STEMology s1e34

[00:00:00] Sophie: Welcome to episode 34 of STEMology,

[00:00:03] David: a podcast sharing some of the interesting fun, and sometimes just patently bizarre news in science technology, engineering, or maths.

[00:00:10] Sophie: Your hosts are Dr. David Farmer and Dr. Sophie Callabretto

[00:00:14] David: in today’s episode of symbology, we’ll be chatting about eco stabbers, fluid mechanics,

[00:00:20] Sophie: tuskless elephants, and the horse father.

Eco-stabbers

[00:00:24] David: Wood, Sophie.. It’s not just good for making tables anymore. It’s not just good for making trees with anymore. It’s also good for making knives with.

[00:00:33] Sophie: Yes. Our researchers from the University of Maryland have developed a potentially more sustainable way to make sharp knives using hardened wood. Dave.

[00:00:43] David: So, I like this Sophie cause I’m from a place called Glasgow, right. Which is quite a stabby place. So I like abreast of innovations in this area.

[00:00:51] Sophie: I thought you gonna be like, we have so much wood.

[00:00:53] David: No, not very much, but it’s all actually, but a lot of stabbings. and the other thing about it [00:01:00] is Glasgow is they’re about of course, to have the COP 26, climate summit. So a lot chat about renewability and sustainability. So I really feel like this is bringing a Glasgow flavor to the renewable sustainability scene.

[00:01:11] I love it. Eco stabbers.

[00:01:13] Sophie: Yeah, no, it’s great. So, you know, we’ve got this issue, Dave, where we need sharp knives to cut things, which is true.

[00:01:19] David: absolutely

[00:01:20] Sophie: and normally sharp knives are made of things like steel or ceramics and other sharp human made materials or human made materials that we make sharp. But the whole problem is a lot of these things they need to be made in furnaces at like extreme, extreme temperatures.

[00:01:34] And we know that the hotter, we need things to be, more energy need We need to put in. And then our climate discussion comes back because here is the thing about energy. It’s got to come from somewhere and it’s better if it’s sustainable, or, that if we just don’t use as much energy, Dave

[00:01:48] David: just less, just use less.

[00:01:50] And possibly, possibly by making innovations in the knife realm.

[00:01:54] Sophie: Yeah. So I thought this was really fun. So they’ve made it, they’ve gotten this new method to treat wood, which we can get [00:02:00] into, and it makes wood 23 times harder. And a knife made from this material is nearly three times sharper than a stainless steel dinner table knife.

[00:02:09] And let’s remember that a dinner table. And I was like, is that just a bread knife? It’s not a steak knife.

[00:02:13] David: Um, I don’t know, because they talk about cutting a steak and they say it cuts through a medium rare steak with ease. So I wonder if maybe they did, But then a steak knives usually got serrations and

[00:02:24] Sophie: yeah, I mean, potentially they could be, I mean, they’re shaping this at some stage. They possibly shape it to make it a steak knife shape, but yeah, basically they’ve made, they’ve got wood and they made it cut meat and I

[00:02:33] David: got wood and they come,cut meat. It’s great.

[00:02:35] Sophie: yeah. and you’re right and they said they can cut through a medium, well done steak easily.

[00:02:40] and this, the whole idea with this hardened wood knife is that it can be washed and it can be reused. And so it’s a really good alternative for these steel and ceramic knives, but even like disposable plastic knives. Like I know that a lot of the time, if you go to festivals, now you have the plastic knives that are actually made of like, Corn or something, but, but I don’t know how many, maybe a lot of [00:03:00] energy goes into producing those as well.

[00:03:01] I don’t know. And just quickly before we get into anything, Dave, in terms of, I did say the wood is becomes 23 times harder, that’s rated based on the Brinell scale, which is a Brinell B R I N E double L for everyone playing at

[00:03:16] David: oh, Brinell

[00:03:17] Sophie: Brinell

[00:03:17] David: No. I don’t know

[00:03:18] Sophie: I don’t know

[00:03:18] David: Brinell

[00:03:19] Sophie: brian Brinnell and the idea is that it characterizes the indentation hardness of material through the scale of penetration of an indent.

[00:03:28] So basically I think you just drop something on something and however much it indents like that will tell us how hard it is.

[00:03:36] David: Brinell, I hit it with something scale

[00:03:39] Sophie: And it either dented a lot or a little or none at all.

[00:03:43] David: 23

[00:03:44] Sophie: 23 points to Brinell yeah, so I think that the issue is like the older. So we use wood for a lot of things, Dave, but usually when we use wood, we’re just kinda making stuff. So, basically you might steam, you compress it. You might do a few things, but it’s not gonna make it super hard.

[00:03:59] And those are the [00:04:00] material often rebounds after shaping when we do our normal wood processing. And so the magic here is that they really they’re really into cellulose. cellulose.

[00:04:10] David: So into cellulose.

[00:04:11] Sophie: it is the main component of wood, but only makes up 40 to 50% of wood. So

[00:04:16] David: right. And they pointed out that cellulose has a high high ratio of strength to density. So basically for a given amount of it, it’s stronger than you would think.

[00:04:25] Sophie: Yeah. and then stronger than a lot of engineered materials, like metals and polymers and ceramics and stuff.

