1 00:00:03,040 --> 00:00:05,360 Speaker 1: Welcome to Stuff to Blow Your Mind production of My 2 00:00:05,480 --> 00:00:14,840 Speaker 1: Heart Radio. Hey you welcome to Stuff to Blow your Mind. 3 00:00:14,960 --> 00:00:17,599 Speaker 1: My name is Robert Lamb and I'm Joe McCormick. Can 4 00:00:17,640 --> 00:00:19,919 Speaker 1: we're back with part three in our series on a 5 00:00:20,160 --> 00:00:23,720 Speaker 1: symmetry in animals when the left and the right side 6 00:00:23,760 --> 00:00:26,960 Speaker 1: do not match. If you have not listened to parts 7 00:00:27,000 --> 00:00:28,880 Speaker 1: one and two yet, why not go back and do 8 00:00:28,960 --> 00:00:31,440 Speaker 1: that first, then you'll be all caught up. But in 9 00:00:31,520 --> 00:00:35,199 Speaker 1: the last episode of this series, we were talking about 10 00:00:35,400 --> 00:00:39,919 Speaker 1: asymmetrical development in the clause of the American lobster or 11 00:00:39,920 --> 00:00:45,280 Speaker 1: Homarus americanus, and how during larval development, the lobsters previously 12 00:00:45,360 --> 00:00:50,519 Speaker 1: symmetrical clause differentiate into one real thick boy. It's a 13 00:00:50,600 --> 00:00:53,840 Speaker 1: crusher claw, it's gigantic, it's got like moler like teeth 14 00:00:53,920 --> 00:00:56,960 Speaker 1: on it, and it's got slow muscle fiber. And then 15 00:00:57,000 --> 00:01:00,840 Speaker 1: the other one turns into a sharper cutter, pincher claw 16 00:01:00,960 --> 00:01:04,119 Speaker 1: that can close very fast because of its fast muscle fiber. 17 00:01:04,640 --> 00:01:08,280 Speaker 1: And we talked about attempts to pin down exactly why 18 00:01:08,400 --> 00:01:11,160 Speaker 1: and how this happens at this these early stages in 19 00:01:11,240 --> 00:01:16,319 Speaker 1: lobster development. But there are other crustaceans where the mismatch 20 00:01:16,440 --> 00:01:19,600 Speaker 1: between left and right is much more extreme than it 21 00:01:19,680 --> 00:01:23,080 Speaker 1: is even in the American lobster. And I think we 22 00:01:23,080 --> 00:01:27,080 Speaker 1: should begin this episode by considering the male of the 23 00:01:27,120 --> 00:01:32,800 Speaker 1: many species of fiddler crabs. So fiddler crabs comprise it's 24 00:01:32,840 --> 00:01:35,679 Speaker 1: not just one species of animal, its many species within 25 00:01:35,720 --> 00:01:38,680 Speaker 1: a family of crustaceans known as O. C. Pot to 26 00:01:38,760 --> 00:01:42,199 Speaker 1: day And uh. Once again, I think we keep saying 27 00:01:42,200 --> 00:01:44,000 Speaker 1: it during the series, but this is one you should 28 00:01:44,000 --> 00:01:46,760 Speaker 1: go and look up pictures of because you need to 29 00:01:46,800 --> 00:01:50,600 Speaker 1: have it in your head. In some species, male fiddler 30 00:01:50,640 --> 00:01:53,880 Speaker 1: crabs have one claw that grows not just bigger than 31 00:01:53,920 --> 00:01:56,840 Speaker 1: the other one, not not even just significantly bigger than 32 00:01:56,840 --> 00:02:00,960 Speaker 1: the other one, but hilariously bigger than the other one. Yeah. Like, 33 00:02:01,560 --> 00:02:03,480 Speaker 1: like going back to lobsters for a second, you'd be 34 00:02:03,520 --> 00:02:06,160 Speaker 1: forgiven if you were just not aware of the fact 35 00:02:06,200 --> 00:02:09,480 Speaker 1: that lobster has had this different this this difference between 36 00:02:09,520 --> 00:02:12,800 Speaker 1: one claw and the next. Uh. You know, certainly many 37 00:02:12,880 --> 00:02:17,920 Speaker 1: illustrations I'm thinking, like restaurant logos and whatnot, may not 38 00:02:18,000 --> 00:02:20,600 Speaker 1: even bother to make one claw look different from the other. 39 00:02:20,800 --> 00:02:24,280 Speaker 1: But with the fiddler crab, it is very pronounced. It 40 00:02:24,440 --> 00:02:29,200 Speaker 1: is it is absurdly different one side from the other. Yeah. 41 00:02:29,320 --> 00:02:32,040 Speaker 1: And for a bit of experts summary on what life 42 00:02:32,120 --> 00:02:34,919 Speaker 1: is like for your average fiddler crab, I wanted to 43 00:02:35,000 --> 00:02:37,440 Speaker 1: quote from a New York Times interview I was reading 44 00:02:37,480 --> 00:02:41,920 Speaker 1: with a researcher named Sophie L. Moles, who is a 45 00:02:42,000 --> 00:02:46,600 Speaker 1: scientist at Anglia Ruskin University in Cambridge and has done 46 00:02:46,639 --> 00:02:49,560 Speaker 1: some research on fiddler crabs, including the use of a 47 00:02:49,720 --> 00:02:53,119 Speaker 1: robotic fiddler crab claw that I want to come back 48 00:02:53,120 --> 00:02:55,720 Speaker 1: to later in this episode, but just in summarizing fiddler 49 00:02:55,720 --> 00:02:59,720 Speaker 1: crab life, she says, they live in burrows and you 50 00:02:59,760 --> 00:03:02,440 Speaker 1: only see them at low tide. At high tide, they 51 00:03:02,440 --> 00:03:04,520 Speaker 1: go back into the burrow and they seal it up. 52 00:03:04,960 --> 00:03:08,560 Speaker 1: They feed on mud flats by sifting the sediment through 53 00:03:08,600 --> 00:03:13,040 Speaker 1: their mouth parts and eating micro organisms. That's the buffet 54 00:03:13,080 --> 00:03:15,880 Speaker 1: of life. You just sift the mud in your mouth 55 00:03:16,000 --> 00:03:19,720 Speaker 1: and get the microbes out. But Moles goes on. The 56 00:03:19,760 --> 00:03:23,440 Speaker 1: female has two little claws to normal size claws for 57 00:03:23,520 --> 00:03:26,160 Speaker 1: her which she uses to help that feeding, to help 58 00:03:26,200 --> 00:03:29,640 Speaker 1: pass the sediment up to her mouth. The male has 59 00:03:29,840 --> 00:03:33,240 Speaker 1: one that it uses for feeding, and the other is huge. 60 00:03:33,760 --> 00:03:36,320 Speaker 1: It's greatly enlarged to the point that it can be 61 00:03:36,360 --> 00:03:40,760 Speaker 1: approximately half of his body weight. It's often really brightly 62 00:03:40,800 --> 00:03:43,880 Speaker 1: colored as well. Now, what the males do is they 63 00:03:43,960 --> 00:03:47,480 Speaker 1: wave this claw in a species specific pattern. So each 64 00:03:47,600 --> 00:03:50,480 Speaker 1: species of fiddler crab has its own kind of wave, 65 00:03:50,880 --> 00:03:53,680 Speaker 1: and they do this to maintain a territory but also 66 00:03:53,840 --> 00:03:58,360 Speaker 1: to attract a female. Uh So, for for a rough 67 00:03:58,400 --> 00:04:02,400 Speaker 1: analogy on the size and appearance of a fiddler crab claw, 68 00:04:03,000 --> 00:04:07,200 Speaker 1: uh just imagine an adult human that had one normal 69 00:04:07,280 --> 00:04:09,880 Speaker 1: sized right hand, but then a left hand with a 70 00:04:09,960 --> 00:04:12,880 Speaker 1: digit span of about four ft in that hand washs 71 00:04:13,000 --> 00:04:17,599 Speaker 1: eighty pounds. Yeah. One uh. One example of this is 72 00:04:17,640 --> 00:04:19,280 Speaker 1: that is Brobabing, a book I'm going to reference in 73 00:04:19,400 --> 00:04:23,239 Speaker 1: a bit Um Animal Weapons by Douglas j Emlyn. Uh. 74 00:04:23,279 --> 00:04:25,520 Speaker 1: He says, if you're if you're basically if you're at 75 00:04:25,560 --> 00:04:28,039 Speaker 1: the store, go pick up the largest bag of dry 76 00:04:28,160 --> 00:04:31,239 Speaker 1: dog food that you can find and start carrying it around, 77 00:04:31,680 --> 00:04:34,960 Speaker 1: and that will give you approximately what we might think 78 00:04:35,000 --> 00:04:38,640 Speaker 1: of is the male fiddler crab experience. So yeah, so 79 00:04:38,720 --> 00:04:41,880 Speaker 1: imagine the largest sized bag of dog food. Not just 80 00:04:42,000 --> 00:04:44,960 Speaker 1: you're carrying it around, but that is one of your hands, 81 00:04:45,640 --> 00:04:49,480 Speaker 1: and again the other one is regular sized. So what 82 00:04:49,480 --> 00:04:53,560 Speaker 1: what is going on with having a crab claw that big. Well, 83 00:04:53,600 --> 00:04:57,720 Speaker 1: it turns out that the main theory explaining this asymmetric 84 00:04:58,080 --> 00:05:01,839 Speaker 1: size difference in fiddler crab claws is much like the 85 00:05:01,880 --> 00:05:05,919 Speaker 1: main theory for explaining the narwhal tusk, that this hugely 86 00:05:06,120 --> 00:05:11,120 Speaker 1: asymmetrically exaggerated feature found in males is probably primarily a 87 00:05:11,279 --> 00:05:16,320 Speaker 1: sexually selected trait, meaning it's more important for maximizing reproductive 88 00:05:16,360 --> 00:05:20,039 Speaker 1: success than it is for direct survival value, though it 89 00:05:20,160 --> 00:05:25,640 Speaker 1: may be in part reproductively attractive attractive to mates because 90 00:05:25,800 --> 00:05:30,080 Speaker 1: of some value it has in helping maximize like burrowing. So, 91 00:05:30,240 --> 00:05:33,440 Speaker 1: for example, things that have been cited are that a 92 