like completely harmless. Yeah, you wouldn't want to swim in its Scrooge McDuck style or anything. Right. So it's not like completely harmless, but you mostly don't have to worry about these tiny razor gears from the ancient diatoms. But for the wrong kind of insect, this is just a valley of thorns. It is just this terror. Yeah. For the wrong sort of insect, like a sprinkled line of this stuff is just a barrier of death that they either will die in attempting to cross or they just cannot cross. They just will say, no, I won none of it. All right. Well, I'm going to leave it off there. But, but I would, you know, as with any of this, I'd love to hear from anyone out there who has experience using diatomaceous earth, particularly as a pesticide or chicken farmers right in. I want your, your opinion on all of this. The chicken farming world is mostly new to me. I had some chickens stay in my backyard once, like over the course of a weekend. They were guests. I don't know what they were up to aside from just pooping everywhere. But yeah, I didn't get a lot of insight into what they wanted when it came to a dust bath. Man, you know, just last night I had an interesting experience with some overwhelming bird poop scenarios. I was, I was about to go out paddling on the river last night after work and I just happened to be standing in a place right under a part of the bridge where there are many, many swallow nests up above. And I was just notalizing, noticing like, man, I just put my kayak down and suddenly there's bird poop on it. Oh, there's more. Oh, there's more. What's going on? And then I realized all around me it was just a, it was just a, yeah, a frenzy. Yeah, it can be quite overwhelming at times. Yeah. I don't know if they all try to poop on purpose at the same time. Is that a thing? I had similar thoughts in the last week. I was, you know, I was up in Denver with my family and we did some walks and, you know, I encountered this pretty much wherever I go, wherever there are, you know, geese. But geese will just poop everywhere. And I was wondering, it's like, do they prefer to poop on human walkways? And at first I was entertaining that idea. And then I was really noticing like, no, they're just pooping everywhere. I don't think they really have a preference. But, but I don't know, this would be, this kind of gets into something we're going to be talking about in the next episode when we get into a little bit into cat litter and talk about diatomaceous earth and cat litter. But it's possible sometime down the line, we should do an episode on where to poop and where to urinate and how animals decide what is the approximate place to do this. Like what sort of material or environment should I do it in? Where should I do it? In terms of like, you know, top or bottom of a tree, that sort of thing. There are a number of, just a number of examples that come to mind that, that are, that are pretty fascinating, you know, even in a, you know, captive environment, you know, we'll see in situations where the animal will choose like a gecko will always have one particular corner in which it does its business. And I'm sure everyone out here, you know, certainly pet owners and people who raise animals can think of various examples of this as well. But anyway, it might be something we could come back to in a future episode. Yeah, cross species investigation of bathroom strategies, I think would be, would be good. Okay. Well, as we've said, next time we're going to get into more, we'll talk about cat litter, probably talk about dynamite, probably talk about more diatom biology, and, and plenty more. So, join us again next time. All right. 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