[00:04:30] David: Which is not to say you can’t have strong versions of engineering things. It’s more that you could have less, or you could have lower mass of and have something that’s very strong, as opposed to a knife, which will end up being very heavy.

[00:04:41] Sophie: yeah, so wood is 40 to 50% of cellulose, love. love, but the rest of it is things like Hemi cellulose and lignin, and So the whole idea is what they want to do is remove the weaker components from the wood but they want to keep our cellulose, our strong cellulose skeleton. So it sounds like they’ve got a two-step process, which I can [00:05:00] understand, which makes me think that it’s probably like very hard and ingenious, but it’s like weirdly simple, Dave.

[00:05:05] So it’s like, we take our wood and then we de-lignify it and to rid of it. Do I say, is it lignin or lignin?

[00:05:13] David: And I’m not sure. I like lignin.

[00:05:14] Sophie: Let’s say. Okay. D yeah. So Linnaean and so basically

[00:05:19] they partially delignify. So typically, um, wood is rigid when you take the lignin out it becomes soft, flexible, and somewhat squishy, which sounds gross, but I love it.

[00:05:30] And then they just hot press. this delignified wood, by applying pressure and heat, and that removes, it just sorta like removes the water and all of like the rubbish channels that used to be in the woods to feed trees. It’s like, we’re getting rid of everything we don’t want. We just want our beautiful cellulose fiber, which is like very, very hard.

[00:05:49] And then the idea is you’ve just got your processed material and you can carve it into shapes. And then the, also one of the key things you need to do is encoated in oil to extend its lifetime and [00:06:00] also cause cellulose being, you know, what trees are made of. They just love to absorb water and we don’t want them to do that when we’re washing our knives, we don’t want water laden

[00:06:09] David: Like you’re cutting into a steak and your knife just suddenly goes

[00:06:13] Sophie: and it’s just like a squishy bloody mess. You can like squeeze the knife and just like you have juices, like ooze, ooze out of it. That’s gross.

[00:06:20] David: A disaster. Isn’t it

[00:06:22] Sophie: I don’t

[00:06:22] David: though. So presumably That’s not what happened. So, and once they’d done these apparently quite easy to understand processes, they used high resolution microscope examined the microstructure to determine the origin of the strength. And they found that the strength. So they say the strength of this material is very sensitive to the size and density of defects. And they, through this process has significantly reduced or removed the defects in natural wood. So Yeah. as you said, the channels to transport water, so that all of the removal, that is the strength giving property of this whole process

[00:06:55] Sophie: And like, if there’s any other like voids or weird pits or, you know, natural or otherwise, [00:07:00] yeah, so basically it means that all of those channels, and everything’s almost gone, we had this like compacted super hard wood. and the idea of. Do you know, the first step of it requires boiling the wood at a hundred degrees in a bath of chemicals, which sounds like the worst bath.

[00:07:15] but you can reuse those chemicals from batch to batch. And then if you compare that with making ceramics and things, you need to get the temperatures more to kind of like a few thousand degrees celsius to like,

[00:07:27] David: not, to refute your first point, but that sounds like a worse bath.

[00:07:31] Sophie: A few thousand degree chemical. No, you’re right. Like that one is, well, I don’t know, like how I think you’d just be a bit dead I think that both, I get to the point where I’m just dead, that not one is worse than the other.

[00:07:41] David: So we’re talking about magnitude of suffering as opposed to rapidity of death.

[00:07:45] Sophie: mean

[00:07:46] David: What’s constitute a bad bath? So this is not just like book’s a bit rubbish or like you’ve run out of candles or your bath bomb is a bit overpriced. It’s

[00:07:55] Sophie: The water is actually chemicals and they were actually at thousands of degrees.

[00:07:59] David: Yeah.

[00:07:59] Sophie: Yeah. [00:08:00] That’s

[00:08:00] David: Yeah, you’d be a bit dead very quickly. Okay. So maybe a hundred degree?

[00:08:04] Sophie: Well, yeah, cause I think if you, yeah, surely would I get killed quicker by a thousands of degrees, chemical bath than a hundred degree chemical bath, in which case I want the thousands one. Cause I think I don’t want to suffer in my chemicals.

[00:08:15] I’ve made some bad decisions. I mean a chemical, chemical ball for a reason. I can’t tell you. And now I just want it to be over.

[00:08:22] David: Yeah, sure. Okay. Okay. So I think you’re right. The original bath is the worst bath.

[00:08:27] Sophie: yeah, so, but luckily we just do this to a wood and don’t need to get messed up chemical ba and then the whole idea is with these, like any other wooden implements in the kitchen, Dave, these knives can be used many times, as long as you’ve resurfaced them. You can sharpen them. You just have to, you know, you got to treat like a nice chopping board, like a thing.

[00:08:47] You’ve got like a beautiful Acacia chopping board and you’ve got an oil that baby, and you’ve got to do all the things like you know, to keep her nice. You just do the same thing to your very hard sharp wood knives

[00:08:56] David: Yeah, absolutely. Or your nice metal knives. You have a nice kitchen[00:09:00] you wanna, you know, sharpen it little and often

[00:09:02] Sophie: Yes. So you can slice all those tomatoes, you know, cause otherwise, you know, no one, like you go to cut that tomato and that kind of, you see, it’s like pushing into the skin and you’re nah, it’s the worst. Or he goes like, if you’re at someone else’s house and you got to use that knife and you’re like, oh mate job.

