The Infinite Monkey Cage - The Magic of Mushrooms

Episode Date: July 15, 2023

Brian Cox and Robin Ince find out about the secret world of fungi, hidden beneath our feet. They are joined by biologist Merlin Sheldrake and mycologist Katie Field. They hear about the hidden life of fungi, including their hundreds of mating types, predatory behaviour and crucial role in life beginning on Earth. Katie shares how mycologists like her are using fungi to come up with creative solutions to climate change.New episodes are released on Saturdays. If you're in the UK, listen to the full series first on BBC Sounds: bbc.in/3K3JzyFProducer: Caroline Steel Executive Producer: Alexandra Feachem

This is the first radio ad you can smell. The new Cinnabon pull-apart only at Wendy's. It's ooey, gooey and just five bucks for the small coffee all day long. Taxes extra at participating Wendy's until May 5th. Terms and conditions apply. BBC Sounds. Music, radio, podcasts. Hello, I'm Brian Cox. I'm Robin Ince and this is the Infinite Monkey Cage. And this is entirely true, by the way, before we actually do start doing the show.

I nearly capsized this show because Brian almost doesn't want to do the show we're going to do tonight. Because on the way here, as usual, I stopped off in a second-hand bookshop and picked up a few things, and I found a book for Brian that he's been so obsessed with for the whole afternoon

that we've done almost no research whatsoever right and some of you go oh I imagine it was a book about the event horizon or Lagrangian mechanics or the delicious wines of the Meursault area in France but it's not what book did I get you? Buses Illustrated. I saw that in a shop in Chorley Wood, right? And I went, if I give that to Brian, he won't even notice the shiny things. He'd been so excited.

This is it. The Guildford chassis went out of production some years before the war, but you often still see them on the road. The Guildford chassis. Guildford chassis fans in? Yes. I gave him that for about an hour and a half,

and he was going, oh, look, and there's a map of various different routes many of them discontinued in the oldham area and uh and then there's there's an illustration isn't there there's a see-through bit of bus that you were particularly keen on in here and liverpool corporation passenger transport bus fleet it's got all of them here a42 a43 to 82 a83 to 101 a102 A113 to 142, A143 to 178. And if you think, oh, but does it get racy? Yes, it does.

An unusual conversion. What became of an old Southend trolley bus? Well, you'll have to listen to next week to find out. Today's show, I should say, is not about the science of buses or the pseudoscience of the Segway. We are actually talking about fungi, if we've actually done enough research in any way to talk about fungi. You can tell, can't you, that we were a bit late on the script.

The most logical link we could come up with was not buses but fungi. Yeah, we are definitely going back on the BBC Segway course, I think. Do you want to get on the Segway? You can get on a bus. Exactly. I knew this was going to happen. You have not... Segway, not Segway. They're homophones. So anyway... I bet he's a fun guy at parties. This show is cancelled. We are not doing this.

Today's show is about fungi. What are we going to be talking about? Today, we are discussing the magic of mushrooms. How important is this often overlooked kingdom of life? How do they live and what is their role in the past, presence and future of life on Earth? Joining us to discuss fungi in all their endless forms, most beautiful, we have a professor of plant soil processes, an expert on mushrooms, the winner of the Royal Society Science Book Prize in 2021 for a book on mushrooms, and the last connection is far more dubious someone who is

not that keen on the horror film shrooms which is short for mushrooms anyway they are hi i'm casey field i'm professor of plant soil processes at the university of sheffield and the thing that surprises me most about fungi are that in a single gram of soil, you can have up to 200 metres of the fine thread-like filaments that we call hyphae. Wow. I'm Merlin Sheldrake. I'm a biologist and a writer. I do research into fungi and I become confused,

ever more confused at the weird and wonderful things that they can do. The most surprising thing about fungi is that they're able to solve massively complex problems without a brain. The opposite of the current government. I'm Phil Wang. I'm a comedian. And I think the most surprising thing about fungi is that shiitake mushrooms are a great way to sneak a swear word onto Radio 4. And this is our panel. Now, we should start off, when we did the sound check, Brian suddenly got worried. He went,

but is it fungi or fungi? Or is it, so first of all, what is the correct pronunciation? I know three ways you can pronounce fungi. You can have fungi, fungi, or fungi. I think it's a matter of personal preference. And Merlin, how do you feel? I agree. I always go with fungi. I find fungi a bit strange because I don't say fun-jus, so I figure that I say fungus, I'll say fungi. And Phil, do you say fun-jus? I say fun-gi. I don't know, it's just agis? I say fungis. I don't know, it's just a personal preference. I like fungis, because then you've got Raymond Briggs' Fungis the Bougie Man,

