Hey, you welcome to Stuff to Blow your Mind. My name is Robert Lamb and I'm Joe McCormick. And it's Saturday, which means we're going on down into the old vault to pull out a classic episode of the show for you. This one is from last year. This one is from March thirty first, twenty twenty two, and it is the Three Pupil Die Part two. This is the follow up to the episode that aired last Saturday about about strange pupils and irises in myth, legend and reality. Welcome to Stuff to Blow Your Mind, a production of iHeartRadio. Hey, welcome to Stuff to Blow your Mind. My name is Robert Lamb and I'm Joe McCormick. In our last episode, we discussed a common but enthralling literary motif in Irish mythology, the triple and the sevenfold eye, three or seven pupils, three or seven irises found in the eyes of beautiful heroes, divine seers, destructive monsters. We also discussed the structure and functionality of the human eye and the rare instances in which we actually see double pupils in human eyes. In this episode, we're going to explore more curious eyes from the natural world, as well as more accounts of marvelous eyes from ancient history and literature. But first a pop culture update. At the end of last episode we were talking, I spoke briefly about some double eyes that I remembered from some movies, album covers, etc. Well, our good producer Seth provided us with two additional examples of double eyes and popular culture that we didn't think of last time. Number one, the double irises and pupils of Aminet in twenty seventeens. The Mummy. This is the Tom Cruise Mummy film. Oh boy, did not see it, but I think this is like the the titular Mummy, or at least one of them. I think she is the Mummy in this film. I'm okay, I haven't seen this one, not even on an airplane, but I'm not opposed to it. I mean, I've seen a lot of crummy mummy movies over the years, and usually there's something interesting in them. Yeah, at least sometimes you get an Arnold Foslou or something. Yeah. And then the second example Seth brings up is the album cover to Bubba by Haitian Canadian musician k Trenada featuring the artist with otherworldly blue eyes that have double pupils, double irises. I listened to a track from this album while we were working on notes. It was good. I haven't had a chance yet, but I do love the album cover. It's pretty great now. One of the sources that we mentioned in the last episode was the Evil Eye in early Irish literature and law. This was published in Celtica twenty four back in two thousand and three, and this was by Jacqueline Borsch and the author of Fergus Kelly is also cited on this paper because there's like a part one in a part two, but I believe we're we dealt with material from part one. Celtica, the journal this is in is a scholarly journal for Celtic studies out of the Dublin Institute for Advanced Studies. So most of this deals of course with Irish law, Irish traditions, Irish mythology, and despite the popularity of this motif of the multiple pupils, multiple irises within the Irish tradition, we also encounter discussions of this sort of thing in other traditions as well, and shares a few of these The first one comes to us from A Plenty of The Elder and the Natural History. Plenty discusses individuals in Africa said to possess quote, the power of fascination with the eyes and can even kill those on whom they fix their gaze for any length of time, more especially if their look denotes anger. Now that's you're pretty basic evil eye scenario right there. You encounter variations of this throughout the world, based on the fact that, yes, you can shoot somebody a really terrible look and you can almost feel it. Of course, going back into the ancient world, the belief was often that it was more than you know, giving somebody the stink eye produced more than just a bad feeling, that it could literally curse them or cause them magical harm. Yes. But the neat thing here where it ties into what we're talking about in these episodes is Plenty goes on to connect this to multiple pupils quote. A still more remarkable circumstance is the fact that these persons have two pupils in each eye. Apollo Nides says that there are certain females of this description in Scythia who are known as the Bitha and Philarchus states that a tribe of the theebe in Pontus, and many other persons as well, have a double pupil in one eye and in the other the figure of a horse. Double pupil in one eye, the other the figure of a horse. Now, with passages of this kind, we're often faced with the question is this based on some distorted or exaggerated retelling of something that somebody actually saw, or is it just pure creative imagination or you know, tall tales, And it's always interesting to wonder about the former, But ancient accounts like Plenties are clearly full of the ladder, especially when telling stories about peoples who live in far away parts of the globe. You know, this section that we're quoting from plenty is from I can't remember what it's called. There's like one of his books is all about the nations of the world, and it's just all these weird stories of like here's a people who live somewhere far away, and here's this strange thing they do or something that they wear that would be fascinating to my readers. Like there's one part where he talks about a tribe of people somewhere who do not have heads and instead have eyes in their breasts. So it need not be the case that Plenty is necessarily here repeating a misunderstood or exaggerated story about somebody who actually had something like polychoria or some other unusual condition of the pupils. But of course it is always possible. Yeah, it does make you wonder, you know, to what extent would there be, like, you know, some account of an individual with this rare condition, some memory of this rare condition, and then it gets folded into some of these traditions and beliefs at one point or another in their long lives. Yes, though of course it could again just be something somebody made up, like the people who don't have heads and have eyes in their breasts, right right, Like, we can dream up individuals with like four arms, and it's pretty interesting and we can draw all sorts of meaning from that, but it doesn't mean that people with four arms ever actually existed, you know, that there's any actual biological basis on which that was based. Though. I do think it's really interesting that he doesn't just say, Okay, they've got two pupils in each eye, but that they've got two pupils in one eye and in the other eye a horse. Yeah, And like the first place my mind went was, Okay, is it actually shaped like a horse a distortion that is roughly horse shaped? Or is it? Does it mean that this is like some sort of telephone game, you know, translation game version of a horizontal pupil like one finds in the eyeble horse. That's interesting, and that'll tie into a scientific paper we're going to talk about in a bit. I found an editor's footnote in the Bostock translation of Plenty, which notes, quote, some of the commentators have supposed that Plenty or Phi larcis from whom he borrows, because remember, this isn't an original observation of Plenties, He's like copying this from some other writing of this person named phi Larcus, but Philarcus from whom he borrows. Whether they were misled by the ambiguity of the Greek term eCos, which signifies either a horse or a tremulous motion of the eye. But even admitting this to be the case, the wonder is scarcely diminished, for we have the double pupil in one eye, while this supposed tremulous motion is confined to the other. So so if Fostuck is correct there, it's that this word had had a double meaning, and one of them was like a you know, a quivering of the eye. I guess I would assume that's like when somebody's eye is twitching. But yeah, you wonder, well, why why is it just that the other eye is twitching when when the first eye has two pupils in it, that's also strange, maybe not as strange as a horse. I was. I was looking for answers on this as well, and I ran across a nineteen eighteen paper titled of the Papula duplex and Other Tokens of an Evil Eye in the Light of Ophthalmology by Walton Brooks McDaniel, And according to Brooks, here one doctor Kirby Flower Smith, a professor of Latin and at John Hopkins University, who had I looked VI had died in nineteen eighteen, interpreted the Plenty passage as having some sort of connection to the idea that the affliction of the eye was caused by quote a horse shaped demon, horsehead masked demon. Yeah. McDaniel also begins to discuss the the idea that if you know, if you look into another eye, you know certainly with the right lighting and so forth, you look into another person's eye, you can see your own reflection. And so McDaniel mentions that in some traditions that individual you see in the eye is interpreted, you know, not as yourself, but as the signifier of the soul, and that there are even some traditions where if the individual looks in some way inverted, that is because of witchcraft. And in this this this is one of those weird situations where then McDaniel mentioned something else that leads me back to a source that I'm very familiar with, and yet I totally blinked on this particular detail, or or maybe I'd never read this one particular tale, but he ends up referring back to Strange Tales from a Chinese Studio by Poosh song Ling. That's a show, favorite, folks. Should we do we have a Strange Sales from a Chinese studio? Buzzer? I doubt we do, but at any rate, it's it's it's a book that I really enjoy. This is a Ching Dynasty collection of stories that Pous song Ling collected and retells, and you know there's a lot that's that's lost in translation. Out of Mandarin. But but there's still remarkable fun, sometimes funny, and sometimes it's just very strange. Uh. Sometimes it's it's you know, it's all about what they would have meant to the people who read them. But they're a lot of fun. There's a Penguin edition of it translation that I've I read again and again over the years, and yet I completely blanked on this one story. It's called Talking Pupils. I think maybe the reason that I haven't read this one recently is sometimes i'll read these to my son and I'll sort of glance at them, and if it looks like there's something that might be scandalous in it, or you know, a little dirty, then I'll skip over the tale. There aren't many, but occasionally there's one like that. So anyway, this story Talking Pupils concerns the tale of one Feng Dong quote, a gentleman of considerable