[00:09:15] And,

[00:09:16] David: the less, yeah, bathing chemicals Those degrees.

[00:09:20] Sophie: chemicals with your dull knife.

[00:09:23] David: It is.

[00:09:25] Sophie: That’s it, there you go. Wooden knives for the future? I love the idea. and also I think, yeah, as long as they’re polished and stuff, because I don’t know about you, Dave, but I’ve also used, wooden cutlery at hippy festivals and you can just feel it, you know, when you like eat something on a fork and the wooden fork just drags on your mouth and you’re like, I’m going

[00:09:42] It’s the worst sensation

[00:09:44] So this, I felt this like very dense, like nicely shaped and polished wood. Sounds great.

[00:09:50] David: Into it. Love it. Brilliant work. Eco stabbers.

Fluid Mequacknics

[00:09:53] Sophie: [00:10:00] Dave, what the duck.

[00:10:04] David: So it turns out That by paddling in an orderly line behind their mother, ducklings are not just following for the sake of following. They’re actually saving energy swimming.

[00:10:15] Sophie: They’re physics masters. Yeah. So we knew, we know that, like we understand this idea of sort of being streamlined. And like, if you there’s someone like moving through water or even like a cyclist moving through air, it’s to be behind that person because like, you get a, like a little bit of a relief that stuff with drag water. We know the stuff, but no one has actually looked at these specific physics of duck swimming as to how this reduces energy use.

[00:10:39] David: Yeah, that’s right.

[00:10:41] Sophie: University of Strathclyde we’re sorted now.

[00:10:44] David: They’ve figured it out. So, they’ve worked at the exact, they’ve done some modeling, I believe. There’s, I’m going to need you to explain to me Sophie, some fluid mechanical modelling to explain exactly how they’ve done the physics, but before we get to the how, which should we talk about the what. Because, so I went back, I [00:11:00] find this fascinating.

[00:11:00] I went back into the literature because before they talk about how. This, the waves coming off the mother reduce energy for the ducklings. They talk about some evidence that it does reduce energy expenditure for the ducklings. And for this, they did actual experiments with actual ducks.

[00:11:15] Right. And I fucking love this cause it’s just bonkers and it’s beautiful. Right.

[00:11:20] Sophie: Tell me about it. Cause all I know Dave is that ducklings could save up to 62.8% in metabolic energy if they’re swimming in the leader’s wake, I don’t know how or why. Tell me right now, cause you are excited. excited No one can see David’s face. He’s very excited.

[00:11:34] David: so what they did was so first they fix some one day old ducklings and they imprinted them on a female Mallard duck decoys. Right. So they think this decoy is their mother. So basically.

[00:11:45] Sophie: It’s mean already. I

[00:11:47] David: I know, but they’re looking after They’re doing it for science. And they’re looking after the ducks.

[00:11:51] Sophie: And so they’ve done something gross to mouse skin or something that often happens

[00:11:55] David: No, that often happens on this podcast. Yeah. So they’ve imprinted on this at duck [00:12:00] decoys, right. And then they’re trained daily to swim behind the decoy because obviously the ducks will usually follow their mother. So now they’re following the decoy, so they’re trained to swim and then they train them to swim in a recirculating water channel.

[00:12:12] So basically, the ducks are stationary, but the water’s moving and the ducks are swimming through it. Right. So that’s the next step. The next step is they lowered a metabolic chamber over the whole thing. Basically, you’ve got ducklings following a decoy mother in moving water in a chamber where they’re in control of how much oxygen goes in and how much oxygen comes out.

[00:12:35] Sophie: Oh my God.

[00:12:36] David: Which means they can actually measure how much oxygen is being consumed by the ducks for a unit time. Right? Yeah.

[00:12:44] So here’s where we get to the wake. Right? So the decoy, the ducklings are following the decoy. So they looked at two situations, one where the decoy was actually, and the decoy was duck shaped.

[00:12:54] It wasn’t like just a bucket or something It was actually,

[00:12:57] Sophie: they’re not playing with the ducks too much. It’s [00:13:00] like, look, it looks like your mother. We’ll give you that.

[00:13:02] David: Your mother is Godzilla. No, it was actually duck shaped. So they either had the duck in the water. So it was producing a wake or they raised this slightly out of the water. So the ducklings would still follow it, but it was not producing a wake.

[00:13:15] Sophie: Yeah. Okay.

[00:13:16] David: So you’ve got this decoy and it’s being followed by one to four ducklings, and then they look at the amount of oxygen coming out of the chamber when the thing is in the water or out of the water. And sure enough, sure enough, when the duck decoys in the water, the ducklings consumed less oxygen. That was the first finding. The second finding was when you had multiple ducklings, even if the decoy was in or out of the water, they go energy saving just by being a little cache of ducklings together. energy saving effect of having the mother in the water and an energy saving effect of having the ducklings close together.

[00:13:53] I just think that’s a brilliant, beautiful bit of science.

[00:13:58] Sophie: That’s not even the story of this.

[00:14:00] David: not even a story. This is the background that I just think it’s great. And that was from a book chapter by Fish et al., which we’ll put in the show notes. Please have a look at it. Cause it’s great.

