Microbes: Secret Rulers of the World?

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Speaker 10 BBC Sounds, music, radio, podcasts.

Speaker 11 Welcome to the first monkey cage of 2019.

Speaker 12 This is a very special year for lovers of science and lovers of conspiracy theories.

Speaker 15 Or is it?

Speaker 12 Something for everyone who enjoys an entirely pointless Twitter spat.

Speaker 11 50 years ago, human beings walked on the moon, or did they?

Speaker 12 And 50 years ago, the US Air Force closed Operation Blue Book, the investigation into unidentified flying objects, concluding there was no evidence of extraterrestrial life or technology, entirely ignoring the fact that the moon is a spaceship.

Speaker 19 Where did you read that?

Speaker 12 I actually learned that from an excellent book called Our Mysterious Spaceship Moon, which is £35 on eBay. So at that price, it must be correct.

Speaker 19 Did you see that clip on YouTube where Buzz Aldry met that moon hoaxer?

Speaker 20 No. What do you mean?

Speaker 19 I mean that I'm going to demonstrate the conservation of momentum to you.

Speaker 11 There we go, and that is how a physicist threatens you with a punch.

Speaker 21 So,

Speaker 19 yes, this is,

Speaker 19 although Robin doesn't think so, a sign show. Yes, this is a sign show.
We have no listeners who believe that multicellular organisms capable of building a spacecraft have visited Earth.

Speaker 19 Or if we do, they can write in afterwards and complain to our usual complaint address, which is monkeys at slash dev slash null.

Speaker 19 That's a Unix joke

Speaker 19 because the Unix operating system was also invented in 1969 at Bell Labs in the United States.

Speaker 12 However, we do have a panel who believe it's possible for a unicellular alien to exist beyond Earth, but within our solar system, because today's episode of Monkey Cage is about microbes, masters of Earth and quite possibly masters of the universe.

Speaker 12 Though I would imagine Hasbro would have made a lot less money if He-Man had been a microbe doll.

Speaker 12 So, with us to discuss the wonder of unicellular life, we have a distinguished panel of half-human, human, half microbes, and they are.

Speaker 7 I'm John Copley, I'm Associate Professor of Ocean Exploration at the University of Southampton.

Speaker 7 And I think the next place we're going to find exciting microbes is in the hitherto unimagined organ of an undiscovered deep-sea animal, where they'll be enabling that animal to do something incredible.

Speaker 10 Beat that. I'm Monica Grady.
I'm Professor of Planetary and Space Sciences at the Open University.

Speaker 10 And to be honest, some microbe in some animal at the bottom of the ocean just leaves me, well, you know, not excited at all. I know where the smart money is.
The smart money is on microbes on Mars.

Speaker 10 And I'll tell you something else.

Speaker 10 She-woman rather than he-man. Microbes as mistresses.
I think that's what we should look for.

Speaker 23 My name is Ed Byrne, and I'm a stand-up comedian, except when I'm on shows like this, when I'm a sit-down comedian.

Speaker 5 And

Speaker 23 I believe that the next place where the new exciting microbe will be found will be in the sinus cavity of one of my two sons, because that is where every microbe known to man has managed to find itself over this whole winter.

Speaker 23 It'll just be there. Something new, something exciting that will form another way to form a different virulent strain of snot.

Speaker 20 And this is our panel.

Speaker 12 I've got to admit, I think Eddie's right.

Speaker 15 There is something incredible.

Speaker 13 It's only when you're a parent you really realise how many different varieties of snot there are.

Speaker 1 And just the gluiness of a new.

Speaker 23 I had no idea when we had children just what an open door to the world's diseases I was letting into my house. They are just vectors in

Speaker 23 cute faces.

Speaker 5 They're just...

Speaker 23 I used to know things. I used to know who the new hot young comedians were.
I even used to know who does some hot new musicians. Now I know what ear infection is going round.

Speaker 23 Oh, oh yes, I hear that's a nasty one.

Speaker 23 That's where I am now.

Speaker 4 Anyway,

Speaker 12 I really shouldn't have started by talking about this, so we've gone downhill very, very quickly.

Speaker 23 Take all responsibility. It was me who started it, really.

Speaker 24 But really, who's to blame?

Speaker 23 The microbes.

Speaker 19 Well, and the presenter of the programme.

Speaker 13 And science itself.

Speaker 1 Brian.

Speaker 19 Monica, we like definitions. So can we start with the definition? What do we mean by microbe?

Speaker 10 Well, we mean something very small, microscopic in size.

Speaker 10 We generally mean something that's only got one cell, so unicellular. It's got all the bits in it that it needs to function, to grow, to reproduce, to take in nutrition.

Speaker 10 The sort of classic ones are things like an amoeba.

Speaker 10 You get unicellular plants, unicellular animals, and that's what microbes are: small things.

Speaker 13 And John, you were actually the person who suggested the title of the show, you know, Rulers of the World.

Speaker 13 So, why, you know, these things which are so small, these unicellular organisms, how do they rule the world?

Speaker 7 Well, microbes have had the planet themselves for an awfully long time. Before Johnny came lately, life forms like us appeared.

Speaker 7 So microbes probably appeared maybe around about four billion years ago in the 4.6 billion year history of our world.

Speaker 7 And animals probably appeared about only 570, I think a recent paper said maybe 588 million years ago. So, for an awfully long time, microbes had the place to themselves.

Speaker 7 They're the great engineers of the life support system that we all depend on, and not just creating it, but also maintaining it over those billions of years.

Speaker 7 And they influence everything from potentially, maybe even our health and behavior. And they have also influenced human history over time as well.

Speaker 15 So, why is it that

Speaker 15 that's a very long period of time for just evolution to go, this is fine, this unicellular, that's fine.