which is just a lovely kind of sounding name to me. Katie, now we've got the language out of the way, fungi. What a typical thing of a physicist to say, now we've got the language out of the way. Nonsense. We'll be using a nonsense system instead but fungi what are they so fungi i mean they're an entire kingdom of life all right so you have animals

plants bacteria they exist in loads of different forms so you can have filamentous fungi which are the ones that kind of exist as really fine thread-like filaments. You have single-celled fungi, things like yeasts. You even have aquatic fungi. So, I mean, they're an entire kingdom of life. I didn't know that yeast was a fungus. Is that obvious? Is it just me? Well, let's put that to a vote. Who thinks Brian has shown himself to be a yeast

and therefore baking fool? How many different species of fungi are there? It's a good question. The numbers that are currently bandied around range from about 3 million to 6 million. The second thing that you hear is that we've only described less than 10% of those millions and millions of species.

It's remarkable because when you think about it, as you said, a kingdom of life. The idea that there are millions and millions of them, can you give me some sense of the diversity of fungi? Do they range in size and form? So I think when we talk about fungi, most people kind of think about mushrooms, right? But in reality, the mushroom is just the fruiting body of a fungus.

So what you don't see when you see a mushroom perhaps sprouting out of the soil is kind of the acres of hyphae that actually grow underneath it and are the main body of the fungus itself. There's so many species and so many different types. Decaying fungi, the ones that kind of eat dead stuff and decompose it. You have pathogenic fungi, things that cause diseases. You have my particular favourite fungi, the mycorrhizal fungi. They're the ones that form partnerships with plant roots and help plants to grow. Yeah, you've got all the single cell fungi then.

So things like yeasts, without which we would not have bread or wine or beer. And you used a singular when you said acres. Is that a single living organism? Okay, so this is a really controversial point. What is a single fungus? what is a single fungus what makes an individual fungus and that seems really obvious when you're talking about things like animals or insects or birds reptiles etc but for a fungus that exists there's like this network of threads that grow through stuff eating it as it goes they don't exist as a single entity in the way that we know it right

if it comes across another thread like filament they can just fuse and become one they can move nuclei between each other and kind of still just be one so it's a big debate actually in the fungal community as to what makes an individual fungus and what side of the debate do you land on i'm on the side of the debate that this is a debate without a firm answer, because it's just endlessly confusing. It's one of the ways that thinking about fungi makes the world look different. Well, hang on a sec. If we've been told that individuality is so important,

if we live lives in societies where we have passports and have to fill tax returns, and all of this reinforces our understanding that individuality is just a basic part of being a living organism. Then we get so confused when you have a network and you can take a fragment of that network and grow it over here and you can take endless fragments of this network and grow them into separate networks which would appear like separate organisms doing their things, looking after themselves,

and they could all fuse again to form one network. So I don't think there is a good answer, which is why it's so fun to ask this question. So, Phil, how do you... I mean, that phrase, the fungal community, first of all, is something rather magnificent. But to me, initially, that would sound like a group of people at a gym, all who have athlete's foot.

You know, there's a kind of... What is your initial reaction to fungi? I have had reactions to fungi, but I've got a cream for that now. I think, obviously, the poster boy of the fungal world is the mushroom. And now, of course, I'm into, because of The Last of Us, which was a very popular video game, and then a TV show, which is all about a fungus taking over the world. I mean, a fungus is cool, man. And I'm into that kind of fungus too. So edible fungus and fictional fungus. Those are my specialties. Have you ever been in that kind of fungus too. So edible fungus and fictional fungus.

Those are my specialties. Have you ever been in that group of comedians who sometimes gather on the last night of Glastonbury, find something that's grown underneath a tree, eat it and are then found in a little chef some months later, confused but filled with the strangest of dreams? Are you talking about wacky fungus? Wacky fungus, yeah. Yeah. Are you talking about wacky fungus? Wacky fungus, yeah.

Yeah. I've had some wacky fungus. I lost all sense of time. I don't know if this will annoy Brian, but... LAUGHTER But time stopped existing, which would put Brian out of a job, so I... Well, no, it didn't.

Sorry? It didn't. I'm telling you, man, you weren't there. Could you talk through the history of fungi? So in terms of the history of life on Earth, where do we first see them emerge? Yeah, the history of fungi, it goes way, way, way back, far beyond animals, far beyond plants even.

