Surprising Symmetries

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I'm Dr.

Adam Rutherford.

And I'm Dr.

Hannah Fry.

And you are going to send us your everyday mysteries.

And we are going to investigate them using the power of science.

Science.

Science.

I like it.

Okay, hello and welcome to a special left-handed episode of Curious Cases.

And actually, weirdly enough, this one links back to something that we said in our pre-season teaser about snogging.

But this is not an episode on snogging.

This is an episode on Left and Right.

And features a snail.

that during the course of the recording pretty much got into some snogging with another snail right on my hat.

Do you you know what?

I lied when I said there was no snogging.

On with the episode.

In many ways, this programme represents the perfect balance of two forces, opposite, yet attuned, yin and yang, lightness and dark, Rutherford and Fry.

If you say so.

Actually, today's question is about symmetry, not about Zen Buddhism.

Joanne Walker sent in her question to curiouscases at bbc.co.uk to ask, why are we symmetrical?

Why do we have two of most things?

Ears, arms, legs, ovaries, testes, kidneys, lungs, and many more.

It's the universe perfectly in balance with our bodies.

I think that's enough from you, Grasshopper.

But wait, there's more.

She also goes on to ask, but why are we also not symmetrical?

Our heart, liver, stomach, and other internal organs.

What has happened in nature which caused this symmetry and then this fight against symmetry?

Well, Joanne, this is a very good point.

Why are we symmetrical on the outside, but all higgledy-piggledy inside are squishy?

In technical terms, of course.

Indeed, they are.

Now, to start this off, it's a biological question, but I think first we should address the mathematical definition, which is inherent to Joanne's question.

Hannah, we are symmetrical, right?

We are, but we tend to only have reflectional symmetry.

I haven't yet met anyone who has rotational symmetry.

You've obviously never played in an amateur rugby team.

Okay.

Fair point.

So, humans have reflectional symmetry on the outside.

Yeah, well, most animals also are symmetrical on the outside, too.

In fact, we define most animals by their symmetry.

So, we call them the bilateria.

They, which includes us, all have a head and a tail and a back and a front.

That's not all animals, though.

Not all animals have a front and a back.

I'm thinking here about jellyfish, for example.

Right, well, biology, the science of exceptions, it's almost all.

In fact, there are notable groups of animals that don't have this reflectional symmetry and that have no symmetry or that have rotational symmetry.

So, I'm thinking of the Tenophores or the Cnidarians or the Placozoans.

Which in English are called

jellyfish and comb jellies and placozoans are just like blobs.

Basically it's the Latin for flat animals.

Okay hang on a second though so if you exclude blobs and jellyfish for a moment are you saying then that everything that has a front and a back and a head and a tail is symmetrical because I'm thinking here about fiddler crabs for instance which have one claw that's much bigger than the other.

Yeah well I didn't give give you the full definition of bilateria because bilateria only need to be symmetrical when they're babies, when they're embryos.

So, for example, flatfish are very asymmetrical, but they start off being symmetrical, bilaterally symmetrical, and then their heads go

and they twist all the way round.

And then there's other examples like there's the honey badger, which has one tooth down the bottom jaw that it doesn't have on the other side.

And gnwhls are a bit like that as well, because their tusk is actually a it's actually tooth, an extended tooth.

It's the incisor.

That is quite interesting.

As much as I'm enjoying this list.

Oh, and there's barn owls as well because they have one big ear and one small ear to help them.

Presumably all the better to hear you with.

Well, look, these lists are very interesting, Adam, but I think maybe we should get an actual expert in to talk to us.

In the studio today, we have Sebastian Simmel, who is a professor of evolutionary developmental biology at the University of Oxford.

Seb, okay, let's take us back to the beginning here, if we can.

How did bilateral symmetry first emerge?

Well, in some ways, making something bilaterally symmetrical isn't really that difficult.

I mean, all you need to do is make a front and a back and a top and a bottom on a three-dimensional object, a primitive animal of some sort, and that would by default be bilaterally symmetrical.