Speaker 16 What do we know what events it takes for evolution to then take things off to such a variety of different forms of shapes and organisms and multicellular organisms?

Speaker 7 There are a lot of building block blocks that have to be in place before you can get kind of complex multicellular life like us.

Speaker 7 There's a lot of different metabolic pathways, the atmosphere is very different from what it was in the early history of the earth. An awful lot needed to happen before you could get anything like us.

Speaker 23 So, is the leap from nothing to microbe as big as the leap from microbe to multicellular?

Speaker 28 Really good question, Edge.

Speaker 4 Really good question.

Speaker 23 I didn't realise how profound I was being.

Speaker 23 Genuinely just curious.

Speaker 5 I mean,

Speaker 10 from my perspective, you start off with your building blocks, your atoms, your molecules, carbon dioxide, water, whatever, and then they make more complex molecules.

Speaker 10 And then somehow those complex molecules become an organism and they've bound themselves, they have a membrane to separate themselves from everywhere else, and they can reproduce and pass information on forwards.

Speaker 10 So, those two things, having a membrane and translating information, are really, really big things.

Speaker 10 So, for my money, to go from building blocks to microbes is a much, much bigger step than going from microbes to humans.

Speaker 19 I think Haldane said, didn't he, that that's the mystery. The mysteries in going from an atom to a cell.
Once you've done that, then you can kind of

Speaker 19 understand the rest.

Speaker 19 But which raises an interesting question, actually, about why we only expect to find microbes somewhere like Mars, given that, as you say, that

Speaker 19 in your opinion, the real difficulty is from going from

Speaker 19 geology to biochemistry in the first place.

Speaker 10 Well, I mean, one of the main things that we know about life on Earth is that it needs water. And so, we take that as a

Speaker 10 a given. You know, if we're going to find life anywhere, we're going to need something that deals with water.
And there are places in the solar system where there is water or has been water.

Speaker 10 Mars is one of them. Some of the satellites of the giant planets are other ones.

Speaker 9 However, water isn't

Speaker 10 you know, unique. Well, no, that's not true.
Water is unique, but it's a liquid, it acts as a solvent, and that's all life needs. It needs something to be able to transfer nutrients and gases

Speaker 10 and to hold a body rigid. Any old solvent would do, but water happens to be liquid over a range of temperature of 100 degrees.
It can dissolve a whole lot of stuff.

Speaker 10 There's no other solvent that can do that. So we say, right, okay, you need water for life.
So let's look for water.

Speaker 19 John, many biologists would say that because, as you said, life began on Earth pretty pretty much as soon as it could, so perhaps 3.84 billion years ago, that that's an easier step, perhaps, than going through the eukaryotic cell and onwards to multicellular life.

Speaker 19 And what's your view of the

Speaker 19 well, the question is, is do you think it may be inevitable, given the right conditions, as Monica said, with water and perhaps geological activity, that life becomes essentially inevitable?

Speaker 7 There's a suggestion that maybe, with the right ingredients in place, it is in some way inevitable.

Speaker 7 It may be some consequence of the physical chemistry of some of the transition metals that are involved in catalysing various reactions and so on.

Speaker 7 And once you've got everything in place, I mean, it did appear to happen, as you've mentioned, quite quickly in the early history of the Earth.

Speaker 7 And yet, it is, in terms of complexity, it is the big leap from nothing to microbe, really is a big step.

Speaker 7 And then, since then, I mean, what excites me about the microbes here on Earth is their ubiquity. So, we find them everywhere from 20 miles, 32 kilometers, up in the stratosphere.

Speaker 7 They can survive those conditions before they come back down to Earth, you know, where it's cold, it's dry, they're not protected very much from radiation from space.

Speaker 7 It's very much like the conditions on Mars.

Speaker 7 And yet we can find them in these things called lignite deposits, which is a sort of fossilized peat, and that occurs in some places two and a half kilometers below the ocean floor.

Speaker 7 And there are microbes living there as well. So now they are everywhere and they're thriving in so many different ways.

Speaker 23 Well, when you say they're like the Brian Cox of life,

Speaker 23 you're everywhere, man. You're ubiquitous.

Speaker 19 In certain circles.

Speaker 24 When you say, I mean, that seems when we talk about microbial life, and as we kind of alluded to in the introduction, though, as well, the idea of that there's microbes and there's us, and then actually

Speaker 14 we were saying, so 50%, is that right?

Speaker 13 That we are, how much of us is microbial life?

Speaker 20 And how true is that of

Speaker 29 most or even all living things?

Speaker 7 So, yes,

Speaker 7 we used to think that it was about, we were outnumbered in terms of cells, sort of 10 to 1 by microbes, but more recent work has said no, it's about, it's about one to one.

Speaker 7 So, yeah, I mean, plants live in partnership with microbes, animals live in partnership with microbes.

Speaker 13 So, when we say we're half microbes, but we're not, I mean, that's not, we're all human, aren't we?

Speaker 20 But it requires being, how does it divide up?

Speaker 14 I mean, why if I accidentally flush out all my microbes?

Speaker 30 What's going to happen then? So,

Speaker 23 why, when Jeff Goldblum got into the teleporter, why did he only fuse with the fly? Why wasn't he genetically absorbed by the microbes and just a big half-human, half-microbe get out of it?

Speaker 19 Or a fungus? I mean, but it wouldn't have been as much fun, would it, I suppose, if he'd been a mushroom.

Speaker 5 I mean, it's kind of...

Speaker 15 It would have been a different show.

Speaker 5 It would have been a very, very different film.

Speaker 10 And you couldn't see what had happened to all the microbes when he went into the transporter, Because they might also have become half of a fly microbe as well as half of a human microbe.

Speaker 23 There was a whole other story happening, a million other stories happening.

