1 00:00:06,240 --> 00:00:08,320 Speaker 1: Hey, you welcome to Stuff to Blow Your Mind. My 2 00:00:08,400 --> 00:00:09,240 Speaker 1: name is Robert. 3 00:00:09,080 --> 00:00:12,840 Speaker 2: Lamb and I'm Joe McCormick, and today we're bringing you 4 00:00:12,880 --> 00:00:16,439 Speaker 2: an episode from the vault. This one, originally published on 5 00:00:16,520 --> 00:00:19,840 Speaker 2: June twenty eighth, twenty twenty two, is called The Lesser 6 00:00:19,880 --> 00:00:23,119 Speaker 2: of Two Crab Claws, Part one, So part one in 7 00:00:23,120 --> 00:00:25,360 Speaker 2: a series I think, not just about crab clause, but 8 00:00:25,400 --> 00:00:29,520 Speaker 2: we were focusing generally on asymmetry in the natural world. 9 00:00:29,920 --> 00:00:31,440 Speaker 1: That's right. But if you got to pick someone to 10 00:00:31,480 --> 00:00:35,560 Speaker 1: be the spokes organism or organisms for this, it's clearly 11 00:00:35,640 --> 00:00:38,519 Speaker 1: it's the crabs, good old fiddlers, right, Yeah. 12 00:00:41,840 --> 00:00:45,599 Speaker 3: Welcome to Stuff to Blow Your Mind, a production of iHeartRadio. 13 00:00:51,680 --> 00:00:54,200 Speaker 1: Hey, welcome to Stuff to Blow your Mind. My name 14 00:00:54,240 --> 00:00:55,320 Speaker 1: is Robert Lamb. 15 00:00:55,200 --> 00:00:58,800 Speaker 4: And I'm Joe McCormick. And for the next few episodes, 16 00:00:58,840 --> 00:01:02,720 Speaker 4: we're going to be doing a series on a symmetry. 17 00:01:02,760 --> 00:01:05,680 Speaker 4: And to introduce this series, I wanted to talk a 18 00:01:05,760 --> 00:01:09,480 Speaker 4: little bit about a favorite animal of ours, the narwal. 19 00:01:09,440 --> 00:01:12,920 Speaker 1: Yes, what is it? The corpse whale of the ocean, 20 00:01:12,959 --> 00:01:14,080 Speaker 1: the unicorn of the sea. 21 00:01:14,480 --> 00:01:17,600 Speaker 4: Right, yeah, so corpse whale, that's literally what its name means, 22 00:01:18,040 --> 00:01:22,280 Speaker 4: whale of course wall, but gnar meaning corpse, So yeah, 23 00:01:22,360 --> 00:01:24,840 Speaker 4: it's like a dead body whale, having to do with 24 00:01:24,920 --> 00:01:27,960 Speaker 4: its gray and modeled appearance as it sort of floats 25 00:01:28,000 --> 00:01:30,119 Speaker 4: around near the top of the water. But the more 26 00:01:30,160 --> 00:01:33,160 Speaker 4: famous feature of this whale, apart from looking like a corpse, 27 00:01:33,680 --> 00:01:37,839 Speaker 4: is its horn or tusk or we can dispute what's 28 00:01:37,880 --> 00:01:40,760 Speaker 4: the best word to use for it here, but yeah, 29 00:01:40,760 --> 00:01:43,279 Speaker 4: as you say, it is the unicorn of the Polar seas. 30 00:01:43,720 --> 00:01:47,360 Speaker 4: So the nar wall is a medium sized Arctic marine 31 00:01:47,400 --> 00:01:51,240 Speaker 4: mammal in the suborder of toothed whales or Odonto seti, 32 00:01:51,760 --> 00:01:55,880 Speaker 4: and it is immediately recognizable because most males of the 33 00:01:55,960 --> 00:01:59,920 Speaker 4: narwals and occasionally some females as well, possess a giant 34 00:02:00,200 --> 00:02:04,160 Speaker 4: spike or tusk growing straight out of their faces, and 35 00:02:04,360 --> 00:02:08,080 Speaker 4: this tusk can grow absurdly long, up to about three 36 00:02:08,160 --> 00:02:12,799 Speaker 4: meters or ten feet, and the orientation of this tusk 37 00:02:12,960 --> 00:02:15,880 Speaker 4: looks very unusual compared to most other mammals. So you 38 00:02:15,880 --> 00:02:19,200 Speaker 4: think about other mammals with horns or tusks, you might 39 00:02:19,240 --> 00:02:21,880 Speaker 4: think about bovines, in which the horns rise up off 40 00:02:21,880 --> 00:02:23,959 Speaker 4: the top of the head, or you might think about 41 00:02:23,960 --> 00:02:26,519 Speaker 4: the rhinoceros, where it points up from the end to 42 00:02:26,560 --> 00:02:29,480 Speaker 4: the snout, so kind of, you know, up from the ground, 43 00:02:30,040 --> 00:02:32,240 Speaker 4: or you might think about the tusks of a bore 44 00:02:32,400 --> 00:02:34,520 Speaker 4: or an elephant kind of coming out of the mouth 45 00:02:34,520 --> 00:02:38,440 Speaker 4: at an angle. But no, in the in the narwall, 46 00:02:38,600 --> 00:02:41,359 Speaker 4: you have a whales body, which again is a sort 47 00:02:41,360 --> 00:02:44,000 Speaker 4: of modeled gray tube that can grow about four to 48 00:02:44,080 --> 00:02:47,600 Speaker 4: five meters long in adulthood, and then the tusk just 49 00:02:48,240 --> 00:02:51,960 Speaker 4: juts straight out of the face, adding another three meters 50 00:02:52,080 --> 00:02:54,240 Speaker 4: or so or up to another three meters or so 51 00:02:54,360 --> 00:02:57,720 Speaker 4: in length. So when the tusk is present, the animal 52 00:02:57,760 --> 00:03:01,160 Speaker 4: is sort of shaped like a dart or like a spear. Now, 53 00:03:01,200 --> 00:03:03,400 Speaker 4: when we've talked about nar wals before, I think, especially 54 00:03:03,440 --> 00:03:07,079 Speaker 4: in our episodes on the unicorn legend, we talked a 55 00:03:07,120 --> 00:03:11,800 Speaker 4: lot about the theories behind the origin and the purpose 56 00:03:12,360 --> 00:03:14,920 Speaker 4: of the tusk. We're not going to completely rehash that 57 00:03:15,040 --> 00:03:18,200 Speaker 4: discussion here, though, I did want to note a development 58 00:03:18,720 --> 00:03:21,600 Speaker 4: which was in a more recent paper I came across 59 00:03:21,639 --> 00:03:24,760 Speaker 4: addressing the biological function of the tusk. So a long 60 00:03:24,880 --> 00:03:28,440 Speaker 4: running question for marine biologists who study the narwal is 61 00:03:29,000 --> 00:03:33,360 Speaker 4: why this giant tusk it looks very unwieldy, What is 62 00:03:33,400 --> 00:03:37,160 Speaker 4: it for what is the evolutionary justification. And this can 63 00:03:37,200 --> 00:03:40,040 Speaker 4: be difficult to study because it is not a trivial 64 00:03:40,160 --> 00:03:44,080 Speaker 4: task to go out and just observe narwals in the wild. 65 00:03:44,400 --> 00:03:47,440 Speaker 4: Not only do they live underwater, but they live under 66 00:03:47,480 --> 00:03:50,600 Speaker 4: the Arctic ice. So they remain veiled in a great 67 00:03:50,640 --> 00:03:54,320 Speaker 4: deal of mystery. But we're not without some clues. And 68 00:03:54,400 --> 00:03:56,440 Speaker 4: I guess the place to start is that the tusk 69 00:03:56,560 --> 00:03:59,880 Speaker 4: looks so threatening to the naive human brain that we 70 00:04:00,120 --> 00:04:02,560 Speaker 4: immediately want to say it is a weapon, right, you know, 71 00:04:02,600 --> 00:04:05,240 Speaker 4: it is a spear, It is a dart. That's what 72 00:04:05,280 --> 00:04:07,880 Speaker 4: I without even thinking about it, compared the animal too. 73 00:04:08,320 --> 00:04:10,480 Speaker 1: Right, right, you think of it being some sort of 74 00:04:10,520 --> 00:04:14,400 Speaker 1: a javelin or spear, a harpoon on the front of 75 00:04:14,440 --> 00:04:17,839 Speaker 1: this whale that it's using to to skewer things, or 76 00:04:17,880 --> 00:04:20,920 Speaker 1: that it's using this to sort of fence with other whales. 77 00:04:21,240 --> 00:04:23,039 Speaker 4: Yeah, so you think it must be for you know, 78 00:04:23,120 --> 00:04:26,800 Speaker 4: stabbing sharks or skewering fish prey or something. Though it's 79 00:04:26,839 --> 00:04:29,960 Speaker 4: funny that people think, oh, yeah, it's for skewering fish 80 00:04:30,000 --> 00:04:32,640 Speaker 4: that they're going to eat. But if that were true, 81 00:04:32,800 --> 00:04:34,840 Speaker 4: wouldn't that be a little awkward? Like how would it 82 00:04:34,880 --> 00:04:38,359 Speaker 4: get the fish to its mouth after that? Yeah, like 83 00:04:38,440 --> 00:04:41,760 Speaker 4: you would think normally, you don't need a stab and 84 00:04:41,920 --> 00:04:44,240 Speaker 4: then eat. If you're a whale, you just eat, You 85 00:04:44,360 --> 00:04:47,120 Speaker 4: just bite and then swallow them. Anyway, there have been 86 00:04:47,279 --> 00:04:50,599 Speaker 4: some accounts of what appear to be various offensive uses 87 00:04:50,640 --> 00:04:54,800 Speaker 4: of the tusk, but these might be coincidental or secondary behaviors. 88 00:04:54,839 --> 00:04:58,200 Speaker 4: And then there are all other odd proposals, including things 89 00:04:58,240 --> 00:05:02,200 Speaker 4: like stabbing through surface ice to create holes for breathing. 90 00:05:02,440 --> 00:05:04,880 Speaker 4: Of course, remember the narwhal is an air breathing mammal, 91 00:05:05,400 --> 00:05:07,839 Speaker 4: but the fact that the tusk is hollow and filled 92 00:05:07,880 --> 00:05:11,760 Speaker 4: with sensitive nerve endings has led some researchers to believe 93 00:05:11,920 --> 00:05:15,200 Speaker 4: it is a sensory organ and there is some evidence 94 00:05:15,240 --> 00:05:17,719 Speaker 4: that it can be used for gathering and even potentially 95 00:05:17,760 --> 00:05:22,280 Speaker 4: for sharing information about the characteristics of seawater, maybe things 96 00:05:22,320 --> 00:05:26,680 Speaker 4: like temperature, salinity, and so forth. However, one of the 97 00:05:26,720 --> 00:05:30,400 Speaker 4: most important clues about the primary evolutionary justification of the 98 00:05:30,440 --> 00:05:34,440 Speaker 4: tusk is the fact of sexual dimorphism, So the tusks 99 00:05:34,480 --> 00:05:39,080 Speaker 4: are almost always found in males, and one obvious conclusion 100 00:05:39,120 --> 00:05:42,479 Speaker 4: from this is that the tusk can't be necessary for 101 00:05:42,520 --> 00:05:45,680 Speaker 4: survival or else females would have them as well, right, 102 00:05:45,760 --> 00:05:50,960 Speaker 4: So it can't provide a major individual survival advantage, or 103 00:05:51,000 --> 00:05:53,720 Speaker 4: else you'd expect all individuals to have them, or we 104 00:05:53,760 --> 00:05:58,119 Speaker 4: would at least observe the whales that have them out 105 00:05:58,200 --> 00:06:01,040 Speaker 4: competing the other one the ones that don't have them 106 00:06:01,080 --> 00:06:03,919 Speaker 4: in survival, which is not the case. So one of 107 00:06:03,920 --> 00:06:07,559 Speaker 4: the leading theories then is that it's a sexually selected trade. 