accomplishments while at the same time having a reputation as an unprincipled libertine. Oh yeah, so clearly that's why I might have skipped over this in recent years. Anyway, So Fang was this is how the story goes. Fang is strolling the countryside and he happens on a fine carriage on the road. One of the female attendants to the carriage is quite fetching, so he moves in for a closer look. But as he does so, he's able to peek between the curtains of the carriage itself and he sees a beautiful young woman within, and he's captivated. The female attendant is having none of this, though, and she verbally shames him, you know, calls him a you know, a weirdo and a snooper. And not only does she verbally shame him, she reaches down grabs him dust out of the road and throws it in Fang's face. Oh, dirty fighter. Yeah, but you know, he had it coming. He was up to no good and he gets punished for it. So he's he's initially he's trying to get the dust out of his eyes. The carriage carries on. When he is able to see again, you know, struggling, the carriage is completely done. It's you know, it's vanished around the bend or whatever. So he has heads on home, but his eyes continue to bother him, so he seeks some help. A friend looks into his eyes, and this friend says, yeah, there's a visible film over each of your eyeballs, and meanwhile, tears won't stop flowing. In time, the film thickens and a spiral what is described as a spiral shaped protuberance begins growing from his right eye, resisting all manner of treatment. Eventually he's completely blind, and you know he's he's distraught over this. But he hears about a Buddhist sutra known as the Sutra of Light, and it's said to be able to heal eye ailments or ailments of this sort. So he gets a side friend to read it to him, and he learns it by heart, and he recites it over and over again, and after a while it gives him solace. You know, he feels a little better. His side is not back. But then one day he begins to hear voices, two voices, one from each of his eyeballs. Oh, I love this. The eyeballs are talking, both of them. Well, as it turns out, not the eyeballs but things within the eyeballs. There's one voice within each eyeball, and they start talking to each other, and they're talking about how dark it is in their homes and how they'd really like to just get outside and go for a stroll. And then so pusong Ling says quote, then he felt a slight irritation in both nostrils, as if two little creatures were wriggling down his nose. After a while, he felt the creatures return and make their way back up his nostrils and into the eye sockets. Again, this is anatomically correct because, as we know, the tear ducks that drain tears away from the eyes drain into the nasal cavity, which is why your nose when you cry. Oh very good. So what does Feing do at this point, Well, he gets his wife to take him to the old garden, and he has her observe him in the garden to see if anything like this happens again. Maybe the garden will coax whatever it is out of his eyeballs. And this is what happens. Quote. It was not long before she saw two little mannekins, neither of them any larger than a bean, emerged from his nose and fly buzzing out of the door. They were soon well out of sight, but we're back again in next to no time, flying together up onto his face and in at his nostrils. Like a pair of homing bees or ants. So is he getting relief when they fly away? I don't think so. No. Oh, it's just it happens, and he doesn't know what this is about, so it keeps happening. It happens again each day for three days, and finally one of the voices complains that the tunnel that they're using to get out of the eyeball is a bit round about and there's got to be a better way. It's time that they make some sort of proper doorway. So I'm going to read the rest of this year that it really gets to the juicy part. I'm just I'm filled with dread. It's not a good idea when the tenants in your eyeballs decided to start renovating on their own. Yeah, so that is how it goes. The wall on my side is very thick, replied the right eye. It won't be easy. I'll try to make an opening on my side, said the left eye. Then we can share my door. Presently, Fang thought he felt a scratching and a splitting in his left eye socket, and an instant later he could see he could see everything around him with absolute clarity. Beside himself with a delight. He promptly informed his wife, who inspected his eyes afresh and found that in the left eye a minute aperture had appeared in the film, a hole no larger than a cracked peppercorn, through which gleamed the black globe of a pupil. By the next morning, the film in the left eye had disappeared altogether. But the strangest thing of all was that, on careful inspection, there were now two pupils visible in that eye, and the right eye was still obscured by its spiral shaped growth. Apparently, both of the two eye mannequins his talking pupils had now taken up residence in the left eye. So although Fang was still blind in one eye, he could see better with his one good eye than he had ever done with two. From that day fourth, he was a great deal more circumspect in his behavior and acquired unimpeccable reputation in the district. Okay, so no more creeping on ladies and carriages. Right, he learned his lesson, He was punished for his creepy behavior, and now he's back and ready to be a good citizen with one eye that can see better than two, right, because two pupils. Now that this again is from the Penguin Classics edition. It's a John Minford translation, and this was super interesting as well. Minford shares this in the notes pupils. The traditional Chinese expression for pupil, tong wren, means literally man in the pupil from the reflection of oneself that one sees in the eye of another. Wow. Yeah, that was that was really that. I was really impressed by that. And I was talking to my wife about it because I was looking around a little bit after this and I saw an article about photography and about being able to zoom in on the eye of an individual in a modern photograph and see the reflection potentially of the photographer and oh yeah, because of the high resolution, I guess, yeah, yeah. And I was asking my wife about this, and she pointed out that one thing that photographers can do is you can pull up, say a headshot that another photographer is done. You can zoom in on the eye and you can see what their lighting setup is. So I was impressed by that as well. Oh, I'm impressed. That's a real James Bond level trick. I do not know what to make of the spiral growth though I looked around briefly on that and I was not able to find any answers that seemed fencing. I have no expertise on spiral growths from eyes. All right, I want to go back to Borsch for just a minute here, because she has a couple of other examples that she brings up. One apparently tolomeos Chinos. This would have been a figure from the late first early second century. CE once described a beautiful woman as being quote with a double pupil. Okay, And in the last episode we talked about some legends in which a character with multiple pupils this was assumed to be a marker of beauty. Right, So this is interesting because it seems to suggest that this is not just isolated within Irish literary traditions, that perhaps somewhere else in the world there was this idea that double pupil equals beauty. And I mean, who am I to say it's not beautiful? You know, it's not like you look at images of actual double pupil situations and you're not hortified by them or anything, no more so than if you look at a super close up of any human Eyeball also mentions that ovid portrays a woman with double pupils having the evil eye at one point, so tying back into the evil eye tradition. But anyway, Bors concludes quote to conclude this section, Both angry eyes and eyes with multiple pupils have been connected with the concept of the evil eye, there is no strict identity between the phenomena. Multiple pupils can also be a sign of beauty, sharp sight, and clairvoyance. Okay, so we're not really converging on a unity of theme here. If you're in an Irish legend or myth and you have a character with multiple pupils in one eye, it seems they could either be somebody who has a lot of insight, somebody who can see very far away, somebody who can see the future, somebody who is beautiful, or somebody who is monstrous or can do curses. And there is this idea too that it's it's part of like the supernatural body, that when you have some sort of a demigod figure, it's the human body. It's almost like it mutates with the divinity within it like the human The normal human body cannot contain this level of power and therefore, extra things are going to happen, you know, extra pupils, extra fingers, that sort of thing. And this ties directly into another example I found, and this one comes from Chinese traditions as well. This is from the nineteen sixty seven book Chinese Civilization and Bureaucracy, Variations on a Theme by Hungarian born French senologist Eten Balahs working with working from another source as well, Essay on the Extinction of the Soul by Faun Shin, a Chinese philosopher and writer who lived four fifty through five fifteen CE. The subject here, as far as eyes are concerned, is one of the legendary sage rulers of antiquity in China. This would concern a time during the third millennium BC. And so the structure of this paper seems to concern like questions and answers. And so first we have this question. The body of the sage is similar to the body of ordinary men. Yet there is a difference by which the sage is distinguished from ordinary men. From this, it can be inferred that body and soul are different. Answer not at all. Pure gold glitters and unwashed gold does not pure gold. That glitters surely cannot be made of the same unglittering material as that of unwashed gold. How much less, then, can the soul of a sage be lodged in a vessel such as the ordinary man. Nor would it be possible for the soul of an ordinary man to dwell in the body of a sage. Therefore, fengg Sum is depicted as having eyebrows of eight colors, and zong Huo's eyes with double pupils, signon as having the face of a dragon, and tie how the mouth of a horse, all of which are outward bodily signs of their exceptional nature. All the seven openings were found in the heart of pie Con. The gall bladder of poe U was as big as a fist, which shows that their inner organs were unusual. Thus we know that certain parts of the bodies of sages are quite out of the ordinary, and that sages are not