Speaker 18 Are you going to think that that film about a man and a fly being transported in a mass transporter may have had scientific flaws?

Speaker 16 And this is

Speaker 14 that line, I dreamt I was a f I I think I was a fly who dreamt he was a man, is very different, isn't it?

Speaker 20 Where I think I was a mushroom who dreamt he was a man.

Speaker 14 It just doesn't have the same melodramatic impact, does it?

Speaker 19 But you can't be a fly microbe, can you?

Speaker 19 Because fly cells are eukaryotic. So you couldn't be a prokaryotic fly, could you?

Speaker 10 Well, it could be a microbe that lives on a fly.

Speaker 19 But well, but are they different to the microphone?

Speaker 9 So here's the thing.

Speaker 7 So we've got microbes living on us and inside us,

Speaker 7 but not

Speaker 7 directly inside ourselves, although in a sense we have.

Speaker 7 Because inside our cells, we have these things called mitochondria, which are the powerhouse of our cells, and they are probably the ghosts of something called alpha proteobacteria back about two and a half billion years ago.

Speaker 7 An alpha proteobacterium got together with an Archean and formed some kind of new kind of cell.

Speaker 7 And so these structures inside us, these mitochondria, they really look like proteobacteria. And that's probably their origin.

Speaker 7 So I think Lynn Margulis was one of the great champions of this idea of this sort of symbiotic relationship developing more complex life.

Speaker 7 And she said, you know, the world wasn't conquered by combat, it was conquered by networking.

Speaker 23 I just love the fact that you used the word ghost as well.

Speaker 23 People weren't disturbed enough by how much of their bodies are actually

Speaker 23 diseases, essentially. I mean, really, I don't, but also parts of our own cells were essentially haunted.

Speaker 7 But it's startling how they do look

Speaker 7 like these things.

Speaker 7 So, the first time I ever did something called transmission electron microscopy, which is a way of looking at inside cells.

Speaker 19 We all remember the first time we

Speaker 7 all forget your first time.

Speaker 7 But it's an incredibly fiddly thing.

Speaker 7 You have to take this little bit of tissue and you have to kind of shave these very, very fine

Speaker 7 sort of slices off of it to then put under the microscope. And it is like planing a piece of wood under a microscope to try and get a lovely ribbon of wood off of it.

Speaker 7 And you're swearing all the time because they're breaking or they're too thick or whatever. Eventually, you get one after hours.

Speaker 10 You've dulled your diamond knife and you've got to pay another five thousand pounds to get a new one.

Speaker 7 Eventually, you get one. You stick it in the microscope, and

Speaker 7 suddenly it becomes this incredibly large landscape when you switch on the electron beam and you can look at this thing in great detail and you start to explore it.

Speaker 7 And apparently, what all the rookies do, and I did this myself, first time out, is you find a cell, you find a mitochondria, and you go, Oh my god, it looks like the textbook.

Speaker 7 And you zoom in on it at 80,000 times magnification and take a picture of it, even if it's not what you're interested in.

Speaker 19 So, you mentioned Lynn Margolis there. So, the theory is

Speaker 19 that the origin of our cells, the complex cell with the nucleus and the mitochondria and so on, was this event where a bacterium got inside something else, an archaean?

Speaker 7 Possibly, possibly.

Speaker 7 There may have had to be a little bit of preparation, it may have to have sort of protected its own genetic material with some sort of nuclear membrane before another prokaryote came along, but it's a possibility.

Speaker 10 Because I find that some sort of dating, then

Speaker 19 I mean, I find it a remarkable thought, because this is perhaps the most widely accepted theory, isn't it, for the origin of multicellular life, that it was a merger of two microbes at some point.

Speaker 19 And it's a suggestion it's almost a single, it's called a fateful encounter, isn't it? It's almost a single event.

Speaker 7 A single event. And there could have been definite advantages from doing this.

Speaker 7 So one of the things that happened in the early history of the Earth was to start with, there was no oxygen in the atmosphere.

Speaker 7 And then eventually, a form of photosynthesis that produces oxygen arose, and oxygen started to trickle into the atmosphere. But it's really toxic to all the life that was around then.

Speaker 7 And then respiration, which is the way of taking a food molecule and breaking it down in lots more steps than fermentation, which is the other way of breaking down a food molecule.

Speaker 7 You get more energy out of it, and it produces simpler waste products, carbon dioxide, easier to handle than alcohols and acids.

Speaker 7 Oxygen, you know, that uses oxygen at the end of it. And that's great because you take something that's a problem and then life finds a use for it.

Speaker 7 And so bringing in something that does that inside a cell helps to control this toxic oxygen that life's now challenged with that's

Speaker 7 gradually trickling into and building up in the environment.

Speaker 19 It amazes me though,

Speaker 19 when I first read about this, that really this story is that a single event in some ocean, presumably somewhere two and a half billion years ago-ish,

Speaker 19 is the root of all complex life on Earth. A single merger between two cells is a remarkable idea, isn't it?

Speaker 23 Oh, but there's a hand-up over there.

Speaker 7 Yes.

Speaker 10 I mean, it might only have happened, you know,

Speaker 10 one merger might have been the successful thing that went on, but it didn't necessarily only happen once. It might have happened several times, many, many times over millennia, and

Speaker 10 the fusion wasn't successful or didn't go on. So, yeah, there was eventually something evolved, and that's you know, that's the whole deal with evolution.

Speaker 10 You have to build something that's going to be able to cope with

Speaker 10 its environment.

Speaker 9 Took a while, it took a while, didn't it?

Speaker 23 But that every all of life then did still come from the one that caught, the single one that caught is still pretty much in that thing of that idea of ever being able to trace themselves back to Genghis Kahan.

Speaker 10 The last universal common ancestor, Luca.