[00:14:10] Sophie: I know a mathematician whose surname is Duck but ah, that’s unrelated.He’s a fluid mechanism anyway, so yeah, the idea is like they knew this, questions that they wanted to ask were why are they swimming in formation? What is the best swimming formation and how much energy can be preserved by each individual in swimming formation.

[00:14:26] But they asked these questions in a unique way and they were looking at. The interference phenomenon of the free water surface. So the whole idea was you lowered the pretend duck into the water and you get a wake, right. The wake is caused because there’s a bluff object, which is the duck and water is moving around it.

[00:14:43] And so the question is, and that’s going to create little waves and stuff. And so they wanted to know about this from actual the interference of the waves. And so what they did you’re right. They had a simplified mathematical model, which they tested numerically, which I want to talk to you about in a second, because lack of detail makes me worry, Dave, but this was [00:15:00] in, this was published in the journal of fluid mechanics, which is I would

[00:15:02] say, possibly the best fluid mechanics journal in the world. So we hope that they have, looked at this in more detail than I have, but yeah. So the whole idea is that they observed these two cool things and they’ve called them wave riding and wave passing. And basically, all it is is like wave superposition.

[00:15:21] So I don’t know if you remember from like school. I can’t remember we did this in school, but like if you have like a sign wave day, but I just want you to think of like a sin wave or a cosine wave. They’re the same. They’re just like out of phase. And the whole idea is if we have two waves on top of each other in phase the peaks lineup, and then you get like a double peaks.

[00:15:38] David: you’ve bigger waves. Yeah. Yeah,

[00:15:40] Sophie: Yeah, exactly. So basically we call that constructive interference because of the superposition, but if then they’re out of phase, so a peak lines up with a trough, then they basically cancel each other out and then you get destructive interference. And so like you get no wave nothing. And so the whole idea is that, so when the mother is there, you’re [00:16:00] getting a wave that is like coming off the mother. And then, so what they did is they calculated the thing using it’s essentially just a drag reduction coefficient. So, what they looked at was they calculated everywhere in their computational domains. They had their mother duck analytic first, just one duck behind.

[00:16:16] And they calculated this drag coefficient, which has to do with basically this, the superposition and the positive. so the constructive and the destructive interference, and they basically made a map of where the duck would be sitting. To get like, Positive interference. I they’re getting like a little kick from the waves.

[00:16:32] The whole idea basically they’re surfing. So what they do is they worked out that these ducks, they can naturally align themselves with giving themselves a wave kick just behind them. So it pushes them forward if they were in any other spot. Like if you had the constructive interference in front of them, it’s kind of like having you know, when you’re like trying to go over a wave and you have to like swim on top.

[00:16:53] And it’s, there’s more energy than if you’ve got like you’re. Yeah. You’re basically surfing in a wave is pushing you from behind. Ducklings can intuitively [00:17:00] pick these positions out. So by swimming behind the mother, what they actually found, if they were in this, what they called the sweet spot, the sweetest spot, they get 158% less wave drag

[00:17:13] then when swimming alone. So they get this huge kick behind them. So that’s what they’ve called wave riding. So essentially the ducklings are picking spots where they’re getting this constructive interference behind them and giving them like a little kick in the butt in a good way. But then what you then get is wave passing.

[00:17:29] And cause, you know, as you said, even if there were. Like in your duck experiment, Dave, the one that you

[00:17:35] David: The one that I did,

[00:17:36] Sophie: yeah. you said that even if they were all there, like the ducks behind were getting some kind of advantage, and this is what they’ve called wave passing. So the whole idea is like, you’re getting this kind of wake and these little waves from the mother.

[00:17:47] And then the first duck is kind of then still a bluff object in front of the next duck And so you’re passing on some of these kinds of beneficial effects and what they found is, so [00:18:00] basically your first duck and they did this, like, it was like very precise. The first duck, you get 158% wave drag reduction.

[00:18:07] So basically like the drag is felt 158% less than if the mother wasn’t there. And then in the second duck there’s enough wave energy to still gain a propulsive force for the, yeah, the duckling behind the first duck. So it’s 132% reduction. And the whole idea is though that they’re also going to have drag from the waves.

[00:18:28] So it gets like a little bit nitty gritty, but the whole idea is a hundred percent of that wave reduction they have to use to actually overcome the wave drag in itself, which means they still get 32% increase propulsive force. And then by duck three, basically, it’s kind of like net in net out is equal.

[00:18:44] So they still get a benefit. And their job is basically to sustain those waves and pass them onto the trailing one. So not only really get these ducks, riding the waves and then passing on the good wave energy to the ducks behind them. my issue though, as I said is just with the computations, Dave.

[00:18:59] [00:19:00] So there was a throw away line in the paper that said the three-dimensional boundary element method applied to solve the Laplace equation and calculate the wave drag, was the one that we used in this, those used in this. And so the Laplace equation is just like, you know, we talked about Naviar – Stokes before, Laplace is just easier Naviar-stokes.

[00:19:18] Cause what we’re saying is the flow is irrotational i.e there’s no vortex. There’s no swirling motion. It’s just all in one direction. I mean, what it actually says is the curl of the velocity field is zero, but it basically means there’s no swirling. It’s just all in one direction, so it’s easier to solve.

