This is a “kind of, sort of, vaguely close” copy of the words that David & Sophie speak in this episode.

IT IS NOT 100% accurate.  We are very sorry if we have spelt something completely incorrectly.  If it means a lot to you to have it corrected, email us at stemology@ramaley.media

s1e5 Transcript

Sophie: [00:00:00] Welcome to episode five of STEMology,  a podcast that is your one stop podcast shop for the interesting fun, and sometimes just patently bizarre on using science, technology, engineering or maths.

[00:00:13]David: [00:00:13] Your hosts are Dr. Sophie Calabretto and Dr. David Farmer

[00:00:17] on today’s episode, we’re going to be talking about fake mucus, naturally  pointy things.

[00:00:21]Sophie: [00:00:21] Pretty fish, scary, scary words, and statistical shark deterrence

Fake Mucus

[00:00:35] David: [00:00:35] So mucus. It’s schticky, it’s slimy. It comes out of your nose in large quantities when you’re sick. Thoughts, Sophie. Okay.

[00:00:44] Sophie: [00:00:44] I do have some thoughts. The first thought is that when I was looking up mucus for this story, the fact that we produce 1.5 to two liters of mucus every day in our respiratory tract alone is one of the most revolting things I have genuinely

[00:00:59] David: [00:00:59] I can one up you on that because do you know what happens to that mucus? It gets moved up through your respiratory tree via ciliary action to your nasal pharynx where that’s right. You swallow it.

[00:01:09]Sophie: [00:01:09] Mm. Hmm. Dave, tell me about mucus. Why are we talking about mucus?

[00:01:15] David: [00:01:15] mucus is something that your body produces basically. in, uh, well, I guess in places like your mucus membranes. You have membranes called mucus membranes in your body. These are in places like your guts and in your respiratory system. And basically you have these mucus membranes in places that skin just won’t do .

[00:01:32]Sophie: [00:01:32] So Dave, tell me, why are we talking about mucus?

[00:01:35] David: [00:01:35] So we’re talking about music because, because it’s a sticky thing that your body produces to trap bacteria and particulates and things. And it does this in places like your respiratory system, where having skin there wouldn’t really do, but you’re exposing it to the outside world. And skin wouldn’t really do, because you need to use your respiratory system to do things like breathe, so you need to bring air into contact with the blood so that you’re exchanging gases. So to have skin there wouldn’t really do the trick. So you have to have something far thinner. Called a mucus membrane. And the reason it’s a mucus membrane is cause you have mucus there to protect the airway because you can’t have skin.

[00:02:08]So mucus is this slimey stuff. It’s a protein. Well, it’s a collection of things. One of which is the protein mucan. And when mucan is exposed to water, it increases its volumes 600 times. My dad actually used to say that you wanted to come back as a mucus molecule because he thought it was so amazing that it got so much bigger.

[00:02:25] I don’t know what that says about my dad or about his relationship to me, but I thought it was weird. Anyway, it

[00:02:31] Sophie: [00:02:31] Interesting.

[00:02:33] David: [00:02:33] it gets way bigger and therefore it can trap, because it’s so sticky,  things like bacteria and stop them communicating. And then it can also, you know, take them up to your nasal pharynx where you swallow them and they go into your guts where you destroy them in the stomach acid.

[00:02:46] And

[00:02:46] Sophie: [00:02:46] Or do you know, I was thinking like, you know, if you go to an outdoor music festival and you’ve been dancing around and you’ve been inhaling dust in a way that you’ve not realized, and then you blow your nose after and you, it just comes out black. And you know what I think. It’s good that it’s in that mucus and not in my lungs.

[00:03:01] I don’t think that would do well in my lungs.

[00:03:04] David: [00:03:04] And so the reason we’re talking about all this today is because researchers at MIT and Case Western reserve university in Cleveland. These researchers at these university have made fake mucus.

[00:03:15]Sophie: [00:03:15] they have made fake mucus, but so what they did, Dave was I believe  they managed to make these synthetic mucans. So the thing that your dad is super into, these protein building blocks of mucus, which are described as fuzzy pipe cleaners. So what we have is a long protein spine. And then we have strands of carbohydrate polymers called glycans.

[00:03:37] So the long protein spine obviously is the wire in your fuzzy pipe cleaner. And then the polymers, the carbohydrate  polymers are the fuzzy parts. And what they’ve realized, it’s sort of, it’s unclear how a lot of these mechanisms work, but the fact that they’ve been able to fabricate this synthetic mucan could actually help them understand it.

[00:03:57] But what I got really caught up with was the crazy process that they use to try and create these mucans, because weirdly, it’s not that simple. One might imagine it’s very simple, but it’s not. And so they had to make slime. So they had two approaches, so they both involve taking a carbon ring. So a ring that’s made of carbon, and then there’s a process that you can sort of split it and you can open it.