Speaker 7 Well, here we're talking about the origins of one of those three trunks in the tree of life, the cells that are like ours. There's still the other two as well.

Speaker 7 And tracing that tree of life back to where those three trunks come together gets really difficult.

Speaker 7 Because what we can do today is we can look at all the living things that are like at the end of all the branches of the tree and we can compare their genes and we can see how similar they are genetically.

Speaker 7 And from that, we might think we can deduce when they shared common ancestors and start to trace back, you know, the roots towards the roots of the tree.

Speaker 7 But microbes do some weird stuff that makes that very difficult. So, usually,

Speaker 7 we assume we get our genetic material from our parents.

Speaker 7 So, for example, if we were to do some genetic tests and Ed,

Speaker 7 I end up sharing more genes in common with you than, say, Brian, then we might deduce that you and I had a common ancestor more recently in our past, in family history, than I did with Brian.

Speaker 7 But what microbes can do is two microbes that are completely different, that are not related, can bump into each other and can kind of exchange genetic material between themselves, almost like just by shaking hands.

Speaker 7 So now it looks like they share genetic material, but it's not come from a common ancestry. It's just because they bumped into each other and they swapped some genetic material between them.

Speaker 7 So that means, you know, that's what we call horizontal gene transfer instead of vertical heredity.

Speaker 7 And it means that really confuses things when we try and trace back towards the roots of the tree of life.

Speaker 23 Well, they can mix their genes without reproducing with each other.

Speaker 7 Yeah, they can exchange genetic material. So this happens all the time.

Speaker 7 It happened quite recently, we think, with Clostridium botulinum, which is the nasty microbe that produces a neurotoxin that causes botulism.

Speaker 7 Well, a new form of botulism has now been detected in a completely different microbe, a microbe, an enterococcus microbe, one of the things that lives in a lot of guts.

Speaker 7 It turned up in a cow pat in South Carolina, and clearly the gene for this toxin has probably, by this kind of transfer, ended up in this different type of microbe.

Speaker 7 So, they're swapping these genes around.

Speaker 7 And it means when we try and trace back down to the base, well, you know, the roots of the tree of life, a lot of this horizontal gene transfer is taking place.

Speaker 7 And instead of a tree, it becomes like a big sort of ball of sort of wibbly-wobbly, horizontally transfer-y stuff.

Speaker 23 Wibbly-wobbly ball.

Speaker 13 I think you have very clearly shown there why some people would decide to go with theoretical physics rather than biology.

Speaker 5 And eventually we found it in a cow pad.

Speaker 22 We'd had to look in a load of them.

Speaker 17 But then we all went, hooray, as we threw the cow pad into the the air.

Speaker 18 It was a day of merriment, dance, and eventually food poisoning.

Speaker 14 I do, by the way, I think you're more closely related to Brian because you both got great hair.

Speaker 5 What are you talking about?

Speaker 12 I think you've both got the great hair, Gene.

Speaker 5 You have actually great hair.

Speaker 5 You barely have hair.

Speaker 5 This is great hair. Great hair.

Speaker 11 No, great head.

Speaker 5 Do you know what? I've never got it. Do you know what?

Speaker 11 Why don't you pronounce the T.

Speaker 12 What I love there is the fact that, you know, every now and again you see the true narcissism of the comedian.

Speaker 18 Grey hair?

Speaker 5 I'll never give it any such T V jobs if people are listening to that.

Speaker 19 I like what you said as well. It's like

Speaker 5 you said grey hair.

Speaker 14 Will you have your hair greyed so people think you're a human boy?

Speaker 5 No streaks.

Speaker 19 Essentially,

Speaker 19 when we talk about microbes, it's sort of almost tempting to think of them as primitive organisms, but that would be wrong, wouldn't it? Because they they evolve at the same rate as everything else.

Speaker 19 So, can you give us some sense of how diverse and complicated they are?

Speaker 7 Oh, gosh.

Speaker 7 They're all around us, and we don't necessarily need a microscope to see what they're up to. So, they do lots of different things, and they come in lots of different forms.

Speaker 7 So, for example, I mentioned they're sort of architects of our planet's life support system. One of the things that we need, in addition to building our

Speaker 7 molecules out of carbon, is we need nitrogen. It's in our proteins, it's in our DNA, it's in our RNA.
But a lot of the nitrogen, most of it in the atmosphere, is not in a form that we can use.

Speaker 7 So we rely on microbes to carry out something called nitrogen fixing to make it available for other life forms.

Speaker 7 So if you go to a lawn and you find a clover and very carefully take it out of the ground with its roots intact, you might see, if you look closely, little knobbly bits on the roots of the clover.

Speaker 7 And if you squeeze it, there'll be this sort of pinkish blood that emerges.

Speaker 7 And that pink, it's actually a form of hemoglobin produced by bacteria living in these nodules on the roots, and that's to lock up the oxygen to keep it away from the nitrogen fixing that they're doing for the plant.

Speaker 7 So that's a way you can kind of see microbes doing their thing around you. And then I go out walking my dog in the countryside on some quite peaty ground, and I'll sometimes see these sort of

Speaker 7 little ponds, puddles, and there'll be what looks sometimes a little bit like an oil sheen on the surface of the puddles. And you think, oh, that's terrible.
You know, someone spilt some oil here.

Speaker 7 And then you look at it closely and you think, well, hang on, it's not quite that rainbow colour. It's a bit more sort of just a silvery

Speaker 7 colour. and if you poke it, it breaks up into jagged bits, not like an oil slick.
And it's actually a raft of manganese-oxidising bacteria that are living on the surface of that little puddle.

Speaker 7 So they're all around us, and we can learn to see the signs.

Speaker 13 Again, this is another bit where people listening at home are thinking, Do I want to do theoretical physics or do I want to go to more biological?

