Instant Genius - The secret world hidden in the ground below us

Episode Date: August 23, 2026

Though we’re often not aware of it, the ground beneath our feet is teeming with an abundance of life and activity – from the complex networks of fungi and tangled roots put down deep into the Earth by the plants that live on its surface to the staggering variety of organisms that make their homes in the damp and darkness of the soil. This vast, fascinating ecosystem is vital for the health of the planet but remains largely unstudied. In this episode we’re joined by Dr Frank Ashwood, a lecturer in ecology and entomology at Lincoln University, New Zealand, to talk about his latest book, The World Beneath Our Feet – The Hidden Life of Soil and Why it Matters to us All. He tells us how more than half of the planet’s biodiversity is found living within soil, how the animals that live underground have inspired innovations in medicine and technology and how we may be able to use our knowledge of soil biology on Earth to help us in our quest to establish colonies on other planets. Take your curiosity further with a subscription to BBC Science Focus magazine. Every issue is packed with fascinating insights into the science behind everyday life, the latest breakthroughs and expert analysis, delivered straight to your door. Receive an extra £5 when you subscribe using the code SF5OFF, (minimum spend £20, see full terms and conditions on our website).  https://www.ourmediashop.com/bbc-science-focus-magazine-pod30 Learn more about your ad choices. Visit podcastchoices.com/adchoices

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motion. Elevate your savings with the Scotia high interest savings account. Always earn high regular interest rates that grow the more you save and invest. Conditions apply. Visit Scotiabank.com slash h-I-SA to learn more. Scotia Bank, you're richer than you think. Hello and welcome to Instant Genius, a bite-sized master class in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. Though we're often not aware of it, the ground beneath our feet is teeming with an abundance of life and activity. From the complex networks of fungi and tangled roots put down deep into the earth

by the plants that live on its surface, to the staggering variety of organisms that make their homes in the damp and darkness of the soil. This fast, fascinating ecosystem is vital for the health of the planet, but remains largely unstudied. In this episode, we're joined by Dr Frank Ashwood, a lecturer in ecology and entomology based at Lincoln University New Zealand to talk about its latest book, The World Beneath Our Feet, the Hidden Life of Soil and Why It Matters to us all. He tells us how more than half of the planet's biodiversity is found living within soil, how the animals that live underground have inspired innovations in medicine and technology, and tells us how we may be able to use our knowledge of soil biology on Earth

to help us in our quest to establish colonies on other planets. Welcome to the podcast. Thanks so much for joining us. Hi Jason. Thanks for having me. Great to have you on. So today we're talking about your book, The World Beneath Our Feet, the Hidden Life of Soil and Why It Matters to Us All. So I think the best place to start then is, you know, for anyone who has had a look at the book,

When you think about soil, you know, most people just think of the shallow bit of land that we grow food in or we plant our roses in, for example. But we're talking about a much larger and nuanced set of ecosystems. So first of all, can you tell us exactly what we mean when we say soil? Yes, soil is a very complex thing in a way in itself. It's alive. Soil is a living thing. And most people probably think, as you said, of soil as a kind of dark sort of. of mineraly, maybe organic material that you find, and that's true. But soil is a lot more than

that as well. So soil is a combination of multiple things. To make a true soil, you need the mineral components. So that's the sand, the silt and the clay. So that's the stuff that comes from eroded rocks. But that in itself isn't soil. That's just sort of eroded rocks. And so we only really tend to consider it true soil when you have a few extra things. So water is very important. not too much, not too little, as we're experiencing in the UK at the moment, maybe a bit too little. Air, oxygen and carbon dioxide are important. But the crucial thing that makes soil, really soil, is life and organic matter.

So that's when you have decomposing plant material and that kind of thing, adding carbon and nutrients to the soil, and then you've got all the life that's in there. And that's the thing that I'm really passionate about. Yeah, so we'll dig into that. Excuse the part. Sorry, we'll dig into that a little bit more as we get on. But I think something really fascinating that you talk about in the book is how, you know, going way back in time, how soil, as we know it, developed on Earth, something I'd never really thought about.