I think the oldest fossil fungus that's been found was more than a billion years old. So they existed on earth way before other terrestrial life forms. And then about 450 million years ago, some algae washed up onto the shores. If you can imagine sort of ancient earth shores before there were any plant life or any soils. And the fungus made contact with these algae and they actually helped the algae turn into plants. So the plants we see on the land today are descendants of a merger if you don't know what the correct term is between algae and fungi? Kind of yeah so it's a little bit unknown whether the first plants when they came onto the land

it's a bit unknown whether they brought the fungus with them and they were already a partnership, or did they form partnerships with these already terrestrial types of fungi? Why they did it is kind of interesting. It kind of makes a bit of sense when you start thinking that Earth at that time, it didn't have soil, right? It was just bare rock.

It was kind of skeletal, sort of primordial rocky soil type stuff that isn't actually soil. And those first plants that came onto land, they didn have roots either they just had like hair like rhizoids we call them the kind of like single cell projections they form these partnerships with fungi that then are able to sort of secrete acids which then dissolve rock and then they can assimilate the nutrients that come out of the rock and they then transferred it to those first plants coming onto the land so in that way they then transferred it to those first plants coming onto the land.

So in that way, they actually helped nourish those early plants and helped them kind of get a foothold on land. What did they have to gain from that? What's in it for the fungi? Exactly, what's in it for the fungus? Carbon, right? Yeah, tell us all this stuff. Yeah, so especially, again, it makes sense.

When you start thinking about what conditions were like on early Earth and there's no soil, there wasn't that much organic organic matter around so these early fungi didn't have much to eat they weren't able to kind of degrade stuff and so these little plants coming onto land they're basically like sugar factories right they're doing photosynthesis they're turning sunlight and water and carbon dioxide into sugar and the fungus by hooking up with a plant is able to access that sugar so it's like a ready meal almost for it so they're kind of exchanging nutrients that the fungus is getting from the rocks for sugars that the plant is making so the initial colonization of the land on earth

was a symbiotic relationship essentially probably yeah probably there's these amazing fossils from a place called rhynie which is up in scot. And they're like the most amazing set of fossils of early plants. And the fossils are so incredible that you can even make out in individual plant cells. You can make out fungal structures from these 420 million year old plants. When you start thinking about the implications of that, it really blows your mind because plants coming onto the land started changing the atmosphere. They started sucking CO2 out of it. And as they got bigger and the demand for CO2, so carbon dioxide for photosynthesis, got greater, that caused a huge crash in carbon dioxide in the atmosphere,

but also a huge rise in oxygen, which made the atmosphere breathable, which meant animals could then evolve and start breathing oxygen. And eventually gave rise to us right so really we're only here because of fungi and they're almost hidden from you today are overwhelmed by the other kinds of life on earth but i think i read somewhere that there were fungi that were huge things like house-sized things living on the on the land at some point in the past there are vast fossils a whole lineage of life called Prototaxites, and people have found these fossils. They're huge. They could be eight metres tall. And people have speculated

for a long time about what they actually were. And we still don't know for sure what they actually were. But after various hypotheses and replaced hypotheses, we've sort of ended up at a place where they're at least part fungal, it seems. Eight metres? Does it look like a mushroom? It looks like an eight meter tall mushroom obelisk no this is artistry constructions of these things and the fossils are imperfect and this is maybe like those those fantasies about what dinosaurs used to look like and are they predominantly now below ground most fungi are they mainly now below ground so so fungi put themselves in their food this is one of the key things about them.

Animals tend to put food in their bodies, but fungi put their bodies in their food. And that makes it hard to study them and it makes it hard to see them. But I like to think of it from the fungus's point of view. And so when I see a big tree, I think of the big tree as the fungus's sort of prosthesis, the fungus's way of getting above ground and interacting with the sun and with the air. So rather than just fungi being a sort of closeted underground and not visually expressing themselves katie how much has your vision of the natural world changed exactly in that way that merlin was just saying that suddenly a wood or a tree or those things around us where there might be life that is perhaps even invisible how much does that change the visualization you have of that environment i think when you start

realizing when you're just walking around even in urban environments in city centers right more than 90 of the above ground plant growth that you see is associated with some sort of fungus underground right so when you start thinking about that and you start thinking how complex the above ground world is you know it it's at least as complicated as that below ground, probably more so. I've seen apartment buildings in London that are completely fungus. So, yeah, I guess it really does change the way you think about the natural world.