Speaker 15 Am I a pokey, squeezy kind of person,

Speaker 15 or am I a kind of chalky equation-y kind of person?

Speaker 1 It's amazing that

Speaker 23 the nitrogen-fixing bacteria that certain certain plants have, but that's where then the whole basis of crop rotation comes from, is that the fact that you have to every cycle

Speaker 23 plant something that has the nitrogen-fixing bacteria that then replenishes the soil. Which they didn't know that that's what it was doing.

Speaker 23 When they discovered crop rotation, that they planted certain plants that somehow the soil fixed itself. And it's,

Speaker 23 why does it do it? You just, it is one of those ones you go,

Speaker 23 the most stalg atheist, you kind of go, why does that do that, though? There must be a plan.

Speaker 19 No, there isn't. Evolution.

Speaker 5 I know.

Speaker 23 You have to then go and go, No, there isn't.

Speaker 27 No, you're right.

Speaker 13 But there is a lovely moment when I suddenly saw you as a 13-year-old boy in school being taught crop rotation, thinking, when on earth is this going to be useful?

Speaker 4 Some decades later, you find yourself on Radio 4 and go, now. Thank you very much, Mrs.
Forbes.

Speaker 23 I grew up with that crop rotation until much later in life.

Speaker 28 I think, I know.

Speaker 19 It was the great moment when he found he could use that knowledge, and then he accidentally tries to use it as an argument for the existence of God on a sideshow.

Speaker 28 Just blew it at the last minute.

Speaker 23 For the record, I was not trying to argue for the existence of God. I was merely trying to argue for how sometimes you've discovered something like that, and

Speaker 25 you have to actively

Speaker 23 fight the fact that it makes you think that way.

Speaker 12 Oh, whenever I'm rotating to my crops, that's when I see Odin.

Speaker 16 The moniker.

Speaker 22 Let's move on quickly.

Speaker 26 Now, in terms of microbial life, trying trying to find evidence, because that's what I presume at the moment in terms of trying to find life beyond the planet Earth, microbial life is the thing which we're focusing on.

Speaker 26 Would that be correct?

Speaker 10 Yeah, that's true. I mean, what John's been saying about different types of microbes, they all live in different sorts of environments.

Speaker 10 So, some of them can live in boiling water, some of them can live in water that's below freezing point because it's got so much salt d dissolved in it, some of them can survive huge pressures

Speaker 10 living very deep below the surface of the Earth. Some of them can survive very, very high radiation fluxes.
So we know microbes are practically indestructible.

Speaker 10 We know they formed very early on in Earth's history. And we know that places like Mars were formed from the same ingredients as the Earth.
So everything's there.

Speaker 10 The stage is set for microbes to have evolved on Mars.

Speaker 10 And there are some arguments that say that, well, hang on a minute, 4.5 billion years years ago, when the planets were forming on the Earth, it was boiling hot.

Speaker 10 It was the surface of the Earth was molten, the atmosphere was made of steam and very high hydrogen content, and nothing could survive.

Speaker 10 Okay, yeah, Mars was like that for a bit, but Mars cooled much more quickly. And so it could be that actually life got going on Mars before it got going on Earth.
So actually,

Speaker 10 you know, because of transfer of materials, we know we've got meteorites from Mars. We could have had these microbes coming from Mars, hitching a ride on meteorites and seeding the Earth.

Speaker 15 We have a lot of Geoff Wayne fans listen to this.

Speaker 18 Since the last time, do we know what the chances of anything coming from Mars are at the moment?

Speaker 23 Are they still what they have been before?

Speaker 10 I think they're about a million to one.

Speaker 5 They are still being to know. That is good to know.
That is good to know.

Speaker 10 Following the statistical discourses written by Terry Pratchett, we know that million-to-one chances happen nine times out of ten.

Speaker 19 There's an argument, isn't there?

Speaker 19 So some eminent scientist named Fred Hoyle had the idea for a while, didn't he? It's called panspermia, isn't it?

Speaker 10 That's something different.

Speaker 10 Panspermia is life

Speaker 10 coming from

Speaker 10 out there to us, okay,

Speaker 10 beyond the solar system. So panspermia is very specifically beyond the solar system.
And this is what Fred Hoyle used to explain life on Earth.

Speaker 10 Now, to me, that makes no sense at all because you've still got the problem of where did life form

Speaker 10 beyond the solar system. You know, let's just, you know, let's keep it simple and let's have life getting going in the solar system.

Speaker 10 And,

Speaker 10 you know, I don't know whether life got going on Mars and so did the Earth.

Speaker 10 It's something that we hope we'll find out, you know, in the next 15 or so years when we bring samples directly back from Mars.

Speaker 10 It's not quite panspermia. I think let's say it's an evolutionary offspring of panspermia.

Speaker 19 How do we search for microbes? How would we recognise them? So if we drill into some subsurface water deposit, let's say on Mars, what experiments are we doing?

Speaker 10 Well,

Speaker 10 you're going to be looking for signatures.

Speaker 10 I mean, unless you actually drill a hole on Mars and see some worms, you know, then you're going to have to look for something fossilized, you're going to have to look for particular chemical signatures,

Speaker 10 combinations of chemical signatures. And you know, only if we're extremely lucky are we likely to find, you know, something that is a recognizable fossil microbe.

Speaker 19 And does that assume that the metabolism would be similar to life on Earth? Or if it's radically different, would we recognize it?

Speaker 10 Well, again, it's difficult enough to recognise fossilized bacteria on Earth. You know, the stuff from the Pilbara was caused huge huge and still does cause huge controversy.

Speaker 10 You know, are these things

Speaker 10 actually fossilized bacteria or are they simply traces where fluids have flowed through the rock and left an imprint behind?

Speaker 19 So, is that one of the oldest rock deposits? Is that what you're referring to?