Yeah, so, I mean, we're going back many hundreds of millions of years here into when sort of around, I think around 400 million years ago, maybe a little bit before that, their plants started to actually colonize the planet, simple, simple plants. and as they broke down and as they evolved roots and those broke into the ground, they began to accumulate organic matter and unlock the nutrients from what was up till then just rock. And then once that started happening, soil began to form. And this incredibly biodiverse ecosystem that we have, about 60% of all the world's biodiversity is in the soil, began to evolve and these communities took place all around the world. It's an incredible thing.

Yeah, so you sort of split the book into different chapters talking about the layers, I suppose, if you could call that of soil. So the first one, the sort of the most visibly obvious one as we walk around a forest or something, is called litter. So what do we mean by that? And what is it? It's called litter because it sort of litteres the ground like garbage, if you like. But it's essentially leaf litter, so fallen leaves every autumn when trees lose their leaves, they drop to the floor. of the forest, or we include deadwood in that as well. And it's essentially any kind of decomposing plant material that is breaking down into the soil, that's the litter. There's also an underground

type of litter as well, which is the plant roots. So plants, roots are always dying and regrowing, and so deep in the soil, there's also this kind of input of what we call litter there, which is the decomposing plant roots. And that's really where all of the carbon goes in that fuels the food webs that take place within the soil. So it's hugely important. Yeah, so you say this, the kind of the processes that go on here are sort of the foundation of how soil is brought to life, you know, can we unpack that idea a little bit, please? Certainly, yeah. So without that organic matter input, there would be no food, essentially, for everything else that's in the soil. So you've got all of your springtails and mites and woodlis and millipedes and things that people may or

may not be familiar with all depend on the. that regular input of organic material from the plants decomposing in order to then feed them and they chew it up and they poop it out. And then that releases nutrients back into the soil for other organisms and for plants to recycle. So the soil is essentially this big recycling plant or factory that keeps nutrients and carbon sort of churning over and keeps itself kind of fueling and ticking over. And as that happens, soil continues to develop and get deeper. and over time you build up this thick layer of soil. And depending where you are in the world

and what the vegetation cover is like, you can either get sort of a thin smattering of sort of dark, organic rich topsoil, or you can have metres deep of really spongy, slowly decomposing acidic organic matter like you find under some of the boreal forests, for example, in the very north of the planet. So it's an incredibly diverse thing,

and it really depends where you're in the world as to what your soil looks like. But no matter where you are, those same processes are still happening. Yeah, so you mentioned there something called the soil food web, something that you discuss in the book. So again, that was a new concept to me.

So, you know, what is that? A food web is a way of sort of simplifying an explanation for the way that things interact with each other, the way that organisms in any ecosystem interact. So you can have above ground food webs as well. And it's basically just a way of saying how things interact with each other and feed upon each other quite often. And so in the soil,

you have lots of different levels, just as we have above ground. You know, you have predators and you have herbivores and fungivores and all these things. And they all sort of feed on each other or they feed on plants and that kind of thing. So the way that those all interact is what we call a food web. And the more complex the food web, so the more different organisms you have in your environment or doing different things or the more organisms you have sort of doing similar things, the more resilient that environment is typically to change. So you talk about sort of resilience of food webs and that happens where ecosystems or habitats are kind of left to do their thing

for a long period of time and they reach this kind of stable state. So when humans go through and we start digging up and screwing up forests or other long-term grasslands and things like that, we impact those food webs and that can create a sort of vulnerability in those habitats to change. Yeah, so we'll have a look at that in a bit. that was one of the questions that I had. But I just wanted to investigate another term that comes up quite a lot in the book.

That's humus. So, you know, what do we mean by that? Not to be confused with hummus. Which is a clangor I made while recording the audiobook. I did say hummus once I have to say. Must have been hungry. I hope that didn't make it in. Yeah, so humus is an interesting one.