00:05:33,480 --> 00:05:36,800 Speaker 1: male that has a very big claw can also probably 93 00:05:36,880 --> 00:05:39,440 Speaker 1: dig a very big burrow, which is better for a 94 00:05:39,480 --> 00:05:43,200 Speaker 1: female to go into to incubate her eggs. And also, 95 00:05:43,720 --> 00:05:47,400 Speaker 1: like crustaceans, tend to just keep getting bigger as they 96 00:05:47,440 --> 00:05:50,679 Speaker 1: as they grow as they grow older, So a bigger 97 00:05:50,720 --> 00:05:54,480 Speaker 1: crab with a bigger asymmetric claw is also probably an 98 00:05:54,520 --> 00:05:58,679 Speaker 1: older male, which is good in crab mating terms because 99 00:05:58,720 --> 00:06:01,240 Speaker 1: that probably means he has served I have more seasons 100 00:06:01,240 --> 00:06:04,560 Speaker 1: of life, and is just generally fitter, better able to 101 00:06:04,600 --> 00:06:08,720 Speaker 1: survive and has good genes. Yeah, yeah, And I mean 102 00:06:08,839 --> 00:06:11,440 Speaker 1: part of the obvious display here too is like, look 103 00:06:11,440 --> 00:06:13,520 Speaker 1: at this thing I have grown. It is so big, 104 00:06:13,839 --> 00:06:15,880 Speaker 1: and yet I am still alive. I am able to 105 00:06:15,920 --> 00:06:20,840 Speaker 1: sustain myself. Plus this massive claw, it's like the sports 106 00:06:20,920 --> 00:06:24,280 Speaker 1: car of the crab anatomy. Yeah. That that's another thing 107 00:06:24,320 --> 00:06:25,800 Speaker 1: that has often been put up. There's sort of a 108 00:06:25,839 --> 00:06:30,640 Speaker 1: theory in some sexually selected traits in biology that says, well, 109 00:06:30,680 --> 00:06:34,800 Speaker 1: they may operate on the basis of essentially advertising a handicap. 110 00:06:34,920 --> 00:06:38,600 Speaker 1: They offer a good faith display that even by working 111 00:06:38,720 --> 00:06:42,039 Speaker 1: at a disadvantage, you're still fit enough to to do 112 00:06:42,160 --> 00:06:45,960 Speaker 1: well within your environment by having this ridiculous thing attached 113 00:06:46,000 --> 00:06:48,679 Speaker 1: to you. So a male fiddler crab is running around 114 00:06:48,680 --> 00:06:51,159 Speaker 1: also basically advertising. I mean, this would be true of 115 00:06:51,160 --> 00:06:54,120 Speaker 1: all the males with the big the big claw, and 116 00:06:54,200 --> 00:06:56,960 Speaker 1: that they have basically have to their capacity to eat, 117 00:06:57,320 --> 00:06:59,600 Speaker 1: you know. So these crabs eat by shoving mud and 118 00:06:59,640 --> 00:07:01,839 Speaker 1: to bring into their mouths, and that's true for males 119 00:07:01,839 --> 00:07:04,800 Speaker 1: and females, but of course you can't do that with 120 00:07:04,839 --> 00:07:09,240 Speaker 1: that gigantic claw. So essentially the male fiddler crabs they 121 00:07:09,279 --> 00:07:13,960 Speaker 1: got them one good eating hand. Whereas females have to. Yes, absolutely, 122 00:07:13,960 --> 00:07:16,240 Speaker 1: And you know this is something that that that Emelyn 123 00:07:16,320 --> 00:07:20,160 Speaker 1: gets into an animal weapons um, basically getting into just 124 00:07:20,240 --> 00:07:24,520 Speaker 1: the energy costs of having this gigantic claw. Uh So 125 00:07:24,560 --> 00:07:27,280 Speaker 1: some of this is gonna be repeated what we just said, 126 00:07:27,280 --> 00:07:30,600 Speaker 1: but it all kind of builds together. So, first of all, 127 00:07:30,720 --> 00:07:33,480 Speaker 1: male fiddlers, he says, burn a lot of energy just 128 00:07:33,560 --> 00:07:35,640 Speaker 1: to have these, just to you know, develop them and 129 00:07:35,680 --> 00:07:39,560 Speaker 1: carry them around resting. Metabolic rates of males with big 130 00:07:39,600 --> 00:07:43,720 Speaker 1: claws are almost twenty percent higher than females due to 131 00:07:43,760 --> 00:07:46,640 Speaker 1: the cost of the claw. And then, of course, on 132 00:07:46,720 --> 00:07:50,560 Speaker 1: top of this, you're gonna have to scamper around. We 133 00:07:50,640 --> 00:07:53,360 Speaker 1: see everyone out there. I think it's probably seen crabs 134 00:07:53,400 --> 00:07:56,560 Speaker 1: about doing their business on the beach. You've got to 135 00:07:56,560 --> 00:07:59,280 Speaker 1: scamper around, You've got to run with that giant claw, 136 00:07:59,400 --> 00:08:02,320 Speaker 1: and so this is going to be energetically demanding as well. 137 00:08:02,800 --> 00:08:05,040 Speaker 1: Yeah I can how fast can you run holding that 138 00:08:05,080 --> 00:08:07,560 Speaker 1: dog food bag? Exactly? Yeah, this is this is where 139 00:08:07,560 --> 00:08:11,120 Speaker 1: he originally brought up the dog food bag. But um, 140 00:08:11,440 --> 00:08:14,040 Speaker 1: he also cites a study This one was really fun. 141 00:08:14,400 --> 00:08:17,520 Speaker 1: This is two thousand seven study that was published in 142 00:08:17,600 --> 00:08:22,240 Speaker 1: Functional Ecology by Alan and Levinton, and they were testing 143 00:08:22,280 --> 00:08:26,400 Speaker 1: this out by putting male fiddler crabs on treadmills, little 144 00:08:26,440 --> 00:08:31,080 Speaker 1: treadmills inside of air tight boxes. Now, sadly I could 145 00:08:31,080 --> 00:08:33,080 Speaker 1: not find photos of this that I brought up the 146 00:08:33,080 --> 00:08:36,679 Speaker 1: original paper and there were no photos or illustrations, so 147 00:08:36,760 --> 00:08:39,520 Speaker 1: I only have my imagination to go on. Here. This 148 00:08:39,559 --> 00:08:42,000 Speaker 1: is the shrimp shrimp on a treadmill paper that you 149 00:08:42,080 --> 00:08:46,560 Speaker 1: promised in previous parts, right right, Yeah, shrimp on a 150 00:08:46,559 --> 00:08:49,320 Speaker 1: treadmill for anyone not familiar, That frequently brought up as 151 00:08:49,520 --> 00:08:52,360 Speaker 1: there was an actual shrimp on a treadmill study, and 152 00:08:52,640 --> 00:08:55,480 Speaker 1: it was used as an outrageous example of like, look 153 00:08:55,480 --> 00:08:57,880 Speaker 1: at what the scientists are doing. They won't cure cancer, 154 00:08:57,920 --> 00:09:00,360 Speaker 1: but they'll put a shrimp on a treadmill. And as 155 00:09:00,400 --> 00:09:02,840 Speaker 1: we've discussed in the show before, that's that's kind of ridiculous. 156 00:09:02,920 --> 00:09:05,560 Speaker 1: I mean, these are not the scientists that would be 157 00:09:05,600 --> 00:09:07,880 Speaker 1: developing the cure for cancer. These are the ones that 158 00:09:07,880 --> 00:09:10,800 Speaker 1: would be studying, say, the metabolic rates of shrimp or 159 00:09:10,840 --> 00:09:14,360 Speaker 1: in this case crabs, right there, not mutually exclusive pursuits 160 00:09:14,400 --> 00:09:17,240 Speaker 1: to begin with. But then also sometimes you don't even 161 00:09:17,280 --> 00:09:20,360 Speaker 1: know what benefits that new knowledge about animal life could 162 00:09:20,400 --> 00:09:23,520 Speaker 1: lead to down the road. Yeah. Absolutely, And so the 163 00:09:23,840 --> 00:09:27,160 Speaker 1: study put the crabs on the treadmills inside of the 164 00:09:27,160 --> 00:09:29,040 Speaker 1: air tight boxes. And you might be one of will, 165 00:09:29,080 --> 00:09:31,920 Speaker 1: why the air tight box It sounds like something from 166 00:09:31,960 --> 00:09:35,280 Speaker 1: a Saw movie. Uh No, it's because as the crabs 167 00:09:35,360 --> 00:09:38,559 Speaker 1: exert themselves, uh, they burn through oxygen and they produce 168 00:09:38,640 --> 00:09:41,080 Speaker 1: c O two. And so the researchers are then able 169 00:09:41,120 --> 00:09:44,480 Speaker 1: to measure the gas concentrations inside of the little boxes, 170 00:09:44,960 --> 00:09:48,760 Speaker 1: and they use these readings to calculate the exact metabolic 171 00:09:48,840 --> 00:09:52,360 Speaker 1: costs of running. As one might expect, the males with 172 00:09:52,440 --> 00:09:57,199 Speaker 1: big claws burned more energy to run compared to smaller males, 173 00:09:57,720 --> 00:09:59,840 Speaker 1: males with the smaller claw or females and of course 174 00:09:59,880 --> 00:10:04,760 Speaker 1: just have two regularly sized claws, and these big males 175 00:10:04,760 --> 00:10:08,080 Speaker 1: with the big claws also tired out more quickly. And 176 00:10:08,160 --> 00:10:11,160 Speaker 1: then there's the impact on feeding, which we've already alluded to. 177 00:10:11,320 --> 00:10:14,520 Speaker 1: You know, we we've all seen a crab eat. I know, 178 00:10:14,559 --> 00:10:17,720 Speaker 1: we've talked about it on the show. Crabs disassemble their food. 179 00:10:18,280 --> 00:10:21,400 Speaker 1: Their claws and mouth bits work very hard to break 180 00:10:21,440 --> 00:10:23,520 Speaker 1: everything down, or in the case of Fiddler, crabs are 181 00:10:23,520 --> 00:10:26,679 Speaker 1: often just sifting through and finding those little tiny pieces 