Speaker 10 It's a very old rock deposit, and it is in the Pilbara, isn't it?

Speaker 9 The Bill Shopston.

Speaker 7 There's also an even older deposit on Greenland.

Speaker 7 There was what people assumed was a stromatolite there, 3.7 billion years old, and very recently a paper saying, well, hang on a minute, you could possibly have produced these structures by a non-living process.

Speaker 7 It's very hard to tell. And even some of the chemical signatures that we usually associate with life aren't, there may be some non-living processes that can produce the same kind of signatures.

Speaker 7 So I think NASA have recently come up with something called a ladder of life, which is sort of, you know, different layers of evidence you might hope to build up.

Speaker 7 And it's not supposed to be definitive, it's really to stimulate discussion.

Speaker 27 But

Speaker 23 haven't you just, like in the last 20 years, discovered how many microbes there are, in for instance, a drop of seawater?

Speaker 23 So you've only just realized in the last 20 years been able to detect microbes that are alive in water now,

Speaker 23 and we're discussing detecting microbes that have been fossilized from water on Mars that existed millions of years ago.

Speaker 19 Barely put it a third of the age of the universe ago.

Speaker 7 And so when we're looking at them today,

Speaker 7 we can identify their DNA, you know, because they are alive. You know, looking for past traces of life when that's gone, when it's just other things left behind, yes, is absolutely much harder.

Speaker 7 And it is really 20, 30 years that we've had these tools.

Speaker 7 I mean, I went to sea for the first time on a research expedition 25 years ago, and we were studying hot springs on the ocean floor, and we had a microbiologist on board.

Speaker 7 And he'd previously been studying microbes in cows' guts. And we were at sea for seven weeks, and I don't think anything grew on his petri dishes

Speaker 7 because these things don't.

Speaker 9 I think only about 0.1%

Speaker 7 of microbes in the environment are easy to culture in a laboratory. But now we have molecular probes to identify them.

Speaker 7 So, you know, there's a lot going on in the living world, let alone in the past.

Speaker 13 So, Monica, how do you, if you're looking at a sample, say in a meter or whatever it might be, what are the different levels of testing in terms of, because there have been close calls, have there?

Speaker 18 There have been beliefs that, oh, it looks like maybe we found microbials, or maybe it's just in the newspapers, I don't know.

Speaker 26 In the science world, you might be not, but.

Speaker 10 Well, in 1996, a group of scientists found a structure within a rock that had come from Mars, and they identified it as a fossilized bacterium that had been found on Mars.

Speaker 10 And the evidence they used was that the rock came from Mars, the mineral grains that it was in were from Mars, this thing had obviously been in the rock when it was fossilized, and there was carbon associated with it.

Speaker 10 Now, all those things were true, but it still doesn't add up to that fossil being coming from Mars.

Speaker 10 I mean, this rock had spent 13,000 years in Antarctica, and many other meteorites from Antarctica have biological fossils in them.

Speaker 10 because we know that fossilisation

Speaker 10 doesn't take long.

Speaker 10 You know, those of you who've gone thrown things in like Mother Shipton's Well in Knaresborough and seen it fossilise, and we know about stalactites in caves, they don't take long to form, so it doesn't take long for something to fossilise.

Speaker 10 So it's very difficult. You're going to have to rely on chemical signatures, isotopic signatures,

Speaker 10 not just shape. You can't rely on shape.
But it's all in the context of

Speaker 10 where it's actually actually come from. I don't know, I don't know whether we're just being unduly optimistic that we're going to find this.
I don't know, it's going to be very difficult.

Speaker 20 Is it better not to look for microbes and like up the game and look for sea monkeys or something?

Speaker 9 Well,

Speaker 10 you know, we've got all these infinite monkeys that are kept in a cage, and goodness knows whether any of them have ever been to Mars.

Speaker 10 But I think if there was anything higher, more evolved on Mars, like meerkats or something like that,

Speaker 10 they would have been seen. I mean, I did try to discuss the possibility that on Mars there are lava caves.

Speaker 10 Okay, so there are so if you think there are huge volcanoes, and when the lava flows down the volcanoes, you can get big tubes of lava which have then become hollowed out. And so in these caves,

Speaker 10 they're protected from the radiation on Mars's surface. And we do know there's a mission at Mars at the moment called the Trace Gas Orbiter, which is looking for methane.

Speaker 10 Now, methane shouldn't be stable because it is destroyed very quickly.

Speaker 10 But methane is produced by cows and termites.

Speaker 10 And I have tried to posit that there are herds of cows in the lava tubes producing methane, but I haven't actually managed to get this into a peer-reviewed publication yet.

Speaker 19 You've got to just admit that that's not likely, just for the record.

Speaker 10 For the record, it's incredibly unlikely, yes. It's very, very unlikely, yes.

Speaker 23 And there's probably not mayor cats either. No, they would have tried to sell us car insurance by now, there wasn't.

Speaker 19 But you did mention that this is one of the most tantalizing measurements, isn't it, from the trace gas obviously.

Speaker 19 There are seasonal methane changes on Mars, which some people take to be a potential biosignature.

Speaker 10 Yeah, I mean, one of the things is methane is destroyed very rapidly in the atmosphere because of the radiation, the sun's radiation. And so something is putting it back there.

Speaker 10 Now, there are plenty of non-biological processes that will do this in terms of perhaps the impact of an asteroid coming down, heating part of the surface, melting ice and releasing any methane that's been trapped in there from weathering of some of the basalts that are on the surface of Mars.

Speaker 10 So there are non-biological explanations, but it's such a strange signal, comes and goes. It doesn't seem,

Speaker 10 it seems to be, I think, I can't remember. I think there's more of it in the summer rather than there is in the winter.