There's this whole unseen world that we don't necessarily... It doesn't get the sort of press, I guess. It doesn't get the public appeal of, we don't necessarily it doesn't get the sort of the press i guess it doesn't get the public appeal of i don't know pandas in a bamboo forest right but it's as important we've dealt with that in the past about pandas being overrated and the boat was in tart yeah lazy lazy pandas oh no so i wanted to say phil you just mentioned that i want to find out you know where you know we would find fungus, where the people listening to this at home, where they're most... So just taking your home,

where would you imagine are the most likely places to find outcrops of fungus? OK. Oh, man. Well, outside of my body, probably... Well, I guess anywhere moist, right? You know, like my feet or just corners of the bathroom or I guess a shower.

There must be a lot of fungus in the shower. You can get products to help with that. Is that the feet or the shower? All of them. It does raise that question, doesn't it? So how many different species of fungus are currently living on Phil? Phil, if you just start to pop behind the curtain. raise that question doesn't it so how many different species of fungus are currently living on phil i think there's going to be a lot i mean you'll serve like the arid deserts of your forearms are going to create habitats for certain types of youth with very different types of habitat from those that live in your ears and and on your scalp so you are a planet to endless micro fungi

happily making their lives evolving, doing all the things they do. And that's before you get onto the ones that are inside you doing all sorts of other things. So I think it's an unknowably large number. It's a wonderful review, isn't it? You are a planet of fungi. We all put on weight in lockdown, right?

But it's a large number. So it's hundreds and hundreds and hundreds every individual can we begin to characterize them as you said katie rightly this is a whole kingdom of living things and you mentioned a few of them you mentioned the decomposers the parasitic fungi predators so what does it mean to be a predatory fungus so i guess it depends how you think about predatory if you think about a fungus that wants to eat a block of wood, is it predating that wood? And you can think about it like that.

You can put a block of wood on a dish and you can watch a wood-rotting fungus explore the dish and then find the block of wood and then prune back the parts of its network that don't go anywhere and consolidate this highway connection with the block of wood. And that's a kind of predation process, I guess. But there are fungi that do hunt animals in a way that in more familiar kind of predation to us and they hunt nematode worms and there's lots of different ways to hunt nematode worm this is an ability that has

evolved independently in different parts of the fungal lineage some are able to they eavesdrop on nematode life by being sensitive to chemicals that nematodes produce to do basic things like reproduce and communicate with each other and some fungi produce nooses which lure nematodes towards them and then the nematode goes into the noose and then the noose inflates in a tenth of a second immobilizing the nematode giving the fungus time to grow through its mouth and digest it from the inside you know are other ones that produce stalks. You sound so casualist. The most horrifying thing any of us have heard all day. It gets worse. There are ones that produce stalks, oyster mushrooms. Many people might enjoy eating oyster mushrooms, but if they are hungry, then they can produce stalks with a poisonous droplet

at the top, which attracts, like a beacon attracts nematodes to hit the toxic droplet they get paralyzed again giving the fungus time to grow inside it but you have perhaps the weirdest ones i find are the ones that they produce mobile cells little swimming cells they swim through the watery soil films and they're attracted to nematodes and when they get to a nematode they stick to it and they harpoon it with a specialized kind of cell called a gun cell giving the rest of the fungus time to grow up and to catch up with this site of this kill and make merry so it's lots of ways to do it phil what i need to say by the way is merlin was i think very calm there compared to last week we did bees versus wasps and at least when you were talking

about the nematode infiltration there you weren't smiling smiling gleefully. But Dave, who we had on last week, when he was talking about the genitals of a bee exploding, you had a face like a clown. It was terrifying. You will find out as you hang around these scientists, more often than not, that there's something a little bit evil about them. I think that's one of the less evil ones.

Are fungi quite... Are they almost sentient then? They sound like a little more active than plants. So fungi are actually more closely related to animals than they are plants. Even though they're quite often lumped in with plants, they share a lot more in common with animals. Right, so I can tell all my vegan friends they can't eat mushrooms. Because that's burgers done for them. I mean, they don't have a brain it's a much a definition isn't it of what you consider consciousness as and sentience so i mean they don't think in the way that we

think that we can think about thinking perhaps but i mean that's not to say they don't they have their own agenda and they're doing their own thing it It's almost impossible for us to understand, right? They're kind of like aliens. They're just an entirely different life form to us, or animals. Could a fungal network grow large enough that it effectively becomes a big brain if there are enough separate processes going on in it? I wouldn't have thought so.