182 00:10:26,720 --> 00:10:30,880 Speaker 1: to eat. Anyway, it's what Inland describes as quote delicate 183 00:10:30,960 --> 00:10:35,480 Speaker 1: and tedious, and with the females it means it often 184 00:10:35,520 --> 00:10:38,520 Speaker 1: means the feeding claws are just working incessantly. Yeah, you 185 00:10:38,559 --> 00:10:40,360 Speaker 1: can see video of this. So there's just like a 186 00:10:40,400 --> 00:10:44,600 Speaker 1: conveyor belt. They're just machines kind of shoveling the sediment 187 00:10:44,679 --> 00:10:47,080 Speaker 1: into the mouth. But the male, on the other hand, 188 00:10:47,240 --> 00:10:50,320 Speaker 1: like we said, only has the one claw that's suitable 189 00:10:50,400 --> 00:10:53,120 Speaker 1: to eat with anymore. He's got that big claw just 190 00:10:53,400 --> 00:10:56,200 Speaker 1: setting there, and then the other claud the normal size claws, 191 00:10:56,240 --> 00:10:59,240 Speaker 1: is the one that he's using to eat. So, uh, 192 00:10:59,360 --> 00:11:02,840 Speaker 1: this cuts their energy intake in half, just as lugging 193 00:11:02,840 --> 00:11:06,559 Speaker 1: the giant claw around increases their energy output. So they 194 00:11:06,600 --> 00:11:10,760 Speaker 1: generally have to feed faster and or more often in 195 00:11:10,840 --> 00:11:13,559 Speaker 1: order to make up the difference. Right again, because you've 196 00:11:13,559 --> 00:11:17,000 Speaker 1: got to they've they've divided their body into eating hand 197 00:11:17,080 --> 00:11:22,800 Speaker 1: and and handsome hand. Right, And this is this complicates 198 00:11:22,800 --> 00:11:25,320 Speaker 1: things for the crabs even more because remember, uh, this 199 00:11:25,400 --> 00:11:27,920 Speaker 1: is not an apex predator we're talking about here. The 200 00:11:27,960 --> 00:11:31,679 Speaker 1: crab and the fiddler crab especially, they have to concern 201 00:11:31,720 --> 00:11:35,960 Speaker 1: themselves with predators especially of the avian variety. Send So 202 00:11:36,080 --> 00:11:38,719 Speaker 1: of the of this crab with this big claw that's 203 00:11:38,720 --> 00:11:43,319 Speaker 1: having to do extra feeding, that means extra exposure to 204 00:11:43,440 --> 00:11:46,880 Speaker 1: potential predation. In fact, studies have proven out that these 205 00:11:46,920 --> 00:11:50,800 Speaker 1: males are picked off by birds at an enhanced rate. Right, 206 00:11:50,840 --> 00:11:53,640 Speaker 1: So you're saying because it eats slower, because it can 207 00:11:53,640 --> 00:11:55,840 Speaker 1: only eat with one of its claws, it has to 208 00:11:55,880 --> 00:11:58,439 Speaker 1: spend more time outside the burrow, and that's got a 209 00:11:58,520 --> 00:12:01,240 Speaker 1: target on its back. Exact. Yeah, it's more time out 210 00:12:01,240 --> 00:12:06,000 Speaker 1: in the open, more time exposed to predators, and the 211 00:12:06,120 --> 00:12:10,360 Speaker 1: predators in many cases they they have advanced tactics for 212 00:12:10,440 --> 00:12:15,199 Speaker 1: dealing with these. Um, these these either tired or distracted 213 00:12:15,360 --> 00:12:18,840 Speaker 1: or essentially one claude crab at this point when it 214 00:12:18,840 --> 00:12:21,760 Speaker 1: comes to the feeding process. Uh Inland points to a 215 00:12:21,800 --> 00:12:25,320 Speaker 1: study from Christy Blackwell and Cooga regarding fiddler crabs in 216 00:12:25,360 --> 00:12:30,160 Speaker 1: Panama getting basically taken out by grackles fed on by 217 00:12:30,160 --> 00:12:32,760 Speaker 1: grackles who as the type of bird that have devised 218 00:12:32,800 --> 00:12:37,719 Speaker 1: a diagonal faint attack um where they kind of they 219 00:12:37,720 --> 00:12:39,439 Speaker 1: come in, they kind of fake the crab out and 220 00:12:39,480 --> 00:12:42,560 Speaker 1: apparently this is even more effective on the male crabs. 221 00:12:42,960 --> 00:12:45,960 Speaker 1: Now you might think, well, but wait a minute, Um, 222 00:12:46,200 --> 00:12:49,240 Speaker 1: having a bigger claw surely also means that that crab 223 00:12:49,320 --> 00:12:52,360 Speaker 1: can pinch with greater force, which you would think could 224 00:12:52,400 --> 00:12:55,880 Speaker 1: make it able to defend itself better. Right, Yeah, I 225 00:12:55,880 --> 00:12:59,000 Speaker 1: mean you you might you might think that, but but 226 00:12:59,120 --> 00:13:02,120 Speaker 1: then you know, as we'll into like these claws, uh, 227 00:13:02,240 --> 00:13:06,000 Speaker 1: this big claw anyway, it doesn't seem to be that 228 00:13:06,200 --> 00:13:09,280 Speaker 1: useful when you're dealing with something like a hungry grackle 229 00:13:09,360 --> 00:13:12,040 Speaker 1: that's sweeping in at you. Uh So, like the end 230 00:13:12,080 --> 00:13:14,559 Speaker 1: result is that the big claude males, they're easier to find, 231 00:13:14,679 --> 00:13:18,080 Speaker 1: they're easier to pick off, they're potentially more tired, and 232 00:13:18,800 --> 00:13:21,680 Speaker 1: also they're a better uh they're they're a better kill 233 00:13:21,760 --> 00:13:24,160 Speaker 1: for the predator because that big old claw has big 234 00:13:24,160 --> 00:13:27,280 Speaker 1: old meat in it. So there's every reason in the 235 00:13:27,320 --> 00:13:29,600 Speaker 1: world to kill them and eat them if you were 236 00:13:29,640 --> 00:13:32,400 Speaker 1: a grackle or some other hungry bird. Now, from what 237 00:13:32,520 --> 00:13:36,000 Speaker 1: I've read about fiddler crab claws, it seems like what 238 00:13:36,040 --> 00:13:39,040 Speaker 1: they are most of the time used for is is 239 00:13:39,480 --> 00:13:43,360 Speaker 1: is probably visual signaling, but they are on occasion actually 240 00:13:43,480 --> 00:13:46,920 Speaker 1: used for fighting or actually used as a weapon. Yeah. Yeah. 241 00:13:46,960 --> 00:13:50,000 Speaker 1: Emlin gets into this in the book as well. Highlighting 242 00:13:50,200 --> 00:13:53,200 Speaker 1: particularly the work of John Christie. I believe he was 243 00:13:53,200 --> 00:13:57,199 Speaker 1: in the second study that that was cited there that 244 00:13:57,320 --> 00:14:00,760 Speaker 1: we decided. Uh So basically, yeah, they wave them around 245 00:14:00,800 --> 00:14:04,920 Speaker 1: to communicate their reproductive fitness. They do fight other male 246 00:14:05,080 --> 00:14:08,920 Speaker 1: fiddler crabs with them, so they do serve as actual 247 00:14:09,000 --> 00:14:13,240 Speaker 1: weapons in contests for those burrows that we were talking about. 248 00:14:13,840 --> 00:14:16,520 Speaker 1: But inland rights that quote, for every few minutes of 249 00:14:16,640 --> 00:14:22,480 Speaker 1: outright fighting, mail spend dozens of hours waving, in other words, communicating, 250 00:14:22,800 --> 00:14:25,800 Speaker 1: showing off that claw, saying look, you know, look at 251 00:14:25,800 --> 00:14:27,920 Speaker 1: this mighty claw. I imagine what I can do with it. 252 00:14:28,240 --> 00:14:30,720 Speaker 1: That happened. That's that's what's going on. Most of the time, 253 00:14:31,000 --> 00:14:33,800 Speaker 1: a very small amount of the time they're actually using it. 254 00:14:34,000 --> 00:14:37,320 Speaker 1: So it's ultimately more of a deterrence than anything. And 255 00:14:37,360 --> 00:14:42,160 Speaker 1: this is evolutionarily sound because fighting is dangerous. The battle 256 00:14:42,160 --> 00:14:47,440 Speaker 1: itself is dangerous and can certainly be fatal to an organism, 257 00:14:47,680 --> 00:14:52,880 Speaker 1: but fights can also just wound you, making you more 258 00:14:52,920 --> 00:14:56,800 Speaker 1: susceptible pupredation. It may distract you and allow the grackle 259 00:14:56,880 --> 00:14:59,360 Speaker 1: or some other creature to come in and take you out. 260 00:14:59,800 --> 00:15:03,120 Speaker 1: So even though there are hard disadvantages to developing such 261 00:15:03,160 --> 00:15:08,000 Speaker 1: a deterrence, and he compares this to other animals as well, 262 00:15:08,120 --> 00:15:10,360 Speaker 1: like anytime you see something that you might label an 263 00:15:10,360 --> 00:15:14,400 Speaker 1: elaborate weapon. Uh in some sort of an animals anatomy, 264 00:15:14,480 --> 00:15:17,960 Speaker 1: there's a huge payoff there. Nothing is free, nothing is cheap. 