So, one of the ways you can think about this, if you imagine a kind of a beanie hat, it's radially symmetrical, and the body organization there is a little bit like a jellyfish.

It's got a sort of mouth end at the bottom and then a not mouth end at the other end.

And that's a radially symmetrical organization.

Now, if you want to turn that radial symmetry, which is what we think the primitive condition before bilateral symmetry evolved was, then all you need to do is to mark one bit of that hat.

anywhere around the circumference.

And once you do that and you turn that hat end on and look at it, you'll see that you can only now draw one one truly reflective plane of symmetry through it because any other that has to go through the mark that you've made.

So any other plane that you draw, that mark is going to be on the left side or the right side.

It's not bilaterally symmetrical.

You're taking something which you could spin around and look at it from any direction and it would be the same.

And as soon as you just put one dot on it, suddenly you can only break it in half and get reflectional symmetry from it.

Absolutely, yeah.

So the beanie hat then, I guess, is a bit like, I don't know, a prehistoric blob that suddenly gets an eye.

Is that sort of what I should be imagining here?

Well, if you're thinking of beanie hats, yes.

So, okay,

what kind of creatures are we talking about?

I mean, we're not actually talking about blobs here, are we?

The first bilaterally symmetrical organism would almost certainly have been a small, quite flat, worm-like animal, perhaps a few millimetres long.

We don't really know because things like that that are small and soft and squishy don't really fossilise that well or that often.

Well, hold on a second.

How long ago are we talking about here?

When did we transition from blobs to things with symmetry?

I mean, when I say we, I don't mean specifically us.

Well, we don't absolutely know quite how long ago it was, but we're talking at least 560 million years ago, sometime back in the Cambrian or possibly a bit before the Cambrian.

And we know that from fossils that stem from that time, which tell us that bilateral symmetry had evolved around about that, by that point.

And we know it from molecular biological data, so comparing gene sequences.

Both of those tell us it was at least that 560 billion years ago, and probably a little bit more than that.

And presumably, this happened many times in evolutionary history.

Well, we only have evidence for one, which is the one that gave rise to all of the bilaterally symmetrical organisms on the planet.

Once.

One dot on a beanie hat.

That's

really extraordinary.

If this only happened once and it stuck, and almost all creatures on Earth, bar the ones that Adam was talking about earlier, have this.

It must have been quite a useful thing.

Why was it immediately useful to have bilateral symmetry?

Well, truthfully, we don't really know that it was.

It's possible that these first bilateral organisms spent quite a long time in sort of relative obscurity.

crawling around on the mud and the sea floor or whatever their habitat was before they really radiated and to give rise to all of the lineages that we know today that's the bilateral.

And those different lineages really did exploit that bilateral symmetry to make more complicated body plans with all of the bits, all the muscles and skeletal elements joined together to make highly mobile predators.

And by now, having symmetry, by now, I mean, in terms of the complexity of organisms that exist

in the modern world, symmetry is definitely useful.

Oh, yes, yes.

I think biomechanically, it's got to be better for moving at any kind of pace through water and later on for moving any kind of pace through air when animals eventually learn to fly as well.

Symmetry is useful if

you're running.

It's hard to imagine a highly asymmetric animal being

very readily motile.

And those things

make for a more active animal that can get around more quickly.

Okay, so we've got multiple things happening here.

One is a sort of developmental process.

It just is easier.

to if you're going to grow something on one side you're going to grow it on the other and the other is the sort of selective, the practical aspects of it, which is that having, I don't know, two fins makes much more sense if you want to go in this direction than having one or three.

Well, also means you don't end up swimming round in a circle, which is, I guess, useful.

The thing is, though, the way we're talking about this is we're describing these natural examples as though they're perfectly symmetrical.

And actually,

creatures aren't perfectly symmetrical, which is something that you can tell very easily by looking at the symmetry of somebody's face.

Now, Adam, you're a good-looking man, according to some, mainly your mum.

But even you, Adam, would you believe it, have some subtle asymmetries in your otherwise beautifully symmetrical face.

And you can demonstrate this most clearly of all if you take your picture and mirror each half of your face.