[00:19:32] So they solve that and they also calculate the wave drag. And I went and I found this, I think the three-dimensional boundary element method is just like, a type of finite element method. Don’t worry about it. In this paper, they have an in-house multi body hydrodynamic interaction program called M hydro that I can find absolutely no information about,

[00:19:53] David: Okay. So they did a thing probably was lots of work and they haven’t told us about it.

[00:19:56] Sophie: No. And, but the fact that it’s in JFM makes me feel [00:20:00] more okay about whatever this magical thing is that they use to calculate it. But yeah, so like, and basically this paper I thought was nice as well, because it just had lots of great pictures. So it kind of like, here’s a little map behind the duck.

[00:20:11] These are the good regions, these are the bad regions, what happens when we put ducks there.

[00:20:14] David: Yeah. It had heat maps, which lulled me into thinking that I would be able to understand it, but I’m glad that you could explain it so concisely.

[00:20:20] Sophie: So the heat map was just of the, that, drag reduction coefficient. So that was saying here’s yeah, here’s the good bits. Here’s the bad bits. And like, weirdly, these ducklings can kind of just like they, cause they can feel like the forces and stuff. So they could just naturally like move to these like sweet spots and just save all this bloody energy just by trailing mama.

[00:20:40] David: Yeah. Love it.

[00:20:41] Sophie: Yeah. That’s it. That’s all I

[00:20:43] David: it’s a lot of excitement in there about the ducks

[00:20:46] Sophie: Yeah. But good on them. It’s just, he’s this thing about nature, Dave, it’s just very good at doing stuff that we’re a bit rubbish and we’re like, we’re slowly catching up, but like, you know, we’ll get there eventually, but there you go. So if you are swimming behind another person, make sure you hit that, uh, [00:21:00] duckling sweet spot and you could reduce your wave drag reduction by 158%.

[00:21:05] You’re welcome.

Tuskless Elephants

[00:21:07] David: So the most distinctive characteristic of elephants, Sophie, is maybe trunks and that, maybe memories, but after you get past those things, you might well come to tusks.

[00:21:30] Sophie: Also can’t they not jump.

[00:21:32] David: don’t know. Can they not jump.

[00:21:34] Sophie: Maybe that’s

[00:21:34] David: Is that one of those things like dogs can’t look up.

[00:21:37] Sophie: you hear. You hear as a kid that look? All I’m saying is that that came up as the order completion number one, despite what you may have seen in your setting, when in cartoons elephants, can’t jump. According to video by Smithsonian, unlike most mammals, the bones in elephant’s legs all pointed downward, meaning they don’t have this spring required to push off of the ground.

[00:21:55] That’s not what talking about. Dave, we’re talking about ivory purchase, messing with evolution. Let’s [00:22:00] get back to

[00:22:00] David: Exactly right. So back to tusks.

[00:22:02] Sophie: to tasks.

[00:22:03] David: So we know that poaching is a thing, we know that poaching of elephants is a thing. And that usually what poachers are after is the ivory from the tusks, apparently a multi-billion dollar illegal industries

[00:22:13] Sophie: Just paint wood white guys have solved your problem?

[00:22:17] David: It’s white stuff. Come on. also all your friends are gonna think you’re a dickhead

[00:22:20] Sophie: Yeah.

[00:22:21] David: basically this problem is so bad that elephants have started to display a tuskless phenotype. So evolution has stepped in to the point where elephants without tusks are being selected for and we’re seeing fewer and fewer tusks.

[00:22:34] Sophie: Yeah. So the study we’re about to talk about has just come from one park in Mozambique, but they said during the Mozambican, I’ve never said that word before, out loud during the Mozambican civil war, armies hunted elephants And other wildlife has things like food and, ivory and things.

[00:22:50] And they said that in this particular, um, Gorongosa national park. The number of large herbivores dropped by more than 90%. So apparently they had [00:23:00] 2,542 elephants in. And so the beginning of the civil war was in 1977 and two decades later, that 2,542 had dropped to 242 elephants, which is like,

[00:23:12] David: yeah, we’re the worst.

[00:23:14] Sophie: And then, as you said, what they’re seeing now, there’s, we’ve got video footage and photographic records that show as a number of elephants that have plummeted the proportion of tuskless female, African Savannah elephants, which the ones that live in this particular park, have risen from about 18% to 51%.

[00:23:32] so evolution has given them a little leg up because all we want to do is kill everything.

[00:23:36] David: Yeah. So what this team have done is analyze the genetics of 18 tusks and 18 tuskless female animal.

[00:23:44] Sophie: I’m just gonna jump in that Dave, that was misleading. There’s actually seven tusks and 11 task lists, but they make it of both. Yeah. Don’t worry. It’s a supplementary material part.

[00:23:53] David: Okay. So they, they looked at some of each.

[00:23:56] And they look what they were looking for was mutations [00:24:00] that could explain the changes in tusks or tusklessness in these animals. And they found some genes that apparently in mammals and in people where they’ve been studied, cause either tooth brittleness or the absence of a pair of upper incisors, which are an inverted commas, the “anatomical equivalent” of tusks.

[00:24:19] Sophie: I also have in quotation marks as well. Yeah.

[00:24:22] David: Yeah. So, what they know about one of these genes, so the gene is called AMELX or Anil AMELX. Let’s call it.