265 00:15:18,440 --> 00:15:21,200 Speaker 1: When it comes to the development of these things, there's 266 00:15:21,200 --> 00:15:25,040 Speaker 1: an energy cost involved. Uh So even though they're there 267 00:15:25,040 --> 00:15:28,760 Speaker 1: are all these disadvantages to growing, say a giant crab claw, 268 00:15:29,080 --> 00:15:32,320 Speaker 1: there are also strong benefits in not having to actually 269 00:15:32,440 --> 00:15:36,160 Speaker 1: fight all of the time. Yeah. I mean I think 270 00:15:36,280 --> 00:15:40,080 Speaker 1: this this goes against our intuition because we think of 271 00:15:40,240 --> 00:15:43,760 Speaker 1: fighting in terms of winning and losing. So like fight 272 00:15:44,080 --> 00:15:46,400 Speaker 1: it fight as a winner who wins and thus they 273 00:15:46,440 --> 00:15:49,400 Speaker 1: come out good the effect for them is positive, and 274 00:15:49,440 --> 00:15:51,520 Speaker 1: a loser who loses, and of course the effect for 275 00:15:51,560 --> 00:15:53,920 Speaker 1: them is negative. But in fact, in nature, I would 276 00:15:54,000 --> 00:15:58,000 Speaker 1: argue that most fighting is probably actually lose lose because 277 00:15:58,080 --> 00:16:02,120 Speaker 1: even the winner is probably blee, somewhat injured or tired 278 00:16:02,160 --> 00:16:04,920 Speaker 1: out by the fight, putting them at a later disadvantage 279 00:16:04,960 --> 00:16:08,120 Speaker 1: for survival, even if they come out on top in 280 00:16:08,200 --> 00:16:12,120 Speaker 1: that particular struggle. Yeah. Yeah, And all of this makes 281 00:16:12,160 --> 00:16:14,200 Speaker 1: even more sense when you we start looking at the 282 00:16:14,600 --> 00:16:18,160 Speaker 1: closer to the scenario of these of of fighting and 283 00:16:18,640 --> 00:16:22,520 Speaker 1: protecting these burrows and trying to to move females. Again, 284 00:16:22,560 --> 00:16:24,520 Speaker 1: the male set up shop in front of key burrows 285 00:16:24,520 --> 00:16:27,280 Speaker 1: that are offered as brooding burrows to prospective females, and 286 00:16:27,320 --> 00:16:29,880 Speaker 1: this is where they make their show and this is 287 00:16:29,920 --> 00:16:32,280 Speaker 1: where they fight if it comes to that. And the 288 00:16:32,600 --> 00:16:35,520 Speaker 1: numbers here are apparently great. They're just tons of crabs 289 00:16:35,560 --> 00:16:41,080 Speaker 1: out there and they're they're just face off after face off. Uh. 290 00:16:41,160 --> 00:16:43,280 Speaker 1: And again, most of these face offs are not going 291 00:16:43,360 --> 00:16:46,000 Speaker 1: to result in a big, drag out fight. A lot 292 00:16:46,040 --> 00:16:48,840 Speaker 1: of them are just going to be uh displays. But 293 00:16:48,960 --> 00:16:52,400 Speaker 1: still uh. Lifting that that crab claw in the air 294 00:16:53,040 --> 00:16:55,040 Speaker 1: and to signal with it, that's going to have an 295 00:16:55,160 --> 00:16:59,080 Speaker 1: energy cost and so this is ultimately exhausting too many crabs. 296 00:16:59,120 --> 00:17:01,560 Speaker 1: Crabs will eventually they have to bow out and work 297 00:17:01,600 --> 00:17:04,199 Speaker 1: their way back up to good burrows. So there's like 298 00:17:04,240 --> 00:17:07,800 Speaker 1: this whole system of communication. Uh. Most of the these 299 00:17:07,840 --> 00:17:11,359 Speaker 1: faceoffs don't rise to the level of full intensity battle, 300 00:17:12,000 --> 00:17:14,600 Speaker 1: and the display of the claw allows the male crabs 301 00:17:14,640 --> 00:17:18,000 Speaker 1: to easily determine who they have a chance against, so 302 00:17:18,040 --> 00:17:20,119 Speaker 1: they're able to size each other up like Okay, this 303 00:17:20,200 --> 00:17:23,479 Speaker 1: is a battle, um that I definitely can win, and 304 00:17:23,520 --> 00:17:26,119 Speaker 1: he knows I can win it, so we're done. This 305 00:17:26,240 --> 00:17:28,960 Speaker 1: is a display only situation. Okay, he's a crab that 306 00:17:29,040 --> 00:17:31,960 Speaker 1: can definitely beat me, so I'm not gonna mess with him. Uh, 307 00:17:32,040 --> 00:17:34,880 Speaker 1: We're just gonna carry on our ways. This one, however, 308 00:17:35,160 --> 00:17:36,960 Speaker 1: we're gonna have to communicate a little bit and we 309 00:17:37,040 --> 00:17:40,080 Speaker 1: might have to fight because we seem to be evenly matched. Yeah. 310 00:17:40,119 --> 00:17:42,719 Speaker 1: That's actually the most dangerous situation is when it's not 311 00:17:42,800 --> 00:17:51,760 Speaker 1: clear which one is stronger than. All right, Well, I 312 00:17:51,760 --> 00:17:53,919 Speaker 1: wanted to come back to something which was earlier. I 313 00:17:53,920 --> 00:17:57,880 Speaker 1: mentioned that New York Times interview with the researchers Sophie Moles, 314 00:17:58,080 --> 00:18:02,720 Speaker 1: who was one of the authors of a paper published 315 00:18:02,720 --> 00:18:09,240 Speaker 1: in ten in Biology Letters UH called Robotic Crabs, revealed 316 00:18:09,240 --> 00:18:12,399 Speaker 1: that female fiddler crabs are sensitive to changes in male 317 00:18:12,520 --> 00:18:16,280 Speaker 1: display rate. The other authors here were Michael D. Jenions 318 00:18:16,440 --> 00:18:19,560 Speaker 1: and Patricia are Why Backwell, yes, I might have referred 319 00:18:19,560 --> 00:18:22,960 Speaker 1: to her earlier as Blackwell, my apologies. Oh I didn't 320 00:18:22,960 --> 00:18:26,399 Speaker 1: catch that. You should apologize. Well, I just want to 321 00:18:26,400 --> 00:18:28,879 Speaker 1: make sure I get the names right. I think I 322 00:18:28,920 --> 00:18:31,520 Speaker 1: had a type in my notes there, so but from 323 00:18:31,560 --> 00:18:34,400 Speaker 1: the crabs perspective, I think it is important to realize 324 00:18:34,440 --> 00:18:38,040 Speaker 1: that this really is a study that involved creating crab 325 00:18:38,119 --> 00:18:42,359 Speaker 1: sex robots like this is creating that it was an 326 00:18:42,400 --> 00:18:46,720 Speaker 1: attempt to create the hunkiest male robot crab clause that 327 00:18:46,760 --> 00:18:49,919 Speaker 1: have ever been put together with the explicit purpose of 328 00:18:49,960 --> 00:18:53,440 Speaker 1: attracting female fiddler crabs. So I'm just gonna read directly 329 00:18:53,480 --> 00:18:57,800 Speaker 1: from their abstract. Uh they write quote. Males often produced dynamic, 330 00:18:57,840 --> 00:19:01,239 Speaker 1: repetitive courtship displays that can be demanding to perform and 331 00:19:01,359 --> 00:19:05,159 Speaker 1: might advertise male quality to females. A key feature of 332 00:19:05,200 --> 00:19:09,600 Speaker 1: demanding displays is that they can change in intensity, escalating 333 00:19:09,600 --> 00:19:13,280 Speaker 1: as a male increases his signaling effort, but de escalating 334 00:19:13,320 --> 00:19:17,000 Speaker 1: as a signal or becomes fatigued. Here we investigated whether 335 00:19:17,080 --> 00:19:21,520 Speaker 1: female fiddler crabs of the species Uka mio Bergi are 336 00:19:21,560 --> 00:19:25,200 Speaker 1: sensitive to changes in male courtship wave rate how fast 337 00:19:25,240 --> 00:19:30,000 Speaker 1: the arm is waving. We performed playback experiments using robotic 338 00:19:30,160 --> 00:19:33,399 Speaker 1: male crabs that had the same mean wave rate but 339 00:19:33,480 --> 00:19:38,720 Speaker 1: either escalated, de escalated, or remained constant. Females demonstrated a 340 00:19:38,800 --> 00:19:43,240 Speaker 1: strong preference for escalating robots, but showed mixed responses to 341 00:19:43,320 --> 00:19:47,080 Speaker 1: robots that de escalated fast too slow compared to those 342 00:19:47,080 --> 00:19:50,639 Speaker 1: that waved at a constant medium rate. These findings demonstrate 343 00:19:50,680 --> 00:19:53,840 Speaker 1: that females can discern changes in male display rate and 344 00:19:53,920 --> 00:19:57,880 Speaker 1: prefer males that escalate, but that females are also sensitive 345 00:19:57,920 --> 00:20:02,720 Speaker 1: to pass display rates indicative prior vigor. So if you 346 00:20:02,760 --> 00:20:05,439 Speaker 1: are a male fiddler crab, it's not just important to 347 00:20:05,440 --> 00:20:08,879 Speaker 1: have a big claw, but it apparently, at least with 348 00:20:08,920 --> 00:20:12,240 Speaker 1: this species, is more attractive to females if you start 349 00:20:12,280 --> 00:20:15,879 Speaker 1: waving it faster and faster as the female comes close 350 00:20:15,920 --> 00:20:18,280 Speaker 1: to you. And from this New York Times interview with 351 00:20:18,320 --> 00:20:21,440 Speaker 1: the lead author of their moles, uh it was there 352 00:20:21,520 --> 00:20:24,479 Speaker 1: was the question where the female is terribly disappointed when 353 00:20:24,520 --> 00:20:26,960 Speaker 1: they realized they'd been tricked. You know what happened once 354 00:20:27,040 --> 00:20:30,159 Speaker 1: they finally got up to the waving robot arm that 355 00:20:30,200 --> 00:20:33,520 Speaker 1: they were so interested in, Well, Mole says quote, once 356 00:20:33,560 --> 00:20:35,959 Speaker 1: they got to the robot, they would touch the baseplate 357 00:20:36,000 --> 00:20:39,520 Speaker 1: of it and realize there's something wrong here, it's not real, 358 00:20:39,880 --> 00:20:42,560 Speaker 1: and they would usually at that point stop moving or runaway. 