It's a hard one to define. I've tried in the book. And you could ask a hundred different soils. scientists, what humusians need to get 100 slightly different answers. Essentially, it is very slowly decomposed organic matter that it's got to a point where it's unrecognizable from what it came from. So, for example, if you had a bunch of pine needles in a forest, and they were breaking down very, very slowly because they're not very palatable to soil organisms. They're quite acidic and they're very hard to digest. So they tend to break down very slowly over time, which is why we get

big spongy soils in those areas. And that material that's accumulating is humus. And it's essentially just material that's breaking down so slowly or is almost impossible to decompose that it just hangs around for a long time. And it's a really important storage of carbon. So a huge amount of carbon is locked away in heavily humic soils. Yeah. So you mentioned there the sort of the top layer, the litter. But then you've got top soil, which I think most people would have heard of if they've watched, gardener's world or something like that. And then beneath that, a deeper layer called subsoil. So how do we delineate between those two different types? That's a great question. And as always, there's no hard and fast answer really. The way we tend to do it is think of top soil as where a lot of the

interactions with plant roots happen, or at least on the surface. So you could probably say about 10 centimetres down is generally the top soil, because that's where most of the biological action is happening in the soil. So you've got organic matter from the surface being decomposed and broken down and recycled. And you've also got interactions with plant roots. And where all of those things are happening, you get a lot of life happening in the soil there. And so that's the most biologically active and the most nutrient-rich area of the soil. And so that's what we kind of tend to think of as top soil. Depending on what your soil type is, it might be very obvious what your top soil is because after that, water has gone through and leached, we call leached, basically it means washed out

a lot of the nutrients, and you get this kind of like grey subsoil that looks a bit lifeless. And then it's quite clear where your subsoil is because the top bit's darker and seems very biologically active and the rest is just like a grey slab. And it's got less organic matter in it, so it tends to be kind of a bit more pale. But that's not to say that there isn't much going on down there because there is a lot of life in the subsoil too. And there's also a lot of carbon locked away down there. So it is really important. It's just a bit of a different habitat than the topsoil. Yeah, so you mentioned there the huge amount of biodiversity within soil. So let's have a look at some of the things that make

their homes there. So we'll have heard about things like, you know, earthworms and, you know, various invertebrates that live on the surface. But as you go further down, there's all sorts of fascinating things down there, aren't they? And one that you mentioned is, one of our team's favorite is the tardy grade. So what can we say about those? Yes. So this was actually my favorite chapter to write, I have to say. This was the one I was really looking forward to when coming up with the idea for the book, because it's a chance to get a bit weird with things, because the subsoil is this realm where almost different rules kind of apply, if you like. So, you know, it's lightless. It's quite compacted. The what we call poor spaces, which is the

amount of open, kind of gaps in the soil are quite limited compared to the topsoil. So all of the animals and other organisms that live down there are facing quite a lot of interesting challenges. And as a result to that, they've adapted these incredible ways of getting around either drought or flooding, low oxygen, all these kinds of challenges that they have to lightlessness. There's no light down there obviously. So they have to kind of sacrifice their eyes. There's all these incredible adaptations that they make for life down there. And so I really enjoyed writing that chapter, drawing out just how alien the creatures might be to us down there, but just how incredible their evolution is to get them to the point where they can actually survive some of the harshest

conditions on Earth. And one of the champions of that, of course, are the tardy grades. So you do find tardy grades elsewhere. You can find them, if anyone wants to go and try and find a tardy grade for themselves, an easiest thing to do is probably to get a bit of moss off of brick wall. and wet it, put it in a little dish of water and sort of squeeze it a bit. And then if you've got access to a hand lens or a sort of low-powered microscope, you could probably see some tardy raids swimming around in there. But they're quite small, so they are quite hard to find, very hard to see with a naked eye. But pop them under a 10-time magnification lens of some kind,

and you'll see them swimming around. But they're incredible survivors. So they can withstand easily most of the negative things that soil, life on earth, can throw at them, drought, an oxia, so no oxygen, water logging. They can survive, not that they need to in the soil, but we know that they can survive the vacuum of space. We know that they can survive incredible amounts of radiation, solar radiation.