It's rare that you get such a definite answer, so thank you. I love that question because it also sounds like a pitch for a film. We talked about the predatory fungi. The one I think you said before we came on, the one your students like to talk about most, I ask you to describe, are the parasitic fungi. As if it wasn't horrific enough, could you go to the parasitic fungi? Yeah, so these are the ones I think, is it The Last of Us?

Yes. Yeah, The Last of Us was inspired by... They might have scorned on your face. The cordyceps. Well, I've not seen it. I've that is it The Last of Us yes yeah The Last of Us was inspired by the cordyceps well I've not seen it I've never seen it I need to watch it because it's all the students go on about at me. Bill can you just explain it before so let's have first of all can you give us the yeah this is my one opportunity to be the expert tonight. So in the universe of the last of us a cordyceps starts to take over the minds of humans and they become zombies basically and the fungus uses them to infect other people and eventually grow like a huge underground network and could they connect all the zombies up it's pretty cool and i think it's all very scientifically accurate okay so it's definitely inspired by real

fungi and real stuff that they do right so there is a parasitic fungus called cordyceps that will kind of infect insects and then it kind of takes over their brains and it causes them to do all sorts of weird stuff so it can actually it can make them commit suicide in some cases or it can it kind of grows out of their heads in an advantageous spot for the fungus to disperse its spores so it'll make them climb ridiculously high structures for an ant like grass which for an ant is pretty big right yeah yeah so it'll so it can they'll grow up to the top of these stalks where the fungus will bust out of its head and produce its mushroom, which will then kind of disperse the spores from a height

at an advantage to the fungus. So from a fungal perspective, this is a big challenge. How does a fungus get into this animal body? It's got an animal body, an animal nervous system. It's doing all these animal things, this locomotion with twitchy, muscly organs. And the fungus has got to get in there and it's got to puppet its behavior. It's got to take over this animal body, whether it be a cicada, an ant, a spider. And the fungus can puppet the behavior

of these creatures with exquisite precision. Carpenter ants, for example, they have the Ophiocordyceps fungus, which cause it to as Katie says climb up high but not just climb up high but bite onto not just the underside of leaves but to the veins on the underside of leaves and infected ants orient to the direction of the sun and most of them bite around noon and this is the time when the fungus is most able to spread its spores so there's these wild questions over how is it able to do this? It seems to be able to produce dynamic cocktails of drugs within the body of the ant in the right place, at the right point within its nervous system. And despite the fact that the ant's body is 40% fungus, it's still able to bite and climb. So there's some really major questions here about how these

organisms can do what they do and solve this kind of wildly complex problem that that boggles our mind it's a fascinating isn't it it's almost as if you have to think of this thing as a single living system the fungus and the it's almost like a symbiont it becomes like that i mean the the ants behavior it's it's fascination with heights it's summit disease it's called, or it's death grip it's called when it bites onto the leaf. These are fungal behaviours, these are not ant behaviours. The fungus has caused the ant to veer off the tracks of its ant evolutionary story and onto the evolutionary tracks of the fungal story. This is a fungus in ants clothing. I've just got to check, what why i've just got to check what why is it only fortunately insects that the fungus can infect in this way or is there any example of a fungus infecting something and controlling

something rather more complex or larger let's say i mean there's a whole field that's called neuro microbiology and it's evolved to study the ways that the microbes that live in our gut are able to interface with our nervous systems and influence our behavior and it's evolved to study the ways that the microbes that live in our gut are able to interface with our nervous systems and influence our behavior and it's a young field but really some remarkable things are emerging from there and so there's plenty of ways that we are influenced by microbes in our behaviors and we don't really understand quite how responsible they might be for some of the things that we do but you just threw that away didn't you we don't understand how responsible those because it raises very very big worrying for people it's not gonna hold up in court is it

very worrying it was the fungus the fungus did it which kind of yogurt are you blaming well it's one of those ones with a corner i'm not sure whether it's a jam in the side but it is i we should stop just for a moment and go i mean this stuff to me still does blow my mind this is what happens with natural selection over this enormous plateau of time eventually the most successful one is the one that gets the ant you know on the highest bit all of those things i think you know you can't stop every now and again just thinking this is an incredible process yeah presumably there's some cordyceps only got the ant halfway up the blade of grass there's remarkable cases of whole lineages of cicada that they eat sap and they need microbes to make that more nourishing and nutritious and they've actually domesticated