359 00:20:43,200 --> 00:20:46,480 Speaker 1: Some of them actually responded as if he were a 360 00:20:46,520 --> 00:20:50,359 Speaker 1: real male crab, which is by tickling him. What the 361 00:20:50,400 --> 00:20:52,760 Speaker 1: females do is go up to the mail and use 362 00:20:52,840 --> 00:20:56,080 Speaker 1: their legs on one side of their body to tickle him. 363 00:20:56,119 --> 00:20:58,719 Speaker 1: This communicates to him that she's interested in him as 364 00:20:58,720 --> 00:21:01,200 Speaker 1: a mate and not just trying to steal his home. 365 00:21:01,920 --> 00:21:06,080 Speaker 1: So this this study did indeed implicate female fiddler crabs 366 00:21:06,160 --> 00:21:10,200 Speaker 1: tickling metal base plates because they thought it just that 367 00:21:10,560 --> 00:21:13,480 Speaker 1: claw is so huge, it's swinging so fast, I've got 368 00:21:13,480 --> 00:21:15,760 Speaker 1: to believe it's it might be a real crab. This 369 00:21:15,800 --> 00:21:18,359 Speaker 1: sounds like something that could be factored into, I don't know, 370 00:21:18,400 --> 00:21:23,280 Speaker 1: Battlestar Galactica sort of situation like that. The replicants, the robots, 371 00:21:23,280 --> 00:21:25,520 Speaker 1: they look just like us, they behave just like us, 372 00:21:25,520 --> 00:21:30,880 Speaker 1: except um tickling them will reveal their true nature. Anyway, 373 00:21:30,880 --> 00:21:33,639 Speaker 1: in the spirit of of our enthusiasm for the shrimp 374 00:21:33,680 --> 00:21:35,880 Speaker 1: on the treadmill, the crab on the treadmill, I want 375 00:21:35,960 --> 00:21:39,399 Speaker 1: more studies with robot crab hunks. We have to build 376 00:21:39,440 --> 00:21:42,560 Speaker 1: the most attractive male crab that has ever been that 377 00:21:42,640 --> 00:21:46,000 Speaker 1: has ever existed on Earth. And uh, but I guess 378 00:21:46,000 --> 00:21:47,520 Speaker 1: we have to be careful with it because we don't 379 00:21:47,520 --> 00:21:50,960 Speaker 1: want to drive crabs to to extinction by like now 380 00:21:51,040 --> 00:21:54,680 Speaker 1: now the real crabs only desire the robot. It's weird 381 00:21:54,760 --> 00:21:58,000 Speaker 1: how this does line up with the sort of trope 382 00:21:58,000 --> 00:22:01,000 Speaker 1: of them the muscle man on the beach attracting the 383 00:22:01,040 --> 00:22:03,960 Speaker 1: women and in the in the nerd that's that's also 384 00:22:04,000 --> 00:22:06,200 Speaker 1: inevitably on the beach as well and make get sand 385 00:22:06,280 --> 00:22:09,640 Speaker 1: kicked in his face or whatnotum, But it also does 386 00:22:09,680 --> 00:22:12,280 Speaker 1: bring to mind, like even with with humans, there's sort 387 00:22:12,320 --> 00:22:16,359 Speaker 1: of there's there's fitness, and there's like visible fitness, but 388 00:22:16,400 --> 00:22:19,040 Speaker 1: then there's also like fitness to the level where it's 389 00:22:19,040 --> 00:22:23,119 Speaker 1: no no longer purely functional anymore. Like there's like, for instance, 390 00:22:23,160 --> 00:22:25,399 Speaker 1: there's the muscle that might aid in the delivery of 391 00:22:25,400 --> 00:22:28,960 Speaker 1: a punch, and then there's like the the the muscle 392 00:22:29,640 --> 00:22:32,840 Speaker 1: build up that say, makes it harder to move around 393 00:22:32,960 --> 00:22:34,920 Speaker 1: or or makes it, you know, more difficult to say, 394 00:22:34,960 --> 00:22:37,840 Speaker 1: touch portions of your back, the sort of thing. I 395 00:22:37,920 --> 00:22:40,280 Speaker 1: totally know what you're saying. Though, Also that reminds me 396 00:22:40,359 --> 00:22:43,359 Speaker 1: I always want to caution people, you know, just don't 397 00:22:43,480 --> 00:22:46,720 Speaker 1: don't try to extrapolate too much from from animal sex 398 00:22:46,720 --> 00:22:49,600 Speaker 1: and attractiveness studies to humans, because you know, crabs and 399 00:22:49,680 --> 00:22:53,400 Speaker 1: humans are pretty different, right right, And certainly the reasons 400 00:22:53,400 --> 00:22:56,840 Speaker 1: that humans do things um and uh, and the way 401 00:22:56,880 --> 00:22:58,960 Speaker 1: they react to things are generally there's a lot a 402 00:22:59,000 --> 00:23:01,159 Speaker 1: lot more going on. There's there's this whole level of 403 00:23:01,280 --> 00:23:05,760 Speaker 1: human complication. It's taking place on the surface of whatever 404 00:23:05,800 --> 00:23:08,200 Speaker 1: else is going on all Right, after we've talked about 405 00:23:08,240 --> 00:23:12,000 Speaker 1: all of these examples of animals that broadly have bilateral 406 00:23:12,000 --> 00:23:15,960 Speaker 1: symmetry but then some major deviation from it, I've been 407 00:23:16,000 --> 00:23:21,359 Speaker 1: thinking about how symmetry and asymmetry come about at the 408 00:23:21,400 --> 00:23:25,040 Speaker 1: cellular level, because you know, you can imagine why it 409 00:23:25,080 --> 00:23:28,960 Speaker 1: would be genetically efficient to have bilateral symmetry, like you 410 00:23:28,960 --> 00:23:31,199 Speaker 1: you just basically need half of a body plan and 411 00:23:31,200 --> 00:23:33,359 Speaker 1: then you just copy it over on the other side. 412 00:23:34,760 --> 00:23:38,080 Speaker 1: But within that broadly symmetrical framework, you know, we get 413 00:23:38,119 --> 00:23:41,640 Speaker 1: these deviations major and minor. And it's not all narwhal 414 00:23:41,720 --> 00:23:44,399 Speaker 1: tusks and fiddler crab claws things that are like huge 415 00:23:44,400 --> 00:23:47,200 Speaker 1: and noticeable. There are plenty of forms of a symmetry 416 00:23:47,280 --> 00:23:49,879 Speaker 1: that are common but harder to spot, such as the 417 00:23:49,920 --> 00:23:54,360 Speaker 1: orientation of internal organs. You know, you're digestive tract and 418 00:23:54,520 --> 00:23:59,639 Speaker 1: it's associated organs and your heart and circulatory system, or 419 00:23:59,680 --> 00:24:04,159 Speaker 1: all asymmetrical they have different organs and pathways situated on 420 00:24:04,200 --> 00:24:07,160 Speaker 1: the left and right of the body cavity, and there 421 00:24:07,160 --> 00:24:11,040 Speaker 1: are also minor more invisible variations at the cellular level 422 00:24:11,240 --> 00:24:15,399 Speaker 1: in within mostly symmetrical creatures like us. So how do 423 00:24:15,480 --> 00:24:19,480 Speaker 1: these deviations from perfect symmetry come about at the level 424 00:24:19,480 --> 00:24:22,960 Speaker 1: of cell division, which is actually you know, actively building 425 00:24:23,000 --> 00:24:26,639 Speaker 1: your body's tissues. How do the cells know which side 426 00:24:26,720 --> 00:24:29,439 Speaker 1: is which and how to do something different on the 427 00:24:29,520 --> 00:24:32,000 Speaker 1: left than what they're doing on the right. Well, one 428 00:24:32,080 --> 00:24:35,560 Speaker 1: jumping off point here is I came across an interesting 429 00:24:35,640 --> 00:24:41,119 Speaker 1: article about this in Quantum Magazine from January by Tim 430 00:24:41,240 --> 00:24:45,600 Speaker 1: Vernemon called how Life Turns a symmetric which is worth 431 00:24:45,600 --> 00:24:47,800 Speaker 1: a read in its entirety, but I just wanted to 432 00:24:47,840 --> 00:24:50,760 Speaker 1: summarize and jump off from a few things I learned 433 00:24:50,760 --> 00:24:52,879 Speaker 1: from it. And one of the big takeaways is that 434 00:24:52,960 --> 00:24:56,120 Speaker 1: I think we have some good answers about at least 435 00:24:56,200 --> 00:25:01,720 Speaker 1: some strong factors for like mammalian or vertebrate symmetry and 436 00:25:01,760 --> 00:25:05,840 Speaker 1: symmetry breaking something. We know some things about the genetic 437 00:25:05,880 --> 00:25:08,680 Speaker 1: and cellular basis for a symmetry in the body, but 438 00:25:08,720 --> 00:25:11,480 Speaker 1: we still don't know everything yet, And so one of 439 00:25:11,520 --> 00:25:14,400 Speaker 1: the ideas thin gets brought up in this article is 440 00:25:14,560 --> 00:25:19,359 Speaker 1: the nodal lefty genetic connection, and it goes like this. 441 00:25:19,520 --> 00:25:23,399 Speaker 1: Since the nine nineties, scientists have been studying a gene 442 00:25:23,760 --> 00:25:28,440 Speaker 1: called nodal in O d A L which appears specifically 443 00:25:28,440 --> 00:25:32,840 Speaker 1: on the left side of the developing embryo of At 444 00:25:32,880 --> 00:25:36,000 Speaker 1: the time this article is written, they said every vertebrate 445 00:25:36,000 --> 00:25:41,399 Speaker 1: animal yet studied and associated with this gene is a 446 00:25:41,520 --> 00:25:45,800 Speaker 1: somewhat confusingly named gene called lefty, which appears to work 447 00:25:45,840 --> 00:25:50,280 Speaker 1: specifically to suppress the nodal genes activity on the right 448 00:25:50,400 --> 00:25:53,760 Speaker 1: side of the