[00:04:19] And now you have.

[00:04:20] David: [00:04:20] You mean like a molecular ring? Not a

[00:04:21] Sophie: [00:04:21] Yeah, sorry, not like not a pretty ring made of carbon. So a molecule and you break it and now we have a row of carbon. And then to basically create your polymer, you just need to join a chemical group to your carbon, but there are two different ways to do it. You can join it so that the two chemical groups are joined on the same sides and the polymor, and that’s called the SIS form. Or you can join the chemical groups on opposite sides and that’s called the transform and they did both of these. And they found that if they did the transform one, it didn’t work.

[00:04:51] And what you got with a polymer that turned into an I quote, a weird blob. And so when they did the SIS polymer process, what they got was these nice elongated polymer chains that captured toxins better than real mutants. So they made a better mucan. And in fact, the bit that I thought was super gross and, and it’s great cause it’s water soluble.

[00:05:13] So we can  put mucans into gels and creams. And I just don’t know if I want mucans in my gels and creams.

[00:05:18] David: [00:05:18] Well, that’s exactly what I was thinking. So yeah. Topical creams and gels, maybe even eye drops and I’m sure everyone listening is like. Oh good, my eye drops are way more like the stuff that pours out of my nose when I’m sick.

[00:05:28] Sophie: [00:05:28] Yeah. Do you know what my eye drops are missing? Mucus, uh, but having said that there’s a, there’s a lot to be done. So they were able to create these mucans, but in the mucans, they weren’t even able to make those glycan bristles so they could just make the wire of the fuzzy pipe cleaner, but they couldn’t make the fuzziness of it.

[00:05:45] But this is still a, it’s a pretty big step, I think, in chemistry and in getting mucus into your eyedrops

[00:05:51]David: [00:05:51] mucus, mucus, slime, fake slime, fake mucus. I’m on board.

Pointy Things

Sophie: [00:06:06] So Dave, from slimy thing to pointy things,

[00:06:10] David: [00:06:10] I was going to say the same segue.

[00:06:12] Sophie: [00:06:12] nailed it. So we’re talking about pointy things Dave, because there are a lot of pointy things in body parts.

[00:06:18] Um, and what I’m

[00:06:20] David: [00:06:20] well, blah, blah, blah, blah, blah, blah. Okay. Yes, let’s be specific.

[00:06:23] Sophie: [00:06:23] like teeth and horns and claws and beaks. So, you know,

[00:06:27] David: [00:06:27] I see.

[00:06:28] Sophie: [00:06:28] Yeah, so those kinds of pointy things, and we’ve got some scientists at  Monash university who have actually come up with this very, very interesting mathematical model. so what we find a lot is we’ve got these mathematical ratios and models and things that appear in nature.

[00:06:45] Right. So have you heard of  the golden ratio or the golden spiral?

[00:06:50] David: [00:06:50] I believe I have, but I don’t think I know actually what it is or what its significance is

[00:06:55] Sophie: [00:06:55] To be honest, I’m going to be a little bit bleak at the moment. I don’t think it’s that interesting. Basically, it’s just a self-similar spiral. It’s a kind of curve, but it happens to appear in nature. So if you look at a bunch of, I dunno, mollusks, or even nerves in the cornea or spiral arms on a galaxy, they all follow this logarithmic spiral, basically.

[00:07:13] So we get very excited because we can write this down mathematically and it appears in nature. And then the golden ratio is in, if you face it, the golden ratio, which is a special number, which is 1.6, something, something, something, something you have a very pretty face. And if the growth factor in your logarithmic spiral is the golden ratio, then you get the golden spiral and that’s the prettiest kind of spiral. So they’ve done something similar, but with teeth, so. With pointiness in teeth. So what they’ve actually found was a power law model that would describe the structure of teeth, which is interesting because if you think so teeth, aren’t just cones.

[00:07:49]If you think of a crocodile tooth, this is the one that if I visualize it, it made more sense to me. So think of a cone. Yeah,

[00:07:55] David: [00:07:55] It’s one of the most Australian things you’ve ever said, but please go on.

[00:07:59] Sophie: [00:07:59] but they’ve got the best teeth Dave, and seeing, you know, if you think about it, it’s sort of tapered, it’s sort of like, so it’s still a cone, but it kind of curves to a point at the end. Yeah. So what they’ve done is they’ve created a model that can describe that particular  behavior. So they call that particular cona a power cone, and they had this power law model.