only superior to ordinary human beings, but also surpass all other creatures in bodily form. That's just science. I love this passage so much. I mean, I love that it's basically an autopsy of supernatural sages, of determining how they're they're but like you can imagine this scene in a movie. Oh yeah, this is beautiful, the gall bladder as big as a fist, showing that the inner organs are unusual. This is great, and you know, and this is this is not a totally unique view of the body of the holy person or the saint. I mean, you know, there are tons of traditions all around the world, including like the idea that certain types of saints or holy people, because of their spiritual nature, their bodies would be found to be say, incorruptible, like they don't rot the way most spoties do. Yeah. So, but Balais adds some notes on this and points out that the legends about the eyebrows of eight colors and the eyes with double pupils He's come from Mahan times and are contained in a number of different works. So yet another example of of of exceptional eyes in the bodies of exceptional you know, heroic mythic individuals. Now, in the last episode, we talked a bit about human eye anatomy and some medical literature on polychoria, or the condition of having multiple pupils within the same eye. But I thought in this episode it would be a good idea to turn to pupils of the animal kingdom more broadly, because there's a lot we can learn about the function of pupils by looking at the pupils of non human animals. That's right. I mean, just consider the vast diversity we have in the animal world, and I mean even just dealing with the vertebrate world, it's pretty remarkable, not even getting into compound eyes of flies and so forth. But consider humans. We have round pupils. House cats have vertical slits, Tigers have round pupils, Goats and horses horizontal. Dolphins have crescents, cuttlefish have w shaped pupils, some frogs have heart shaped pupils, and geckos have these sort of what looked like pinholes arranged in a vertical line. I always love a good crocodile pupil. Oh, yes, tend to be rather vertical. Yeah, it's and it's also it's a window into the crocodile soul. But seeing all this different diversity does raise some questions because you think, okay, well, you know, the bodies of animals are shaped by their environment. You know, that's what evolution does. It tends to give you the equipment that best helps you do whatever you need to do within your ecological niche. So why do different animals have different pupils? How to differently shaped or sized pupils help an animal adapt to how it's supposed to survive in the world. Yeah. According to Martin Banks, the vision scientist at the University of California that cited in a twenty fifteen NPR story, eye shapes of the animal world hint at differences in our lifestyles. Land animals of sufficient height tend to have round pupils. Thus you have big cats that have round pupils. Meanwhile your small house cat cat has vertical pupils. Verticals are more the domain, it seems, of smaller ambush predators, giving them an excellent ability at judging distances, of which, of course, is going to be super important when you're pouncing out of the shadows and trying to capture like a small rodent or your owner's foot. Horizontal pupils, on the other hand, are widely under stood as a means of keeping a wider swath of the surroundings in sight while you're grazing, and an expanded field of view. So you can think of this as the panoramic potential prey view of the world, right, So I was actually looking into this. The paper that Banks is connected with is one that was published in twenty fifteen in Science Advances, and it's by Martin Banks, William Sprague, urg And Schmall, Jared Parnell, and Gordon Love and it's called why do animal eyes have pupils of different shapes? And what you say is correct. They looked into this question and they found, yeah, there are some very strong correlations between how an animal survives and what shape its pupils are, at least among land vertebrates. And so you tend to have, like you're saying, horizontal pupils if you are a herbivore, whereas ambush predators predators that sit around and wait for their prey, they tend to have vertical slits, especially if they're active of it in both daytime and nighttime. And meanwhile, active predators, predators that hunt and chase down their prey instead of sitting and waiting, they are more likely to have round or circular pupils. And this is not a coincidence. The author has found some pretty good reasons why the pupils would be allotted in these ways. So first of all, you would have to wonder how does it work this lay way, Like why would vertical pupils be useful if you are an ambush predator, especially as you were saying, an ambush predator of low height, because height matters. So if you're an active predator chasing down prey, you likely have round pupils, or if you're an ambush predator that is taller, you probably have round pupils vertical slits of what you're really likely to see if you're a sit and wait, jump out predator and you're close to the ground. So I want to read a section from this paper, and there's a couple bits of terminology. To understand the quote I'm about to read, it'll use the term stereopsis. Stereopsis is depth perception that is created by comparing the difference between what is seen by two different eyes focusing on the same image. So we use stereopsis to judge depth when we look at an image by the brain says, okay, we've got two different data points of the eyes, and it compares them together and gives you this three D image with depth. But then the other term is defocus blur, This refers to the blurriness and objects that are either close or farther away, closer or farther away than you're focusing. So the authors of this paper right quote, vertically elongated pupils create astigmatic depth of field, such that images of vertical contours nearer or farther than the distance to which the eyes focused are sharp, whereas images of horizontal contours at different distances are blurred. This is advantageous for ambush predators to use stereopsis to estimate distance says of vertical contours, and defocus blur to estimate distances of horizontal contours. So rob if you'll scroll down a bit in the notes here, I attached a picture that they put in the paper to simulate what it looks like to a creature that's gazing out at the world with vertical slit pupils, and it's a very interesting So they've got a picture with a toy bird sitting on the ground, presumably a foot or two ahead of where the camera is positioned, and then there's some objects in the foreground in in the background, and what you'll notice about this picture is that the bird is very much in tight focus, but then for objects around it there is there is an uneven amount of blurriness in the vertical and horizontal directions. So like there's a plant stalk that's poking right up in the foreground and its shape is fairly in focus when you're looking at it height wise, you know, like the stalk is sort of sort of blurry but sort of in focus. But things in the horizontal direction, like the top of the pot that the plant is sitting in, are very blurry. And apparently it allows these animals to use both the stereopsis, the comparing the two different eyes if the animal has two front facing eyes, and the way that images are blurred when they're at different levels of distance from the object in focus to judge depth very well. So you can really nail that bird when you jump. So sorry if that was a little complicated, but it took me while to understand. I was trying to figure out, like why the vertical slits actually help with the hunting. But yeah, I think it makes sense if you especially if you look up the picture, you can say like, oh, okay, this is yeah, this is for an animal that is precisely trying to target a jump at something. Yeah, and you've got one shot pulling it off. But there was another thing noted in this pain that I thought was really interesting, and this was actually just in the introduction, but it was about advantages of slit shaped pupils over round ones in general. So we were just talking about vertical pupils for a load of the ground ambush predators. But slit pupils in general can be advantageous because they allow for much greater changes in the area of the pupil and thus greater variation in the light conditions they can adapt to. So you've got a human pupil. To constrict a round human pupil like ours, you need that ring shaped sphincter muscle that we talked about at length in the last episode. But to close a slit pupil, it uses two muscles that close the sides of the slit together. And as a result of these morphological differences, there is a different amount that you can increase or decrease the area of the pupil and the amount of light that it can pull in. So, to read from the paper quote, the vertical at pupils of the domestic cat and gecko undergo area changes of one hundred and thirty five and three hundredfold, respectively, whereas human circular pupil changes by about fifteenfold. Yeah, species that are active in night and day need to dilate sufficiently under dim conditions while constricting enough to prevent dazzle in daylight. So a slit pupil provides the required dynamic range. So this is why a slit pupil is good. It's great for high dynamic range for an eye that works great in both bright daylight and in pitch dark. And you know, I can't help but think with smaller predators as well. I mean, these are generally going to be creatures that are not only predator but prey as well. So it's not like they can just hold up, you know, all day. I mean, they may try to hold up all day, but they might need to play the survival game during daylight as well, assuming they're not actively hunting during the day as well of course, right right, So, yes, a slit pupil is great for being highly adaptable to whatever the light situation is, But the directional orientation of the slit depends more on your ecological niche like you were talking about earlier. So again, yeah, the grazing herbivores, like horses, they will have horizontal slits to help them keep a panoramic view of the environment and watch for movement or predators approaching. But another interesting finding of the authors here, these pupil orientations for herbivores only work if the animal keeps the pupil parallel to the horizon, and grazing herbivores actually spend much of their time with their heads bent down to the ground eating grass. So what gives