Speaker 10 And so it's really interesting. And this is what the Trace Gas Orbiter is going to be looking for.

Speaker 19 What are the most extreme environments that we've detected microbes?

Speaker 7 So the current record for thermotolerance is an Archean that can survive, reproduce at 122 degrees C. So, temperature-wise, that's pretty impressive.

Speaker 19 So, boiling water does not kill

Speaker 7 this archaean. Yeah, I mean, it's living in the deep ocean where water doesn't boil at that temperature, but there may be similar ones in

Speaker 7 hot springs and Yellowstone and places like that, approaching that as well.

Speaker 19 Just about archaea, because we haven't really, just for completeness, the bacteria and archaea. So the archaea were only recognised really a few decades ago.

Speaker 19 Can you describe just very briefly the difference? Because everyone knows about bacteria, but archaea is a word that many people have never heard of.

Speaker 7 Well, the differences

Speaker 7 perhaps seem a little bit subtle. There's a difference in what the outer coating of the cell is made of between the bacteria and the archaea.
That's probably one of the big differences.

Speaker 7 There are a few other metabolic differences. And also what the archaea can do.
I mean, I think most of the methane-producing microbes that we're familiar with are archaea.

Speaker 7 So, there's definitely differences like that as well.

Speaker 19 Isn't there some idea that these are very that they split very early on in the history of life on Earth? They're almost different forms of

Speaker 7 different space.

Speaker 7 And then

Speaker 7 we are closer to archaea than we are to the bacteria.

Speaker 7 And it is down at that messy root of the tree of life where it's hard for us from the ends of these branches to peer back down there and see what's really going on.

Speaker 10 So, where do viruses sit in these?

Speaker 7 Oh, don't ask.

Speaker 5 No idea.

Speaker 5 You said beforehand, don't bring up viruses.

Speaker 4 Oh, did you?

Speaker 5 Oh, sorry.

Speaker 5 He's heard.

Speaker 23 He doesn't know anything about them.

Speaker 10 Oh, right. Okay, I'm sorry.

Speaker 5 Not him personally.

Speaker 5 What about prions then?

Speaker 7 No, we're here to talk about unicellular life, and viruses aren't cells, so in their own right. So we can leave them to oneself.

Speaker 19 We can't let you just say that viruses aren't cells. What are they then?

Speaker 4 We have a very strict set of rules on this show, and that's one of the things you can't say.

Speaker 28 Well, but it's intriguing, isn't it?

Speaker 19 Because actually, just colloquially, you just think, yeah, well, there are cells.

Speaker 5 Packages of genetic material.

Speaker 10 They can't survive by themselves, is that right?

Speaker 19 They can't reproduce.

Speaker 23 They can't sell to reproduce. They're like

Speaker 23 the hermit crab of the microbe world.

Speaker 20 Every time I hear archaea, I just think of a tiny little microbial group of cubs and brownies. Anyway,

Speaker 24 we've only got time for a couple of questions.

Speaker 14 One thing is, we kind of talked about this a little bit, but it's still fascinating.

Speaker 26 If the microbial content of a human body or other mammalian life form, let's step at that, was removed,

Speaker 13 is that even an imaginable situation?

Speaker 7 So, people have done experiments with fruit flies and with mice to look at what happens if we don't have gut microbes, for example.

Speaker 7 In the case of mice, some researchers in Japan raise mice without microbes in their guts, and they found that those mice, I think, produced twice as much stress hormone when they were placed in a stressful situation compared with normal mice.

Speaker 7 So now there is a lot of interest in how our gut microbes do actually influence our physical and even potentially our mental health.

Speaker 7 And then very recently, there was a study on fruit flies by a team led by someone at the California Institute of Technology, and they found that fruit flies lacking a particular bacterium in their microbiome were hyperactive.

Speaker 7 They raced about,

Speaker 7 walking about about 50% 50% faster than fruit flies usually do. And it's a particular enzyme produced by one particular strain of bacteria that kind of puts the brakes on that hyperactive behaviour.

Speaker 13 Ed, how do you feel now you've found out you're 50% microbe?

Speaker 14 At the end of this show, how do you.

Speaker 23 I have to say that my listening to the fascinating discussion that I have been listening to, I feel like my 50%

Speaker 23 microbial content is really the only thing that earns me my place at this table.

Speaker 23 I feel like that's the only thing I go. Well, I feel like I should be here, for I am part microbe.

Speaker 5 Yeah, 50%, apparently.

Speaker 19 Representing the microbes.

Speaker 5 So,

Speaker 27 but

Speaker 19 I just wanted to ask, Monica,

Speaker 19 we've talked about Mars, just very briefly, across the solar system. Where are the other places that we think we may find life?

Speaker 10 Well, Europa is literally a hot favourite. John has referred already to the hydrothermal vents on the base of the ocean floor that he has explored.

Speaker 10 And it could be that on the base of the ocean floor on Europa, there are these hydrothermal vents where there are a whole load of microbes surviving fauna, not flora, because there's no light there, so they don't photosynthesize.

Speaker 10 So, Europa is one place, Enceladus is another place, it seems to have streams of vapor coming from it. But anywhere that

Speaker 10 these beasts can get away from radiation, any little niche where they can find the nutrients they require. I think microbes will be able to survive.

Speaker 10 So, for instance, on the moon, which we used to think was completely dry and lifeless, we know there is quite a lot of ice in some of the craters in the moon.

Speaker 10 Same on Mercury, even though it's so close to the Sun, there are parts of Mercury that don't ever receive the Sun's rays, which are really, really cold. And

Speaker 10 there are these cold spots, and so

Speaker 10 things might exist

Speaker 10 in the ice. So, I think almost anywhere, I reckon, like if you dig a shovel in the earth, almost anywhere on Earth, even in really arid places like the Atacama, you find things.