vertebrate embryo. So the purpose of lefty, 449 00:25:53,800 --> 00:25:56,840 Speaker 1: if I understand core, actually appears to be something like 450 00:25:57,440 --> 00:25:59,600 Speaker 1: telling the right side of the body not to do 451 00:25:59,760 --> 00:26:03,840 Speaker 1: left side of the body stuff. According to the Harvard 452 00:26:03,840 --> 00:26:08,439 Speaker 1: biologist Cliff Tabin, the nodal lefty gene combination seems to 453 00:26:08,480 --> 00:26:12,720 Speaker 1: be the main genetic factor guiding asymmetry in animals, or 454 00:26:12,720 --> 00:26:17,880 Speaker 1: at least invertebrates. So how does this difference get expressed? Well, 455 00:26:17,920 --> 00:26:23,200 Speaker 1: another biologist named Nobo taka Hirokawa has offered an explanation 456 00:26:23,320 --> 00:26:28,919 Speaker 1: that has to do with cilia. Cilia are little hair 457 00:26:29,000 --> 00:26:32,919 Speaker 1: like or thread like projections Technically, they're a type of 458 00:26:33,040 --> 00:26:38,160 Speaker 1: organelle which stick up from cell membranes within the cells 459 00:26:38,320 --> 00:26:43,000 Speaker 1: or of eukaryotes, and they serve various functions like gathering 460 00:26:43,040 --> 00:26:47,520 Speaker 1: sensory information for cells or facilitating the movement of cells 461 00:26:47,560 --> 00:26:52,280 Speaker 1: through fluid. So you might read about us silia motility. 462 00:26:52,440 --> 00:26:55,119 Speaker 1: These these things often moved back and forth, though actually 463 00:26:55,160 --> 00:26:59,920 Speaker 1: they're divided into motile and nonmotile cilia. So how would 464 00:27:00,080 --> 00:27:04,280 Speaker 1: tiny hairs sticking up off of cell membranes have anything 465 00:27:04,359 --> 00:27:07,840 Speaker 1: to do with the body of a vertebrate splitting from 466 00:27:07,840 --> 00:27:12,159 Speaker 1: perfect symmetry into a differentiated left and right half. Well, 467 00:27:12,359 --> 00:27:16,840 Speaker 1: one fascinating clue came in the form of a rare 468 00:27:17,040 --> 00:27:22,359 Speaker 1: genetic disorder found in humans known as cartagen or syndrome. Actually, 469 00:27:22,440 --> 00:27:23,840 Speaker 1: I'm not sure if I'm saying that right, but it's 470 00:27:23,840 --> 00:27:26,280 Speaker 1: spelled k A R T A G E N E 471 00:27:26,600 --> 00:27:32,000 Speaker 1: R cartagen Or syndrome, which presents most often in patients 472 00:27:32,920 --> 00:27:37,760 Speaker 1: as patients with continued respiratory problems such as recurrent lung 473 00:27:37,840 --> 00:27:43,840 Speaker 1: infections and sinus problems, and also sometimes infertility. It turns 474 00:27:43,880 --> 00:27:49,120 Speaker 1: out this condition is caused by a congenital defect that 475 00:27:49,240 --> 00:27:53,600 Speaker 1: prevents the bodies sillia from functioning as needed. So these 476 00:27:53,640 --> 00:27:57,800 Speaker 1: little hair like projections on cells don't function as they 477 00:27:57,800 --> 00:28:01,600 Speaker 1: normally would. Now why that affect respiration? Well? Of course, 478 00:28:01,640 --> 00:28:05,359 Speaker 1: the inside of our breathing passages are aligned with cilia, 479 00:28:05,440 --> 00:28:09,720 Speaker 1: and the cilia need to move in synchronization for I 480 00:28:09,800 --> 00:28:12,040 Speaker 1: think multiple purposes, but one of them is to help 481 00:28:12,119 --> 00:28:17,439 Speaker 1: clear breathing passages of mucus. And this disorder causes the 482 00:28:17,480 --> 00:28:21,000 Speaker 1: cilia to have trouble again with motility, with movement, and 483 00:28:21,040 --> 00:28:23,919 Speaker 1: so they can't really synchronize. They can't really work together 484 00:28:24,080 --> 00:28:27,919 Speaker 1: to get the mucus out of the lungs uh and 485 00:28:28,160 --> 00:28:32,560 Speaker 1: out to the throat to prevent infections. Now, strangely, this 486 00:28:32,720 --> 00:28:38,840 Speaker 1: disorder affecting cilia also frequently coincides with a seemingly totally 487 00:28:38,920 --> 00:28:43,440 Speaker 1: unrelated issue. About half of people diagnosed with cartagon or 488 00:28:43,480 --> 00:28:48,520 Speaker 1: syndrome also have their internal organs flipped. Their body is 489 00:28:48,560 --> 00:28:52,080 Speaker 1: a mirror image of what a thoracic surgeon would expect 490 00:28:52,080 --> 00:28:54,160 Speaker 1: to see if they open you up. So you know, 491 00:28:54,200 --> 00:28:55,840 Speaker 1: the heart on the right and the liver on the 492 00:28:55,920 --> 00:28:58,600 Speaker 1: left and so forth. That's right. Yeah, the the if 493 00:28:58,600 --> 00:29:00,720 Speaker 1: we're looking to spy literature, of course, if we look 494 00:29:00,720 --> 00:29:03,720 Speaker 1: at Ian Flemings, the doctor No. We might remember Doctor 495 00:29:03,720 --> 00:29:05,600 Speaker 1: No has this where his heart is on the other 496 00:29:05,600 --> 00:29:09,080 Speaker 1: side of his body, survives. I think he survives an 497 00:29:09,080 --> 00:29:13,600 Speaker 1: assassination attempt at some point because of this anatomical quirk. Oh, 498 00:29:13,920 --> 00:29:16,840 Speaker 1: somebody shoots him on the wrong side. That's a good 499 00:29:16,880 --> 00:29:26,000 Speaker 1: twist than than than well anyway, So you have that 500 00:29:26,080 --> 00:29:29,960 Speaker 1: association people who have this, who have this congenital condition 501 00:29:30,000 --> 00:29:35,160 Speaker 1: affecting proteins that in turn effect cilia. Uh. They also 502 00:29:35,560 --> 00:29:38,280 Speaker 1: half of the time their organs are are flipped opposite 503 00:29:38,280 --> 00:29:40,520 Speaker 1: of what you normally see. On top of that, there 504 00:29:40,600 --> 00:29:44,520 Speaker 1: was a paper in Nature by Lee at All which 505 00:29:45,280 --> 00:29:49,760 Speaker 1: Vernamon in the article points to called global Genetic Analysis 506 00:29:49,760 --> 00:29:53,800 Speaker 1: in Mice unveil central role for cilia in congenital heart disease. 507 00:29:54,560 --> 00:29:58,640 Speaker 1: And this paper apparently found multiple instances of genes where 508 00:29:58,840 --> 00:30:02,520 Speaker 1: if the gene was defective, the mouse presented with some 509 00:30:02,600 --> 00:30:06,320 Speaker 1: kind of unusual issue related to symmetry and asymmetry in 510 00:30:06,360 --> 00:30:09,160 Speaker 1: the body, some issue with that the haves left and right, 511 00:30:09,720 --> 00:30:13,320 Speaker 1: and in those instances the gene was somehow also related 512 00:30:13,400 --> 00:30:19,440 Speaker 1: to cilia. So these clues UH indicate that somehow silia 513 00:30:19,560 --> 00:30:23,360 Speaker 1: may play a role in symmetry breaking during mammalian development. 514 00:30:24,320 --> 00:30:27,600 Speaker 1: So how could this be Well, A leading explanation has 515 00:30:27,640 --> 00:30:32,160 Speaker 1: to do with something called dorsal flow and a little 516 00:30:32,200 --> 00:30:38,160 Speaker 1: patch on the surface of mammalian embryos called the ventral node. So, 517 00:30:38,200 --> 00:30:41,160 Speaker 1: if you're looking at like a mammalian embryo, the ventral 518 00:30:41,240 --> 00:30:45,560 Speaker 1: node is a little pit or depression on the underside 519 00:30:45,600 --> 00:30:49,400 Speaker 1: or the bottom surface, and the pit is ciliated, meaning 520 00:30:49,400 --> 00:30:52,120 Speaker 1: it's covered in cilia, these little hair like or thread 521 00:30:52,160 --> 00:30:56,840 Speaker 1: like projections. And the explanation goes that the waving of 522 00:30:56,920 --> 00:31:00,880 Speaker 1: cilia in this little pit create a consisder stant direction 523 00:31:01,000 --> 00:31:04,920 Speaker 1: of flow in the fluid around the ventral node. So 524 00:31:04,960 --> 00:31:07,960 Speaker 1: the cilia rotate to get the fluid moving, and then 525 00:31:08,000 --> 00:31:10,920 Speaker 1: they keep it moving in a consistent direction. The fluid 526 00:31:11,000 --> 00:31:13,640 Speaker 1: is always moving to the left along with the with 527 00:31:13,720 --> 00:31:17,520 Speaker 1: the way the silly are waving, and the direction of 528 00:31:17,560 --> 00:31:22,280 Speaker 1: this flow seems to cause a chain reaction that results 529 00:31:22,320 --> 00:31:27,120 Speaker 1: in changes in gene expression, specifically in the a symmetry 530 00:31:27,160 --> 00:31:31,440 Speaker 1: genes coming back to again no dole and lefty. So apparently, 531 00:31:31,480 --> 00:31:36,400 Speaker 1: if the cilia are having trouble with motility, the unidirectional 532 00:31:36,520 --> 00:31:40,040 Speaker 1: left word current of fluid is not established, and the 533 00:31:40,080 --> 00:31:43,520 Speaker 1: symmetry breaking genes aren't expressed as they would normally be, 534 00:31:44,040 --> 00:31:47,400 Speaker 1: which can lead to deviations from the type of mammalian 535 00:31:47,440 --> 00:31:50,160 Speaker 1: a symmetry we would we would see in most most 536 00:31:50,440 --> 00:31:54,280 Speaker 1: members of that species, such as creating a condition where 537 00:31:54,320 --> 00:31:56,960 Speaker 1: the body fifty of the time can have its internal 538 00:31:57,080 --> 00:32:02,200 Speaker 1: organs flipped. However, this be the only factor leading to 539 00:32:02,400 --> 00:32:07,160 Speaker 1: standard symmetry breaking in animal bodies. Vernemon's article also cites 540 00:32:07,200 --> 00:32:11,880 Speaker 1: a Toughs University biologist named Michael Levin who points out 541 00:32:11,880 --> 00:32:15,920 Speaker 1: that some animals, even some mammals, don't have that ciliated 542 00:32:15,960 --> 00:32:20,080 Speaker 1: dorsal node we were just talking about, and Levin believes 543 00:32:20,120 --> 00:32:24,320 Speaker 1: there's some involvement of a factor called the cellular skeleton 544 00:32:24,640 --> 00:32:27,840 Speaker 1: or the cytoskeleton. Did you know that your cells have 545 00:32:28,000 --> 00:32:31,680 Speaker 1: a skeleton of their own? I I don't know. I 546 00:32:31,680 --> 00:32:34,120 Speaker 1: guess I'd heard the word cytoskeleton, but I hadn't quite 547 00:32:34,120 --> 00:32:37,200 Speaker 1: put it together. It's not exactly like your your bigger skeleton. 