there? Well, the researchers looked into this and they found that, in fact, when horses bind down to graze, they rotate their eyes within the sockets to keep the pupils parallel to the horizon. And Martin Banks in that NPR article he gives a quote pointing out that this is weird because the eyes have to rotate in opposite directions, you know, think about the eyes on opposite side. So yeah, and apparently they couldn't find any references to anybody ever writing about this before, which is funny given how much time people spend around horses. But yeah, so that's what horses do when they've been down to the grass. Their eyes swivel in the sockets to maintain the pupil slit as parallel to the horizon. Wow, this is another one of the I don't know, we've we've talked about this before, and you know, imagining alien life forms and so forth, but also getting into just ideas of consciousness, like how much of our our understanding of ourselves in the world seems to come down to how we view the world and how we focus attention um and yet to try and put yourself in the mindset of a mind that is that perceives the world in this manner that you know, that that has eyes that are always focused on the horizon in order to get this panoramic view of all the potential threats that could be interfered with they're feeding one lass. Funny note that was in that NPR coverage of this paper was about depictions of dinosaurs in Jurassic World and other movies. So you know, you've got this some kind of giga predator dinosaur. It's just like the ultimate what do they call it in Jurassic World. It was like the Killer Rex or so this is the this is the Hannibal electro one, Yeah, Kilamus maximus, yeah, something like that. Yeah. Well, they talk about the temptation to depict predators like this with vertical slits for eyes, because I think we correctly detect that as a predatory trait. You look at a crocodile's eyes, it's got these creepy vertical slits, and that makes sense because a crocodile is an ambush predator that operates low to the ground. But they say, actually this, you know, the Kilamus maximus dinosaur is an active predator and it's very tall, so it would probably have round pupils like ours. And the funny thing is, you can't even use the frog excuse, like oftentimes that is used to excuse sort of stuck in the mud depictions of dinosaurs in the Durassic Park Traffic Jurassic World movies. They'll say, well, you have to remember they also used frog DNA, So the fact that they don't have feathers that has to do with the frog DNA. But it was the frog DNA, then perhaps they would all have heart shaped pupils depending on the type of frogs that were used. Right, Yeah, And that brings us back to the next thing, which is, so we were talking about the orientations of slit shaped pupils versus round pupils in terrestrial vertebrates. But when you start looking at the eyes there are the pupils of animals that live in the water. You starts even weirder shapes in dolphins and cuttlefish and all kinds of things have these strangely shaped pupils. Yeah. The cuttlefish pupil especially is very fascinating to look at. Definitely look up a picture of it if you're not picturing it right now. It looks like this WAVYW. It looks kind of like, you know, the face on the Pringles can. Is that mister Pringles, Doctor Pringles, I can't remember, doctor Pringles. Man, which is that Governor Pringles? Governor Pringles, yes, Senator Pringles, Yes, we have Walter K. Pringles. He has a mustache and um under under certain light conditions, the cuttlefish eye looks like that mustache in my opinion. But the interesting thing is that, yes it has the cuttlefish ye has this signature W shape in bright light, but it's actually circular in low light. According to the W shaped pupil in cuttlefish by a math ger at All, published in Vision Research in twenty thirteen. The two main theories um were that the shape is either for camouflage, so it's just it has a weird pupil because it's doing all sorts of strange things with its chromatic force to you know, to change its its appearance and therefore it has you know, strange things going on as high as well, or that it has to do with distance calculations. It's coming down to some of the same factors that we just discussed in terms of vertical and horizontal pupils. But in this case, the researchers proposed that the w shaped pupil might aid in balancing out the vertically uneven light field of its natural habitat m Okay, So here's a quote from from that paper. Quote. While an animal's retina can deal with a wide range of light intensities in one scene, reducing this range would limit the need for rapid local adaptation during vertical gaze shifts. Since cuttlefish do not have an instant three sixty field of view, they must rely on gaze shifts to provide them with the complete view of the surrounding world. Okay, so they have to move their eyes to look around them, right, and you know, in this we have to think about light in the aquatic world, you know, where you know, the ever present darkness of the depths and then the periodic light field a realm of the upper depth. And if you're something like cuttlefish, you're having to navigate both. And it kind of comes down to some of the ideas we're discussing with with with load of the ground predators. You know, you have to sort of be adaptable to both realms, but in this case you need to be able to to simultaneously deal with the light in the darkness. By the way, coming out of the water for a second, the gecko pupil I was reading about essentially as a vertical pupil aiding in a nocturnal ambush predator's lifestyle. But it does look really cool and they are apparently really incredible hunting eyes according to some of the articles that I looked at. But then, oh, another aquatic eye of note is the dolphin pupil, and it's it's interesting that while it resembles a horseshoe or crescent, when it's fully dilated, it constricts down to two tiny openings that are sometimes referred to as a double bowl. Pupil um, and this apparently comes down to the fact that the eye the pupil shape who with dolphins has to do with dolphins or noted for having exceptional vision both in and out of the water. They know, they're they're they're they're able to to position their bodies so that they're gazing out of the water, and they have great vision in that circumstance as well. But I included a photograph here for you, Joe, and I encourage listeners to look this up as well. Um. The first picture shows the horseshoe pupil, and then the second picture shows the double pupil when everything's fully constricted. Yeah, it does look amazing though, if you do look up scientific diagrams of the eye. I think what these are explaining that's normally happening is like that the the sort of horseshoe or or U shaped pupil when it constricts, what it actually constricts down to is something that looks kind of like two earbuds connected by a wire, and the wire is just very narrow. Yes. Yes, now some of you might be wondering, Okay, you're talking about mythic figures with strange eyes, and now we've we've talked about a number of different real life organisms that have some sort of interesting eyes going on. Is it possible that that that the myth makers and the storytellers of old were inspired by eyes they saw in nature. And I didn't really find anybody talking about this, I mean outside of Yes, if you're watching some sort of modern show and reptile people show up and they have vertical slits and their eyeballs, yes, obviously somebody decided let's give them reptile eyes. Um. Though again, if they're reptile people, I mean, if they're like, I don't know, five six feet tall or something, they should probably have round eyes. What if they crawl around on their bellies all the time that's how they hunt. Oh oh, okay, then yeah, vertical slits, go for it. But I was thinking, Okay, the cuttlefish has this amazing looking eye. Any possibility there, well, I mean, the common or European cuttlefish can be found in Irish waters, and cuttlefish shells or cuttlefish bones were used as ornaments by the Celts, according to DJ Conway in the book Celtic Magic Ireland. However, it's famously light on reptile species, So I don't think geckos would have had an impact on any literary motifs. And and ultimately, I don't think anybody was pulling up any cuttlefish and checking out their their eyeballs either or you know, I've I found nothing to suggest that, but my mind went there, so I thought i'd mentioned it to everybody. You know, I think this show is a safe place to admit research dead ends. Sometimes we just got to do that. Yeah, unless there's a paper out there I'm missing, And if so, as always, if there's something we've missed, right in and let us know, we would love to be corrected. Well, should we tighten the sphincter, constrict the pupil on this one, that's right, book, what's what we should do. We should limit the light coming in at this point. But we'd love to hear from everyone out there. If there are particular mythic figures, literary figures, pop culture examples of of multi pupil, multi irist, multi lobed eyes, right in and let us know about them, Send some pictures if they exist. We would love to hear from you. Likewise, if there are other you know, we really only spend a little bit of time here with the animal world. There's so many fascinating animal eyes out there, so if there are examples that you're particularly fond of right in, let us know. And then, of course there are other areas of this that we've just touched on in these two episodes that we could easily come back and discuss more about, like oh, the evil Eye as we were discussing like that could be its own deep dive on the show, no doubt, all right. In the meantime, if you would like to check out other episodes of Stuff to Blow Your Mind, it publishes every Tuesday and Thursday, core episodes. In the Stuff to Blow Your Mind podcast feed, we have listener mail episodes on Monday, short form Artifact or Monster Fact episodes on Wednesday, and on Friday we do Weird House Cinema. That's our time to set aside most serious concerns and just talk about a strange motion picture. Huge thanks as always to our excellent audio producer Seth Nicholas Johnson. If you would like to get in touch with us with feedback on this episode or any other, to suggest a topic for the future, or just to say hello, you can email us at contact at Stuff to Blow Your Mind dot com. Stuff to Blow Your Mind is production of iHeartRadio. For more podcasts from my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you're listening to your favorite shows.