[00:08:18] So what they do is they take their tooth. So what, when does take a lot of cross-sections of our tooth. So we’re going to start from the tip and then we’re going to take lots of cross sections towards the base, and we’re going to draw slices. Yeah in. Thank you. I can only think of it as a cross-section. It’s a slice, there are other words. So you go from the tip of the tooth to the base of the tooth. And so draw a line up the middle. So that’s our tip distance and it just so happens that at each cross-section or slice, if you plot the average radius. So of course, a tooth isn’t necessarily a nice circular cross-section.

[00:08:52] If it was just a circular cross-section, we’ll just call it a radius. But the average radius is just the square root of the area of that particular cross section divided by PI. So it’s a measure of the radius. And if you it’s just that. So if you plot the average radius versus the tip, the length from the tip of the tooth, it’s a log log plot, and we’re not going to talk about that, but if you plug it in a certain way, you, you get a straight line

[00:09:16] and a straight line is it’s very simple.

[00:09:18]David: [00:09:18] So basically if you look at the relationship between the cross-sectional area of the tooth and how far you are away from the tip of the tooth, that is the same all the way down the tooth. So then you can say this as a general thing and not some you can say it’s not something like biologically, it’s not some weird process that changes over time that produces this curvature.

[00:09:39] It’s probably a constant process that happens that enables you to form this pointy thing that gets wider and wider as it grows.

[00:09:45] Sophie: [00:09:45] Exactly. And so not only can they do that, they can write down an actual mathematical equation that describes that. And it’s a power law and a power law just means that it’s something raised to the power. So what you find is that average radius is equal to 10, to the power of some scaling factor that has to do with the width of the tooth multiplied by that tip distance to the power of whatever the slope of that line is, which mathematically is actually very, very simple for such a complicated structure and these power laws. These are one of these interesting things that turn up in nature all the time. So power laws you can use those to describe magnitudes of earthquakes. You can use them to describe the foraging patterns of just various species of animals, even the frequencies of words in most languages.

[00:10:31] But my favorite one. Is that there were some people who did some work in the US a few years ago, and I actually wrote a piece about them and they found a power law in what they called the murder probability. So if you have a serial killer who has a predilection to kill people, the murder probability is proportional to the number of days since their last murder event, raised the power of a constant.

[00:10:55] And that constant depends with the different serial killers.

[00:10:57] David: [00:10:57] So basically they get more likely to kill the longer it’s been since they last killed.

[00:11:01] Sophie: [00:11:01] well there’s and then there’s like some randomness thrown in and stuff, but yeah, a little bit, but yeah, so these Power Laws turn up everywhere. And in fact it turns up in the tooth and then they went further and they created something called the power cascade, which describes that kind of the folding of the tooth shapes.

[00:11:15] You know, we’re saying that sort of it tapers off to

[00:11:17] that tip because you cascade down from the tip and that sort of is a power law as well.

[00:11:23] David: [00:11:23] And amazingly, so, and this applies across animals. So we’re talking about giant sharks, Tyrannosaurus, mammoths, and human beings. And it works for claws, hooves, horns, spider fangs, snail shells, antlers, and the beaks of mammals, birds, and dinosaurs, which has just a lot of things.

[00:11:39] Sophie: [00:11:39] And even teeth that aren’t just one point. So if you’ve got, you know, a multi cuspid tooth, and if you think of like a dog’s teeth near the back, they’ve got lots of different points. And if you look at those separately, they all behave like this model.

[00:11:54]David: [00:11:54] And I also really enjoyed one of the conclusions they said was that the model can be used to predict the age of mammals with ever-growing teeth, including elephants and rodents. So listeners, if you have like a pet mouse or a pet elephant that’s maybe come to you a bit later in life, maybe a rescue rescue, rodent, or rescue elephant.

[00:12:11] And you want to establish unequivocally it’s age, send us a wee measurement and we’ll have a look at its teeth and we should be able to help you with that.

[00:12:19] Sophie: [00:12:19] Yeah. We won’t even need to cut it in half and count the rings.

Flamboyant Fish

David: [00:12:32] Fish have teeth. Which are presumably described by power laws. And, um, have you ever kept fish Sophie sea in an aquarium or a

[00:12:44]Sophie: [00:12:44] No Sorry, Dave. I think I ruined that, but no, I’ve never had, I’ve had a pet, like a dog and a cat and this, but not, not a fish.

[00:12:52] David: [00:12:52] That’s not the same. So, so there are these kinds of fish called Fairy wrasses right? And I hope I’m pronouncing that correctly cause I’m going to keep pronouncing it that way for the whole piece, fairy wrasses.

[00:13:01] Sophie: [00:13:01] That is my assumption as to how that word is pronounced too. So that’s good.

[00:13:05] David: [00:13:05] let’s keep going with it. And these are commonly kept in aquariums or aquaria, depending on how big of a word Nazi you want to be.