Speaker 10 And I bet the solar system's like that.

Speaker 19 So, in this picture of the solar system with material being transferred around it, so almost microbes, you can imagine microbes raining down on pretty much everything in the solar system, and irrespective of

Speaker 19 where they originated, you could imagine perhaps them surviving in these places. So we could live in a living solar system.

Speaker 10 Yeah, I mean, it does, it does make us think that perhaps we are a spaceship on our way to somewhere else.

Speaker 19 Does it make me think that?

Speaker 11 That could have been such a poetic end to the show.

Speaker 5 Oh, no.

Speaker 23 Bearing in mind the fact that microbes were around for billions of years before we came along, is it not a and the fact that we are 50% microbe?

Speaker 23 Is it not possibly that we are merely, this is just life finding a way, and that we are merely conveyancies for microbes, that we are nothing more than vessels for microbes to communicate themselves better throughout the galaxy.

Speaker 23 The microbes are just waiting for us to perfect space travel so they can move on and over.

Speaker 10 So they are indeed then the masters of the universe.

Speaker 5 They are, and we are just transporting themselves.

Speaker 23 We're just they're vessels.

Speaker 7 You've actually described one of the biggest revelations in modern biology.

Speaker 5 God, I keep kidding on these things.

Speaker 7 it's this idea that

Speaker 7 organisms are actually a partnership between multicellular life form, animal or plant, and microbes. And that's essential to their survival.

Speaker 7 This is actually how they've evolved. They've evolved together in this kind of tandem, tango-like dance.

Speaker 7 When conditions change, your animal or your plant doesn't necessarily have to evolve new adaptations through genetic changes.

Speaker 7 It might be able to swap for a different microbial partner that can help it cope with the new conditions.

Speaker 7 But in return, we are the vessels for those microbes or as those higher life or more complex life forms. So that's very much how we're looking at it.
And then, where's the organism?

Speaker 7 You know, and this is what you were saying, Robin. Where do we stop? Where do the microbes begin?

Speaker 20 What I love now is, Ed, that you've moved on so much that next year someone goes, You go to the British Comedy Awards tonight, Ed?

Speaker 14 Nah, clashes with the Nobel Prize, and I'm up for one of those as well.

Speaker 4 So can't go, sorry.

Speaker 23 Nobody's ever asked me if I'm going to the British Comedy Awards.

Speaker 17 We've also asked the audience a question, question, as usual, and this week we asked them, What's the smallest thing that makes you scared?

Speaker 19 Mine says Robin Insier.

Speaker 19 The smallest thing that makes you scared.

Speaker 15 Brian Cox's brain cell.

Speaker 9 Ooh, well, they are very

Speaker 9 good.

Speaker 5 That wasn't designed to make him feel good.

Speaker 29 Somebody here has written Michael Gove.

Speaker 23 And they've actually signed us, Right Honourable Theresa May MP.

Speaker 5 A plank.

Speaker 19 A plank

Speaker 15 with a C and a K at the end.

Speaker 19 C and a K at the client. A plank length.

Speaker 23 Somebody's written for the smallest thing that makes you scared. My wife's moral compass.

Speaker 23 But when it says where it says name, they've just written, I'd rather not say.

Speaker 23 Somebody who knows what side their bread is buttered on.

Speaker 19 They are carrying on the light-hearted theme, my lifespan in relation to the entire history of time.

Speaker 24 And at this point, we move into the Beckett part of the evening.

Speaker 23 Well, that makes Pat Daly's answer

Speaker 23 quite boring in comparison, which is simply moths' eggs.

Speaker 23 Oh, do the nuts get a moths?

Speaker 5 The eggs. That's what really gets me.

Speaker 14 Well, because they're the ones that, you know, there's always those urban myths you hear about.

Speaker 30 Yeah, and he wouldn't get his hair cut or anything.

Speaker 26 And anyway, it ended up, he had moths' eggs inside it, and they all hatched and came out of his eyes.

Speaker 4 Anyway, so.

Speaker 21 I used to love those stories.

Speaker 19 What Who's that an impression of?

Speaker 20 Oh, just like Sony's really into different stories about, you know, and they just said, don't look back at the car, don't look back at the car, she looked back, and there's a bloke who pulled someone's head off, spanging it on the roof, wouldn't he?

Speaker 15 And the babysitter turned out that the murderer was inside the house, wasn't he?

Speaker 23 And the Sony Award for best non-specific impression.

Speaker 14 Next week, oh, by the way, thank you very much to our fantastic panel, who are John Copley, Monica Grady, and Ed Byrne, who I would like to say has very beautiful, luxuriant brunette hair.

Speaker 5 And

Speaker 11 next week, we're looking at the future of humanity and whether it's worth bothering with.

Speaker 12 Should we just stop now and give it to another species? I think it's time the octopus had a go, to be quite honest. What is our greatest threat?

Speaker 11 Is it climate change, artificial intelligence, or whatever lives in our mysterious spaceship moon?

Speaker 19 Conservation of momentum is the biggest risk to you.

Speaker 5 He wants a fight. Good night.

Speaker 5 In the infinite monkey cage.

Speaker 10 Till now,

Speaker 31 Before you go, let me just squeeze in here and tell you about the flip podcasts from BBC Radio 4.

Speaker 31 Each month, there's a new book set to listen to from people like Rhys James, Mae Martin, and Joe Lysett. Subscribe to the Flip podcast on BBC Sounds.

Speaker 28 Be our guest at Disney's enchanting musical, Beauty and the Beast. Experience this timeless, classic tale brought to life like never before.

Speaker 28 Fill your heart with joy and Disney magic at this dazzling and beloved production.

Speaker 32 Coming to the Orpheum Theater July 14th through August 9th. Tickets on sale now at BroadwaySF.com.