Hey, you welcome to Stuff to Blow your Mind. My name is Robert Lamb and I'm Joe McCormick. And it's Saturday, which means we're going on down into the old vault to pull out a classic episode of the show for you. This one is from last year. This one is from March thirty first, twenty twenty two, and it is the Three Pupil Die Part two. This is the follow up to the episode that aired last Saturday about about strange pupils and irises in myth, legend and reality. Welcome to Stuff to Blow Your Mind, a production of iHeartRadio. Hey, welcome to Stuff to Blow your Mind. My name is Robert Lamb and I'm Joe McCormick. In our last episode, we discussed a common but enthralling literary motif in Irish mythology, the triple and the sevenfold eye, three or seven pupils, three or seven irises found in the eyes of beautiful heroes, divine seers, destructive monsters. We also discussed the structure and functionality of the human eye and the rare instances in which we actually see double pupils in human eyes. In this episode, we're going to explore more curious eyes from the natural world, as well as more accounts of marvelous eyes from ancient history and literature. But first a pop culture update. At the end of last episode we were talking, I spoke briefly about some double eyes that I remembered from some movies, album covers, etc. Well, our good producer Seth provided us with two additional examples of double eyes and popular culture that we didn't think of last time. Number one, the double irises and pupils of Aminet in twenty seventeens. The Mummy. This is the Tom Cruise Mummy film. Oh boy, did not see it, but I think this is like the the titular Mummy, or at least one of them. I think she is the Mummy in this film. I'm okay, I haven't seen this one, not even on an airplane, but I'm not opposed to it. I mean, I've seen a lot of crummy mummy movies over the years, and usually there's something interesting in them. Yeah, at least sometimes you get an Arnold Foslou or something. Yeah. And then the second example Seth brings up is the album cover to Bubba by Haitian Canadian musician k Trenada featuring the artist with otherworldly blue eyes that have double pupils, double irises. I listened to a track from this album while we were working on notes. It was good. I haven't had a chance yet, but I do love the album cover. It's pretty great now. One of the sources that we mentioned in the last episode was the Evil Eye in early Irish literature and law. This was published in Celtica twenty four back in two thousand and three, and this was by Jacqueline Borsch and the author of Fergus Kelly is also cited on this paper because there's like a part one in a part two, but I believe we're we dealt with material from part one. Celtica, the journal this is in is a scholarly journal for Celtic studies out of the Dublin Institute for Advanced Studies. So most of this deals of course with Irish law, Irish traditions, Irish mythology, and despite the popularity of this motif of the multiple pupils, multiple irises within the Irish tradition, we also encounter discussions of this sort of thing in other traditions as well, and shares a few of these The first one comes to us from A Plenty of The Elder and the Natural History. Plenty discusses individuals in Africa said to possess quote, the power of fascination with the eyes and can even kill those on whom they fix their gaze for any length of time, more especially if their look denotes anger. Now that's you're pretty basic evil eye scenario right there. You encounter variations of this throughout the world, based on the fact that, yes, you can shoot somebody a really terrible look and you can almost feel it. Of course, going back into the ancient world, the belief was often that it was more than you know, giving somebody the stink eye produced more than just a bad feeling, that it could literally curse them or cause them magical harm. Yes. But the neat thing here where it ties into what we're talking about in these episodes is Plenty goes on to connect this to multiple pupils quote. A still more remarkable circumstance is the fact that these persons have two pupils in each eye. Apollo Nides says that there are certain females of this description in Scythia who are known as the Bitha and Philarchus states that a tribe of the theebe in Pontus, and many other persons as well, have a double pupil in one eye and in the other the figure of a horse. Double pupil in one eye, the other the figure of a horse. Now, with passages of this kind, we're often faced with the question is this based on some distorted or exaggerated retelling of something that somebody actually saw, or is it just pure creative imagination or you know, tall tales, And it's always interesting to wonder about the former, But ancient accounts like Plenties are clearly full of the ladder, especially when telling stories about peoples who live in far away parts of the globe. You know, this section that we're quoting from plenty is from I can't remember what it's called. There's like one of his books is all about the nations of the world, and it's just all these weird stories of like here's a people who live somewhere far away, and here's this strange thing they do or something that they wear that would be fascinating to my readers. Like there's one part where he talks about a tribe of people somewhere who do not have heads and instead have eyes in their breasts. So it need not be the case that Plenty is necessarily here repeating a misunderstood or exaggerated story about somebody who actually had something like polychoria or some other unusual condition of the pupils. But of course it is always possible. Yeah, it does make you wonder, you know, to what extent would there be, like, you know, some account of an individual with this rare condition, some memory of this rare condition, and then it gets folded into some of these traditions and beliefs at one point or another in their long lives. Yes, though of course it could again just be something somebody made up, like the people who don't have heads and have eyes in their breasts, right right, Like, we can dream up individuals with like four arms, and it's pretty interesting and we can draw all sorts of meaning from that, but it doesn't mean that people with four arms ever actually existed, you know, that there's any actual biological basis on which that was based. Though. I do think it's really interesting that he doesn't just say, Okay, they've got two pupils in each eye, but that they've got two pupils in one eye and in the other eye a horse. Yeah, And like the first place my mind went was, Okay, is it actually shaped like a horse a distortion that is roughly horse shaped? Or is it? Does it mean that this is like some sort of telephone game, you know, translation game version of a horizontal pupil like one finds in the eyeble horse. That's interesting, and that'll tie into a scientific paper we're going to talk about in a bit. I found an editor's footnote in the Bostock translation of Plenty, which notes, quote, some of the commentators have supposed that Plenty or Phi larcis from whom he borrows, because remember, this isn't an original observation of Plenties, He's like copying this from some other writing of this person named phi Larcus, but Philarcus from whom he borrows. Whether they were misled by the ambiguity of the Greek term eCos, which signifies either a horse or a tremulous motion of the eye. But even admitting this to be the case, the wonder is scarcely diminished, for we have the double pupil in one eye, while this supposed tremulous motion is confined to the other. So so if Fostuck is correct there, it's that this word had had a double meaning, and one of them was like a you know, a quivering of the eye. I guess I would assume that's like when somebody's eye is twitching. But yeah, you wonder, well, why why is it just that the other eye is twitching when when the first eye has two pupils in it, that's also strange, maybe not as strange as a horse. I was. I was looking for answers on this as well, and I ran across a nineteen eighteen paper titled of the Papula duplex and Other Tokens of an Evil Eye in the Light of Ophthalmology by Walton Brooks McDaniel, And according to Brooks, here one doctor Kirby Flower Smith, a professor of Latin and at John Hopkins University, who had I looked VI had died in nineteen eighteen, interpreted the Plenty passage as having some sort of connection to the idea that the affliction of the eye was caused by quote a horse shaped demon, horsehead masked demon. Yeah. McDaniel also begins to discuss the the idea that if you know, if you look into another eye, you know certainly with the right lighting and so forth, you look into another person's eye, you can see your own reflection. And so McDaniel mentions that in some traditions that individual you see in the eye is interpreted, you know, not as yourself, but as the signifier of the soul, and that there are even some traditions where if the individual looks in some way inverted, that is because of witchcraft. And in this this this is one of those weird situations where then McDaniel mentioned something else that leads me back to a source that I'm very familiar with, and yet I totally blinked on this particular detail, or or maybe I'd never read this one particular tale, but he ends up referring back to Strange Tales from a Chinese Studio by Poosh song Ling. That's a show, favorite, folks. Should we do we have a Strange Sales from a Chinese studio? Buzzer? I doubt we do, but at any rate, it's it's it's a book that I really enjoy. This is a Ching Dynasty collection of stories that Pous song Ling collected and retells, and you know there's a lot that's that's lost in translation. Out of Mandarin. But but there's still remarkable fun, sometimes funny, and sometimes it's just very strange. Uh. Sometimes it's it's you know, it's all about what they would have meant to the people who read them. But they're a lot of fun. There's a Penguin edition of it translation that I've I read again and again over the years, and yet I completely blanked on this one story. It's called Talking Pupils. I think maybe the reason that I haven't read this one recently is sometimes i'll read these to my son and I'll sort of glance at them, and if it looks like there's something that might be scandalous in it, or you know, a little dirty, then I'll skip over the tale. There aren't many, but occasionally there's one like that. So anyway, this story Talking Pupils concerns the