[00:13:10] And is it because they have any utility? Is it because of respect to develop members of society? No, it’s because they’re objectified because they’re just so damn pretty

[00:13:18]Sophie: [00:13:18] They are so pretty.

[00:13:20]David: [00:13:20] they’re not just pretty, there are lots and lots and lots of different species of these that are all pretty in their own way.

[00:13:26]Sophie: [00:13:26] Basically they’re little, pretty, sometimes slightly fluorescent, colorful little pretty fish for your aquarium.

[00:13:35] David: [00:13:35] And researchers at the university of Sydney now say they may know why there are so many different kinds of pretty fish called fairy wrases or classified as fairy wrases.

[00:13:46] Sophie: [00:13:46] which I love. And it has to do with maybe ice sheets and glaciers, which I think is really fun. Because if I looked at one of those pretty fairy wrases, I wouldn’t say, do you know what, you have evolved in quite a special way because of where you evolved in the ocean and maybe the ice sheets that developed there at some stage in the past.

[00:14:02]David: [00:14:02] So we should probably explain a little bit about speciation. And so basically, if you imagine that you have a species of fish and they’re all exactly the same and they reproduce altogether, then nothing much can really well, I mean, stuff can happen to them, but it’s going to happen to all of them.

[00:14:16] It’s like having a pot of soup. If you add seasoning to the soup, you’ve added to the whole soup, you can’t have like little factions of soup within the same pot,

[00:14:24] Sophie: [00:14:24] what if part of your soup mutates, Dave?

[00:14:27] David: [00:14:27] Well, yeah, but if  then it will still be the same. Uh, well, I guess that would be a kind of

[00:14:32] Sophie: [00:14:32] No, I’m just being difficult. And then the mute, the mutant soup or bread with the rest of the soup. And then you’ll still have like you know,

[00:14:37] David: [00:14:37] Yeah. So, okay. Okay. So still fairly uniform soup. So this analogy is hanging on by the skin of its parallel teeth. And so if you split that soup  into two pots, then now you can do alternate things to different pots and end up with completely different kinds of soup. And that’s kind of what happens in nature sometimes.

[00:14:54] So if you have something like a continent that splits and that splits a population of animals, those animals will now evolve in complete isolation. And so they can end up being very, very different from one another. So that’s kind of how speciation can happen and how different species can emerge.

[00:15:10] So basically what they’re saying about these fairy wrases is that  the appearance and the rising and falling of, is it the rising and the falling of the ocean that does it.

[00:15:21] Sophie: [00:15:21] Yeah. So I think it all has to do with the particular location. So apparently fairy wrases evolved in the coral triangle, which is an area in the Western Pacific ocean. So if you start at the Philippines down to Papa new Guinea to the edge of the Solomon Islands, right? So that’s, that’s one side and then you go all the way over to sort of, you cut Indonesia in two, but that particular area in there as the coral triangle, and that includes in that area, we have the Indo Australian archipelago.

[00:15:46] So at the moment, that’s just, that’s lots of islands, right? I’ve got lots of little islands and fish can swim around the islands and they’re all fairly happy. But apparently, during one of the major evolutionary stages of these wrases , what we had was a sort of an ice age, so it completely changed the seascapes.

[00:16:02] So you had sort of ice sheets and you had glaciers, which used up a lot of the ocean water, the sea level fell. And then a lot of the Coral reefs and those kinds of things became land bridges. And in fact, part of those changes might explain why human ancestors were able to access Indonesia and Australia.

[00:16:20] So meant that the fish couldn’t get through

[00:16:23] David: [00:16:23] They dropped that just so casually that the

[00:16:25] Sophie: [00:16:25] very

[00:16:25] David: [00:16:25] name, sea level changes might have been responsible for letting people reach Australia for the first time.

[00:16:29] Sophie: [00:16:29] Yeah. And so, and so effectively, those, you know, the fact that we have these land bridges now, and we have ice and stuff meant that that’s there you’re two different pots of soup, essentially. But what happened was because this happened over an extended period of time, we have these cycles in the climate.

[00:16:46] And so what you would find is then the glaciers and things would melt and the sea levels would rise and you can mix your two wrasses together and they would hang out for, I don’t know, Some amount of time that I don’t know, and then would hit another sort of ice age-y event and then we would have ice again, and we would separate them.

[00:17:01] And apparently that happened up to about five different times. And so the way that they’ve described this repeating action is a species pump. So basically you got these spaces that have been isolated from each other, and then you can pump these species into an area of water where they can interact and like mix and hang out and then you separate them again.