108 00:06:07,640 --> 00:06:11,039 Speaker 4: It's a body feature without a major role in survival, 109 00:06:11,400 --> 00:06:16,080 Speaker 4: which grows very prominent in males because it increases reproductive success, 110 00:06:16,200 --> 00:06:19,960 Speaker 4: maybe by being more appealing to female narwals, or maybe 111 00:06:19,960 --> 00:06:23,120 Speaker 4: by causing rival males to stay away and so forth 112 00:06:23,560 --> 00:06:26,280 Speaker 4: and anyway. So the recent paper I found was one 113 00:06:26,400 --> 00:06:29,960 Speaker 4: by Graham at All published in Biology Letters called the 114 00:06:30,040 --> 00:06:33,920 Speaker 4: longer the Better Evidence that narwal tusks are sexually selected. 115 00:06:34,520 --> 00:06:37,359 Speaker 4: This was from twenty twenty. And of course this paper 116 00:06:37,360 --> 00:06:40,320 Speaker 4: acknowledge is that it's really difficult to study narwals in 117 00:06:40,360 --> 00:06:42,240 Speaker 4: the wild to figure out what the tusk is for, 118 00:06:42,320 --> 00:06:46,080 Speaker 4: so instead it asks if we can infer anything about 119 00:06:46,120 --> 00:06:50,279 Speaker 4: tusk function from examining the natural variation in narwal tusk 120 00:06:50,400 --> 00:06:52,920 Speaker 4: measurements that have been taken over the course of the 121 00:06:53,000 --> 00:06:56,600 Speaker 4: last thirty five years, and so their sample comprise two 122 00:06:56,720 --> 00:07:00,479 Speaker 4: hundred and forty five individual adult males, and based on 123 00:07:00,520 --> 00:07:03,880 Speaker 4: these measurements, the authors conclude that the evidence does suggest 124 00:07:03,920 --> 00:07:07,799 Speaker 4: the primary driver of tusk evolution is sexual selection. 125 00:07:08,200 --> 00:07:08,680 Speaker 1: Quote. 126 00:07:08,920 --> 00:07:12,680 Speaker 4: By combining our results on tusks scaling with known material 127 00:07:12,720 --> 00:07:15,720 Speaker 4: properties of the tusk, we suggest that the narwal tusk 128 00:07:15,800 --> 00:07:18,640 Speaker 4: is a sexually selected signal that is used during male 129 00:07:18,720 --> 00:07:22,960 Speaker 4: mail contests. So how would you conclude this, Well, the 130 00:07:23,080 --> 00:07:27,800 Speaker 4: tusk demonstrates a growth pattern known as hyper allometry, which 131 00:07:27,920 --> 00:07:31,280 Speaker 4: means a body feature that grows faster than the body 132 00:07:31,320 --> 00:07:35,560 Speaker 4: as a whole. So, for example, most body features are 133 00:07:35,640 --> 00:07:39,880 Speaker 4: roughly allometric. They're linearly allometric, so they grow in size 134 00:07:39,920 --> 00:07:42,680 Speaker 4: proportional to the rest of the body. If your body 135 00:07:42,720 --> 00:07:46,600 Speaker 4: is bigger overall, you probably also have longer shin bones 136 00:07:46,680 --> 00:07:50,560 Speaker 4: and larger hands and so forth. Some features might be 137 00:07:50,760 --> 00:07:55,560 Speaker 4: hype bo allometric or sub allometric they grow less than 138 00:07:55,560 --> 00:07:59,880 Speaker 4: the body as a whole. But narwal tusks are hyper allometric. 139 00:08:00,080 --> 00:08:04,280 Speaker 4: In the largest individuals, the tusks grow longer than simple 140 00:08:04,360 --> 00:08:07,560 Speaker 4: linear scaling would predict, so they're not just big in 141 00:08:07,640 --> 00:08:10,600 Speaker 4: proportion to the rest of the body. They're way bigger 142 00:08:10,640 --> 00:08:15,480 Speaker 4: than that. They just they get ridiculously huge. And so 143 00:08:15,600 --> 00:08:19,240 Speaker 4: this is not proof, but it is characteristic of traits 144 00:08:19,320 --> 00:08:22,240 Speaker 4: that are sexually selected. And the authors right in their 145 00:08:22,520 --> 00:08:26,880 Speaker 4: conclusion quote, sexually selected signals used in mail mail competition 146 00:08:27,000 --> 00:08:31,000 Speaker 4: are more likely to exhibit hyperallometry when compared to other 147 00:08:31,120 --> 00:08:35,439 Speaker 4: sexually selected traits because the information being signaled is simple, 148 00:08:35,840 --> 00:08:39,120 Speaker 4: I am bigger than you. To convey this message, males 149 00:08:39,160 --> 00:08:42,520 Speaker 4: exaggerate the size of their signals, which facilitate the detection 150 00:08:42,760 --> 00:08:47,920 Speaker 4: of size discrepancies between individuals, reducing the likelihood of engaging 151 00:08:47,920 --> 00:08:52,079 Speaker 4: in potentially dangerous fights. And they note that this could 152 00:08:52,080 --> 00:08:56,160 Speaker 4: explain the so called tusking behavior that's been observed, where 153 00:08:56,280 --> 00:08:59,880 Speaker 4: male narwhales sometimes appear to be crossing tusks or almost 154 00:08:59,880 --> 00:09:04,160 Speaker 4: like dueling with their tusks, which could actually be not 155 00:09:04,280 --> 00:09:07,439 Speaker 4: a form of fighting, but a way for the animals 156 00:09:07,480 --> 00:09:10,480 Speaker 4: to compare the size of their tusks in order to 157 00:09:10,679 --> 00:09:14,959 Speaker 4: avoid a fight. So, in an interesting twist, it could 158 00:09:14,960 --> 00:09:17,920 Speaker 4: be the case that our naive intuition that this tusk 159 00:09:18,160 --> 00:09:21,800 Speaker 4: is a weapon is true in a sense, but it's 160 00:09:21,840 --> 00:09:27,160 Speaker 4: a weapon designed specifically to look scary because it will 161 00:09:27,200 --> 00:09:31,800 Speaker 4: discourage actual fighting between males in sexual competition most of 162 00:09:31,840 --> 00:09:35,480 Speaker 4: the time. So it's you know, two rival males are 163 00:09:35,600 --> 00:09:38,679 Speaker 4: competing for a chance to mate, and one of them goes, Wow, 164 00:09:38,800 --> 00:09:41,760 Speaker 4: that other one's tusk is absurdly long. No need to 165 00:09:41,800 --> 00:09:44,880 Speaker 4: fight this out, My mistake, see you later. Now, they 166 00:09:44,880 --> 00:09:46,960 Speaker 4: say that the existing evidence sort of points us in 167 00:09:47,000 --> 00:09:50,400 Speaker 4: this direction, but it's not conclusive. There are alternate explanations. 168 00:09:50,480 --> 00:09:53,640 Speaker 4: Maybe the large tusk plays a role in mate choice itself, 169 00:09:53,720 --> 00:09:59,360 Speaker 4: maybe females prefer males with larger tusks, but they're in general, 170 00:09:59,400 --> 00:10:01,800 Speaker 4: there's still just a lot we don't know about these animals, 171 00:10:01,840 --> 00:10:04,840 Speaker 4: so the book is not completely closed on this question. 172 00:10:05,480 --> 00:10:09,000 Speaker 4: And it's also possible that the tusk has multiple secondary functions, 173 00:10:09,000 --> 00:10:11,880 Speaker 4: for example, as a sensory organ like we talked about earlier. 174 00:10:12,320 --> 00:10:15,520 Speaker 4: Though again, as I mentioned earlier, those secondary functions can't 175 00:10:15,520 --> 00:10:19,160 Speaker 4: be all that crucial for survival, or we would see 176 00:10:19,200 --> 00:10:22,120 Speaker 4: that we would see that playing out in narwhal populations. 177 00:10:22,160 --> 00:10:24,480 Speaker 4: The ones with the tusks would be more likely to survive, 178 00:10:24,559 --> 00:10:27,640 Speaker 4: and that's not what we find now. To bring it 179 00:10:27,880 --> 00:10:30,480 Speaker 4: back to the reason I wanted to talk about narwals, 180 00:10:30,480 --> 00:10:34,480 Speaker 4: in today's episode. You may remember one strange fact about 181 00:10:34,480 --> 00:10:37,880 Speaker 4: the narwal's tusk from our previous episodes where these animals 182 00:10:37,880 --> 00:10:41,240 Speaker 4: came up, and it's that the narwal's tusk is not 183 00:10:41,840 --> 00:10:46,760 Speaker 4: an external caratinous horn like that of the rhinoceros. Instead, 184 00:10:47,040 --> 00:10:50,640 Speaker 4: it is a tooth. And I don't just mean it 185 00:10:50,679 --> 00:10:53,000 Speaker 4: is made out of the same stuff as a tooth. 186 00:10:53,400 --> 00:10:56,400 Speaker 4: It is literally a tooth. It is a tooth from 187 00:10:56,440 --> 00:10:59,920 Speaker 4: the upper jaw that has been repurposed by evolution to 188 00:11:00,320 --> 00:11:04,680 Speaker 4: grow into a tusk by changing the orientation of growth 189 00:11:04,760 --> 00:11:08,000 Speaker 4: so that it grows straight out forward forward out of 190 00:11:08,040 --> 00:11:11,920 Speaker 4: the jaw and then erupts from the flesh of the face. 191 00:11:11,960 --> 00:11:15,240 Speaker 4: It literally grows through the flesh of the upper lip 192 00:11:15,640 --> 00:11:18,640 Speaker 4: and then continues growing rapidly, and as we've seen, even 193 00:11:18,760 --> 00:11:23,280 Speaker 4: hyper elemetrically. But here's what I've been getting hung up on. 194 00:11:23,840 --> 00:11:26,960 Speaker 4: The narwhal's tusk is not only a tooth. In almost 195 00:11:27,000 --> 00:11:32,680 Speaker 4: all cases, it is the left canine, the left maxillary 196 00:11:32,840 --> 00:11:36,160 Speaker 4: canine tooth having erupted from the upper lip. 197 00:11:36,520 --> 00:11:38,920 Speaker 1: And this is certainly something when you learn it for 198 00:11:38,960 --> 00:11:41,000 Speaker 1: the first time, it does it does feel a little 199 00:11:41,040 --> 00:11:43,920 Speaker 1: bit wrong. I mean, a number of these these factoids 200 00:11:43,920 --> 00:11:46,680 Speaker 1: about the nar whale perhaps feel a little wrong, you know, 201 00:11:46,760 --> 00:11:49,720 Speaker 1: because ultimately it's just a far weirder and perhaps sillier 202 00:11:49,800 --> 00:11:52,640 Speaker 1: animal than most of us assumed. 