548 00:32:37,240 --> 00:32:40,800 Speaker 1: I mean, it's not like bones. The cytoskeleton is a 549 00:32:41,160 --> 00:32:44,600 Speaker 1: system of protein filaments that are, at least in a 550 00:32:44,600 --> 00:32:47,080 Speaker 1: metaphorical sense, sort of like the bones of a cell. 551 00:32:47,760 --> 00:32:49,720 Speaker 1: Uh to describe them, I want to quote from a 552 00:32:50,400 --> 00:32:55,120 Speaker 1: review in Nature by Fletcher and Mullins. Quote. The ability 553 00:32:55,120 --> 00:32:59,840 Speaker 1: of a eukaryotic cell to resist deformation, to transport intrust 554 00:33:00,000 --> 00:33:04,360 Speaker 1: cellular cargo, and to change shape during movement depends on 555 00:33:04,480 --> 00:33:11,080 Speaker 1: the cytoskeleton, an interconnected network of filamentous polymers and regulatory proteins. 556 00:33:11,760 --> 00:33:15,320 Speaker 1: Recent work is demonstrated that both internal and external physical 557 00:33:15,400 --> 00:33:19,840 Speaker 1: forces can act through the cytoskeleton to affect local mechanical 558 00:33:19,840 --> 00:33:24,120 Speaker 1: properties and cellular behavior. Attention is now focused on how 559 00:33:24,160 --> 00:33:29,480 Speaker 1: cytoskeletal networks generate, transmit, and respond to mechanical signals over 560 00:33:29,560 --> 00:33:33,320 Speaker 1: both short and long time scales. An important insight emerging 561 00:33:33,400 --> 00:33:37,680 Speaker 1: from this work is that long lived cytoskeletal structures may 562 00:33:37,720 --> 00:33:42,840 Speaker 1: act as epigenetic determinants of cell shape, function, and fate. 563 00:33:43,600 --> 00:33:46,240 Speaker 1: And it's exactly this last comment that I think is 564 00:33:46,280 --> 00:33:49,080 Speaker 1: most relevant here, because in the case of symmetry breaking, 565 00:33:49,760 --> 00:33:53,800 Speaker 1: it may be that features of this cellular skeleton, this 566 00:33:53,920 --> 00:33:57,800 Speaker 1: system of sort of strands of of polymers and proteins 567 00:33:57,840 --> 00:34:00,320 Speaker 1: that helped give a cell its shape and help it 568 00:34:00,920 --> 00:34:04,880 Speaker 1: resist deformation when it's under pressure and things like that, 569 00:34:04,880 --> 00:34:10,200 Speaker 1: that this system may ultimately epigenetically determine the development of 570 00:34:10,200 --> 00:34:14,560 Speaker 1: cells and ultimately the handedness or asymmetry of the whole body. 571 00:34:15,800 --> 00:34:18,040 Speaker 1: This was so this next part was also a surprise 572 00:34:18,080 --> 00:34:20,120 Speaker 1: to me. I don't think I knew this. Apparently sells 573 00:34:20,239 --> 00:34:25,680 Speaker 1: themselves have a kind of handedness or asymmetry. Some cells 574 00:34:25,719 --> 00:34:28,480 Speaker 1: are sort of left oriented and some are right oriented, 575 00:34:28,560 --> 00:34:31,560 Speaker 1: and you can see this in their behavior when they're 576 00:34:31,600 --> 00:34:34,680 Speaker 1: moving through fluid and they come up against an obstacle. 577 00:34:34,800 --> 00:34:37,239 Speaker 1: So that you can have experiments where you show that 578 00:34:37,280 --> 00:34:40,560 Speaker 1: cells are flowing around along in a controlled environment and 579 00:34:40,600 --> 00:34:43,320 Speaker 1: then they bump up against something, a bump a surface. 580 00:34:43,680 --> 00:34:46,839 Speaker 1: When that happens, the cell will tend to turn in 581 00:34:46,960 --> 00:34:50,880 Speaker 1: one direction or the other, and that preference for a 582 00:34:50,920 --> 00:34:56,560 Speaker 1: particular way of turning tends to remain consistent for each cell. 583 00:34:56,680 --> 00:34:59,640 Speaker 1: You have sort of left turning cells and right turning cells, 584 00:35:00,680 --> 00:35:05,239 Speaker 1: and experiments in fruit flies demonstrate that these small differences 585 00:35:05,320 --> 00:35:10,359 Speaker 1: at the cellular level can snowball into major morphological differences 586 00:35:10,400 --> 00:35:15,200 Speaker 1: at the body level. Vernamon's article mentions researchers named Leo 587 00:35:15,320 --> 00:35:20,000 Speaker 1: Juan and Kinji Matsuno, who each identified proteins within the 588 00:35:20,000 --> 00:35:25,480 Speaker 1: cellular skeleton specifically the actin and myosin's as having an 589 00:35:25,480 --> 00:35:28,680 Speaker 1: influence on whether a cell becomes left handed or right handed. 590 00:35:29,320 --> 00:35:32,719 Speaker 1: And there there may also be some interplay between proteins 591 00:35:32,760 --> 00:35:37,440 Speaker 1: in the cytoskeleton and the asymmetrical expression of the nodal gene, 592 00:35:38,080 --> 00:35:40,839 Speaker 1: each playing a role. But then there's one more thing 593 00:35:40,880 --> 00:35:43,319 Speaker 1: that gets mentioned towards the end of this article, uh 594 00:35:43,480 --> 00:35:45,719 Speaker 1: that the Quanta article that I thought was interesting, which 595 00:35:45,760 --> 00:35:48,960 Speaker 1: is that other factors leading to asymmetry. Of course, there 596 00:35:49,040 --> 00:35:51,239 Speaker 1: might be some that haven't been discovered yet, but one 597 00:35:51,320 --> 00:35:56,560 Speaker 1: candidate has to do with communication between cells, for instance, 598 00:35:56,600 --> 00:36:00,560 Speaker 1: based on the relative prevalence of proteins on a cell surface, 599 00:36:00,600 --> 00:36:04,400 Speaker 1: which would in turn determine how cells trade electrical charges 600 00:36:04,480 --> 00:36:07,760 Speaker 1: back and forth between each other. And the Quanta article 601 00:36:07,880 --> 00:36:11,080 Speaker 1: cites Michael Levin again saying quote, if we block the 602 00:36:11,120 --> 00:36:17,080 Speaker 1: communication channels, asymmetrical development always goes awry. And by manipulating 603 00:36:17,120 --> 00:36:20,040 Speaker 1: this system, we've been able to guide development in surprising 604 00:36:20,080 --> 00:36:25,560 Speaker 1: but predictable directions, creating six legged frogs, four headed worms, 605 00:36:25,960 --> 00:36:29,440 Speaker 1: or froglet's with an eye for a gut without changing 606 00:36:29,480 --> 00:36:33,000 Speaker 1: their genomes at all. And in a final twist, bringing 607 00:36:33,000 --> 00:36:35,840 Speaker 1: this back to medicine. UH, it's interesting that all of 608 00:36:35,840 --> 00:36:39,160 Speaker 1: this knowledge might one day be useful in finding treatments 609 00:36:39,200 --> 00:36:44,360 Speaker 1: for pathological growth and development patterns and somatic cells by 610 00:36:44,480 --> 00:36:48,040 Speaker 1: sort of harnessing these systems, by harnessing the bodies existing 611 00:36:48,080 --> 00:36:53,120 Speaker 1: mechanisms for detecting and UH and directing its own shape, 612 00:36:53,520 --> 00:36:55,680 Speaker 1: you know, the way the cells come together to to 613 00:36:55,800 --> 00:36:59,720 Speaker 1: form larger structures that might be harnessed for for treating 614 00:37:00,000 --> 00:37:03,600 Speaker 1: cases where cell cell development is going wrong. Yeah, that's 615 00:37:03,640 --> 00:37:06,360 Speaker 1: that's fascinating, you know, coming back to what you said earlier, 616 00:37:06,400 --> 00:37:09,040 Speaker 1: I don't know if prior to this, if someone had 617 00:37:09,040 --> 00:37:10,920 Speaker 1: just stopped me on the street, like a man on 618 00:37:10,960 --> 00:37:14,560 Speaker 1: the street reporters situation asked me if sells off a skeleton, 619 00:37:14,560 --> 00:37:17,640 Speaker 1: if I would have been able to correctly answer regarding 620 00:37:17,680 --> 00:37:22,000 Speaker 1: the site of skeleton. Here this is this is pretty fascinating. 