tale of one Feng Dong quote, a gentleman of considerable accomplishments while at the same time having a reputation as an unprincipled libertine. Oh yeah, so clearly that's why I might have skipped over this in recent years. Anyway, So Fang was this is how the story goes. Fang is strolling the countryside and he happens on a fine carriage on the road. One of the female attendants to the carriage is quite fetching, so he moves in for a closer look. But as he does so, he's able to peek between the curtains of the carriage itself and he sees a beautiful young woman within, and he's captivated. The female attendant is having none of this, though, and she verbally shames him, you know, calls him a you know, a weirdo and a snooper. And not only does she verbally shame him, she reaches down grabs him dust out of the road and throws it in Fang's face. Oh, dirty fighter. Yeah, but you know, he had it coming. He was up to no good and he gets punished for it. So he's he's initially he's trying to get the dust out of his eyes. The carriage carries on. When he is able to see again, you know, struggling, the carriage is completely done. It's you know, it's vanished around the bend or whatever. So he has heads on home, but his eyes continue to bother him, so he seeks some help. A friend looks into his eyes, and this friend says, yeah, there's a visible film over each of your eyeballs, and meanwhile, tears won't stop flowing. In time, the film thickens and a spiral what is described as a spiral shaped protuberance begins growing from his right eye, resisting all manner of treatment. Eventually he's completely blind, and you know he's he's distraught over this. But he hears about a Buddhist sutra known as the Sutra of Light, and it's said to be able to heal eye ailments or ailments of this sort. So he gets a side friend to read it to him, and he learns it by heart, and he recites it over and over again, and after a while it gives him solace. You know, he feels a little better. His side is not back. But then one day he begins to hear voices, two voices, one from each of his eyeballs. Oh, I love this. The eyeballs are talking, both of them. Well, as it turns out, not the eyeballs but things within the eyeballs. There's one voice within each eyeball, and they start talking to each other, and they're talking about how dark it is in their homes and how they'd really like to just get outside and go for a stroll. And then so pusong Ling says quote, then he felt a slight irritation in both nostrils, as if two little creatures were wriggling down his nose. After a while, he felt the creatures return and make their way back up his nostrils and into the eye sockets. Again, this is anatomically correct because, as we know, the tear ducks that drain tears away from the eyes drain into the nasal cavity, which is why your nose when you cry. Oh very good. So what does Feing do at this point, Well, he gets his wife to take him to the old garden, and he has her observe him in the garden to see if anything like this happens again. Maybe the garden will coax whatever it is out of his eyeballs. And this is what happens. Quote. It was not long before she saw two little mannekins, neither of them any larger than a bean, emerged from his nose and fly buzzing out of the door. They were soon well out of sight, but we're back again in next to no time, flying together up onto his face and in at his nostrils. Like a pair of homing bees or ants. So is he getting relief when they fly away? I don't think so. No. Oh, it's just it happens, and he doesn't know what this is about, so it keeps happening. It happens again each day for three days, and finally one of the voices complains that the tunnel that they're using to get out of the eyeball is a bit round about and there's got to be a better way. It's time that they make some sort of proper doorway. So I'm going to read the rest of this year that it really gets to the juicy part. I'm just I'm filled with dread. It's not a good idea when the tenants in your eyeballs decided to start renovating on their own. Yeah, so that is how it goes. The wall on my side is very thick, replied the right eye. It won't be easy. I'll try to make an opening on my side, said the left eye. Then we can share my door. Presently, Fang thought he felt a scratching and a splitting in his left eye socket, and an instant later he could see he could see everything around him with absolute clarity. Beside himself with a delight. He promptly informed his wife, who inspected his eyes afresh and found that in the left eye a minute aperture had appeared in the film, a hole no larger than a cracked peppercorn, through which gleamed the black globe of a pupil. By the next morning, the film in the left eye had disappeared altogether. But the strangest thing of all was that, on careful inspection, there were now two pupils visible in that eye, and the right eye was still obscured by its spiral shaped growth. Apparently, both of the two eye mannequins his talking pupils had now taken up residence in the left eye. So although Fang was still blind in one eye, he could see better with his one good eye than he had ever done with two. From that day fourth, he was a great deal more circumspect in his behavior and acquired unimpeccable reputation in the district. Okay, so no more creeping on ladies and carriages. Right, he learned his lesson, He was punished for his creepy behavior, and now he's back and ready to be a good citizen with one eye that can see better than two, right, because two pupils. Now that this again is from the Penguin Classics edition. It's a John Minford translation, and this was super interesting as well. Minford shares this in the notes pupils. The traditional Chinese expression for pupil, tong wren, means literally man in the pupil from the reflection of oneself that one sees in the eye of another. Wow. Yeah, that was that was really that. I was really impressed by that. And I was talking to my wife about it because I was looking around a little bit after this and I saw an article about photography and about being able to zoom in on the eye of an individual in a modern photograph and see the reflection potentially of the photographer and oh yeah, because of the high resolution, I guess, yeah, yeah. And I was asking my wife about this, and she pointed out that one thing that photographers can do is you can pull up, say a headshot that another photographer is done. You can zoom in on the eye and you can see what their lighting setup is. So I was impressed by that as well. Oh, I'm impressed. That's a real James Bond level trick. I do not know what to make of the spiral growth though I looked around briefly on that and I was not able to find any answers that seemed fencing. I have no expertise on spiral growths from eyes. All right, I want to go back to Borsch for just a minute here, because she has a couple of other examples that she brings up. One apparently tolomeos Chinos. This would have been a figure from the late first early second century. CE once described a beautiful woman as being quote with a double pupil. Okay, And in the last episode we talked about some legends in which a character with multiple pupils this was assumed to be a marker of beauty. Right, So this is interesting because it seems to suggest that this is not just isolated within Irish literary traditions, that perhaps somewhere else in the world there was this idea that double pupil equals beauty. And I mean, who am I to say it's not beautiful? You know, it's not like you look at images of actual double pupil situations and you're not hortified by them or anything, no more so than if you look at a super close up of any human Eyeball also mentions that ovid portrays a woman with double pupils having the evil eye at one point, so tying back into the evil eye tradition. But anyway, Bors concludes quote to conclude this section, Both angry eyes and eyes with multiple pupils have been connected with the concept of the evil eye, there is no strict identity between the phenomena. Multiple pupils can also be a sign of beauty, sharp sight, and clairvoyance. Okay, so we're not really converging on a unity of theme here. If you're in an Irish legend or myth and you have a character with multiple pupils in one eye, it seems they could either be somebody who has a lot of insight, somebody who can see very far away, somebody who can see the future, somebody who is beautiful, or somebody who is monstrous or can do curses. And there is this idea too that it's it's part of like the supernatural body, that when you have some sort of a demigod figure, it's the human body. It's almost like it mutates with the divinity within it like the human The normal human body cannot contain this level of power and therefore, extra things are going to happen, you know, extra pupils, extra fingers, that sort of thing. And this ties directly into another example I found, and this one comes from Chinese traditions as well. This is from the nineteen sixty seven book Chinese Civilization and Bureaucracy, Variations on a Theme by Hungarian born French senologist Eten Balahs working with working from another source as well, Essay on the Extinction of the Soul by Faun Shin, a Chinese philosopher and writer who lived four fifty through five fifteen CE. The subject here, as far as eyes are concerned, is one of the legendary sage rulers of antiquity in China. This would concern a time during the third millennium BC. And so the structure of this paper seems to concern like questions and answers. And so first we have this question. The body of the sage is similar to the body of ordinary men. Yet there is a difference by which the sage is distinguished from ordinary men. From this, it can be inferred that body and soul are different. Answer not at all. Pure gold glitters and unwashed gold does not pure gold. That glitters surely cannot be made of the same unglittering material as that of unwashed gold. How much less, then, can the soul of a sage be lodged in a vessel such as the ordinary man. Nor would it be possible for the soul of an ordinary man to dwell in the body of a sage. Therefore, fengg Sum is depicted as having eyebrows of eight colors, and zong Huo's eyes with double pupils, signon as having the face of a dragon, and tie how the mouth of a horse, all of which are outward bodily signs of their exceptional nature. All the seven openings were found in the heart of pie Con. The gall bladder of poe U was as big as a fist, which shows that their inner organs were unusual. Thus we know that certain parts of the bodies