203 00:11:52,880 --> 00:11:56,400 Speaker 4: It is not silly as deadly serious, but it does 204 00:11:56,559 --> 00:11:59,160 Speaker 4: have one tooth just poking out of its lip for 205 00:11:59,400 --> 00:12:01,840 Speaker 4: I don't know, ten feet But you're not allowed to laugh. 206 00:12:03,559 --> 00:12:06,719 Speaker 4: But yeah, anyway, So to quote from a paper from 207 00:12:06,840 --> 00:12:11,880 Speaker 4: twenty twelve in the Anatomical Record by Nuilla at All quote, 208 00:12:11,880 --> 00:12:16,319 Speaker 4: males usually exhibit an erupted tusk on the left side 209 00:12:16,679 --> 00:12:20,120 Speaker 4: and an unerupted embedded tusk on the right. So it's 210 00:12:20,160 --> 00:12:22,679 Speaker 4: got two of these teeth. It's got, you know, that's symmetrical. 211 00:12:22,720 --> 00:12:26,880 Speaker 4: There's one on each side, except usually one just kind 212 00:12:26,880 --> 00:12:28,760 Speaker 4: of grows a little bit and then stays inside the 213 00:12:28,840 --> 00:12:31,400 Speaker 4: upper jaw and doesn't do anything, while the other one 214 00:12:31,920 --> 00:12:35,000 Speaker 4: breaks through the skin and grows up to ten feet long. 215 00:12:35,480 --> 00:12:39,319 Speaker 4: So that's what you usually see. But then the quote continues, 216 00:12:39,320 --> 00:12:43,760 Speaker 4: whereas females usually have two embedded tusks, neither erupting. Other 217 00:12:43,880 --> 00:12:47,960 Speaker 4: less common expressions of narwal dentician include males with two tusks, 218 00:12:48,360 --> 00:12:51,720 Speaker 4: males with two embedded tusks, so neither one comes out. 219 00:12:52,120 --> 00:12:56,319 Speaker 4: Females with one erupted and one embedded tusk and females 220 00:12:56,360 --> 00:12:59,280 Speaker 4: with two erupted tusks. And I checked, I think there's 221 00:12:59,320 --> 00:13:02,360 Speaker 4: only been one one documented case of the latter of 222 00:13:02,400 --> 00:13:05,880 Speaker 4: the females with two tusks coming out. But the authors 223 00:13:05,880 --> 00:13:08,880 Speaker 4: of this paper do extensive analysis to confirm that these 224 00:13:08,960 --> 00:13:11,959 Speaker 4: are not horns, they are teeth, and they figure out 225 00:13:12,000 --> 00:13:14,839 Speaker 4: exactly what teeth they are. They are the upper canines 226 00:13:15,000 --> 00:13:19,920 Speaker 4: than in almost all cases, the left upper canine. Now 227 00:13:19,960 --> 00:13:21,520 Speaker 4: I don't know if I'm alone in this, but I 228 00:13:21,559 --> 00:13:24,000 Speaker 4: am just as struck by the fact that the tusk 229 00:13:24,120 --> 00:13:27,480 Speaker 4: is actually the left canine as I am about the 230 00:13:27,480 --> 00:13:29,640 Speaker 4: fact that it's a tooth to begin with. Why the 231 00:13:29,920 --> 00:13:34,920 Speaker 4: left canine. As the paper mentions, narwals occasionally have two 232 00:13:35,120 --> 00:13:38,440 Speaker 4: erupted tusks, two tusks of about the same length coming 233 00:13:38,440 --> 00:13:40,720 Speaker 4: out together. It's rare, but you find some like that, 234 00:13:41,480 --> 00:13:44,720 Speaker 4: and if you see pictures of the narwalls with two tusks, 235 00:13:45,200 --> 00:13:48,560 Speaker 4: they look much more appropriate to the preferences of nature. 236 00:13:48,640 --> 00:13:50,800 Speaker 4: You can look up images of this online. In fact, 237 00:13:50,840 --> 00:13:54,400 Speaker 4: even though they're much more rare in the wild, a 238 00:13:54,440 --> 00:13:57,400 Speaker 4: lot of the images of narwal skulls have two tusks, 239 00:13:57,440 --> 00:13:59,840 Speaker 4: I guess because the rare ones get photographed more often. 240 00:14:00,640 --> 00:14:02,880 Speaker 1: Well, I mean, I guess. On one hand, the left 241 00:14:02,880 --> 00:14:06,360 Speaker 1: handed side is the sinister side, the sinestral side. So 242 00:14:06,640 --> 00:14:09,400 Speaker 1: if you're going to have a crazy super long tooth 243 00:14:09,400 --> 00:14:13,200 Speaker 1: emerged from your face, maybe the sinister side makes sense. 244 00:14:13,480 --> 00:14:17,160 Speaker 4: Well, that's just your twisted mind working. It's fancy. I mean, no, 245 00:14:17,600 --> 00:14:21,600 Speaker 4: come on, like the two tusks, they look more like 246 00:14:21,680 --> 00:14:24,840 Speaker 4: something that you would just buy intuition expect to find 247 00:14:24,880 --> 00:14:27,880 Speaker 4: in the ocean, much more so than the common one 248 00:14:28,000 --> 00:14:30,160 Speaker 4: tusk skull, which when I see it, I mean, it 249 00:14:30,280 --> 00:14:34,920 Speaker 4: is beautiful, but it also it looks unbalanced and wrong. 250 00:14:35,360 --> 00:14:37,840 Speaker 1: Though. I will say that the two tusts narwhal, if 251 00:14:37,880 --> 00:14:42,080 Speaker 1: you look up images of specimens of this creature like 252 00:14:42,120 --> 00:14:45,480 Speaker 1: this one is perplexing as well because it kind of 253 00:14:45,560 --> 00:14:50,760 Speaker 1: it doesn't form. They're not perfectly parallel to each other. 254 00:14:51,000 --> 00:14:54,440 Speaker 1: It creates kind of a V shape that is a 255 00:14:54,440 --> 00:14:58,520 Speaker 1: little confusing. It certainly makes you lean more into possibilities. Yeah, 256 00:14:58,520 --> 00:15:02,680 Speaker 1: that this is not about stabbing or using these these 257 00:15:02,720 --> 00:15:06,160 Speaker 1: tusks for some sort of a physical practical use, but 258 00:15:06,280 --> 00:15:10,000 Speaker 1: something else like that they look more like communications array 259 00:15:10,360 --> 00:15:12,360 Speaker 1: when you see two of them as opposed to just one. 260 00:15:12,800 --> 00:15:15,440 Speaker 4: Well, yeah, I think having two of them even further 261 00:15:15,600 --> 00:15:19,440 Speaker 4: highlights that these are obviously not practically useful for something 262 00:15:19,560 --> 00:15:22,160 Speaker 4: like like catching prey or eating you know, you just 263 00:15:22,320 --> 00:15:24,240 Speaker 4: you look at that and it's like, how's that going 264 00:15:24,320 --> 00:15:27,120 Speaker 4: to work? And it's obviously they're not using it for that, 265 00:15:27,720 --> 00:15:29,920 Speaker 4: at least not most of the time. I know, there 266 00:15:29,960 --> 00:15:32,320 Speaker 4: are these little anecdotes of somebody saying that, you know, 267 00:15:32,360 --> 00:15:34,320 Speaker 4: they saw a narwhale like tap a fish with a 268 00:15:34,400 --> 00:15:37,640 Speaker 4: tusk or something, so maybe, but that clearly does not 269 00:15:37,840 --> 00:15:40,800 Speaker 4: appear to be a primary use of them. But I 270 00:15:40,840 --> 00:15:43,600 Speaker 4: wanted to come back to the idea that it looks 271 00:15:43,840 --> 00:15:46,400 Speaker 4: it looks wrong at least, even though of course you 272 00:15:46,440 --> 00:15:49,880 Speaker 4: know this is what evolution selected. It is it is 273 00:15:50,040 --> 00:15:53,320 Speaker 4: right for something, it has a use, but it looks 274 00:15:53,360 --> 00:15:56,640 Speaker 4: wrong to our brains, and so it causes you to 275 00:15:56,720 --> 00:15:58,880 Speaker 4: ask the question, well, first of all, why is it 276 00:15:58,920 --> 00:16:02,640 Speaker 4: that evily should drove the nar whall to be unbalanced 277 00:16:02,640 --> 00:16:05,360 Speaker 4: in this way? And second, why is it that my 278 00:16:05,480 --> 00:16:09,840 Speaker 4: intuition tells me incorrectly that a long, single tusk should 279 00:16:09,840 --> 00:16:14,000 Speaker 4: not emerge from the socket of the left maxillary canine, 280 00:16:14,040 --> 00:16:16,760 Speaker 4: like if an animal has one tusk, it should come 281 00:16:16,760 --> 00:16:19,400 Speaker 4: out of a whole right in the middle. And so 282 00:16:19,520 --> 00:16:21,080 Speaker 4: this is going to be the beginning of a series 283 00:16:21,120 --> 00:16:23,040 Speaker 4: of episodes. We're going to do at least two, maybe 284 00:16:23,080 --> 00:16:25,720 Speaker 4: more what we'll see, but they will be on a 285 00:16:26,040 --> 00:16:29,560 Speaker 4: symmetry in the animal world when an animal's left and 286 00:16:29,640 --> 00:16:33,920 Speaker 4: right do not match. So in future episodes we will 287 00:16:33,960 --> 00:16:39,000 Speaker 4: we will explore some theoretical questions about about embryonic development 288 00:16:39,160 --> 00:16:42,920 Speaker 4: and how animal asymmetry comes about. Uh, probably look at 289 00:16:42,920 --> 00:16:46,000 Speaker 4: some crabs and other crustaceans, But today I think we're 290 00:16:46,000 --> 00:16:49,280 Speaker 4: gonna we're gonna look especially at like whales and other 291 00:16:49,520 --> 00:16:53,040 Speaker 4: swimming creatures of the sea, and just generally highlight some 292 00:16:53,160 --> 00:17:02,880 Speaker 4: interesting examples of asymmetry in the natural world. Now, I 293 00:17:02,920 --> 00:17:05,439 Speaker 4: think it's important to acknowledge at the beginning that the 294 00:17:05,720 --> 00:17:09,800 Speaker 4: kind of symmetry or asymmetry we're talking about, the kind 295 00:17:09,840 --> 00:17:13,680 Speaker 4: of symmetry we expect to see in animals, is only 296 00:17:13,760 --> 00:17:18,280 Speaker 4: one specific type of symmetry called bilateral symmetry, and not 297 00:17:18,480 --> 00:17:21,879 Speaker 4: all animals actually possess it, even in an approximate sense. 298 00:17:22,760 --> 00:17:26,720 Speaker 4: So bilateral symmetry is actually a fairly restricted type of symmetry. 