a whole lineage of cordyceps and they have that in special glands in their body and so they've gone way beyond the death part and they've gone into generative nourishing relationship where they can do things they couldn't do before. Katie how would you characterize this behavior Merlin described it very very beautifully this almost almost a different organism that emerges when the fungi inhabit what do you say 40 percent of the end yeah the biomass becomes a how would you characterize that relationship yeah i mean they're all types of symbiosis aren't they so there's kind of a partnership and i think the cordyceps example that merlin's just talked about is an extreme end of symbiosis if you think of these partnerships

as actually that they're more of a continuum so we normally think of symbiosis as being you know everyone benefits from a lovely friendly partnership but in reality it's just interactions of unlike organisms right so they can go from being extreme parasites in that example where the ant's been taken over by the fungus and for the fungal benefit not much benefit on the ant's part there right through to the other end of the scale where something is actually manipulating the fungus and benefiting at the expense of the fungus so a nice example of that is some plants actually they they rely on the fungus that's living within their roots for all of their nutrition so not just for soil nutrients as most plants do but they've actually got to the point where they don't even

bother making their own food anymore right they stop doing photosynthesis and they lose the chlorophyll which is the green pigment in the leaves and instead they rely 100% on the fungus to channel sugars and fats to the plant so it works both ways so I think you've kind of got two extreme examples of either end of that continuum there there's another nice ant fungus example where actually it's a three-way symbiosis actually it's the tree ants and fungus right so these ant trees they're called they form these incredible structures that are induced by the ants living with them and it kind of kicks this genetic pathway into play that kind of then causes the plant to produce these swollen like ant hotels within their structures and the ants live in those hotels very nicely and what they do is they have like a chamber where they go to die and where they put like ant feces and stuff in that chamber and not enough hotels have a death chamber

but the fungus then grows in that chamber from the feces and the dead bodies and the ants then feed that fungus to their offspring so is it that the ants are farming the fungus and they've actually domesticated a fungus to be helpful and clear up after them or has the fungus manipulated the ants into farming that fungus and it's kind of actually now got a nice cozy home in the tree so i think there's like different perspectives of looking at it but either way i mean it's it's crazy evolutionary mystery i guess it's just yeah it does blow your mind yeah i'm just still thinking about the idea of an ant hotel. I just love it.

A little ant concierge. They have different chambers. Breakfast buffet. It's all fungus, but it's nice. Can we run through the life cycle of a fungus? I know that's a silly question because there's a whole kingdom. Choose one of the big. Let's say the mushrooms that we find,

that we're very familiar with, that we see growing at the bottom of our garden... Why don't we go with fly agaric? Because that's like one of the most... The one with the white dot. It is the kind of gnomic mushroom, isn't it? And the fairy tale mushroom, though often not ending in a fairy tale if eaten.

So should we go with that? Are you happy with that? Fly agaric. That's fine, yeah, yeah. Because there's also lots of ways to see a mushroom. You know, like a morel mushroom and a supermarket button mushroom are separated from each other by as big a gulf as a flea and an elephant.

Just say that again, because that ooh was highly impressive, and I think that is just... It's just so we remember that there's lots of ways to be a mushroom as well as there's lots of ways to be a fungus. Just to clarify that, so you mean if you say what's the common ancestor between those two? Yeah would be as far back in time as the common ancestor exactly in an elephant exactly yeah so my question was doubly idiotic then it's amazing how easy it is to forget that this is a kingdom of life that hasn't had a kingdom's

worth of attention and yeah we're catching up all of us yeah so let's run through that then so that the classic mushroom that you find in woodland the particular one that robin showed so maybe we start with a spore and a spore would ultimately come from a mushroom but it might land somewhere it will start branching as hypha one of the fungal cells will emerge from the spore and that will branch and fuse to form a network that network at some point will meet a compatible network that can fuse with it and they can do a sexual process that would allow them to produce a mushroom and to produce viable spores from that mushroom those spores can then travel around and the process can repeat itself this is very very very simplified version fungal sex is it's a byzantine and confusing subject some fungi some

fungal species have over 23 000 mating types most of which are compatible with most of the others and it just gets really really really fiddly i just really 23 what do you mean by mating type well exactly so if most of them are compatible with most of the others, basically it's a different locus on the bit of the genome which is responsible for sexual recombination. And there's that much variation that counts as the different mating types, but they can still fuse with most of the other ones that don't have that same allele of that locus.