of sages are quite out of the ordinary, and that sages are not only superior to ordinary human beings, but also surpass all other creatures in bodily form. That's just science. I love this passage so much. I mean, I love that it's basically an autopsy of supernatural sages, of determining how they're they're but like you can imagine this scene in a movie. Oh yeah, this is beautiful, the gall bladder as big as a fist, showing that the inner organs are unusual. This is great, and you know, and this is this is not a totally unique view of the body of the holy person or the saint. I mean, you know, there are tons of traditions all around the world, including like the idea that certain types of saints or holy people, because of their spiritual nature, their bodies would be found to be say, incorruptible, like they don't rot the way most spoties do. Yeah. So, but Balais adds some notes on this and points out that the legends about the eyebrows of eight colors and the eyes with double pupils He's come from Mahan times and are contained in a number of different works. So yet another example of of of exceptional eyes in the bodies of exceptional you know, heroic mythic individuals. Now, in the last episode, we talked a bit about human eye anatomy and some medical literature on polychoria, or the condition of having multiple pupils within the same eye. But I thought in this episode it would be a good idea to turn to pupils of the animal kingdom more broadly, because there's a lot we can learn about the function of pupils by looking at the pupils of non human animals. That's right. I mean, just consider the vast diversity we have in the animal world, and I mean even just dealing with the vertebrate world, it's pretty remarkable, not even getting into compound eyes of flies and so forth. But consider humans. We have round pupils. House cats have vertical slits, Tigers have round pupils, Goats and horses horizontal. Dolphins have crescents, cuttlefish have w shaped pupils, some frogs have heart shaped pupils, and geckos have these sort of what looked like pinholes arranged in a vertical line. I always love a good crocodile pupil. Oh, yes, tend to be rather vertical. Yeah, it's and it's also it's a window into the crocodile soul. But seeing all this different diversity does raise some questions because you think, okay, well, you know, the bodies of animals are shaped by their environment. You know, that's what evolution does. It tends to give you the equipment that best helps you do whatever you need to do within your ecological niche. So why do different animals have different pupils? How to differently shaped or sized pupils help an animal adapt to how it's supposed to survive in the world. Yeah. According to Martin Banks, the vision scientist at the University of California that cited in a twenty fifteen NPR story, eye shapes of the animal world hint at differences in our lifestyles. Land animals of sufficient height tend to have round pupils. Thus you have big cats that have round pupils. Meanwhile your small house cat cat has vertical pupils. Verticals are more the domain, it seems, of smaller ambush predators, giving them an excellent ability at judging distances, of which, of course, is going to be super important when you're pouncing out of the shadows and trying to capture like a small rodent or your owner's foot. Horizontal pupils, on the other hand, are widely under stood as a means of keeping a wider swath of the surroundings in sight while you're grazing, and an expanded field of view. So you can think of this as the panoramic potential prey view of the world, right, So I was actually looking into this. The paper that Banks is connected with is one that was published in twenty fifteen in Science Advances, and it's by Martin Banks, William Sprague, urg And Schmall, Jared Parnell, and Gordon Love and it's called why do animal eyes have pupils of different shapes? And what you say is correct. They looked into this question and they found, yeah, there are some very strong correlations between how an animal survives and what shape its pupils are, at least among land vertebrates. And so you tend to have, like you're saying, horizontal pupils if you are a herbivore, whereas ambush predators predators that sit around and wait for their prey, they tend to have vertical slits, especially if they're active of it in both daytime and nighttime. And meanwhile, active predators, predators that hunt and chase down their prey instead of sitting and waiting, they are more likely to have round or circular pupils. And this is not a coincidence. The author has found some pretty good reasons why the pupils would be allotted in these ways. So first of all, you would have to wonder how does it work this lay way, Like why would vertical pupils be useful if you are an ambush predator, especially as you were saying, an ambush predator of low height, because height matters. So if you're an active predator chasing down prey, you likely have round pupils, or if you're an ambush predator that is taller, you probably have round pupils vertical slits of what you're really likely to see if you're a sit and wait, jump out predator and you're close to the ground. So I want to read a section from this paper, and there's a couple bits of terminology. To understand the quote I'm about to read, it'll use the term stereopsis. Stereopsis is depth perception that is created by comparing the difference between what is seen by two different eyes focusing on the same image. So we use stereopsis to judge depth when we look at an image by the brain says, okay, we've got two different data points of the eyes, and it compares them together and gives you this three D image with depth. But then the other term is defocus blur, This refers to the blurriness and objects that are either close or farther away, closer or farther away than you're focusing. So the authors of this paper right quote, vertically elongated pupils create astigmatic depth of field, such that images of vertical contours nearer or farther than the distance to which the eyes focused are sharp, whereas images of horizontal contours at different distances are blurred. This is advantageous for ambush predators to use stereopsis to estimate distance says of vertical contours, and defocus blur to estimate distances of horizontal contours. So rob if you'll scroll down a bit in the notes here, I attached a picture that they put in the paper to simulate what it looks like to a creature that's gazing out at the world with vertical slit pupils, and it's a very interesting So they've got a picture with a toy bird sitting on the ground, presumably a foot or two ahead of where the camera is positioned, and then there's some objects in the foreground in in the background, and what you'll notice about this picture is that the bird is very much in tight focus, but then for objects around it there is there is an uneven amount of blurriness in the vertical and horizontal directions. So like there's a plant stalk that's poking right up in the foreground and its shape is fairly in focus when you're looking at it height wise, you know, like the stalk is sort of sort of blurry but sort of in focus. But things in the horizontal direction, like the top of the pot that the plant is sitting in, are very blurry. And apparently it allows these animals to use both the stereopsis, the comparing the two different eyes if the animal has two front facing eyes, and the way that images are blurred when they're at different levels of distance from the object in focus to judge depth very well. So you can really nail that bird when you jump. So sorry if that was a little complicated, but it took me while to understand. I was trying to figure out, like why the vertical slits actually help with the hunting. But yeah, I think it makes sense if you especially if you look up the picture, you can say like, oh, okay, this is yeah, this is for an animal that is precisely trying to target a jump at something. Yeah, and you've got one shot pulling it off. But there was another thing noted in this pain that I thought was really interesting, and this was actually just in the introduction, but it was about advantages of slit shaped pupils over round ones in general. So we were just talking about vertical pupils for a load of the ground ambush predators. But slit pupils in general can be advantageous because they allow for much greater changes in the area of the pupil and thus greater variation in the light conditions they can adapt to. So you've got a human pupil. To constrict a round human pupil like ours, you need that ring shaped sphincter muscle that we talked about at length in the last episode. But to close a slit pupil, it uses two muscles that close the sides of the slit together. And as a result of these morphological differences, there is a different amount that you can increase or decrease the area of the pupil and the amount of light that it can pull in. So, to read from the paper quote, the vertical at pupils of the domestic cat and gecko undergo area changes of one hundred and thirty five and three hundredfold, respectively, whereas human circular pupil changes by about fifteenfold. Yeah, species that are active in night and day need to dilate sufficiently under dim conditions while constricting enough to prevent dazzle in daylight. So a slit pupil provides the required dynamic range. So this is why a slit pupil is good. It's great for high dynamic range for an eye that works great in both bright daylight and in pitch dark. And you know, I can't help but think with smaller predators as well. I mean, these are generally going to be creatures that are not only predator but prey as well. So it's not like they can just hold up, you know, all day. I mean, they may try to hold up all day, but they might need to play the survival game during daylight as well, assuming they're not actively hunting during the day as well of course, right right, So, yes, a slit pupil is great for being highly adaptable to whatever the light situation is, But the directional orientation of the slit depends more on your ecological niche like you were talking about earlier. So again, yeah, the grazing herbivores, like horses, they will have horizontal slits to help them keep a panoramic view of the environment and watch for movement or predators approaching. But another interesting finding of the authors here, these pupil orientations for herbivores only work if the animal keeps the pupil parallel to the horizon, and grazing herbivores actually spend much of their time with their