299 00:17:26,800 --> 00:17:29,879 Speaker 4: There are three dimensions of space, and if you plot 300 00:17:29,920 --> 00:17:32,600 Speaker 4: a human body on those three dimensions, you'll notice we 301 00:17:32,640 --> 00:17:37,040 Speaker 4: are actually only symmetrical along one of those three axes. 302 00:17:37,240 --> 00:17:39,879 Speaker 4: So on height, our heads and our feet, of course, 303 00:17:40,359 --> 00:17:44,200 Speaker 4: are not mirror images of each other. On depth, we're 304 00:17:44,240 --> 00:17:47,479 Speaker 4: also not symmetrical. Our backs do not mirror our fronts. 305 00:17:47,520 --> 00:17:50,800 Speaker 4: We don't have faces or butts on both sides. It's 306 00:17:50,840 --> 00:17:54,439 Speaker 4: only across our width that you find approximate symmetry. Our 307 00:17:54,560 --> 00:17:58,800 Speaker 4: left side roughly mirrors our right side. And in three 308 00:17:58,840 --> 00:18:03,800 Speaker 4: dimensional space, the most perfectly symmetrical form is actually a sphere. 309 00:18:03,840 --> 00:18:06,880 Speaker 4: Since if you divide a sphere in half along any 310 00:18:06,920 --> 00:18:10,320 Speaker 4: plane you want, no matter its orientation, the two sides 311 00:18:10,320 --> 00:18:13,439 Speaker 4: will match. And I hesitate because I'm about to make 312 00:18:13,440 --> 00:18:16,000 Speaker 4: a generalization about geometry. I'm always afraid I'm going to 313 00:18:16,040 --> 00:18:17,960 Speaker 4: say something wrong there. But I tried to look this 314 00:18:18,080 --> 00:18:21,679 Speaker 4: up and confirm it. I believe this is unique to 315 00:18:21,800 --> 00:18:25,520 Speaker 4: the sphere, that all other three D shapes can be 316 00:18:25,640 --> 00:18:29,399 Speaker 4: bisected in ways where the two halves may have equal 317 00:18:29,480 --> 00:18:32,480 Speaker 4: volume but will not match. An outline. But if you 318 00:18:32,520 --> 00:18:36,480 Speaker 4: cut a sphere in half, it's always two perfect temispheres, 319 00:18:36,560 --> 00:18:39,439 Speaker 4: no matter what direction you cut from. And this actually 320 00:18:39,440 --> 00:18:41,920 Speaker 4: connects to a passage in a book I came across 321 00:18:42,400 --> 00:18:47,320 Speaker 4: by the mathematician Hermann Vile called Symmetry from Princeton University 322 00:18:47,320 --> 00:18:52,600 Speaker 4: Press in nineteen fifty two, and Vile is writing about 323 00:18:52,640 --> 00:18:56,960 Speaker 4: the history of association between symmetry and the geometric sense 324 00:18:57,480 --> 00:19:02,240 Speaker 4: and the concept of beauty, you know, moral virtue, and perfection. 325 00:19:03,200 --> 00:19:07,159 Speaker 4: And he writes quote, because of their complete rotational symmetry, 326 00:19:07,560 --> 00:19:10,399 Speaker 4: the circle in the plane and the sphere in space 327 00:19:10,520 --> 00:19:14,960 Speaker 4: were considered by the Pythagoreans the most perfect geometric figures. 328 00:19:15,320 --> 00:19:20,160 Speaker 4: And Aristotle ascribed spherical shape to the celestial bodies because 329 00:19:20,640 --> 00:19:24,840 Speaker 4: any other would detract from their heavenly perfection. Now it's 330 00:19:24,840 --> 00:19:27,720 Speaker 4: interesting knowing what we know now about the cause of 331 00:19:27,800 --> 00:19:31,880 Speaker 4: spherical objects in space, namely gravity, right that as the 332 00:19:31,920 --> 00:19:35,120 Speaker 4: mass of an object increases, it tends to become more 333 00:19:35,160 --> 00:19:38,760 Speaker 4: and more perfectly spherical, with the I guess the end 334 00:19:38,840 --> 00:19:41,520 Speaker 4: point of that being that a black hole theoretically is 335 00:19:41,560 --> 00:19:45,639 Speaker 4: pretty much perfectly spherical, whereas smaller objects in space because 336 00:19:45,720 --> 00:19:49,560 Speaker 4: gravity is not as strong a force on the smoothing 337 00:19:49,600 --> 00:19:52,240 Speaker 4: of their outer edges, they can have more irregular shapes. 338 00:19:52,280 --> 00:19:56,080 Speaker 4: This is why you get irregular potato shaped comets and asteroids. 339 00:19:56,160 --> 00:19:58,480 Speaker 4: But you you start getting up into planet size and 340 00:19:58,800 --> 00:20:02,159 Speaker 4: you move closer and closer. Just spherical perfection. But anyway, 341 00:20:02,280 --> 00:20:05,360 Speaker 4: Vile goes on to quote a poet named Anna Wickham, 342 00:20:05,359 --> 00:20:08,760 Speaker 4: which was actually the pseudonym of a modernist poet named 343 00:20:08,920 --> 00:20:14,720 Speaker 4: Edith Alice Mary Harper in connecting the idea of symmetry 344 00:20:14,880 --> 00:20:19,520 Speaker 4: to God or the divine being. So Wickham writes, quote God, 345 00:20:19,680 --> 00:20:22,600 Speaker 4: thou great symmetry, who put a biting lust in me 346 00:20:22,760 --> 00:20:26,240 Speaker 4: from whence my sorrow's spring, for all my frittered days 347 00:20:26,280 --> 00:20:29,440 Speaker 4: that I have spent in shapeless ways, give me one 348 00:20:29,520 --> 00:20:33,639 Speaker 4: perfect thing. And then Vile writes, symmetry, as wide or 349 00:20:33,680 --> 00:20:36,560 Speaker 4: as narrow as you may define its meaning is one 350 00:20:36,600 --> 00:20:39,199 Speaker 4: idea by which man, through the ages has tried to 351 00:20:39,240 --> 00:20:45,000 Speaker 4: comprehend and create order, beauty and perfection. And equating symmetry 352 00:20:45,000 --> 00:20:48,399 Speaker 4: with beauty, goodness, and perfection and even divinity can be 353 00:20:48,480 --> 00:20:52,240 Speaker 4: found all throughout literature. I think of Blake's The Tiger. 354 00:20:52,359 --> 00:20:54,960 Speaker 4: You know what immortal hand or I could frame thy 355 00:20:55,000 --> 00:20:57,280 Speaker 4: fearful symmetry. I guess it makes you want to say 356 00:20:57,280 --> 00:21:01,840 Speaker 4: symmetry there, but this clearly has not just a geometric 357 00:21:02,000 --> 00:21:04,920 Speaker 4: meaning where the two halves of the tiger do match 358 00:21:05,000 --> 00:21:08,200 Speaker 4: one another roughly because it is an animal with bilateral symmetry, 359 00:21:08,960 --> 00:21:11,800 Speaker 4: but that it means something more than that. Symmetry here 360 00:21:11,840 --> 00:21:14,919 Speaker 4: is in some sense synonymous with greatness or divinity. 361 00:21:15,400 --> 00:21:19,240 Speaker 1: Yeah, it's the tiger is a perfect organism in Blake's 362 00:21:19,240 --> 00:21:23,320 Speaker 1: eye here. Yeah. Yeah. A lot can be said about 363 00:21:23,320 --> 00:21:27,960 Speaker 1: our obsession with symmetry to the point to where it's 364 00:21:28,000 --> 00:21:31,280 Speaker 1: like a flawed obsession with it. Like we think that 365 00:21:31,400 --> 00:21:36,000 Speaker 1: we want, say, perfectly symmetrical faces, when most faces are 366 00:21:36,080 --> 00:21:39,640 Speaker 1: certainly not symmetrical. And if you take even famous and 367 00:21:39,960 --> 00:21:43,040 Speaker 1: you know, often held up as beautiful faces, and you 368 00:21:43,400 --> 00:21:46,400 Speaker 1: do the trick of creating a symmetrical symmetrical face out 369 00:21:46,400 --> 00:21:48,359 Speaker 1: of it, it's going to look wrong to your eyes. 370 00:21:48,720 --> 00:21:51,120 Speaker 1: It may it may look very well look unnatural. 371 00:21:51,440 --> 00:21:56,239 Speaker 4: Well, the whole quest for symmetry in esthetic beauty is 372 00:21:56,280 --> 00:21:58,959 Speaker 4: one of those where it's like there's almost a kind 373 00:21:58,960 --> 00:22:02,760 Speaker 4: of inverse uncann valley. It seems like people's natural preferences 374 00:22:02,760 --> 00:22:06,359 Speaker 4: are something that tends very close to symmetry, but then 375 00:22:06,400 --> 00:22:08,199 Speaker 4: if you get right up to it and go to 376 00:22:08,359 --> 00:22:11,480 Speaker 4: actual symmetry, it's like, oh no, no, no, that looks all wrong. 377 00:22:12,200 --> 00:22:14,040 Speaker 4: So you want to be like right in the zone 378 00:22:14,080 --> 00:22:16,760 Speaker 4: where you're approaching symmetry, but not there. 379 00:22:17,480 --> 00:22:20,120 Speaker 1: Yeah, though there are certainly what you get into design, 380 00:22:20,200 --> 00:22:22,720 Speaker 1: it gets it gets weird because take airplanes for example. 381 00:22:23,680 --> 00:22:27,760 Speaker 1: Airplanes tend to look best to our eye when they 382 00:22:27,800 --> 00:22:31,200 Speaker 1: are perfectly symmetrical, and there are various reasons for that. 383 00:22:31,400 --> 00:22:34,600 Speaker 1: And if you see an asymmetrical airplane, and there there 384 00:22:34,640 --> 00:22:38,880 Speaker 1: have been certainly been some some very asymmetrical looking airplane 385 00:22:38,920 --> 00:22:43,800 Speaker 1: designs here and there throughout aviation history, they do look 386 00:22:43,840 --> 00:22:48,440 Speaker 1: incredibly wrong to the eye. And that yeah, like how 387 00:22:48,600 --> 00:22:50,720 Speaker 1: how how is that a good idea? But I mean 388 00:22:51,359 --> 00:22:54,919 Speaker 1: it can work, it's just you you generally don't see it. 389 00:22:55,400 --> 00:22:57,280 Speaker 4: Well, there's a different logic at work here. But that 390 00:22:57,480 --> 00:23:00,520 Speaker 4: just sort of reminds me, incidentally, of how I'm always 391 00:23:00,560 --> 00:23:02,919 Speaker 4: surprised at the idea that a plane can continue to 392 00:23:02,960 --> 00:23:05,760 Speaker 4: fly with one engine, you know, as like two jet engines, 393 00:23:05,880 --> 00:23:08,159 Speaker 4: like one engine fails, but it can keep flying with 394 00:23:08,200 --> 00:23:11,080 Speaker 4: the other one, Which that doesn't seem right. It seems 395 00:23:11,080 --> 00:23:13,480 Speaker 4: like well, if only one engine is going, then shouldn't 396 00:23:13,480 --> 00:23:16,359 Speaker 4: it just sort of like spin out of control? But no, 397 00:23:16,520 --> 00:23:19,280 Speaker 4: I mean, as long as it's generating forward thrust, it 398 00:23:19,320 --> 00:23:23,520 Speaker 4: can keep going. Usually, But anyway, so