So they've been sent actually out into space and tested. And tidy grades were exposed to both the vacuum of space and intense solar radiation outside the spacecraft. And then when they were brought back in, not only did they wake up and get on with their day, but actually some of the females gave birth as if nothing had happened. So they just don't care. But they've got this incredible ability to go into a thing called a ton state,

which is essentially they shut down all of their metabolic processes essentially. And they just kind of go to sleep. They shrivel up. They look like a little pale raisin. And they just ride it out. And they can ride out basically anything, we think. Two and five Canadians will hear the words, you have cancer. That's why every step and dollar.

raised matters. On September 19th, join thousands in Toronto for the Princess Margaret Cancer Foundation Walk. Challenge yourself, friends, and family to walk 21 kilometers in support of life-saving research. Together, we can carry the fire and help create a world free from the fear of cancer. Register today at pmcfwalk.ca.ca. This episode is brought to you by Accenture. When your advertising operations fall out of sync, everything else fall. follows. Spotify and Accenture are working together to reinvent the rhythm of ad sales, using automation, analytics, and smarter workflows to simplify campaign delivery and access better data across the business. The result? Less time spent on operations, more time connecting brands with the moments and fandoms

that matter most. Learn more at Accenture.com slash Spotify. When you're a mid-sized business, you need every competitive advantage you can get, like an AI solution that works for you, not against you. SAP Grow is built with AI embedded at its core, working across every system, and it's ready to go from day one so you can hit the ground running. Bring it with SAP Grow, AI Cloud ERP for any size business. Yeah, so sticking with these bizarre creatures that are making their homes down there, you also write about a really unusual millipede that sounds like something from a science science fiction film. Can you tell us about that? Yes, so this is Umilipi's Persephone. So it's

actually the world records holder for the legiest animal on earth. And it is the world's only true millipede. So millipede means thousand legs. But up to this point, until a few years ago, no milipede had been found that actually had a thousand or more legs. And so a few years ago in Australia, a chap called Bruno Bazato, who I interview in the book, actually, he discovered in a thing called a trog trap, which is a special piece of equipment that people lower down into holes in the ground, deep mining boreholes. And it essentially is like a can filled with organic matter. And you lower it down on a string down these deep, deep, deep boreholes. And any creatures that are living down there will be attracted to the organic matter and

climb through holes in the side of the can into this material. And then you raise it up after a period of time a few days or weeks and you can then see what's what's crawled in there and the team behind this discovery found these incredible tiny little vermicelli noodle looking millipedes and completely pale blind and they had well over i think it was 1,200 and something legs so that the world's first true millipede and they live very deep down in the ground not not something you'd expect to find but yeah it was it made the they got a nature paper out of it and they called it it's Eumiliope's Persephone, so Persephone named after goddess of the underworld. So, yeah, quite an incredible creature.

Yeah, so that's a couple of examples. But we're only sort of just starting to understand what's going on down there, aren't we? And it's likely home to a kind of gold mine of undiscovered species. I mean, can I say that? Yeah, 100%. I make a point in the book that we always say we know more about the surface of the moon than we do about the bottom of the ocean, and that's true. But I make a point of saying, actually, I think we know less about what's going on in the soil than we do about what's going on in the bottom of the ocean.

And there's going to be a lot more happening in the ground. So we don't know at all what's down there, really. And there's all this potential discovery for incredible evolutionary adaptations and just incredible creatures that kind of boggle the mind. And we're not really looking. There's not the money for it or perhaps the sort of research incentive to go down there too much. but we just have this vast, untapped reservoir of biodiversity. And we risk losing it as well. It would be good to look and see what's actually down there

because, you know, we are having a huge impact on the ground. Humans are impacting the soil a lot. And we don't really know what we're losing before we lose it, which is, I don't know if that's better or worse, to be honest. But, yeah, it'd be nice to have a look. Yeah, so sort of sticking that, you touched on all the kind of fascinating adaptations that the life down there has.