I really can't explain it very well, I'm sorry. How then do we study something like that, with that variety? Yeah, I mean, I don't. I'm still well aware from any sort of reproducing fungi. The ones that I study, and this is just to add to merlin's point he was just making about all these different mating types added into that most of them can also just clone and just divide anyway and whole lineages like the sort of katie and i study they've never been observed to have sex and they're thought to be asexual despite being hundreds of millions of

years although the latest research because everyone's watching yeah the latest research on this is actually suggesting sometimes they do have sex but no one's still never no one's ever seen it yeah no one knows how when what happens so it's not far off the panda then is it when did you first get interested because like lots of different things like people why did you become a dentist you know there's certain kind of things and i don't know why that made that mark still but uh the um you know that point where you first read about fungus and you just thought this is a world that because i can see why because it is remarkable but as you said there's not a great deal of press out there generally with the latest fungus news yeah so i first started getting interested into it was all to do with the evolution story and the evolution of how earth got green 500 million years ago so sort of always been

interested in early earth history and kind of how things came to be but from a biological perspective one of the most important events in earth's history was sort of greening of the continents the movement of plants onto the land and then the oxygenation of the atmosphere and all of the important events that happened after that that were underpinned by fungus, it turns out. Unfortunately, we don't have time machines anymore, so you're not able to go back and get ancient...

Oh, don't get Brian on that again. So we're not able to go back 500 million years and actually get hold of ancient plants to do those sorts of radioisotope tracing experiments and figure out what the fungi were doing. So instead, we have to use sort of modern day plants that share many of the features of ancient plants. So things like liverworts, which are a lovely group of plants that maybe not everyone's familiar with, but you will definitely have seen them growing in the cracks of pavements out and about. There's some outside my hotel, actually. So we use these analogues of ancient plants

and do experiments with them and look to see how they function with fungi, which kind of gives us an idea of how those ancient plants and ancient fungi may have functioned as well. But you do build amazing time machines, don't you? You've got these big tanks where you're simulating ancient climates with these plants growing in them and you can set the climate to you literally turn back the dial and you go back to the paleozoic they're amazing experiments so we run these experiments under simulated paleozoic atmospheres i left that that's cool that bit i

missed it out we simulate ancient atmospheres so we ramp the carbon dioxide in the atmosphere up sort of three or four times what it is today and grow the plants and fungi under that. And then we bring it down to modern day and look at how the partnership changes with those changing environmental conditions. One of the things I'm really interested in is sort of feedbacks to climate. How does the interaction between plants and fungi, how does that influence climate in the past and in the future? Which seems weird when you think about it. How on earth does that happen? How does fungus influence climate in the past and in the future which seems weird when you think about it like how on earth does that happen how does fungus influence global climate and it's all

to do with their relationship with their plant host so if you can imagine a plant that's got a very helpful fungal partner who's giving it loads of nutrients it's able to grow really big and do loads of photosynthesis which then draws carbon out of the atmosphere, produces more oxygen and by drawing carbon out of the atmosphere through photosynthesis you actually cool the climate. If you imagine this on a global scale you can kind of start appreciating the role that fungi play in a very invisible way in actually sculpting the atmosphere that we breathe. That's remarkable. Can I just check, by the way, was that mention of the liverworts growing outside your hotel

a passive-aggressive comment on the fact the BBC have put you up somewhere quite rubbish? Absolutely not. I just wanted to check. Liverworts are a privilege. Merlin, how about you? What first captured your imagination? I grew up spending time outside and being interested in what was what first captured your imagination i grew up spending time outside

and being interested in what was going on around me and composting was a big thing i just take buckets of kitchen waste out to the compost heap and a few months later i helped my dad shovel it and soil onto the garden i just became curious about how how this stuff could change into another form of stuff you know how does this rotting log become soil and so I became interested as a child in a sort of the astonishing power that these microbes seem to have that I was told about why can't I see them if they're so powerful and that was an early way in but then later on like Katie I became very interested in how plants are able to do what they do and how we make sense of plant life and how these mycorrhizal relationships seem to underpin so much of what plants do and yet

get so little time given to them in my for example undergraduate botany class so that was a way in but it just keeps getting more and more fascinating although I don't know much of my practical work is in the field so Katie has these really high-tech time machines with valves and dials I'm often in the field scraping mud into plastic bags. More passive aggression there, I think we noticed. If you're looking at fungi, I think you have to go into the field because you can't really understand what it's about or why it's where it is and why it's doing what it's doing