there's always a 399 00:23:23,520 --> 00:23:26,240 Speaker 4: strong argument, you know, that much of what we find 400 00:23:26,359 --> 00:23:30,679 Speaker 4: beautiful and good is biologically contingent. That it has at 401 00:23:30,760 --> 00:23:33,680 Speaker 4: least in part to do with the kind of animals 402 00:23:33,720 --> 00:23:36,560 Speaker 4: we are and how we relate to our environment. And 403 00:23:36,640 --> 00:23:39,040 Speaker 4: of course we are part of that clade of animals 404 00:23:39,080 --> 00:23:44,160 Speaker 4: known as bilateria. These are the animals featuring bilateral symmetry 405 00:23:44,280 --> 00:23:48,280 Speaker 4: during embryonic development. Now, of course, this is always approximate, right, 406 00:23:48,320 --> 00:23:50,600 Speaker 4: because while you're left in your right in one sense 407 00:23:50,680 --> 00:23:53,400 Speaker 4: do match, there are mirror images of each other, as 408 00:23:53,440 --> 00:23:56,600 Speaker 4: you were just talking about, they're not perfect mirror images 409 00:23:56,680 --> 00:23:58,960 Speaker 4: of each other, and especially on the inside, because we 410 00:23:59,040 --> 00:24:02,800 Speaker 4: have say, asymmetric distribution of our internal organs, like the 411 00:24:02,840 --> 00:24:05,040 Speaker 4: hearts more to one side, the livers more to the other, 412 00:24:05,119 --> 00:24:09,480 Speaker 4: and so forth. But for approximate terms, at least externally 413 00:24:09,960 --> 00:24:12,240 Speaker 4: are left in our right sides match. But not all 414 00:24:12,280 --> 00:24:16,520 Speaker 4: animals exhibit bilateral symmetry. Some have radial symmetry, meaning they 415 00:24:16,600 --> 00:24:20,000 Speaker 4: grow in like repeated structures in a more spiral pattern, 416 00:24:20,480 --> 00:24:23,480 Speaker 4: and there are some like sponges, for example, those are animals, 417 00:24:23,480 --> 00:24:26,400 Speaker 4: but they have no symmetry at all. But most animals, 418 00:24:26,440 --> 00:24:30,680 Speaker 4: like humans, are bilaterally symmetrical. As our bodies grow during 419 00:24:31,080 --> 00:24:35,480 Speaker 4: embryonic development that grow into basically mirrored halves on the 420 00:24:35,560 --> 00:24:38,760 Speaker 4: left and right. But as we've already seen with the narwhal, 421 00:24:39,119 --> 00:24:43,760 Speaker 4: some animals with bodies that mostly adhere to bilateral symmetry 422 00:24:44,280 --> 00:24:49,879 Speaker 4: present with isolated but radical deviations, such as the narwhal's 423 00:24:50,040 --> 00:24:54,120 Speaker 4: left maxillary canine turning into a tusk almost as long 424 00:24:54,160 --> 00:24:57,560 Speaker 4: as the animal itself. And this is not even the 425 00:24:57,600 --> 00:25:01,879 Speaker 4: only example of fascinating ace symmetry in the bodies of wales. 426 00:25:02,400 --> 00:25:06,040 Speaker 1: Yeah, yeah, I want to get into something that we 427 00:25:06,080 --> 00:25:08,159 Speaker 1: may have touched on this a little bit in the past, 428 00:25:09,119 --> 00:25:11,800 Speaker 1: but despite the number of times that whales come up, 429 00:25:12,240 --> 00:25:15,240 Speaker 1: I don't think we've really gotten into everything here. And 430 00:25:15,280 --> 00:25:20,760 Speaker 1: it concerns the nature of the blowhole of wales. Again, 431 00:25:20,800 --> 00:25:24,080 Speaker 1: it just drives home just how mysterious and weird whales 432 00:25:24,160 --> 00:25:28,560 Speaker 1: really are. So I want to start sort of back 433 00:25:28,640 --> 00:25:31,320 Speaker 1: up before we get to where we're going with this 434 00:25:31,359 --> 00:25:34,240 Speaker 1: discussion of blowholes. Start with the Bileen whale. You know, 435 00:25:34,280 --> 00:25:39,040 Speaker 1: these are filter feeders, which, as Ryan Tucker Jones points 436 00:25:39,040 --> 00:25:42,520 Speaker 1: out in red Leviathans, the book about Soviet whaling. And 437 00:25:42,560 --> 00:25:46,920 Speaker 1: I interviewed Ryan last week on the show, a really 438 00:25:46,960 --> 00:25:49,040 Speaker 1: fun episode if anyone wants to go back and listen 439 00:25:49,040 --> 00:25:53,520 Speaker 1: to that. But he touches on just sort of how 440 00:25:53,680 --> 00:25:57,520 Speaker 1: intertwined folk tale and legend and mythology is with our 441 00:25:57,600 --> 00:26:01,200 Speaker 1: understanding of whales and misunderstanding of whales. I want to 442 00:26:01,240 --> 00:26:05,200 Speaker 1: read this one passage quote. Ancient Greeks knew far less 443 00:26:05,200 --> 00:26:08,680 Speaker 1: about whales than did the whaling Scandinavians. And as these 444 00:26:08,880 --> 00:26:13,320 Speaker 1: word origins suggest, whales remain mysterious for Russians. For one thing, 445 00:26:13,400 --> 00:26:17,359 Speaker 1: Baileen whales methods of feeding perplexed them. Lacking teeth, the 446 00:26:17,440 --> 00:26:20,360 Speaker 1: giants seem to have no way of capturing prey. One 447 00:26:20,400 --> 00:26:24,160 Speaker 1: tenth century Russian poem wondered whether whales quote the mother 448 00:26:24,520 --> 00:26:29,120 Speaker 1: of all fish unquote fed themselves on quote heavenly fragrances. 449 00:26:29,880 --> 00:26:34,160 Speaker 1: Direct experience was not necessarily more helpful. A medieval Western 450 00:26:34,200 --> 00:26:37,040 Speaker 1: whaler who cut into a stranded whale's stomach and found 451 00:26:37,080 --> 00:26:40,440 Speaker 1: a gray mass of food concluded that it had fed 452 00:26:40,520 --> 00:26:48,639 Speaker 1: on quote internal fog. That's great. So, yes, whales are mysterious, 453 00:26:48,960 --> 00:26:51,120 Speaker 1: and yeah, you can you can imagine if you really 454 00:26:51,160 --> 00:26:53,240 Speaker 1: didn't know what was going on with the baileen whale, 455 00:26:53,560 --> 00:26:57,199 Speaker 1: you might have trouble figuring out what's going on with 456 00:26:57,320 --> 00:27:01,000 Speaker 1: their with their mouths, what do they try truly feed on? 457 00:27:01,119 --> 00:27:03,600 Speaker 1: What is there enough off on the ocean for them 458 00:27:03,640 --> 00:27:07,760 Speaker 1: to consume if they're not eating our ships and so forth. 459 00:27:08,560 --> 00:27:11,239 Speaker 1: So anyway, if you look at a baleen whale and 460 00:27:11,400 --> 00:27:14,600 Speaker 1: you look away from its mouth, you'll notice, yes, it 461 00:27:15,200 --> 00:27:19,359 Speaker 1: has the blowholes. The blowhole falls well in line with 462 00:27:19,480 --> 00:27:22,560 Speaker 1: bilateral anatomy. There are two of them, in kind of 463 00:27:22,600 --> 00:27:26,000 Speaker 1: a V shape. And guess what if you weren't aware 464 00:27:26,040 --> 00:27:31,280 Speaker 1: of this, here's your fun initial fact. They are repositioned nostrils. 465 00:27:31,760 --> 00:27:35,640 Speaker 4: Imagining the evolutionary journey of those nose holes. 466 00:27:35,760 --> 00:27:38,680 Speaker 1: Yes, because that's it is a journey, the nose holes 467 00:27:38,920 --> 00:27:41,560 Speaker 1: traveling from the front of the snout all the way 468 00:27:41,600 --> 00:27:43,000 Speaker 1: to the top of the head. I mean, we can 469 00:27:43,040 --> 00:27:45,399 Speaker 1: imagine it. It's hard to imagine with our own face, 470 00:27:45,840 --> 00:27:49,080 Speaker 1: but imagine it with a much bigger and more prolonged head. 471 00:27:49,359 --> 00:27:49,840 Speaker 4: Amazing. 472 00:27:50,280 --> 00:27:53,359 Speaker 1: So as Rostin and Roth point out in a twenty 473 00:27:53,400 --> 00:27:56,320 Speaker 1: twenty one paper published in the Journal of Anatomy the 474 00:27:56,400 --> 00:28:02,000 Speaker 1: nasal passage in these whales has rotated dorsally over the 475 00:28:02,040 --> 00:28:07,359 Speaker 1: course of evolution and early in development cessation. Embryos have 476 00:28:07,640 --> 00:28:11,280 Speaker 1: head morphologies that resemble other mammals, so you can actually 477 00:28:11,359 --> 00:28:16,720 Speaker 1: look up embryo images and observe the nasal openings shift 478 00:28:17,000 --> 00:28:19,320 Speaker 1: from the tip of the snout to the back of 479 00:28:19,359 --> 00:28:23,240 Speaker 1: the head. If you want to see some easily accessed 480 00:28:23,280 --> 00:28:27,119 Speaker 1: examples of this, pandas Thumb. A science blog has some 481 00:28:27,200 --> 00:28:31,160 Speaker 1: great images of this in their post whale evolution the Blowhole, 482 00:28:31,480 --> 00:28:33,520 Speaker 1: and I included these for you to look at here, Joe. 483 00:28:34,560 --> 00:28:37,119 Speaker 1: If you look up this blog post, you'll see a 484 00:28:37,160 --> 00:28:40,160 Speaker 1: trio of images with the embryo and there's a little 485 00:28:40,200 --> 00:28:44,200 Speaker 1: white arrow pointing out where the nostrils are and then 486 00:28:44,280 --> 00:28:45,400 Speaker 1: where they travel to. 487 00:28:45,880 --> 00:28:48,920 Speaker 4: It's just as you say, yeah, so earlier in development 488 00:28:48,960 --> 00:28:51,120 Speaker 4: there toward the front like they would be on the 489 00:28:51,120 --> 00:28:53,480 Speaker 4: snout and more like they would have been on the 490 00:28:53,520 --> 00:28:57,360 Speaker 4: whales on the whales land walking ancestors. But yeah, then 491 00:28:57,400 --> 00:29:00,480 Speaker 4: as development moves on, they move up the head up 492 00:29:00,720 --> 00:29:03,200 Speaker 4: to where I don't know if this is the right terminology, 493 00:29:03,240 --> 00:29:05,480 Speaker 4: but you might call like the forehead and then further 494 00:29:05,520 --> 00:29:05,960 Speaker 4: and further. 