And, you know, how about that opening up, you know, the discovery of some of these, opening up the possibility of discovering new medicines or even new technologies? Yeah, well, chapter five in the book, I talk very much about the technological and other benefits that we've sort of gained from soil organisms as a kind of way of revealing to people just how important soil is to a source. So one of the things that people don't know is just how dependent on soil we are for life-saving medicines. So pretty much all of our antibiotics come from soil organisms, mostly bacteria, some from fungi. And they're essentially weapons that the microorganisms are developing to sort of either fight for domination with each other down in the soil, or even to communicate with each other. We think sometimes these antibiotics actually have more of a communication purpose between these microorganisms. But either way, we rely on those desperately and more so now than ever with all of the antimicrobial resistance

that's coming up. We desperately need to be able to find more drugs of last resort if you like to protect us from bacterial infections as they get more resilient to the antibiotics we're using. So we're hugely dependent on the soil. We depend on soil for 95% of our food. And, you know, that's produced only from healthy fertile soil, which needs a lot of good, healthy, resilient food webs and biodiversity happening in the ground to keep those nutrients turning over and keep the crops growing. So it's really in our best interest to protect the soil. Technologically, we've made some startling discoveries from things living in the ground. So one of the things that I like that I talk about in the book is slime mold network adaptation design that we've developed.

So there's these creatures called slime molds. They're just say creatures, they're organisms. They're neither fungi nor animals nor plants. They're something else entirely. And they're these single-celled organisms, but they can get very, very big. and they're one cell technically, but they're packed with lots of nuclei, and they spread out all across their environment. So picture a log, a decaying log in a forest.

And some people may have seen this. If you roll it over, sometimes you can see this sort of vast web of yellow slime that's branching out across the log. Well, that's a slime mold, and it's looking for food, essentially. But what's really incredible about them is when they move throughout their environment, they do so in an incredibly efficient way. So once they've located a morsel of food with a bit of branching protoplasm, they will then engulf that and then sever off all of the other unnecessary connections

between that point and the rest of the body. So that all they're left with is the most efficient route from the rest of the body to that piece of food. And by mapping how they do that, scientists and network engineers have been able to use slime mold intelligence, if you like, to actually refine human networks and find the most efficient routes between things. So that's been applied in some incredible ways. So a lot of freight networks and logistic networks around the world have been sort of redeveloped based on slime mold technology

by looking at the existing way that we move things around by sea or by land and saying, well, what would a slime mold do? And you recreate, you know, it was originally done in the lab and now it's done using computer simulations, but you can use slime mold thought processes to actually find more efficient routes to places and more resilient ones, so more disruptive to change. Two of my favourite applications of it, though.

One, it's been used to find the most efficient way out of an IKEA showroom, which is quite useful potentially for some of us who don't like shopping. And also, it's been used even to map the pattern of dark matter around our universe. So predictive slime mold technology was used to suggest where dark matter might appear. And then it was used overlaid with where we've seen signals from a Hubble telescope. And as predicted, the slime mold was correct, and it's allowed us to actually look at the fundamental underlying shape of our universe. So some incredible things have come from soil organisms that you wouldn't necessarily expect. Yeah, so as we've established that, like, soil is an absolutely fascinating ecosystem that, you know, we can learn all sorts of things from.

But you touched on it a few times there that it may be under threat. So what are some of the biggest threats facing our sort of soil? all ecosystems at the moment? Well, unfortunately, humans are probably the major issue that we face. So obviously through fundamentally changing the landscape, through things like deforestation or changing from natural forest cover to sort of monocultural plantation forestry, all these things have impacts on what's going on in the soil below.