[00:24:30] let’s just, AMELX, so this is associated with an X-linked dominant male lethal syndrome. So basically so far we’ve been talking about tuskless females.

[00:24:39] And the reason we’ve been talking about tuskless females is that the tusklessness has only been observed in the females And this gene that they’ve talked about, they say it’s X-linked, which means that it it’s linked to the X sex chromosome. So just briefly, we all have sex chromosomes. And by we, I mean us and also elephants and these determine what sex will be when we’re made in the womb.

[00:25:00] So, if you’re a female, you have two X chromosomes, and if you’re a male, you have an X and the Y. And basically why this is interesting is because although they could see that this gene was changed, this gene and the fact that it’s X-linked allows them to make a prediction about what reproduction will look like in tuskless females. And, this is kind of like genetics as the study of heritability. So not so much genetics is the study of DNA, which is what it’s become. But before. before DNA and everything. There was a field of genetics and it was just about inheritability of traits in

[00:25:32] Sophie: yeah.

[00:25:32] David: and this is the kind of work they would do.

[00:25:34] So it’s actually kind of really nice that they’ve done this really in-depth molecular stuff, but then they’ve linked it to this very kind of old school genetics, but basically they had a hypothesis which was that if the tusklessness,, as they say, X-linked dominant, basically you’ll have females with two X chromosomes, one of which will be positive for tusklessness

[00:25:53] and one of which will be negative for tusklessness. And because when you’re, if you imagine that elephant has four [00:26:00] offspring, on average, you’ll get four different things. You’ll get a male who has the X gene, which is positive for tusklessness, and why that one is not viable because the mutation kills the males.

[00:26:14] You’ll get a male who’s got X, which is negative for tusklessness, and Y. So that will just be a tusked elephant. And that will just live

[00:26:20] Sophie: Just old bloke elephant. As we know him.

[00:26:23] David: just, Yeah. All male elephant. And then we’ll end up with two females, one of which is tuskless and one of which isn’t. So basically if what they think is true about where this gene is on the sex chromosomes,

[00:26:36] then what we should see is that two thirds of the offspring of female tuskless elements should be female. Because 50% of the males will die. So there’s a 50% likelihood that you produce a male or a female. And if you produce a male, there’s a 50% chance that the male will die. So of all of the offspring of the female tuskless elephants, what they should see is that there should be two thirds [00:27:00] female, and basically they go into the data and say, that’s exactly what they see.

[00:27:04] 65.7% were female, which is pretty much right on

[00:27:09] Sophie: Yeah. In in a terrifying way. Yeah.

[00:27:12] David: Yeah.

[00:27:13] so basically not only do they identify the gene molecularly, they also say, it’s this point. And this is where we’d expect to see if it is this gene that’s producing the changes. And that’s basically exactly what they see.

[00:27:24] And as we’ve talked about on this show before to say that it’s a single gene that’s producing a big change like this, instead of like a Marriott of genes is kind of unusual and kind of a big deal. And that’s probably why I ended up in such a big journal.

[00:27:35] Sophie: and also the cause what I didn’t realize was that they’ve said that the relative survival of tuskless females over the 28 year period is estimated to be more than five times out of the tusk individuals. And it was because like, yeah, I guess if you could, you’re only going to kill an elephant for pretty pokey teeth. Nothing else. And then, I mean, I, you know, granted oversight, I didn’t really get the genetics part. I got, you know, the, in essence, this is what it’s about. So I learned a bunch of [00:28:00] things about elephants and do you know where I ended up David? I need adult supervision when I do anything these days.

[00:28:05] So I was just like, oh, okay. So we’re talking about the African Savanna elephant, which is also known as the African Bush elephant. And I was like, well, what’s the kind of elephant that Thomas Edison killed with electricity when he was

[00:28:18] David: Thomas Edison killed an elephant?

[00:28:19] Sophie: Oh my God. what I learned then was like, so apparently according to a lot of the things, it was in the war against DC versus AC.

[00:28:28] basically Edison wanted to prove that DC current was safer than AC current, even though we know that AC current is better at traveling and doing all these different things and it’s true to be electrocuted an elephant. but.

[00:28:37] David: What a champion

[00:28:38] Sophie: But the, the whole thing was, it turns out that, you know, so that’s, that’s how I understood it.

[00:28:42] I’ve seen documentaries, I’ve seen movies where it’s like, this is Edison, just like killing elephants to prove that his electricity is better than Tesla’s electricity. It turns out the Topsy, the elephant was sentenced to death at Luna park. because she had killed three men over three month period, and then apparently also men at some local police and Workman, [00:29:00] so that elephant was meant to be put to death anyway.

[00:29:02] So they will just like, well, just use your electricity at us. And like, that’s fine.

[00:29:05] And, did you know that the longest tusk of the African Bush elephant measured 3.51 meters and weighed 117 kilogram?

[00:29:13] David: That’s gigantic, That’s considerably heavier and longer than I am.

[00:29:17] Sophie: Yeah, right. So this is, I think this is why you know there, Mozambiques preferred elephant to kill for tusks I don’t know. But yeah, so there you go.

[00:29:24] David: The women, the women don’t have so many tusks anymore because evolution is happening.

[00:29:29] Sophie: Yeah. And they’ve said that because this is yeah, like evolutionary for all the tusks to come back, like it could take like a really, really long time. And like, even after all poaching ceased, like maybe like their tusks will never come back cause we’ve ruined them.