495 00:29:06,440 --> 00:29:11,760 Speaker 1: Yeah, yeah, Now it's obviously natural selection went this way, 496 00:29:12,760 --> 00:29:16,000 Speaker 1: and it's easy to just sort of assume, okay, natural 497 00:29:17,120 --> 00:29:20,080 Speaker 1: evolution and natural selection and knows what it's doing. Who 498 00:29:20,120 --> 00:29:21,960 Speaker 1: are we to question it? So it's easy to sort 499 00:29:21,960 --> 00:29:24,520 Speaker 1: of overlook the basic question in all of this, why 500 00:29:24,960 --> 00:29:27,920 Speaker 1: why does the nostril why did the nose open? The 501 00:29:27,960 --> 00:29:30,840 Speaker 1: nasal openings on these creatures wander over the course of 502 00:29:30,840 --> 00:29:34,160 Speaker 1: their evolutionary development until they're on the top of the head. 503 00:29:34,600 --> 00:29:37,960 Speaker 1: The basic answer is that while these creatures, yes technically 504 00:29:38,040 --> 00:29:41,080 Speaker 1: could still breathe through their nostrils when they were positioned 505 00:29:41,120 --> 00:29:43,160 Speaker 1: at the end of their snouts, they would have to 506 00:29:43,240 --> 00:29:45,600 Speaker 1: lift their snouts out of the water to do so, 507 00:29:46,360 --> 00:29:49,400 Speaker 1: and that requires more energy. If it's if you have 508 00:29:49,440 --> 00:29:52,640 Speaker 1: the nose and the nasal openings positioned higher up on 509 00:29:52,680 --> 00:29:55,920 Speaker 1: the snout, well, that's less lift required to do so, 510 00:29:56,080 --> 00:29:59,240 Speaker 1: less energy, And so this is why we have that 511 00:29:59,320 --> 00:30:03,440 Speaker 1: gradual movement of the nasal openings, and we have fossil 512 00:30:03,480 --> 00:30:06,000 Speaker 1: evidence to back this up, and there are examples of 513 00:30:06,000 --> 00:30:09,120 Speaker 1: this in that pandace thumb post as well. For instance, 514 00:30:09,120 --> 00:30:12,959 Speaker 1: we have fossil evidence of Rhodos status. This is a 515 00:30:13,000 --> 00:30:17,120 Speaker 1: whale from roughly forty seven to forty six million years ago, 516 00:30:17,480 --> 00:30:21,520 Speaker 1: and this one offers a midpoint where we see the 517 00:30:21,600 --> 00:30:23,960 Speaker 1: nasal opening, not at the end of the snout like 518 00:30:24,000 --> 00:30:29,240 Speaker 1: we see in really ancient whale ancestors, and also not 519 00:30:29,280 --> 00:30:30,560 Speaker 1: at the top of the head like we see with 520 00:30:30,600 --> 00:30:33,360 Speaker 1: modern whales, but that midpoint in between. 521 00:30:33,800 --> 00:30:37,000 Speaker 4: Now, I'm not speaking from an expert perspective here, but 522 00:30:37,120 --> 00:30:42,320 Speaker 4: it seems very significant that the blowhole eventually moves back 523 00:30:42,360 --> 00:30:45,120 Speaker 4: to above where the eyes are right because you can 524 00:30:45,160 --> 00:30:49,120 Speaker 4: imagine if a whale has to lift its eyes above 525 00:30:49,280 --> 00:30:51,920 Speaker 4: the surface of the water every time it wants to breathe, 526 00:30:52,000 --> 00:30:54,320 Speaker 4: or at least to point its eyes up away from 527 00:30:54,320 --> 00:30:58,520 Speaker 4: where it's scanning, that's really it's not just taking energy. 528 00:30:58,560 --> 00:31:01,959 Speaker 4: I mean, of course, the energetic investment is significant. Imagine 529 00:31:01,960 --> 00:31:04,280 Speaker 4: if you had to like lift your head up every 530 00:31:04,280 --> 00:31:06,440 Speaker 4: time you wanted to breathe, that would that would get 531 00:31:06,480 --> 00:31:09,280 Speaker 4: tiring after a while. But also if you basically like 532 00:31:09,320 --> 00:31:11,680 Speaker 4: couldn't see what was going on around you every time 533 00:31:11,680 --> 00:31:13,719 Speaker 4: you had to take a breath, because you know, you 534 00:31:13,760 --> 00:31:16,080 Speaker 4: need if you're living under the water, you want to 535 00:31:16,160 --> 00:31:18,760 Speaker 4: keep your eyes fixed below the water. That's where the 536 00:31:18,800 --> 00:31:21,000 Speaker 4: relevant stuff is going on. If you have to lift 537 00:31:21,040 --> 00:31:24,080 Speaker 4: your eyes above the surface of the water, you are 538 00:31:24,160 --> 00:31:26,880 Speaker 4: you are losing sight of your surroundings exactly. 539 00:31:27,000 --> 00:31:30,760 Speaker 1: Yeah, this is the world that the whale has adapted 540 00:31:30,800 --> 00:31:34,920 Speaker 1: to the marine environment, and so over time it just 541 00:31:35,000 --> 00:31:37,640 Speaker 1: gets to the point where as little of the animal 542 00:31:37,680 --> 00:31:40,320 Speaker 1: as possible has to breach the surface of the water. 543 00:31:47,040 --> 00:31:51,400 Speaker 1: So that's basically the symmetrical whale blowhole. But here's the 544 00:31:51,520 --> 00:31:52,920 Speaker 1: here's where it gets fun. This is where it gets 545 00:31:52,960 --> 00:31:57,920 Speaker 1: asymmetrical because not all whales have two blowholes. Though not 546 00:31:58,040 --> 00:32:01,760 Speaker 1: all have those two nasal open repurpose nasal openings on 547 00:32:01,840 --> 00:32:05,000 Speaker 1: the top of their head, toothed wails like the sperm 548 00:32:05,040 --> 00:32:10,240 Speaker 1: whale have just one. In fact, on the sperm whale, 549 00:32:10,360 --> 00:32:13,800 Speaker 1: this single blowhole is at an angle on the left 550 00:32:13,840 --> 00:32:16,120 Speaker 1: side of the head, and this causes it to blow 551 00:32:16,480 --> 00:32:20,280 Speaker 1: forward and slightly to the left. So this can actually 552 00:32:20,320 --> 00:32:24,360 Speaker 1: make sperm whale spouts harder to spot for humans, but 553 00:32:24,520 --> 00:32:27,640 Speaker 1: also makes them easier to identify if you do spot them, 554 00:32:27,880 --> 00:32:32,200 Speaker 1: because it's not just blasting straight up again, it's blasting 555 00:32:32,480 --> 00:32:34,080 Speaker 1: forward and slightly to the left. 556 00:32:34,480 --> 00:32:36,160 Speaker 4: But this is, oh, this is this is putting me 557 00:32:36,200 --> 00:32:40,440 Speaker 4: back in narwhal tusk territory. So it has one nostril. 558 00:32:40,800 --> 00:32:43,560 Speaker 4: So this is not just the nostrils have moved back 559 00:32:43,680 --> 00:32:47,560 Speaker 4: along the center line of the skull of cross evolutionary time. 560 00:32:47,800 --> 00:32:52,000 Speaker 4: The nostrils have actually split and one of them has 561 00:32:52,080 --> 00:32:54,239 Speaker 4: moved back here and the other one, I don't know 562 00:32:54,280 --> 00:32:55,760 Speaker 4: what it's doing something. 563 00:32:55,360 --> 00:32:59,320 Speaker 1: Else, Yeah, the other one. The crazy thing is essentially 564 00:32:59,720 --> 00:33:02,000 Speaker 1: the one is still open and active. The other one 565 00:33:02,040 --> 00:33:05,400 Speaker 1: has sealed over. So the other nasal passage is there. 566 00:33:05,760 --> 00:33:09,360 Speaker 1: It just does not connect to the surface anymore. That 567 00:33:09,400 --> 00:33:12,200 Speaker 1: doesn't mean it's not doing anything. It has another purpose. 568 00:33:13,080 --> 00:33:16,640 Speaker 1: So instead of connecting to the exterior of the animal, 569 00:33:16,960 --> 00:33:20,800 Speaker 1: this other nasal passage supplies air to the phonic lips. 570 00:33:21,240 --> 00:33:24,320 Speaker 1: The phonic lips produce clicks that travel the length of 571 00:33:24,360 --> 00:33:28,840 Speaker 1: the nose and through the spermaceti organ of the head 572 00:33:29,400 --> 00:33:31,440 Speaker 1: to aid in echolocation, or at least this is the 573 00:33:31,440 --> 00:33:34,360 Speaker 1: most well accepted theory of what's going on here with 574 00:33:34,440 --> 00:33:36,720 Speaker 1: the structure of the sperm whale's head. 575 00:33:36,720 --> 00:33:40,880 Speaker 4: So echolocation is using sound waves in order to be 576 00:33:40,920 --> 00:33:44,600 Speaker 4: able to image underwater to see where things are not 577 00:33:44,640 --> 00:33:48,160 Speaker 4: with vision, but by producing clicks that like hit things 578 00:33:48,200 --> 00:33:51,120 Speaker 4: in the water and then come back to the sensory 579 00:33:51,240 --> 00:33:54,240 Speaker 4: organs on the whale so they can navigate their environment. 580 00:33:54,320 --> 00:33:57,960 Speaker 4: And specifically, I think nowhere prey is in the dark waters. 581 00:33:58,160 --> 00:34:01,760 Speaker 1: Yeah, so if you're diving down to eat some squid, 582 00:34:01,880 --> 00:34:06,520 Speaker 1: some giant squid, maybe this is what you would use. Now. 583 00:34:06,560 --> 00:34:09,840 Speaker 1: The evolutionary divergence likely occurred during the oligo scene. This 584 00:34:09,920 --> 00:34:12,439 Speaker 1: would have been thirty three to twenty three million years ago, 585 00:34:12,760 --> 00:34:17,640 Speaker 1: as toothed whales diverged from the ancestors of filter feeding whales. 586 00:34:18,200 --> 00:34:21,480 Speaker 4: And this would totally make sense. So predatory toothed whales 587 00:34:21,760 --> 00:34:26,640 Speaker 4: develop asymmetry related to their ability to echo locate because 588 00:34:26,680 --> 00:34:29,800 Speaker 4: they need to use echolocation to hunt. Filter feeding whales 589 00:34:30,160 --> 00:34:32,600 Speaker 4: did not have the same hunting needs, so their skulls 590 00:34:32,640 --> 00:34:37,160 Speaker 4: remained balanced on the left and right and Rob I 591 00:34:37,239 --> 00:34:39,279 Speaker 4: thought this was a really interesting find, and so I 592 00:34:39,320 --> 00:34:41,840 Speaker 4: was looking to support this. I found a twenty twenty 593 00:34:41,840 --> 00:34:45,120 Speaker 4: paper on the cranial asymmetry of whales and this was 594 00:34:45,200 --> 00:34:49,520 Speaker 4: by Llen J. Coombs at All published in BMC Biology 595 00:34:49,800 --> 00:34:54,000 Speaker 4: in twenty twenty and for this paper, making use of 596 00:34:54,239 --> 00:34:59,360 Speaker 4: museum collections, the researchers compared whale skulls across time, reaching 597 00:34:59,400 --> 00:35:03,080 Speaker 4: back to whale ancestors that lived fifty million years ago 598 00:35:03,560 --> 00:35:07,240 Speaker 4: and the author's right quote, early ancestors of living whales 599 00:35:07,280 --> 00:35:10,799 Speaker 4: had little cranial asymmetry and likely we're not able to 600 00:35:10,840 --> 00:35:15,840 Speaker 4: echolocate our Cheocets display high levels of asymmetry in the rostrum, 601 00:35:16,160 --> 00:35:20,399 Speaker 4: potentially related to directional hearing, which is lost in early neocets. 