[00:17:21] And they think it was because of that particular process that you end up with sort of such variation over what they say is a very rapid evolutionary timescale. Because apparently fairy wrases, diverged from other wrase species about 12 million years ago. But most of the ferry wrase species themselves only emerge between one and 3 million years ago.

[00:17:43] And apparently that’s, I guess that’s very quick on the fish evolutionary timescale.

[00:17:47] David: [00:17:47] that’s quick. And so no, there are more than 60 described species already. And apparently a new species of fairy wrase is described every year.

[00:17:56] Sophie: [00:17:56] Yeah, which is crazy.

[00:17:58] David: [00:17:58] lots and lots and lots of them. I also found interesting. So you’ve got this idea of the species pump and the isolation, but apparently also these fish have very elaborate mating rituals.

[00:18:07] So they’re very, very good at identifying members of their own species. They’re like the bluemottled ones versus the orange back ones or whatever, and they’re so good at identifying each other that effectively, some of them, once they’ve been established by these big geological events. Basically stay as their own species because they’re so good at spotting members of their own species that they don’t mate with the others, which I thought was pretty neat.

[00:18:29] Sophie: [00:18:29] And then, I mean, the other thing on top of this, as they actually think that the evolution of a lot of sea animals could have been affected by these kinds of geological climate events. So they’ve cited as you know, everything from sea stars to giant clam.

[00:18:41] I don’t know if it was in between a sea star and a giant clam, but they said that these glacial cycles often get missed when they’re talking about the  diversification of fishes and other sea creatures, especially around the tropics, that’s something that people don’t even think of in terms of the evolution of these, these animals.

[00:18:57] And I guess, I mean, we’ve shown that we, you and I, Dave, have shown that with the fairy wrases, this is a very important thing to think about.

[00:19:04] David: [00:19:04] It’s an important thing to think about. And just on that, there are some winners of being a fairy wrase , because if you look at the names of them, and.. I have.. there are some really normal ones. There’s, you know, orange back and long fin. Fair enough.

[00:19:17] Sophie: [00:19:17] All right. Hit me, hit me with the others.

[00:19:19] David: [00:19:19] okay.

[00:19:19] Here’s some good ones here. Some of my favorites,

[00:19:21] the exquisite fairy wrase.

[00:19:24] The Hawaiian cleaner wrase.

[00:19:27]The multicolor Lubbock’s wrase

[00:19:29]The carpenter’s flasher wrase. I want to know what it does to be called that.

[00:19:35] And I’ve got my personal favorite. Are you ready from a personal favorite?

[00:19:39] Banana

[00:19:43] Sophie: [00:19:43] Oh dear.,

Shark deterrent

So Dave, from fish, we love to look at, to other big scary things in the ocean that we’re maybe not so keen on like sharks.

[00:20:00] David: [00:20:00] so from fish, we love to look at, to fish we hate to swim with.

[00:20:03] Sophie: [00:20:03] Yeah, I know there are fish, but it just didn’t sound as interesting. But yes, I want to talk about sharks, but I specifically want to talk about personal electronic deterrence as an effective way to prevent sharks. So this is really a statistical story.  basically we have, I’m not gonna say an issue with sharks in Australia, but we’re one of the six known hotspots for shark attacks.

[00:20:26] And I think that just means that we have lots of sharks and we have people who swim and statistically someone’s going to get bitten by a shark at some stage. But we also have these electronic deterrence for sharks, that I did a lot of research on and apparently they mostly don’t work Dave.

[00:20:43] David: [00:20:43] They mostly don’t work. Yes.

[00:20:45] Sophie: [00:20:45] Yeah, they mostly don’t work. But what they did is we had some are researchers from Flinders university and they were sort of looking at the history of shark attacks in Australia. And so it turns out for it to be classed as a shark attack, it has to be in the wild. If you got bitten by a shark that you haven’t captivity, that doesn’t count, you brought it on yourself.

[00:21:06] David: [00:21:06] that’s the difference between shark attack and just idiocy.

[00:21:09] Sophie: [00:21:09] Idiocy. Exactly. So we had this thing, which sounds very exciting to me. basically, It’s where we keep all the information about the shark attacks in Australia. So this thing is called the Australian shark attack file which sounds like a great TV show to me and a what.

[00:21:23] David: [00:21:23] like I’m imagining like a dark office in the basement of some government institution and it’s smoke-filled and there’s like filing cabinets and files stacked really, really high and everything has it kind of X-Files vibe with the sole exception of the fact that the people smoking are all in their bathing suits.

[00:21:40] Sophie: [00:21:40] Yeah, but yeah, Mulder & Scully are definitely there. So we have records in the shark attack file that go back to the 1700’s. But what these people did is they, yeah. It’s nut, I mean, and to be honest, like it’s suggested that maybe some of those are a wee bit dodgy and we’re not quite sure, but, so they looked at records between 1900 and 2020, and they looked at, we have 985 individual incidents reported in Australia from 20 different species.  But what they noticed is once we hit the eighties, the number of  shark attacks really started increasing. And it depends on the country that you’re in. We are number two, in terms of winning, with our increase in shark attacks.