Which you have done.

Which I have done.

To reveal two different Adam Rutherfords.

There we go.

Oh my lord.

Okay, well the one on the left is clearly me, but I look like I've been on a severe diet.

And the one on the right looks like I could be a prop forward.

Why really that?

Like that basically implies that I'm massively fat on one side.

I think these are two different sides of your character.

There's a sort of bookish side and then the rugby player.

Also, very much noticed, talking about that owl earlier, I think one of your ears is quite a lot larger than the other.

But also that when I did this to myself, I am, I fare no better.

Almost all of us have these very subtle asymmetries when it comes to our faces.

The second part of the question was about how, okay, not just on the outside, once you get inside, humans aren't symmetrical at all.

So, you know, the heart, the liver, the lungs are coiled guts.

Your heart's obviously on the left, your liver's on the right, you've got an appendix on the right.

We're totally asymmetrical once you get inside.

Yeah, and that's almost universal.

As I said, biology, the science of exceptions, because there is, in fact, a rare condition called situs inversus, where all of those organs that you just described appendix on the right liver on the right

pancreas on the left and so on are all completely flipped round and it happens at a frequency of about one in ten thousand people so it's pretty rare we know of a few celebrities that have citis inversus who donnie osmond yes um you know the comic actor very funny that catherine o'hara is that the one in home alone and the mum in home alone and the mum in betelgeuse and the mum in shit's creek she she plays the mum in a lot of things.

Yeah, all their organs reversed.

Does it matter?

No, mostly not.

But mostly people with citizen versus never know, and they're perfectly healthy.

And often it's only discovered when they've had a pre-op medical scan.

I've got a couple of friends who are surgeons and I asked them, have you ever come across someone with citizen versus and they said, well, no.

And also, it wouldn't make much of a difference because they'd always have a look before they went in.

Bet it did in the bloomin' 1890s though.

It's like going to do a stomach thing and can't find it.

Yeah, I think that would be an an enormous surprise if you opened someone up and discovered that

their appendix wasn't where you thought it was going to be.

Okay, how does that work though?

How do you get some symmetries on the outside, some asymmetries on the inside?

How does it all come about?

Well, the answer to that, Hannah Fry, is I don't know at all, but I know a man who maybe does and maybe can just help us explore this, and that's Angus Davison, who's a professor of evolutionary genetics at the University of Nottingham.

Angus is with us in the studio.

Now, you study snails in very simple terms because snails are actually bilateria, so they fit into the class of animals which are bilaterally symmetrical, but they're not as well, aren't they?

I mean, they are asymmetric animals, too.

Yeah, that's true.

So, if you look at the tentacles, for example, if you've got two of them and asymmetric, but the shell is asymmetric, so it coils one way or the other.

And internally, all of their organs are asymmetric.

And most obviously, it's the genitals.

The genitals are on one side of the body or the other.

And the majority of snails externally, the vast majority, they have right turning coils, right?

That's correct, yeah.

Ordinarily the shell coils clockwise and then very rarely the shell coils anti-clockwise.

Well the very rarely thing is what we're interested in this programme because you

a few years ago you did the rounds in the press and became a minor celebrity.

Well no in fact it was Jeremy who became the minor celebrity.

Tell us the story of Jeremy.

So I've been working on snails in general for about 20 years and I've never seen a left coiling garden snail.

So one day I got a phone call from a curator of the Natural History Museum, and he had found one of these left-coiling garden snails.

And if we want to understand why they're so rare, what makes them different, we need to.

I'm a geneticist, we want to understand the genetics, so we needed to find another snail for that snail to mate with.

And the problem, as it is, is the genitals are on one side of the body, so left can only mate with left, and right can only mate with right.

So, poor old Jeremy was, unless you could find artificially find another left-handed snail for him, he was a doomed branch of evolution.

Yes, exactly.

I mean, so if we think there's millions of garden snails all around Britain, there probably are a very few other left-coiling snails who are just going about their business now, not quite knowing why they can't find another snail to mate with, because their genitals are on the wrong side of their body.