602 00:35:20,800 --> 00:35:24,759 Speaker 4: The taxon, including the most recent common ancestor of living cetaceans, 603 00:35:25,360 --> 00:35:31,719 Speaker 4: nasofacial asymmetry. So again, asymmetrical placement of the nostrils in 604 00:35:31,760 --> 00:35:35,440 Speaker 4: the face becomes a significant feature of Odonto seti or 605 00:35:35,480 --> 00:35:38,840 Speaker 4: toothed whales in the early Oligocene, just like you said, 606 00:35:39,600 --> 00:35:44,120 Speaker 4: reaching its highest levels in extant taxa. Separate evolutionary regimes 607 00:35:44,160 --> 00:35:48,880 Speaker 4: are reconstructed for Odonta seats living in acoustically complex environments, 608 00:35:49,040 --> 00:35:53,839 Speaker 4: suggesting that these niches impose strong selective pressure on echolocation 609 00:35:53,960 --> 00:35:59,480 Speaker 4: ability and thus increased cranial asymmetry. So, to summarize these 610 00:35:59,520 --> 00:36:04,040 Speaker 4: skulls of toothed whales, specifically, the toothed ones just keep 611 00:36:04,080 --> 00:36:10,120 Speaker 4: getting weirder and more asymmetrical over evolutionary time, so as 612 00:36:10,160 --> 00:36:12,920 Speaker 4: the millions of years march on, the heads are getting 613 00:36:13,200 --> 00:36:16,880 Speaker 4: less and less symmetrical. And this is especially true apparently 614 00:36:17,320 --> 00:36:22,319 Speaker 4: in places where echolocation is more difficult due to environmental conditions. 615 00:36:22,440 --> 00:36:25,680 Speaker 4: And what could be an example of this, Well, I 616 00:36:25,760 --> 00:36:28,360 Speaker 4: was looking in the paper and this could be a coincidence, 617 00:36:28,400 --> 00:36:33,360 Speaker 4: but they note that the narwall has an unusually asymmetrical 618 00:36:33,440 --> 00:36:37,000 Speaker 4: skull apart from the tusk that juts out on one side. 619 00:36:37,640 --> 00:36:39,520 Speaker 4: So to read a quote from this paper with a 620 00:36:39,520 --> 00:36:43,600 Speaker 4: bit of paraphrasing, and remember the genus of the narwall 621 00:36:43,719 --> 00:36:49,200 Speaker 4: is Monodon one tooth, meaning Monodon monodon remains the most 622 00:36:49,239 --> 00:36:53,799 Speaker 4: asymmetric skull in the sample, even when the rostrum is removed, 623 00:36:53,920 --> 00:36:57,640 Speaker 4: which rules out the possibility that an asymmetric tusk and 624 00:36:57,760 --> 00:37:02,440 Speaker 4: residual teeth may be skewing there. All result, their unique 625 00:37:02,480 --> 00:37:07,680 Speaker 4: sound repertoire narrowband structured NBS is ideal for projecting and 626 00:37:07,760 --> 00:37:12,120 Speaker 4: receiving signals in icy shallow waters where the animals can 627 00:37:12,160 --> 00:37:16,399 Speaker 4: detect targets in high levels of ambient noise and backscatter. 628 00:37:17,000 --> 00:37:20,400 Speaker 4: So that's interesting. This could be a total coincidence. I 629 00:37:20,400 --> 00:37:24,200 Speaker 4: would not want to suggest a causal connection, but I 630 00:37:24,239 --> 00:37:26,240 Speaker 4: don't know. It stuck out to me that nar walls 631 00:37:26,320 --> 00:37:32,760 Speaker 4: have both strongly asymmetrical skulls, probably to aid in echolocation 632 00:37:32,920 --> 00:37:39,400 Speaker 4: in a difficult environment, and also extreme asymmetrical teeth, producing 633 00:37:39,440 --> 00:37:42,600 Speaker 4: these tusks, probably as a sexually selected trait. 634 00:37:43,120 --> 00:37:45,960 Speaker 1: Yeah. I mean again, it just goes to show you 635 00:37:46,080 --> 00:37:51,440 Speaker 1: just how weird whales are. Like, They're just so delightfully strange. 636 00:37:51,760 --> 00:37:53,680 Speaker 1: And again, it's easy to it's easy to take it 637 00:37:53,680 --> 00:37:57,000 Speaker 1: for granted if you don't lean in closely enough, you know. 638 00:37:57,440 --> 00:38:00,440 Speaker 4: But as wonderful as whale bodies are, they are not 639 00:38:00,640 --> 00:38:05,120 Speaker 4: the only creatures in the sea with striking and fascinating 640 00:38:05,200 --> 00:38:07,760 Speaker 4: imbalances between their left and right sides. 641 00:38:08,560 --> 00:38:11,960 Speaker 1: Yeah. There there are a number of fascinating examples we 642 00:38:11,960 --> 00:38:13,319 Speaker 1: could turn to, and I don't know, we may we 643 00:38:13,360 --> 00:38:15,600 Speaker 1: may come back to some more in future episodes. But 644 00:38:15,760 --> 00:38:21,520 Speaker 1: one that really caught my attention is Histiotoothus, the cock 645 00:38:21,600 --> 00:38:26,440 Speaker 1: eyed squid. So this is another example of essentially divided 646 00:38:26,480 --> 00:38:33,400 Speaker 1: attention and divided bodies in the deep ocean. So Histiotoothus 647 00:38:33,440 --> 00:38:37,880 Speaker 1: resides in the mesopelagic zone, or the twilight zone of 648 00:38:37,920 --> 00:38:40,719 Speaker 1: the ocean. And you can certainly think of this as 649 00:38:40,760 --> 00:38:47,160 Speaker 1: a realm situated between different kingdoms of illumination because above 650 00:38:47,400 --> 00:38:51,000 Speaker 1: this zone, above the creatures of this realm, well there 651 00:38:51,120 --> 00:38:55,680 Speaker 1: there's that, there's the distant kingdom of light. Okay, uh, 652 00:38:55,719 --> 00:38:59,359 Speaker 1: there's a dim illumination coming down from the sun from 653 00:38:59,400 --> 00:39:02,279 Speaker 1: the the the more sunlit portions of the ocean, and 654 00:39:02,360 --> 00:39:06,719 Speaker 1: so silhouettes can be viewed of creatures above you against 655 00:39:06,760 --> 00:39:11,719 Speaker 1: that faint light below you. Well, there's the great darkness 656 00:39:11,760 --> 00:39:16,000 Speaker 1: of the depths. But in that great darkness you'll glimpse, 657 00:39:16,200 --> 00:39:19,359 Speaker 1: or if you're a squid tom you'll glimpse sparkles and 658 00:39:19,400 --> 00:39:24,520 Speaker 1: pulsations of bioluminescence here and there. And of course both 659 00:39:24,520 --> 00:39:27,480 Speaker 1: of these sightings are important because they both have to 660 00:39:27,480 --> 00:39:30,560 Speaker 1: do with organisms that may be a threat, that may 661 00:39:30,560 --> 00:39:31,640 Speaker 1: be food, etc. 662 00:39:32,320 --> 00:39:34,680 Speaker 4: Oh. Well, this is so interesting because we know of 663 00:39:34,719 --> 00:39:37,759 Speaker 4: lots of examples on the surface world, say like lots 664 00:39:37,760 --> 00:39:40,239 Speaker 4: of herbivores on the surface world that have one eye 665 00:39:40,280 --> 00:39:42,240 Speaker 4: on each side of their head to try to provide 666 00:39:42,239 --> 00:39:44,640 Speaker 4: a sort of you know, as wide a field of 667 00:39:44,719 --> 00:39:47,239 Speaker 4: you as possible, so you can see things approaching you. 668 00:39:47,800 --> 00:39:50,680 Speaker 4: But this is a scenario where you might have a 669 00:39:50,800 --> 00:39:54,160 Speaker 4: head structured like that, but you have totally different seeing 670 00:39:54,320 --> 00:39:56,680 Speaker 4: needs on either side exactly. 671 00:39:56,719 --> 00:40:00,600 Speaker 1: And so that's what we see with Histiotoothis, as described 672 00:40:00,600 --> 00:40:04,600 Speaker 1: by Thomas, Robinson and Johnson in their twenty seventeen paper 673 00:40:04,680 --> 00:40:08,440 Speaker 1: in the Philosophical Transactions of the Royal Society B, it 674 00:40:08,520 --> 00:40:11,839 Speaker 1: is a creature with quote two eyes for two purposes. 675 00:40:12,400 --> 00:40:16,520 Speaker 1: So the squids two eyes here are dimorphic in size, shape, 676 00:40:16,520 --> 00:40:20,640 Speaker 1: and sometimes Lin's pigmentation. I included an image for you 677 00:40:20,680 --> 00:40:24,600 Speaker 1: to look at here, Joe and folks listening in. You 678 00:40:24,640 --> 00:40:27,600 Speaker 1: can look up images of this as well. Not all 679 00:40:27,640 --> 00:40:29,520 Speaker 1: images of the squid are going to really capture this, 680 00:40:29,760 --> 00:40:33,520 Speaker 1: but you'll find some that do. And it's very weird 681 00:40:33,719 --> 00:40:35,960 Speaker 1: when you can see both eyes at once because one 682 00:40:36,760 --> 00:40:39,160 Speaker 1: the the image I was looking at, one eye is 683 00:40:39,280 --> 00:40:42,359 Speaker 1: this great, big, kind of swollen looking eye that has 684 00:40:42,440 --> 00:40:45,719 Speaker 1: kind of a yellowish or greenish tint to it. It 685 00:40:45,760 --> 00:40:48,319 Speaker 1: may appear to be glowing the way that the light 686 00:40:48,400 --> 00:40:52,760 Speaker 1: is catching it, and the other eye appears a smaller, flatter, 687 00:40:53,920 --> 00:40:56,319 Speaker 1: you know, almost looks like if you didn't know what 688 00:40:56,360 --> 00:40:58,080 Speaker 1: you were looking at, you might think, oh, this poor 689 00:40:58,120 --> 00:41:00,800 Speaker 1: squid one of its eyes is in flow and swollen, 690 00:41:00,960 --> 00:41:04,239 Speaker 1: or one of its eyes has been severely wounded and 691 00:41:04,280 --> 00:41:07,720 Speaker 1: doesn't look like it's operating anymore. But no, both eyes 692 00:41:07,840 --> 00:41:12,040 Speaker 1: are operating. They're just pointed in different directions, and they 693 00:41:12,040 --> 00:41:16,759 Speaker 1: have evolved to see differently depending on the environments that 694 00:41:16,800 --> 00:41:17,800 Speaker 1: they're gazing into. 695 00:41:18,320 --> 00:41:23,520 Speaker 4: It's beautiful, one looks like a setting gangrenous sun, and 696 00:41:23,560 --> 00:41:26,680 Speaker 4: the other looks like a blueberry that's a little bit rotten. 