Intensive agriculture, you know, clearing forest for intensive agriculture is one of the major threats that soil faces. And if you think about it, instead of going from a system where you've got organic matter being put back into the ground, into the soil through leaf litter. We've talked about litter. So those inputs of organic matter that happens in a natural system. Instead, now we're going to almost exclusively just taking from the soil in agricultural settings. So unless organic matter is put back in, we are kind of actually depleting the soil of organic matter and nutrients, which are really important for its structure

and its ability to withstand things like flooding or drought. And as we're seeing now, with climate change, there's increased severity of drought and flooding, and like the UK this year has had four successive heat waves and droughts. So all of these things are impacting the ability of the soil to hold itself in place and not be what we call eroded. So as we continue to deplete soil through changing land use and through intensive use of it, it becomes vulnerable to either blowing away or being washed away from flooding. And that's what we're seeing around the world on a really frightening scale, actually, because we're losing a great deal of the world's productive top soils through intensive agriculture and other things.

And it takes a long time for soil to form. Soil is not really a renewable resource. It can take anywhere from 100 years to 1,000 years to naturally create even 2.5 centimetres of topsoil. And most crops need about 15 centimetres of topsoil to grow. So you can kind of see that we're potentially doing things in a way that isn't really sustainable. And so that's the real challenge now is to recognize that and start to make changes in how we do things and hopefully put protecting soil into law, into policy, so that we can continue to feed ourselves, essentially, as well as protect all the biodiversity that we need for our planet to flourish.

So yeah, there's a lot to do. Yeah, so obviously sort of monitoring soil health. It's not as if like sort of monitoring wildlife above ground isn't difficult enough digging. further, deeper into the ground, adds an extra level of complication. But you talk about this idea of ecoacoustics to monitor soil health, you know? Could you tell us about that? Yeah, eco-acoustics is a really fascinating area. It's quite a new and emerging area of research. And it's been used in a lot of things. Before soil, it was used in sort of marine surveys, really effectively. And people would have heard about listening for Whale song and how that's been disrupted by shipping and that kind of thing. So that's

application of eco-acoustics in water. You can apply it to soil as well and that's essentially you're putting a microphone into the ground and you're just listening to, I'm simplifying it a bit, and you're listening to the sound of soil. And it's an incredible symphony of things happening down there. And you can hear earthworms moving through the ground as they, and as they scratch through earthworms, they look smooth, but they've actually got lots of backwards pointing little teeth almost running the length of their body. And you can hear as they're sort of scraping through the soil and pulling themselves along. You can hear water bubbling through plant roots as they push through the ground. You can hear the scurrying of ants and wood lice and other

creatures picked up on the microphone. So you get this incredible soundscape of life in the soil. But it's beyond just being pretty. And it does have a very nice kind of ASMR vibe to it. It's also really useful for monitoring potentially. So you can hear with a little refinement, because it's still early days. It's difficult at this point to pick out individual. organisms perhaps or to do it in a way that might replace traditional sampling or surveying where you have to actually extract the organisms from the soil and look at them and see what you have. We're not there yet, but there's no reason to think we might not get there with a bit of bit more practice and refinement. But you can hear the difference between a healthy, rich

soil abundant in life and perhaps the soil that's not got as much going on. And so it's a nice way of demonstrating in a different medium, just how human impacts might affect soil or how different treatments might be improving soil biodiversity in an agricultural field, for example. You know, if you're trying out different things, you can listen and just hear how much life is going on in there. Is there any difference and how much different variety of life is in the soil? It's really great. If you can hear the videos on YouTube, I encourage people to go and Google it or put it on YouTube and see if you can find these videos. because they're wonderful to listen to. Very ASMR, like I said.