I need to, I'm really sorry.

I need to find out more.

I'm not really sure I understand.

Have you got anything?

I do have some props here, yeah, if you want.

Yeah, so I've got some left- and right-coiling snails here.

These are shells, right?

No, no, they're live snails.

Oh, you've brought snails into the studio.

Fantastic.

Yes, of course.

Hannah doesn't deal brilliantly well with

me.

Shall I pass them to the geneticism?

Thank you.

So if you want to try and match them up.

It's important that you know that Angus came down on the train with his snails in just a normal sandwich bag.

Yes, so what are these?

What species are these?

So those are garden snails.

Yep, yep.

And they mate in what's called a face-to-face or really it's a side-to-side position.

So if you try and line them up,

first find the two right-coiling ones and two left-coiling ones.

I gotta say, when I woke up this morning, I didn't think I was gonna do snail mating on the radio, but uh that's so these two, look, can you see the coil is pointing to the right if I'm going forward that way, and these two,

the coil is pointing to the left?

Okay, I mean I failed on some quite basic things here.

I think in my head, I essentially had a cartoon version of a snail where

the shell is pointing directly upwards.

I don't think I've ever looked at a snail in enough detail, but it's flopped over to one side and then sort of a little you know, a little twist to the top.

Oh, I see what you're saying.

So, in a cartoon, they're often what's called planispiral, where it's just coiling on itself.

They're essentially a spiral.

They are, yeah.

A spiral rather than a coil.

And the little righties here are poking their little eye stalks out.

I'm happy with you.

So, then

which side is there?

Are there genitals?

So, if it's a right-coiling snail, the genitals are on the right-hand side.

So I would make the analogy.

You could talk about handshakes.

The snails have to approach each other from different directions.

Okay, I get it.

It's kind of like if two buses were driving towards each other and they get stuck in traffic, but they're right next to each other.

and the two drivers can wind down the window and talk to each other but only if they're both sitting on the right hand side of their buses otherwise one of them is going to be shouting through a closed door everything's got to work together there.

And if they're the wrong coil, they approach each other, but that's not going to happen.

That explains why, ordinarily, you don't get left-coiling snails, because they've got nobody to mate with.

Okay, but you found Jeremy, and Jeremy was a living snail a few years ago, and you had to seek out, how did you find a potential mate for Jeremy, another lefty?

Yes, so I was very lucky.

We managed to, via the press, put out the call to find a mate for this snail that we called Jeremy.

But actually, it turned out that we found not just one, but actually several mates of refugees to mate with Jeremy.

So through that, we were able to get offspring and study the genetics and the inheritance of shell coiling and asymmetry in snails.

Okay, so and what did you find?

What was different about a left-coiling snail from a genetic point of view compared to a normie?

In Jeremy, we discovered that it was probably just a developmental accident.

There's for some reason, very early in development, the cells twisted clockwise, anticlockwise instead of clockwise.

But in other circumstances, we can show very definitely it's a genetic condition.

So there's a mutation involved in those snails that

switches the early development of the cells.

So when they divide from four to eight cells, usually you get a clockwise twist.

So in the first few hours of a snail's development, there's a clockwise twist.

And if there's a mutation, it goes the other way.

And that's what ultimately ends up making a snail with a clockwise or anticlockwise coiling shell.

Does your understanding, does your work on left-handed snails, such as the two I've got in my hand here, which are really doing their best to escape very very slowly because they're snails.

Does that work give us any insight into why other organisms such as ourselves are asymmetric on the inside?

No.

Thanks for coming.

And could you elaborate on that?

My understanding of why we're asymmetric on the inside comes back to what Seb mentioned.

It was the gut.

And so it's okay if you've got a short gut, it can be linear and goes in one end and goes out the other end if you're lucky.

But once that gut starts being longer than the internal length of your body and it becomes compartmentalized, so it has specialist functions, then it's going to have to go one way or the other.

And as soon as it goes one way or the other or twists in one way or the other, then it's going to become asymmetric.

And as a consequence of that, all of your other organs become asymmetric as well.