heads bent down to the ground eating grass. So what gives there? Well, the researchers looked into this and they found that, in fact, when horses bind down to graze, they rotate their eyes within the sockets to keep the pupils parallel to the horizon. And Martin Banks in that NPR article he gives a quote pointing out that this is weird because the eyes have to rotate in opposite directions, you know, think about the eyes on opposite side. So yeah, and apparently they couldn't find any references to anybody ever writing about this before, which is funny given how much time people spend around horses. But yeah, so that's what horses do when they've been down to the grass. Their eyes swivel in the sockets to maintain the pupil slit as parallel to the horizon. Wow, this is another one of the I don't know, we've we've talked about this before, and you know, imagining alien life forms and so forth, but also getting into just ideas of consciousness, like how much of our our understanding of ourselves in the world seems to come down to how we view the world and how we focus attention um and yet to try and put yourself in the mindset of a mind that is that perceives the world in this manner that you know, that that has eyes that are always focused on the horizon in order to get this panoramic view of all the potential threats that could be interfered with they're feeding one lass. Funny note that was in that NPR coverage of this paper was about depictions of dinosaurs in Jurassic World and other movies. So you know, you've got this some kind of giga predator dinosaur. It's just like the ultimate what do they call it in Jurassic World. It was like the Killer Rex or so this is the this is the Hannibal electro one, Yeah, Kilamus maximus, yeah, something like that. Yeah. Well, they talk about the temptation to depict predators like this with vertical slits for eyes, because I think we correctly detect that as a predatory trait. You look at a crocodile's eyes, it's got these creepy vertical slits, and that makes sense because a crocodile is an ambush predator that operates low to the ground. But they say, actually this, you know, the Kilamus maximus dinosaur is an active predator and it's very tall, so it would probably have round pupils like ours. And the funny thing is, you can't even use the frog excuse, like oftentimes that is used to excuse sort of stuck in the mud depictions of dinosaurs in the Durassic Park Traffic Jurassic World movies. They'll say, well, you have to remember they also used frog DNA, So the fact that they don't have feathers that has to do with the frog DNA. But it was the frog DNA, then perhaps they would all have heart shaped pupils depending on the type of frogs that were used. Right, Yeah, And that brings us back to the next thing, which is, so we were talking about the orientations of slit shaped pupils versus round pupils in terrestrial vertebrates. But when you start looking at the eyes there are the pupils of animals that live in the water. You starts even weirder shapes in dolphins and cuttlefish and all kinds of things have these strangely shaped pupils. Yeah. The cuttlefish pupil especially is very fascinating to look at. Definitely look up a picture of it if you're not picturing it right now. It looks like this WAVYW. It looks kind of like, you know, the face on the Pringles can. Is that mister Pringles, Doctor Pringles, I can't remember, doctor Pringles. Man, which is that Governor Pringles? Governor Pringles, yes, Senator Pringles, Yes, we have Walter K. Pringles. He has a mustache and um under under certain light conditions, the cuttlefish eye looks like that mustache in my opinion. But the interesting thing is that, yes it has the cuttlefish ye has this signature W shape in bright light, but it's actually circular in low light. According to the W shaped pupil in cuttlefish by a math ger at All, published in Vision Research in twenty thirteen. The two main theories um were that the shape is either for camouflage, so it's just it has a weird pupil because it's doing all sorts of strange things with its chromatic force to you know, to change its its appearance and therefore it has you know, strange things going on as high as well, or that it has to do with distance calculations. It's coming down to some of the same factors that we just discussed in terms of vertical and horizontal pupils. But in this case, the researchers proposed that the w shaped pupil might aid in balancing out the vertically uneven light field of its natural habitat m Okay, So here's a quote from from that paper. Quote. While an animal's retina can deal with a wide range of light intensities in one scene, reducing this range would limit the need for rapid local adaptation during vertical gaze shifts. Since cuttlefish do not have an instant three sixty field of view, they must rely on gaze shifts to provide them with the complete view of the surrounding world. Okay, so they have to move their eyes to look around them, right, and you know, in this we have to think about light in the aquatic world, you know, where you know, the ever present darkness of the depths and then the periodic light field a realm of the upper depth. And if you're something like cuttlefish, you're having to navigate both. And it kind of comes down to some of the ideas we're discussing with with with load of the ground predators. You know, you have to sort of be adaptable to both realms, but in this case you need to be able to to simultaneously deal with the light in the darkness. By the way, coming out of the water for a second, the gecko pupil I was reading about essentially as a vertical pupil aiding in a nocturnal ambush predator's lifestyle. But it does look really cool and they are apparently really incredible hunting eyes according to some of the articles that I looked at. But then, oh, another aquatic eye of note is the dolphin pupil, and it's it's interesting that while it resembles a horseshoe or crescent, when it's fully dilated, it constricts down to two tiny openings that are sometimes referred to as a double bowl. Pupil um, and this apparently comes down to the fact that the eye the pupil shape who with dolphins has to do with dolphins or noted for having exceptional vision both in and out of the water. They know, they're they're they're they're able to to position their bodies so that they're gazing out of the water, and they have great vision in that circumstance as well. But I included a photograph here for you, Joe, and I encourage listeners to look this up as well. Um. The first picture shows the horseshoe pupil, and then the second picture shows the double pupil when everything's fully constricted. Yeah, it does look amazing though, if you do look up scientific diagrams of the eye. I think what these are explaining that's normally happening is like that the the sort of horseshoe or or U shaped pupil when it constricts, what it actually constricts down to is something that looks kind of like two earbuds connected by a wire, and the wire is just very narrow. Yes. Yes, now some of you might be wondering, Okay, you're talking about mythic figures with strange eyes, and now we've we've talked about a number of different real life organisms that have some sort of interesting eyes going on. Is it possible that that that the myth makers and the storytellers of old were inspired by eyes they saw in nature. And I didn't really find anybody talking about this, I mean outside of Yes, if you're watching some sort of modern show and reptile people show up and they have vertical slits and their eyeballs, yes, obviously somebody decided let's give them reptile eyes. Um. Though again, if they're reptile people, I mean, if they're like, I don't know, five six feet tall or something, they should probably have round eyes. What if they crawl around on their bellies all the time that's how they hunt. Oh oh, okay, then yeah, vertical slits, go for it. But I was thinking, Okay, the cuttlefish has this amazing looking eye. Any possibility there, well, I mean, the common or European cuttlefish can be found in Irish waters, and cuttlefish shells or cuttlefish bones were used as ornaments by the Celts, according to DJ Conway in the book Celtic Magic Ireland. However, it's famously light on reptile species, So I don't think geckos would have had an impact on any literary motifs. And and ultimately, I don't think anybody was pulling up any cuttlefish and checking out their their eyeballs either or you know, I've I found nothing to suggest that, but my mind went there, so I thought i'd mentioned it to everybody. You know, I think this show is a safe place to admit research dead ends. Sometimes we just got to do that. Yeah, unless there's a paper out there I'm missing, And if so, as always, if there's something we've missed, right in and let us know, we would love to be corrected. Well, should we tighten the sphincter, constrict the pupil on this one, that's right, book, what's what we should do. We should limit the light coming in at this point. But we'd love to hear from everyone out there. If there are particular mythic figures, literary figures, pop culture examples of of multi pupil, multi irist, multi lobed eyes, right in and let us know about them, Send some pictures if they exist. We would love to hear from you. Likewise, if there are other you know, we really only spend a little bit of time here with the animal world. There's so many fascinating animal eyes out there, so if there are examples that you're particularly fond of right in, let us know. And then, of course there are other areas of this that we've just touched on in these two episodes that we could easily come back and discuss more about, like oh, the evil Eye as we were discussing like that could be its own deep dive on the show, no doubt, all right. In the meantime, if you would like to check out other episodes of Stuff to Blow Your Mind, it publishes every Tuesday and Thursday, core episodes. In the Stuff to Blow Your Mind podcast feed, we have listener mail episodes on Monday, short form Artifact or Monster Fact episodes on Wednesday, and on Friday we do Weird House Cinema. That's our time to set aside most serious concerns and just talk about a strange motion picture. Huge thanks as always to our excellent audio producer Seth Nicholas Johnson. If you would like to get in touch with us with feedback on this episode or any other, to suggest a topic for the future, or just to say hello, you can email us at contact at Stuff to Blow Your Mind dot com. 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