[00:22:16] So the number of shark attacks in Australia goes up by 0.35 attacks per year. Which doesn’t sound terrible. But if you project that into the future, it’s going to get worse and worse. And so, what they did is they basically took all the data that they had, and they developed a sinusoidal time series model of per capita incidents.

[00:22:36] So they took all the data and they made a model that basically it told us what was happening over a period of time.

[00:22:43] David: [00:22:43] so sinusoidal is like waxing and waning. So is it waxing and waning because presumably most of the attacks happened in the summer

[00:22:51] Sophie: [00:22:51] um, well, when I looked at this particular thing, it seemed to wax and wane over a far longer periods of time.

[00:22:58] It was a bit weird and I didn’t quite understand.  But you know, that’s what the data says. I don’t know if there are years that they don’t have information. So they took that and then they projected into the future because we know we can see that we have this increase of shark attacks happening.

[00:23:11] They projected it into the year 2066, but they said, okay, what if from now on everyone is wearing personal electronic deterrence for sharks. What difference? Will that make, and so what they did is they statistically projected these numbers into the future, but they have assumed. And so this is from what I could tell it’s based on one particular electronic deterrent, which is called the Freedom Plus

[00:23:36] David: [00:23:36] it’s the one that works. Isn’t it

[00:23:38] Sophie: [00:23:38] It’s the one that works.

[00:23:40]David: [00:23:40] I’m not an expert in this, but from the limited reading I did, it seems to be the one that there’s some actual evidence that it works.

[00:23:45] Sophie: [00:23:45] It’s the world’s only scientifically proven and independently tested electrical  and nothing. And I quote from the website, nothing is more effective. And in fact it’s effective in the sense that it will reduce the probability of a great white shark bite by 56%, which is better than zero, but it’s still not like amazing.

[00:24:06] Yeah. So what they did is they’ve used that as a reduction probability. So that said that if these trends continue on the way they are into the future, but if everyone was wearing one of these, which doesn’t quite make sense, because these things only fit on surfboards, they don’t fit on people, but let’s pretend there’s a way that maybe you could strap it to your torso or something that’s quite flat.

[00:24:25] they found that between 2020 and the year 2066, that 1063 people could potentially avoid being bitten across Australia, if everyone wore that device.

[00:24:40]David: [00:24:40] That’s really specific. I mean, so  I think what’s important to know about this is so we’ve got something, a very, very specific problem. Shark attacks . If you compare it to like heart disease, you’ve got a fairly low number of afflicted people.  but the impact of that is quite broad because we tend to do things like hunt and kill sharks when it happens, like people have very evocative responses to it.

[00:24:59] So we have these shark attacks that we need to deal with in a relatively low number of people, which makes it hard to study. And it makes things like deterents really hard to study because. We’ve got a low number of incidents. And because there are all these different products that are kind of, their main thing is to get sold.

[00:25:15] It’s, it’s difficult to assess the quality of the evidence and say, yes, this one works. So this is a really cool study because it’s a genuine effort to kind of cut through all that and not just do that, but then to make some predictions about what they found. So I think it’s really cool.

[00:25:28]Sophie: [00:25:28] Yeah, and I didn’t mean that I got to learn about all the different shark deterrence, and some of them are really funny Dave. So just very quickly. So then we’ve got the one that works and the reason that the electronic ones work, basically they emit an electric field and it interferes with those sensing organs that sharks have on their snouts. So they called the ampullae

[00:25:45] David: [00:25:45] mean the ampullae of Lorenzini?

[00:25:48] Sophie: [00:25:48] yeah, I do mean that. And I learned that at the age of six, because they used to have a shark book. And that was my favorite thing to say, maybe not my favorite thing, but I was quite into sharks, but yeah, so basically, yeah, the, um, the little organs and they just detect electric current.

[00:26:00] So if you have a fish nearby and it’s heart is beating, we can detect it and we can go and eat it. So it makes them very, very good.

[00:26:07] David: [00:26:07] I read about him. Do you know how these work? So you’ve got  a single row of cells that are electro receptive, which means that  detect electromagnetic fields and the cell can tell the difference between the potential difference between the top and the bottom of the cell.

[00:26:22] So across a really, really tiny, tiny difference. And from that they can get a sense of what’s happening electrically in their immediate vicinity.

[00:26:29] Sophie: [00:26:29] Yeah.