Do you want these snails back by the way?

I mean, they're going for it at the moment.

I think these two are amazing, actually.

They're looking excited, yeah.

Hang on.

Sexy snail action.

Yeah.

Okay.

Well, our producer was just reminding me that this is a family show, so we're going to have to ask you guys to cool your jets and we're going to swiftly move on.

Alright, so let's see where we are then, as a non-expert.

Sounds like all biological creatures have symmetry somewhere, except for those that don't.

And the symmetry is on the outside, but not on the inside, except sometimes the inside is flipped.

And even the bits that are symmetrical on the outside aren't symmetrical when you look really closely.

Is that sad about right?

Yeah, I mean, you just describes biology.

Exceptions are the rule.

Exactly.

Okay, okay.

All right, but when it comes to this symmetry, though, the way that you're describing it there, particularly around snails, is that at some point, snail embryos know their left from right.

They know which way to twist early on in development.

Same with human hearts, presumably, that they know that they end up almost always on the left-hand side question is how do they know like okay imagine if we had somehow made contact with an alien in a really distant planet how would you describe to them which way was left and which way was right this was actually a thought experiment that was posed by the Nobel Prize winning physicist Richard Feynman who was an incredibly charismatic man also slightly problematic at times.

This is in 1964.

He assumed that the aliens could speak English, which is handy.

He also assumed that they were male, because Feynman.

But this is the way that he set up the problem.

What if you somehow made contact with an alien that was, I don't know, in a planet really, really far away, distant side of the galaxy?

How would you describe to them the difference between left and right?

Ordinarily, if you were here on this planet, you could say, okay, if you look at a map of the world, you know, you've got the America's on the left, China's on the right.

But of course, the aliens can't see this planet, which makes things kind of difficult.

Well, could they not use the stars or something, something sort of universal that we use the North Star to navigate and have done for several thousand years?

Couldn't you just look up and say that side of the North Star, we're going to call that left?

Well, no, you can't because these aliens don't share the same night sky as we have.

And actually, once you really get down to it, when you don't have any reference points or objects that you can describe, it becomes incredibly difficult.

Really, really hard.

Now, imagine the same thing, but for an embryo.

Same idea.

How does the embryo figure out which way is left and which way is right?

Well, that is one of the fundamental questions that we've been trying to answer in the last 30 or 40 years in developmental biology.

What are the molecules which say this way is up, this way is down, this way is left, and this way is right?

Well, I actually spoke to Daniel Grimes, who is an assistant professor of biology at the University of Oregon, and he has got a particular idea about the very delicate mechanisms which allow embryos to distinguish the difference between left and right.

So embryos start out as symmetrical clumps of cells and at some stage during their development they have to make a decision this way is left and this way is right.

So in this early developmental stage there's a small area of the embryo called the node.

It's essentially kind of like a depression on the surface and on that surface there are many of these cellular protrusions called cilia.

These little little structures stick out from cells and they rotate or they beat back and forth and what that does is move fluid across the surface of cells.

So how is this relevant for asymmetry?

Well it seems like the first asymmetries in many vertebrates, including zebrafish and humans, occur around these cilia.

So the flow is kind of like a little river inside the embryo, and it moves towards the left-hand side of the embryo.

So that seems to be the initial signal which tells the embryo this way is left, this way it's right.

It's which way that flow is moving.

The fluid flow is the thing which triggers those asymmetries and gene expression.

For instance, the entire left side of the embryo turns on certain genes and pathways which are not present on the right side.

And it's these genes and pathways which will ultimately determine the direction, for instance, that the heart moves during development.

It's just not satisfying enough for me.

I'm not there yet.

Like I accept that there's a chain reaction that somehow or other ends up with your heart being on one side of your body and that when you trace it back it's something to do with fluid flow.

But what is it about the fluid that makes it flow in that direction in the first place?

Well, that I don't know, but my sense is it's sort of largely stochastic.

It's a bit of randomness in the system.

But it can't be because your heart always ends up going in the same direction, mostly.

Daniel's got another idea.