until you can see it where it should be. And then it's all about context, isn't it? It's fine to grow stuff in a Petri dish and poke it with, I don't't know electrodes or radioisotopes and stuff but until you see it in the field and you kind of see it behaving or doing what it should do in its natural habitat that's when you really start to understand what it's about i think when you say the field by the way do you mean the field or do you mean a specific field sorry that was very academic of me was it the field i just thought there might just

be a field where you all go there's one particular field which is i also loved your casual you know it's all very well just a stick electrodes into the pantry dish the picture you painted is of an ecosystem anything you know a woodland as you said a pavement outside a hotel or whatever it is that's more interconnected than we might otherwise have pictured and and the fungi seem to me to be a an integral part of that whole the whole of life i agree and i know with this amazing work that katie's done showing these fluxes between plants and fungi how this can spill out from just the microscopic trading decisions between these this one root and this one fungal thread and spill out over whole continents spill across time and

huge evolutionary stories vast climatic shifts we're still part of and when you think about this soil let's say just the top 20 centimeters underground like this is a third of the mass third of the biomass here can be mycorrhizal fungal tissue. There's a lot of this happening there. And these fungal networks are bound up with plant roots, with bacteria. These fungal networks form highways for bacteria to navigate the crowded obstacle course of the soil. They're bound up with other types of fungi and all sorts of soil animals doing their thing. I think of it like ecological connective tissue, a kind of living seam that binds life into relation and leads us into a more interconnected worldview at a time when I think we really need to be going there. One of my favourite collections

of Calvin and Hobbes cartoons is just called There's Treasure Everywhere. And you kind of feel like that. The stories that you've all been saying, these stories of evolution, these stories of interaction, all of these things, the mutualism, etc. I just find it saying, these stories of evolution, these stories of interaction, all of these things, the mutualism, et cetera, I just find it very, very beautiful. Phil, you studied engineering. Now, at the end of this show, how much do you regret that when you could have... I mean, you know, would you have preferred to do another degree that would have been as impractical for the actual job you do? Well, I mean, if I stopped structural engineering, I could have made a literal ant hotel,

which is now all I want to do, is make a tiny ant hotel. But, I mean, it sounds very complex and very difficult. I thought it was funny earlier when Merlin was describing a very complicated process and said, this is a very simplified version. I just went, ah, I don't think I could have studied this then, because I'm already lost.

Yeah, if you can make a Hilbert's Ant Hotel, Brian will be over the moon as well. A niche joke. It's niche. I would barely even say it was a joke. I would say it was a sentence with a vague amount of hope. Now, we asked the audience some questions. Well, we asked them one question

actually. We said, this was a dangerous question to ask, actually, because I think we may well find out that we've solved a crime, but not with the ones that we're going to read out now. Because we asked them, what's the strangest thing you've discovered on a walk in the woods? Brian, what have you got? The entire cast of The Wombles on a staff team building trip. So this is Charlotte, and Charlotte

is in there somewhere, sitting amongst you, and I tell you this because she said as a person who digs up skeletons for a living, I am the strangest thing you'll find in the woods. Someone out there said that. To be fair, that's

not the scary one. Had it been the other way round, as someone who buries skeletons in the woods, then we would be worried about Charlotte. And Alice says, a bonfire of GCSE revision notes. Thank you very much to our panel, Katie Field, Merlin Sheldrake and Phil Wang. And next week, we are going to be discussing the secret life of sharks. Well, we're not obviously going to be discussing the secret life of sharks.

Well, we're not obviously going to talk about the secret life of sharks, because that's a secret. None of us know about the secret life of sharks, so we're probably going to talk about some scurrilous gossip about a catfish, I would imagine. And also the number 53 bus to Amity Island. We are not going to... No

more buses. This Marcellium network of homophones is just not good enough. We're going to need a bigger boat. Bus. No, we're not going to need a bigger bus. Oh, this remake of Summer Holiday. Because you've got a look of Cliff about you. I look forward to that.

Thank you very much, everyone, for listening. Bye-bye. Thank you. In the infinite monkey cage Without a trowel In the infinite monkey cage Turned out nice again. Oh, sorry, before you go, hello, my name's Greg Jenner. I am the host of You're Dead to Me, the Radio 4 comedy show that takes history seriously

and then laughs at it. And I just wanted to say that if you like laughing, if you like learning, if you like history, or if you hated history at school, well, we are the show for you. Yes, every episode I pair up a top historian with a fantastic comedian, and we have a lovely, funny, fascinating chat about a different subject from world history. We do stuff you did at school, and we do stuff you've never even heard of. So if that sounds like fun, you can check out our back catalogue and our new series on BBC Sounds.

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