[00:29:42] David: Because the shorthand for this effect, his life, finds a way.

[00:29:46] Sophie: yeah, exactly. So there you go, stop killing animals, or they will stop growing and yet, and also everyone check out the show notes for a picture of a tuskless elephant. It’s very upsetting just to look at it. This looks like someone’s teeth has fallen out. Like it’s not, I don’t like it.[00:30:00] It’s like gummy.

[00:30:01] They’ve got those little gummy bits where the tusk should be.

The Horse father

[00:30:13] David: Sophie, like if you told me that you could ride a horse, I would not be surprised. Can you ride a horse?

[00:30:18] Sophie: No, I don’t really I’ve eaten a horse But, I haven’t. No I’ve, I mean, I’ve, I’ve ridden a horse, I mean, but I can’t like ride a horse.

[00:30:25] David: So like as a child, you ride a horse. or

[00:30:27] Sophie: Yeah. My cousin grew up on a property in rural Victoria and she had horses and I rode them a few times there, but I was never really into. Horses weren’t animals that I loved as children.

[00:30:38] So then when I lived in Switzerland and everyone was like, yeah, horse meat is the cheapest one in the supermarket. We all eat horse. Like I wasn’t bothered by it. And so I just ate horse along with them.

[00:30:47] David: So you don’t go with the Western fetishization of horses as magical animals.

[00:30:51] Sophie: No like maybe a unicorn put a horn on it and I’ll be like, Ooh. Yeah. But um, yeah, so, no, I can’t ride a horse, but thanks for asking.

[00:30:59] David: Nah same. [00:31:00] I rode a horse as a kid, but never really got like uh scuba diving for me. It’s like, yeah, this is cool, but I’m not going to like, take it up

[00:31:07] Sophie: Yeah. So Dave, can’t read it. Why, why are we talking about horses Dave? What’s going on in the world of horses this day?

[00:31:12] David: So it turns out that researchers have found for the first time. And I didn’t know that we didn’t know

[00:31:19] the, original origin of the domesticated horse. So at some point in the relatively recent past, like maybe 6,000 years ago, human beings started using horses as beasts of labor and for transportation.

[00:31:34] that’s one thing, you know, to have evidence in history, like written down evidence that horses were used in this way as one thing. But also today we have all these horses around them, then we say, oh, that’s a horse. but also what is the genetic ancestor of that horse? When did that horse become the go-to horse?

[00:31:51] Like what is the Ford model T of horse

[00:31:54] Sophie: gonna say like, when when did we turn horses into pugs is how interpreted

[00:31:58] David: Basically, when did they [00:32:00] become domesticated? And when did the horses that we see around today and call, oh Yeah.

[00:32:05] there’s a horse. When did they become the dominant horse that’s around and a team, apparently I looked at the paper, it took 162 scientists specializing in archeology, paleo genetics. And bafflingly linguistics to work this out.

[00:32:22] Like, what is that? Like, we just couldn’t have done it without that special group of people who bought speak horse.

[00:32:26] Sophie: No, they could say horse in every language.

[00:32:29] David: Okay. That’s probably useful.

[00:32:30] Sophie: Just so everyone involved in this international study could remember what they were studying. word horse, just in all the different languages of all the different, researchers. And I think is how I’ve interpreted

[00:32:44] David: And again, the analysis is saying this and what were we talking again?

[00:32:49] Sophie: oh, I think Cheveu is, um,

[00:32:52] David: Our hair.

[00:32:53] Sophie: I think you want Cheval. Yeah. Cheval is plural and cheval is singular.

[00:32:58] David: Oh Cheval. Uh,

[00:32:59] Sophie: [00:33:00] Oh Cheval. And that’s so Cavallo, Italian.

[00:33:03] David: Oh, nice. See, I’d forgotten what we were talking about. You reminded me.

[00:33:07] Sophie: Dave, who only speaks Italian when saying the word horse. So apparently Dave, they, the conclusion that I will tell everyone, then you tell them how we concluded this, that the first domesticated horse, appeared around 2200 years BCE in Northern and it’s Caucassus. And I was just like Caucassus. And then I was like Caucassus and I looked it up and it was Caucasian.

[00:33:30] And it’s like the region spanning Europe and Asia. And now we lazily, still sometimes use the word Caucasian to basically refer to white people from those areas. I didn’t even know there was an area called Caucassus. Anyway. basically, yeah, about 2,200 years BCE, and then in the centuries that followed this horse spread throughout Asia and Europe, and what they did is they collected sequenced and compared 237 genomes from ancient horses scattered around Eurasia to come up with this finding.

[00:33:59] And [00:34:00] Dave is going to tell us what that means.

[00:34:02] David: Well, I mean, the short answer is genetics. so they looked at, as you say, the genomes of 273 horses spanning a time from 50,000 years ago to 200 years BC . So 50,000 to 200 years BC. and basically from what I can gather, they sequence the DNA from horse bones. So they would grind up the bones and do sequencing of the DNA and presumably the bone marrow.

[00:34:24] And then they would look at all of those different horse genomes and then compare it with the genomes of modern domestic horses. So basically you raise you, as you say, was once populated by genetically distinct horse populations. And then there was this apparently dramatic change in the genomes between 2200 BC when a single genetic profile, which had been previously confined to the pontic steps, began to spread beyond its native region.