Great. So let's leave Earth then and think about future settlements on other planets, which is something that you discuss. And whenever this topic comes up, people often talk about terraforming. So what are some ideas that we might have about that? Yeah, so that's one thing that in the chapter 5 where I talk a bit about this, the technology from soils was, it was new to me when I was researching for the book, actually. I was quite blown away by just how many technological advances and ideas people have gained from looking at soil creatures for when it comes to, or soil organisms, for when it comes to colonising the stars. So some examples are, obviously, it takes a lot of effort to send things to the moon, for example,

or to Mars. And to ship materials and equipment and things there is very energy intensive. So what would be better is if you could actually build things in situ rather than ship building materials to these places. And there are bacteria that can be used to actually calcify and create bricks, if you like, out of inert lunar dust. So by inoculating moon dust or Martian regolith with these microorganisms, they can actually create essentially bricks that you could use in place to build settlements on those planets or on the moons.

So that's one thing. Also, in terms of digging for resources, there are probes that have been developed that are based on earthworms for digging into the ground because it's very difficult. You need a lot of leverage and anchorage to anchor a drill on a planet, especially if there's not much in the way of gravity. What would be more efficient is if you could just get something like an earthworm shaped robot and put it into the ground and let it dig and burrow its way as it pushes ways across. And actually those have been developed or they're under refinement at the moment are sort of probes for digging on other planets based on earthworms to either look for minerals or to help to create infrastructure for human settlement. So there's some incredible stuff that you wouldn't necessarily think of that being developed

based on soil organisms. Fungi could also be used to grow insulation and building materials that could be used for human settlements on the moon and other planets as well, which is another thing. So on Earth, people are starting to look at the use of what's called mycotecture, which is fungal architecture, for building either insulation panels or even actually building buildings themselves. And they're biodegradable at the end of life as well. So they don't last as long as bricks and mortar, but you can recycle them and break them down and just use them for farming mulch. So you could, in theory, have sort of NASA has actually been looking at this, creating human settlements on the moon and Mars. And then at the end of life of those buildings, recycling them and using that organic material

to actually help supplement the agriculture and the farming that would need to take place on those planets to sustain any human settlements as well. So this kind of holistic, cyclical kind of nature of developing human settlements and other planets. And it's all based on, yeah, soil organisms essentially. Yeah, all really fascinating stuff. So just by way of closing, you know, for somebody listening whose interest might have been piqued by some of the topics we've just been talking about.

What are some ways that they can go about, you know, finding out more about what's going on beneath their feet? Well, everybody, hopefully, most people listening, will have access to some sort of soil in their local area, whether it's a garden or a park or something like that. And the easiest thing to do, if you want to manage your patch of soil for biodiversity, is to make sure that you have some areas

where you've got organic matter laying around, so either mulch or leaf litter or the... some logs or even put some rocks and stuff like that down on the ground and leave it for a while and then hopefully things will begin to colonize there and do quite well. And then what you can do if you want to go looking for these things is to turn over those objects. That's probably the easiest thing to do is go find a log, go find a rock and just flip it over gently and have a really good look at what's on the underside because it will surprise you. If you've got access to a little hand lens, so something five times or ten times magnification, even like a reading lens. But

if you can get a hold of something like that, just get your head down there and have a good close look at what you can see. And you'll see things like springtails and mites. You might see an earthworm. They often build a kind of tunnel in an interface with a rock between the rock and the soil. All these things will be there taking shelter under those objects. If you really want to get a fancy with it though. What you could do is if you've got a lamp with an old school light bulb, so unfortunately you need it to generate heat and light, what you could do is take some soil or take some leaf litter and put it on a sieve and put a little cup underneath that sieve, and then you have the lamp over the top of it shining down and that will drive all of the

soil animals that live in the litter and in your soil sample. It will drive them downwards and they'll fall through your sieve into the cup and then you can take a good look at them and it'll be much easier than having to try and sift through the soil to find them. So that's my suggestion. That's a thing called a Tullgren funnel that you'll have just made, which is essentially what soil ecologists, scientists like myself, used just on a more industrial scale to see what's living in the soil. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Dr. Frank Ashwood. To discover more about the topics we've just discussed, check out his book, The World Beneath Our Feet.

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