[00:26:30] David: [00:26:30] I also read that the size of the fields they can measure is comparable to the Earth’s magnetic field. So they may even be able to use this to magnetically guide themselves around the world to navigate.

[00:26:42] Sophie: [00:26:42] Yeah. Yeah. That was also  my understanding. So the way that we make them go away is we just overload those things. So we just shoot electric field out there in a way that it basically, it makes those sensory organs spasm, and the shark goes, yeah, not into this, I’m leaving. So that, that’s the one that works.

[00:26:58] David: [00:26:58] I think that the, the quote was, it creates an unpleasant sensation. which, I mean, it seems very specific. How did they know that? Did they ask, was there a questionnaire afterwards? Like how would you describe this sensation?

[00:27:09] Sophie: [00:27:09] I think they probably just blasted this stuff at  at what

[00:27:12] David: [00:27:12] they go away so nice or it was confusing

[00:27:15] Sophie: [00:27:15] But that’s to, um, compare it to,  their visual based deterrent. So there’s one thing that just generates a lot of bubbles and apparently sharks in the beginning, like, Oh, bubbles, no way. And then they go, Oh, Hey, now I can deal with bubbles.

[00:27:27] And then they just swim through the bubbles. And then there’s also

[00:27:31] David: [00:27:31] behavioral deterrent, which is just stop swimming, like an injured seal.

[00:27:35] Sophie: [00:27:35] yeah. Um, my favorite one was, did you read about the Orca one? So apparently, you know, some sharks aren’t super into Orca whales because you know, they’re an ultra predator and orcas can beat sharks in a fight quite often. So someone went well, what if we had a device that you strapped to you that played Orca calls, would that scare sharks away and it turns out sharks aren’t scared of the sound of an Orca. It is the presence of an orchid trying to mess them up, which is the deterrent. And, uh, so that didn’t work either.

[00:28:04] David: [00:28:04] It’s kind of like him, like impersonating the big kid when you’re walking around. But then when the, when the police shows up, you’re just, it’s still just you, it’s still just you with your Slingshot.

[00:28:13] Sophie: [00:28:13] Exactly anyway. So there’s interesting things we can do with statistics. And maybe if we all started wearing freedom plus surf electronic shark deterrence from now on, we could save  1063 people from shark attacks in the next 40 something years.

Scary stories

[00:28:36]hey Dave, are you scared of sharks?

[00:28:39] David: [00:28:39] I mean, I think I have the level of fear of sharks, the evolution demands.

[00:28:44] Sophie: [00:28:44] So you have a sensible fear of sharks

[00:28:45] David: [00:28:45] I’ve I have a respect  for sharks. I don’t think there’s an irrational fear of sharks. I don’t

[00:28:49] Sophie: [00:28:49] No, I don’t. I, yeah. I don’t think that. Yeah, I agree. So if you visualize a shark’. Does that

[00:28:55] David: [00:28:55] doing it. I mean, I have the amount of fear for my visualization of sharks, that evolution to demands, which is to say, yes, it’s scary. It’s a bit scary. It’s a bit

[00:29:07] Sophie: [00:29:07] scary. So there’s some research that came out of the university of new South Wales and they’ve done it with, and I’ve never heard of this condition before. And they found a group of people who have Aphantasia. Is that how I say that word? Because it just reminds me of that reminds me of the Disney move me, but Aphantasia

[00:29:24] David: [00:29:24] technically it’s a lack of the Disney movie.

[00:29:27] Sophie: [00:29:27] it’s a lack of the Disney movie.

[00:29:29] David: [00:29:29] It’s the lack of the Disney movie Fantasia.

[00:29:31] Sophie: [00:29:31] Which is interesting because a,

[00:29:32] David: [00:29:32] being this thing that we’re going to talk.

[00:29:35] Sophie: [00:29:35] uh, Aphantasia is the inability to visualize mental images, which is the opposite of Fantasia. I guess that does make sense. And what they’ve found is that people with Aphantasia who cannot visualize mental images, are harder to scare with spooky stories than people who can visualize images. So, you know, so if I said, Dave, think of a box and then you could visualize a box. You don’t have Aphantasia, but if, but all the thing, I actually looked up Aphantasia. So apparently  it affects 2 to 5% of the population and. It’s a lot of people. And so people just, yeah, they don’t have the ability to picture something in their minds, but they can still dream.