[00:34:48] and so they also say that the genetic data says that the population of these horses exploded in a manner that has no equivalent in the last a hundred thousand years, which is the first suggestion that [00:35:00] humans were directly involved because it’s probably not natural that all of these horses were suddenly made, but the other really strong genetic indicator that humans were involved in making all these horses this particular genetic background, is that they show genetic changes.

[00:35:18] One of which is linked to more docile behavior in the horses. And the second of which, tends to produce a stronger backbone in this horse. So that’s the other really strong piece of Genetic evidence that humans were involved in the explosion of this particular horses, this particular horse, which was previously confined to the Pontic-Caspian Steppes or steppy at spread through all of Eurasia.

[00:35:44] Which huge, we say Eurasia casually, but it’s a huge area. It’s like massive.

[00:35:49] Sophie: Yeah, exactly. and then people in the past were just like, I want horses to be like a bit nicer than the jerk horses, and I really want to ride it as much as possible.

[00:35:57] David: Yeah.

[00:35:57] Sophie: and to docile and [00:36:00] strong backbone horses.

[00:36:01] David: That’s exactly

[00:36:02] Sophie: But yeah, I was with you. I didn’t realize we didn’t know this about horses

[00:36:05] David: Yeah. They also talk about, so there, this is presumably where the historians come in, the,

[00:36:10] Sophie: And the linguists.

[00:36:11] David: historians in the linguists. yeah.

[00:36:13] So this explosion or the spread of the horses that happened across all of Eurasia also happened at the same time as two things. One was the spread of spoke-wheeled chariots, and other similar technologies, and which may have been due to increase the rigidity of the land.

[00:36:28] There was a bit of fighting going on. So. Basically these chariots spread, because there was a kind of technological revolution happening, which was being used for warfare, as a result of this fighting. and the other thing that happened was the indoor Iranian languages were spread across Eurasia at the same time.

[00:36:46] So they say this is not just genetics nonsense that we’re talking here, understanding this genetics directly helps us understand what happens to people around about this time as they spread from where they had been to, where they were going to one day be.

[00:36:58] Sophie: Exactly. So [00:37:00] it demonstrates the importance of incorporating history of animals when studying human migration and encounters between cultures. but yeah, I thought like, I didn’t realize we didn’t know this. And then of course I, um, I did think about my interaction with horses in the past and thought about like eating horses when I lived in Switzerland.

[00:37:15] And did you know Dave that in October, 2019, the ABC revealed that thousands of retired race horses in Australia were being slotted annually for the export market in human consumption. So apparently Australians don’t eat horse meat, but we export it for other people to eat. Did you know that?

[00:37:31] David: I didn’t know that I don’t find that eating horses to be, I mean, we could have a long conversation about eating animals on any podcast.

[00:37:39] Sophie: true.

[00:37:40] David: I don’t find eating horses any better or any worse really than eating any other animal. Really

[00:37:45] Sophie: and my understanding, and I think I’ve said this too, before, but, and I could be wrong. My understanding is that a horse doesn’t mutton like a sheep does the whole idea is like, in these places where you had work horses, you could work this horse for its entire life. And then when it basically got lame or was, you know, you’d had to kill it [00:38:00] cause it was old and couldn’t do anything.

[00:38:01] David: it’s still

[00:38:02] Sophie: Yeah, you use its feet for things, and then you just like, you can eat most of it. You can use, it’s like, you know, the mane for like violin, bows, whatever you want. And so it was like this very, but yeah. And so I just tastes like a little, it’s like a slightly gamey beef that is quite lean and you just gotta be careful when you cook it.

[00:38:17] and then I have a note here, Dave, and for the life of me, I don’t know what it’s in reference to, except maybe when I was looking up horses. And I’m like, oh, the different uses of horses. Apparently we, they used to be as a drug that they called Premarin, which is a mixture of, um, basically used for home and replacement therapy.

[00:38:35] We don’t do it anymore, but it’s called Premarin and it’s extracted from its estrogens extracted from the urine of pregnant mares and Premarin stands for it. So the Pre is from pregnant, the Ma is from mares and the I N is the I N in urine. So apparently we used to use, estrogen from horse urine in hormone replacement therapy.

[00:38:55] I think maybe I just thought that was a fun fact and I wrote it down. I’m not sure why it’s here. So I thought I’d share it with [00:39:00] you Dave

[00:39:00] David: Thank you Sophie. I appreciate it. And I enjoy it. And I think a, that’s a rare example of a portmanteau of three words.

[00:39:06] Sophie: Yeah. But I think I always find it sloppy when they then pick like two letters from the middle of a word.

[00:39:12] David: Yeah, sure.

[00:39:13] Sophie: it would be Premeur which is, I guess it doesn’t have the same like ring tool

[00:39:18] David: And also anything, that ends with an N makes it sound like a hormone

[00:39:21] Sophie: Yeah. you know, it was, it

[00:39:23] David: adrenaline and noradrenaline and

[00:39:25] Sophie: it was urine and estrogen,

[00:39:27] David: yeah.

[00:39:27] Sophie: my favorite kind of hormone. So there you go. We now know why horses are the way they are. i.e strong in the backbone and docile in nature. And, uh, when they appeared.