He thinks that it might be down to the molecular building blocks of life.

Cilia, they're built, like nearly everything in biology, by proteins.

Those proteins are made out of a molecule called an amino acid.

Those amino acids come in two flavors, two forms.

One type is called the L amino acids, and the other kind is called the D amino acids.

And these are basically the same.

The only difference is they're different shapes.

And they're different shapes in the same way that your two hands are different shapes.

One is a mirror image of the other.

For whatever reason, we don't really understand why.

Life predominantly uses the L kind of amino acid and not the D kind.

So we're kind of using, you know, this one mirror image form and not its counterpart in all of our cells.

So it's a bit speculative, but we could trace back the origin of our organ asymmetries all the way down to this really fundamental molecular difference in the fact that life is using one mirror image form of an amino acid and not the other form to build its proteins.

Okay, so what Daniel is saying there is that we have molecules in our bodies, but specifically proteins.

And proteins, due to the way that they're put together, the way the atoms are arranged, they have a handedness to them, right?

So you imagine that you've got a left hand and a right hand, and you can't superimpose them on top of each other, and we call that chirality.

And all biology that we know of is based on one particular form, which is that we only use L amino acids.

Left-handed amino acids.

Basically, yes.

Where are all the right ones?

Well, they can be synthesized and they exist in the universe.

They're all over the place, just not in living things.

At all.

At all.

Ever.

Biology.

There are some exceptions, but for the purposes of this discussion, never at all.

Anyway, what Daniel seems to be saying is that the fact that that is a real part of biology, that biology only uses these left-handed versions of proteins, that that may be the root cause of the asymmetries that we see in our bodies.

And why you end up with your heart on one side of your body.

Yes.

And I am

unconvinced by this as an argument.

Seb.

Such a lovely idea, isn't it?

That we could trace our own asymmetry back to the sort of a fundamental aspect of the molecules in the universe.

But I'm afraid I'm on Adam's side here.

I'm a little sceptical that we're able to do that.

Angus, what do you think?

Do you think the fact that at a molecular level our basic biochemistry has a handedness, do you think that that is could be a root cause of the fact that there is asymmetrical in our internal organs?

Yes, but I'm going to I'm going to agree with everyone so far.

It is coming from the molecular asymmetry, and we have shown that in snails, for example, it seems to be the cytoskeleton, which is determined by genes.

But how far back you can go to the left and right forms, for example, of amino acids, yeah, I don't think we're there yet.

We like speculation, and we like questions that we don't really know the answers to.

Could you imagine an experiment which might actually help to elucidate whether that is

that the idea that Daniel's putting forward could be correct, that the the handedness of molecules actually determines the handedness of

our asymmetries.

Oh,

that's a very difficult thing to do.

I think if you had unlimited time and money, then perhaps rerunning the history of life on the planet with the opposite handed molecules and seeing where we ended up, perhaps that would do it because you'd predict it would come out the other way.

But I'm not sure you're going to fund me to do that.

Well, funnily enough, this is your lucky deck.

No, no, not at all.

Let's put in the grand proposal now.

Right away.

It's quite a big one.

So again, it comes back to that idea that we were talking about a minute ago.

Is the handedness of biology at a biochemical level,

is that a happy accident?

Is it just something that happened at some point billions of years ago and evolution being a sort of efficient and conservative thing just locked onto it and just hung onto it?

Angus.

We can definitively say that, yeah, evolution has hung on to it, but we can't do that first step to know whether that was always going to go one way or the other.

That requires the money.

And with that final mystery lingering, it's time to say thank you very much to our guests, Sebastian Schimild, Angus Davidson and Daniel Grimes.

So Dr.

Ruthford, when it comes to why our bodies are symmetrical, can we say case solve?

Yes, Dr.

Fry, most animals are symmetrical on the outside, probably thanks to a single event more than half a billion years ago in our evolutionary history.

And it kind of worked, so evolution stuck with it.

But on the inside, if you're trying to squish something large into a small space, like a gut in an abdomen, then it tends to get squeezed to one side.