[00:30:16] So if I say Dave, think of a box and if you had Aphantasia and you couldn’t think of a box, maybe in your

[00:30:20] David: [00:30:20] it’s, you can’t do it voluntarily. You can’t deliberately conjure up an image of something,

[00:30:25] Sophie: [00:30:25] Yeah. And they think it’s, and to be honest, they’re not a hundred percent sure what causes it. So you can, you can have congenital Aphantasia, but you can also have acquired Aphantasia from like brain injury or some kind of psychological cause or something. And they just think it’s a deficit in the feedback connection in the brain and it means that  the visual cortex just can’t be activated to produce an image. So what they did getting back to scary stories is they got a bunch of tables, they got 22 people with Aphantasia and 24 people without, and what do they want to do is basically look at the fear response. So the way that we often do this in psychology is we, we monitor the changing skin conductivity, but basically how much are you sweating?

[00:31:07] So

[00:31:07] David: [00:31:07] are you sweaty? And therefore, are you scared?

[00:31:10] Sophie: [00:31:10] yet? So sweaty is a very good way to measure the body’s physical expression of emotion. So

[00:31:15] David: [00:31:15] you’re not exercising because if you’re working out and you’re sweaty, it’s not because you’re terrified of exercise. I mean, you might be,

[00:31:20] Sophie: [00:31:20] You might be and, um, yeah. And you haven’t designed your experiment particularly well, so what they got was all these people and my favorite bit is, they put them in a dark room and then they hook them up to some kind of machine that monitors their skin conductivity levels. And they started a story. So the story was written in text.

[00:31:39] So this story came up in front of them on a screen and it starts very innocuous and it gets scary. So, you know, imagine you’re at a beach and then I know something I know, and then you’re getting attacked by a shark. I dunno. And what they found was that the skin conductivity grew very quickly with people who could visualize the stories, but  not at all for the people, with Aphantasia.

[00:31:57] So the

[00:31:58] David: [00:31:58] what was striking. Yeah, not at all. Like, it was a flat-line response from

[00:32:02] Sophie: [00:32:02] Flatline response. Like them reading the scary part of the story,  it was equivalent to reading the beige part of the story as well.

[00:32:09]David: [00:32:09] And crucially, when they showed scary pictures of things like snakes and spiders and sharks and things like that to people, to both groups, they both responded. So it’s not that they Aphantasiacs (?) Could not experience fear or something like that.

[00:32:24] They could experience fear, they just didn’t get it from the stories very specifically, because they could get it from the pictures.

[00:32:29] Sophie: [00:32:29] Yeah. And to make it them sort of even experiments, they ramped it up in the same way. So I believe at the beginning they showed them pictures of things like plates, and then once you’d seen the plate, then it was something like, yeah. A snake or a shark, or I think they went to like assault and some other things as well.

[00:32:45]But it was absolutely crazy. So they think that it’s the imagery that might be the link to the sort of fear emotion. And I don’t know, if you think about it, that kind of makes sense to me. Cause you know, people are scared of the dark. Right. But are they scared of dark or are they scared of the stuff they’re imagining is like hanging out in the dark that they can’t see.

[00:33:04] David: [00:33:04] Of course, of course. So I read a thing if you read the paper, it talks about, human cognition and the importance of mental imagery. And they basically say, conjuring up a mental image is a way of trying out future scenarios. So basically if you’re not sure what something would be like, you imagine this, you visualize it mentally, and then you experienced the, whatever emotions come from that.

[00:33:23]You can say sentences, like, Oh, I don’t think I would like that. Or I don’t think I would enjoy that. Or I would find that scary just based on the image. And that’s, what’s also really cool about this is not so much, so this is a study in people with Aphantasia, but it kind of tells us something really interesting about not just those people, but everyone, because obviously we learned some things are scary.

[00:33:46] Right. So if we learn that a spider is scary sometimes during our life, then we associate fear with the spider. And if there is no actual spider, we associate fear with some abstract concept of spider. And what this tells us is that the word spider is not scary. It’s only, it’s only when you connect the word spider to an image of a spider that you find it scary.

[00:34:07] And that’s like, that’s a really fundamental thing to know.

[00:34:11] Sophie: [00:34:11] yeah, I thought this was great.

OUTRO

[00:34:13]  David: [00:34:22] And thank you for listening to another fun episode of STEMology. Be sure to check out the links to all these great stories on our show notes.

[00:34:28]Sophie: [00:34:28] Go visit www.stemology.com.au. If you have any news that you think is STEMology- worthy, drop us an email at stemology@ramaley.media. Would love to give you a mention.

[00:34:41] David: [00:34:41] Your hosts have been Dr. Sophie Calabretto and Dr. David Farmer.

[00:34:45] This is a podcast from Ramaley Media.

[00:34:46] Our executive producer is Melanie De Gioia and our music is from Elizabeth Maniscalco.

[00:34:52]Be sure to hit subscribe on your favorite listening app. So you never miss our episodes.

[00:34:55]Sophie: [00:34:55] We look forward to sharing the latest in all things, science, technology, engineering, and maths with you next week, and be sure to bring your friends.