697 00:41:27,239 --> 00:41:30,719 Speaker 1: Right, So it's thought that the larger of the two 698 00:41:30,760 --> 00:41:34,800 Speaker 1: eyes is honed to spot objects silhouetted against that dim 699 00:41:34,920 --> 00:41:39,080 Speaker 1: light above, while the smaller eye specializes in spotting the 700 00:41:39,120 --> 00:41:43,320 Speaker 1: sources of bioluminescence in the darkness below, and the squid 701 00:41:43,360 --> 00:41:46,960 Speaker 1: will actually position itself in a tail up position in 702 00:41:47,040 --> 00:41:52,920 Speaker 1: order to maximize this split vision. Furthermore, the authors share 703 00:41:51,360 --> 00:41:55,440 Speaker 1: that we do seem to have yellow pigments in the 704 00:41:55,520 --> 00:41:59,759 Speaker 1: larger eye that may serve to break the counter illumination 705 00:41:59,800 --> 00:42:04,520 Speaker 1: camouflage of their prey above. Counter Illumination is an active 706 00:42:04,600 --> 00:42:09,240 Speaker 1: camouflage method by which lights are produced on the body 707 00:42:09,280 --> 00:42:11,920 Speaker 1: to match background lights. So this would be used by 708 00:42:11,920 --> 00:42:14,359 Speaker 1: a creature to blend in with the light above it, 709 00:42:14,680 --> 00:42:18,680 Speaker 1: so that creatures below them don't so cleanly make out 710 00:42:18,680 --> 00:42:21,160 Speaker 1: their dark bodies against the dim lights above. 711 00:42:21,640 --> 00:42:24,480 Speaker 4: Oh that's a good survival strategy. Yeah, say you have 712 00:42:24,600 --> 00:42:26,920 Speaker 4: lights on your underside to mimic the sunlight. 713 00:42:27,320 --> 00:42:30,359 Speaker 1: Yeah. And so the yellow pigments in this larger eye 714 00:42:30,640 --> 00:42:33,000 Speaker 1: apparently helps to sort of break through some of that. 715 00:42:33,680 --> 00:42:37,880 Speaker 1: So the theory is that we see dimorphic specializations in 716 00:42:37,920 --> 00:42:42,560 Speaker 1: each eye as an adaptation to the split visual world. 717 00:42:42,800 --> 00:42:47,279 Speaker 1: And this actually reminded me of a bit from a 718 00:42:47,320 --> 00:42:50,240 Speaker 1: Doctor Seuss book. I had trouble in getting to Sola Salu, 719 00:42:50,719 --> 00:42:52,759 Speaker 1: where you have this character who's dealing with a bunch 720 00:42:52,800 --> 00:42:55,960 Speaker 1: of threats and it goes So I said to myself, now, 721 00:42:55,960 --> 00:42:58,320 Speaker 1: I'll just have to start to be twice as careful 722 00:42:58,320 --> 00:43:01,000 Speaker 1: and be twice as smart. I'll watch out for trouble 723 00:43:01,160 --> 00:43:03,759 Speaker 1: in front and back sections by aiming my eyeballs in 724 00:43:03,840 --> 00:43:07,040 Speaker 1: different directions. And you have this character that's kind of 725 00:43:07,040 --> 00:43:09,880 Speaker 1: like a little bear creature in his eyes or gazing 726 00:43:09,920 --> 00:43:12,920 Speaker 1: off in different directions. But essentially like that's kind of 727 00:43:12,960 --> 00:43:15,239 Speaker 1: what is going on with the cock eyed squid here. 728 00:43:15,520 --> 00:43:18,239 Speaker 4: That's great, it is so I was trying to imagine 729 00:43:18,560 --> 00:43:22,279 Speaker 4: what scenario could give rise to something like this on 730 00:43:22,480 --> 00:43:25,759 Speaker 4: a land dwelling herbivore. You know, so you have like 731 00:43:25,800 --> 00:43:28,680 Speaker 4: a bovine that's grazing, what it needs to have totally 732 00:43:28,680 --> 00:43:31,200 Speaker 4: different types of eyes or vision on one side of 733 00:43:31,200 --> 00:43:33,080 Speaker 4: the head. And I imagine what about some kind of 734 00:43:33,440 --> 00:43:36,399 Speaker 4: bovine that lives on a tidally locked world and it 735 00:43:36,719 --> 00:43:40,640 Speaker 4: lives at the terminator line, So it's one eye needs 736 00:43:40,640 --> 00:43:43,560 Speaker 4: to be like shielded because it's always facing toward the 737 00:43:43,600 --> 00:43:45,799 Speaker 4: hot side of the planet, and the other eye needs 738 00:43:45,840 --> 00:43:48,200 Speaker 4: to be very sensitive because it's always facing toward the 739 00:43:48,280 --> 00:43:49,560 Speaker 4: dark side. I don't know. 740 00:43:49,880 --> 00:43:52,640 Speaker 1: Oh, that's interesting. Yeah, I mean, I guess that would 741 00:43:52,680 --> 00:43:55,120 Speaker 1: be the region that you a life form might be 742 00:43:55,320 --> 00:43:59,160 Speaker 1: likely to live in because you would have less of 743 00:43:59,200 --> 00:44:02,719 Speaker 1: an extreme of heat or cold. But of course it 744 00:44:02,760 --> 00:44:06,200 Speaker 1: would also be a chaotic region as well. You would 745 00:44:06,200 --> 00:44:10,239 Speaker 1: have probably have a lot of climactic weather going on there. 746 00:44:10,400 --> 00:44:12,960 Speaker 4: Yeah's tidally logged plan. It's probably not great for goats. 747 00:44:13,040 --> 00:44:15,280 Speaker 4: But I was just trying to imagine. 748 00:44:15,520 --> 00:44:18,080 Speaker 1: But no, that's conceivably that's the kind of environment that 749 00:44:18,200 --> 00:44:22,160 Speaker 1: might require some sort of drastic change in the positioning 750 00:44:22,200 --> 00:44:25,920 Speaker 1: of the eyes. And the specialization of the eyes. I mean, 751 00:44:26,719 --> 00:44:29,160 Speaker 1: I feel like we I mean, we're so hardwired for 752 00:44:29,480 --> 00:44:32,799 Speaker 1: our surface world environment. It is difficult for us. It's 753 00:44:33,000 --> 00:44:35,400 Speaker 1: a little challenging to put ourselves in the mindset and 754 00:44:35,480 --> 00:44:39,520 Speaker 1: ultimately the ocular world of something like a goat or 755 00:44:39,560 --> 00:44:43,239 Speaker 1: something like a you know, a purely predatory cat or 756 00:44:43,280 --> 00:44:46,640 Speaker 1: something much less. To put ourselves in the mind set 757 00:44:46,719 --> 00:44:50,000 Speaker 1: in the ocular world of the squid or or you know, 758 00:44:50,120 --> 00:44:53,200 Speaker 1: to get into the sense worlds of whales and so forth, it's, 759 00:44:53,800 --> 00:44:57,880 Speaker 1: you know, it's it's a different environment altogether. In these environments. 760 00:44:57,960 --> 00:45:00,640 Speaker 1: As we see from these examples, we've looked like they 761 00:45:01,480 --> 00:45:04,120 Speaker 1: almost literally can pull us in half. You know, they 762 00:45:04,200 --> 00:45:09,880 Speaker 1: can change it. They can break whatever seeming symmetry was 763 00:45:09,920 --> 00:45:13,719 Speaker 1: there in the body originally as it adapts, as it 764 00:45:13,719 --> 00:45:16,000 Speaker 1: evolves to fit this environment over time. 765 00:45:17,200 --> 00:45:19,400 Speaker 4: This raises a question that comes to my mind. Actually 766 00:45:19,480 --> 00:45:22,520 Speaker 4: quite often we think about, like, if there were other 767 00:45:22,719 --> 00:45:27,800 Speaker 4: clades of animals that became very intelligent and had something 768 00:45:27,920 --> 00:45:31,600 Speaker 4: like art, would what would they find beautiful? And how 769 00:45:31,640 --> 00:45:34,400 Speaker 4: would it be different from what we find beautiful based 770 00:45:34,440 --> 00:45:38,879 Speaker 4: on our brains and our biology. Yeah, but I think 771 00:45:38,920 --> 00:45:41,719 Speaker 4: maybe we're going to have to call the first episode there. 772 00:45:41,840 --> 00:45:45,560 Speaker 4: We will certainly be back with more marvels of asymmetry, 773 00:45:45,640 --> 00:45:49,040 Speaker 4: and in subsequent episodes we're going to talk about crabs 774 00:45:49,040 --> 00:45:52,040 Speaker 4: and crustaceans, and I think we'll talk about snakes some 775 00:45:52,280 --> 00:45:55,400 Speaker 4: probably come back to some fish, and maybe some larger 776 00:45:55,480 --> 00:46:00,600 Speaker 4: developmental theoretical concerns about where asymmetry comes from in the 777 00:46:01,239 --> 00:46:02,480 Speaker 4: Kingdoms of Life. 778 00:46:03,120 --> 00:46:05,640 Speaker 1: That's right. In the meantime, you can check out other 779 00:46:05,680 --> 00:46:07,480 Speaker 1: episodes of Stuff to Blow Your Mind and the Stuff 780 00:46:07,480 --> 00:46:10,000 Speaker 1: to Blow Your Mind podcast feed which you can find 781 00:46:10,040 --> 00:46:12,920 Speaker 1: wherever you get your podcast. Tuesdays and Thursdays are our 782 00:46:13,000 --> 00:46:17,760 Speaker 1: core episodes. We have a short form artifact or monster 783 00:46:17,840 --> 00:46:20,799 Speaker 1: fact on Wednesday, little listener mail on Monday, and then 784 00:46:20,840 --> 00:46:23,120 Speaker 1: on Friday we do Weird House Cinema. That's our time 785 00:46:23,160 --> 00:46:25,640 Speaker 1: to set aside most serious concerns and just talk about 786 00:46:25,680 --> 00:46:27,000 Speaker 1: a strange film. 787 00:46:27,239 --> 00:46:30,160 Speaker 4: Huge thanks as always to our excellent audio producer Seth 788 00:46:30,239 --> 00:46:32,640 Speaker 4: Nicholas Johnson. If you would like to get in touch 789 00:46:32,680 --> 00:46:34,960 Speaker 4: with us with feedback on this episode or any other, 790 00:46:35,040 --> 00:46:37,080 Speaker 4: to suggest a topic for the future, or just to 791 00:46:37,080 --> 00:46:39,720 Speaker 4: say hello, you can email us at contact at stuff 792 00:46:39,719 --> 00:46:47,000 Speaker 4: to Blow your Mind dot com. 793 00:46:48,640 --> 00:46:51,560 Speaker 3: Stuff to Blow your Mind is production of iHeartRadio. For 794 00:46:51,680 --> 00:46:54,480 Speaker 3: more podcasts from my heart Radio, visit the iHeartRadio app, 795 00:46:54,600 --> 00:47:11,560 Speaker 3: Apple podcasts, or wherever you're listening to your favorite shows.