But as with everything in biology, there are exceptions to the rule of symmetry.

Jeremy the snail with his lefty shell.

People like Donny Osmond with their insides flipped around.

And owls and Adam Rutherford with one weirdly big ear.

I can tell you really enjoyed yourself today, Adam Rutherford.

Oh, that was great.

And Both of those two are, I mean, they're my people, developmental biologists who specialise in evolution.

So I think I've mentioned on this plot before that my mum is Irish, and normally around the house, she just speaks in what is essentially an English accent with an Irish lilt, but put her around Irish people and suddenly she becomes extra, extra Irish.

What I've noticed today is that Adam is exactly the same, but the biology version.

Because, oh my lord,

if you

think think that episode was complicated, you should have seen what I had to suffer in this last hour and a half in the studio.

Are you on your left and right?

I uh actually not very good.

I think some people are better at remembering them than others.

I broke my thumb, my right thumb, when I was younger and sucked my left thumb until I was like 11.

And so they're very different shapes.

And

so you criticise me for having

slightly different sized ears, which I incidentally challenged and you refused to accept.

But you over there with your freaky asymmetric thumbs.

Oh god, I do not have a symmetrical face.

My thumbs are not symmetrical.

I make no claims to being symmetrical in any form whatsoever.

Okay, well, I mean, after Hannah's weird hands and my weird ears, I think it's time for Curio of the week.

I think it probably is.

Fast and curious, occasionally spurious, totally geek chic,

Rutherford and Friars, Curio of the Week.

We've got a lovely entry for Curio of the Week this week.

It's a letter that has come in from Jasper B, age 12.

Good to protect your own identity there, Jasper.

I appreciate it.

Dear Dr.

Rutherford and Professor Fry, thank you very much.

Inspired by some of your recent episodes, I have decided to send you this article on the dangers of dihydrogen monoxide.

And there is a link here to

a very fancy-looking website, which I've clicked on.

And

it's a campaign.

It's an important campaign for science.

Ban dihydrogen monoxide, the invisible killer.

It says dihydrogen monoxide is colourless, odorless, tasteless, and it kills unaccounted thousands of people every year.

Most of these deaths are not caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there.

Prolonged exposure to its form causes severe tissue damage.

Yes.

I mean, this is very troubling stuff.

It's terrifying.

It's absolutely terrifying.

Dihydrogen monoxide is also known as hydroxyl acid and is the major component of acid rain.

It contributes to the greenhouse effect.

It can cause severe burns and the erosion of our natural landscape.

And apparently, companies dump waste dihydrogen monoxide into rivers and the ocean.

Jasper, thank you so much for alerting us to this terrifying

sounding issue.

Something I think we will look into much further in more detail.

You turned into

watchdog voice then.

Well, Jasper, we thank you very seriously from the bottom of our consumer hearts about this safety issue, which is facing, well, it seems everybody.

I understand that everybody who has ever consumed dihydrogen monoxide ends up dying.

It is 100% the case that that is true.

And we should ban dihydrogen monoxide as soon as possible.

AKA

water.

Thank you very much Jasper.

You are our cura of the week.

We'll be back next week.

Send us in questions, all the usual stuff.

Curious case set bbc.co.uk.

You know what to do.

Hi, I'm Russell Kane, and I want to tell you about my podcast, BBC Radio 4's Evil Genius.

You can find it on BBC Sounds.

Although, I don't know whether you should or not.

It's one of the most confusing, exciting, surprising, infuriating, wonderful, enlightening listens you can have.

Why?

Because we take people from history you thought you had the facts about and let off fact bombs around them.

If you think you know everything about Prince, Elizabeth I, Freud, Frida Carlo, Alan Ginsburg, you don't.

If you want to hear uncomfortable comedians squirming in their seats when they're forced to make a vote one way or the other, evil or genius, because that's what this show is about, cancel or keep, then hit subscribe straight away.

However, if you find it might be triggering and you can't handle it, just forget you've ever heard this.

Anyway, I do hope you come along with me, Russell K.

Right, I'm off to ruin everyone's life who likes prints.

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