621 00:37:22,000 --> 00:37:24,800 Speaker 1: And then to get into its um sort of the 622 00:37:24,880 --> 00:37:29,319 Speaker 1: ramifications of that and how that ends up being reflected 623 00:37:29,440 --> 00:37:33,600 Speaker 1: in the left handedness of the of the overall system 624 00:37:33,719 --> 00:37:35,880 Speaker 1: or the right handeds, whichever the case may be. You know, 625 00:37:35,960 --> 00:37:37,759 Speaker 1: I have to think back once more to the cock 626 00:37:37,840 --> 00:37:41,920 Speaker 1: eyed squid histeo tooth that we discussed in this was 627 00:37:41,960 --> 00:37:45,239 Speaker 1: the first episode. One of the reasons to marvel of 628 00:37:45,320 --> 00:37:48,080 Speaker 1: this amazing creature is that its eyes have evolved to 629 00:37:48,160 --> 00:37:51,000 Speaker 1: look in different directions to different realms of the ocean, 630 00:37:51,120 --> 00:37:55,440 Speaker 1: light and dark. And this seems understandably strange and alien 631 00:37:55,480 --> 00:37:59,480 Speaker 1: to us, but perhaps less so when we remember things 632 00:37:59,520 --> 00:38:01,319 Speaker 1: like left handed in right end and this whenly thing 633 00:38:01,400 --> 00:38:05,680 Speaker 1: about neural asymmetry that defines us on the inside. Uh. 634 00:38:05,719 --> 00:38:08,280 Speaker 1: And of course it's not just us. A Symmetries between 635 00:38:08,360 --> 00:38:10,320 Speaker 1: left and right side of the nervous system are present 636 00:38:10,320 --> 00:38:14,040 Speaker 1: throughout the animal kingdom, from invertebrates to mammals. And as 637 00:38:14,719 --> 00:38:17,920 Speaker 1: one source I was looking at this is by Concha, 638 00:38:18,239 --> 00:38:22,800 Speaker 1: Bianco and Wilson in Encoding Asymmetry within Neural Circuits, published 639 00:38:22,840 --> 00:38:27,799 Speaker 1: in in Nature Reviews Neuroscience. UH. The theoretical advantages of 640 00:38:27,840 --> 00:38:33,080 Speaker 1: brain asymmetry include the capacity for parallel processing, the specialization 641 00:38:33,120 --> 00:38:36,279 Speaker 1: of left and right side for distinct computations, and the 642 00:38:36,320 --> 00:38:41,239 Speaker 1: restriction of information processing within local circuits with short, fast connections. 643 00:38:41,680 --> 00:38:46,000 Speaker 1: But while there are obvious advantages to brain asymmetry, are 644 00:38:46,040 --> 00:38:49,640 Speaker 1: there advantages to brain symmetry. As I was looking into 645 00:38:49,680 --> 00:38:52,960 Speaker 1: this little bit and I read some thoughts from Marco 646 00:38:53,400 --> 00:38:58,000 Speaker 1: Data of the University of Padua who experimented with the 647 00:38:58,040 --> 00:39:02,640 Speaker 1: often lateralized fish species the gold belly top minnow in 648 00:39:02,840 --> 00:39:06,480 Speaker 1: two thousand and nine. Basically, what this experiment consisted of 649 00:39:06,560 --> 00:39:10,480 Speaker 1: was dividing these UH top minnows, these gold belly top minnows, 650 00:39:10,520 --> 00:39:18,040 Speaker 1: into groups of left lateralized, right lateralized, and non lateralized specimens. 651 00:39:18,040 --> 00:39:22,640 Speaker 1: So the seeming advantage to the non lateralized came when 652 00:39:22,760 --> 00:39:27,560 Speaker 1: judging stimuli to either side of the creature through either eye. 653 00:39:28,719 --> 00:39:32,960 Speaker 1: The experiments involved judging advantageous shoals of fish to join 654 00:39:33,120 --> 00:39:36,279 Speaker 1: on either side. Remember you're a small fish in the ocean. Uh, 655 00:39:36,320 --> 00:39:38,360 Speaker 1: there's a lot of survival advantage of being able to 656 00:39:38,440 --> 00:39:42,680 Speaker 1: determine which shoal of fish you should take refuge in. Uh, 657 00:39:42,719 --> 00:39:45,960 Speaker 1: you know their strength in numbers, and so it seems 658 00:39:46,000 --> 00:39:49,960 Speaker 1: that in these fish having a lateral tendency, most uh, 659 00:39:50,280 --> 00:39:52,880 Speaker 1: most often, they just joined the shoal that they saw 660 00:39:53,080 --> 00:39:56,680 Speaker 1: with their dominant eye. So I guess, I guess the 661 00:39:56,719 --> 00:39:59,920 Speaker 1: take home here is that in some cases, yeah, it's 662 00:40:00,000 --> 00:40:02,920 Speaker 1: and it may come down to your dominant side is 663 00:40:02,920 --> 00:40:06,279 Speaker 1: just going to be the tendency that you go in. Uh. 664 00:40:06,280 --> 00:40:08,600 Speaker 1: And it's maybe going to potentially get in the way 665 00:40:08,960 --> 00:40:13,920 Speaker 1: of properly evaluating in this case, two different shows of fish. 666 00:40:14,280 --> 00:40:16,160 Speaker 1: I don't have evidence of this in front of me, 667 00:40:16,239 --> 00:40:18,759 Speaker 1: but it makes me think that surely things like this 668 00:40:19,360 --> 00:40:23,440 Speaker 1: must also be true even with uh, you know, brains 669 00:40:23,480 --> 00:40:25,239 Speaker 1: we would think of as more complex. I mean, I'm 670 00:40:25,239 --> 00:40:29,120 Speaker 1: sure even with humans, handedness probably plays a role in 671 00:40:29,239 --> 00:40:34,000 Speaker 1: like directional reactions to fast stint. You know, something pops 672 00:40:34,040 --> 00:40:37,719 Speaker 1: up and scares you, which direction do you bolton? I will. 673 00:40:37,840 --> 00:40:40,439 Speaker 1: I would be surprised if there is not some kind 674 00:40:40,480 --> 00:40:44,320 Speaker 1: of tendency there that's not purely dictated by where the 675 00:40:44,360 --> 00:40:46,800 Speaker 1: stimulus is, but also has to do with like body 676 00:40:46,800 --> 00:40:52,200 Speaker 1: side dominance. Yeah, and body side dominance and left handedness 677 00:40:52,239 --> 00:40:55,000 Speaker 1: and right handedness and human beings. This is something I 678 00:40:55,000 --> 00:40:58,080 Speaker 1: think we'll have to come back to in a future episode. Uh, 679 00:40:58,120 --> 00:41:01,399 Speaker 1: there's a lot of great research out there, particularly when 680 00:41:01,680 --> 00:41:03,520 Speaker 1: again it comes back to what we're saying earlier about 681 00:41:03,560 --> 00:41:06,000 Speaker 1: how you have whatever is going on on the animal 682 00:41:06,080 --> 00:41:08,719 Speaker 1: level and then you have the human complications involved there, 683 00:41:08,840 --> 00:41:11,560 Speaker 1: because yeah, when you start getting into the whole situations 684 00:41:11,560 --> 00:41:15,120 Speaker 1: of okay, you have a right handed dominant society and 685 00:41:15,120 --> 00:41:18,319 Speaker 1: then you have left handed individuals within that society. Uh, 686 00:41:18,360 --> 00:41:21,319 Speaker 1: you know, what what is the impact? And uh and 687 00:41:21,400 --> 00:41:23,719 Speaker 1: of course there's a there's a lot of There have 688 00:41:23,760 --> 00:41:25,640 Speaker 1: been a number of interesting studies over the years that 689 00:41:25,680 --> 00:41:28,120 Speaker 1: have looked at this, how it plays into sports, how 690 00:41:28,160 --> 00:41:32,840 Speaker 1: it plays into conflict and combat, how it just plays 691 00:41:32,840 --> 00:41:35,680 Speaker 1: into thinking about the world around you. So that would 692 00:41:35,719 --> 00:41:37,359 Speaker 1: be a fun one to come back and uh and do. 693 00:41:37,440 --> 00:41:39,680 Speaker 1: And I know that the lefties especially it will love it. 694 00:41:40,719 --> 00:41:43,240 Speaker 1: But right e's you're most of our audience, so don't worry. 695 00:41:43,560 --> 00:41:49,440 Speaker 1: You'll like it too, You're just less special. Sorry, Okay, 696 00:41:49,560 --> 00:41:52,200 Speaker 1: should we wrap it up there? I suppose we should. Uh. 697 00:41:52,320 --> 00:41:54,359 Speaker 1: So we hope, we hope that you've enjoyed this uh 698 00:41:54,880 --> 00:41:58,279 Speaker 1: partial journey through a symmetry. Like we said there, there 699 00:41:58,280 --> 00:42:00,480 Speaker 1: are plenty of other examples of a symmetry in the 700 00:42:00,520 --> 00:42:03,239 Speaker 1: animal world. We we tried to focus on some of 701 00:42:03,280 --> 00:42:08,719 Speaker 1: the uh, the examples that you know illustrated uh the 702 00:42:08,760 --> 00:42:12,279 Speaker 1: topic the best. But perhaps you're thinking of something we 703 00:42:12,320 --> 00:42:16,160 Speaker 1: didn't mention that bears mentioning, right in, let us know, uh, 704 00:42:16,239 --> 00:42:18,440 Speaker 1: let us know if you're interested in an episode in 705 00:42:18,480 --> 00:42:21,799 Speaker 1: the future about left handedness and right handedness in in 706 00:42:22,120 --> 00:42:25,680 Speaker 1: in Humans anyway you look at it just right in 707 00:42:25,840 --> 00:42:28,440 Speaker 1: We'd love to hear from you past episodes, future episodes, 708 00:42:28,680 --> 00:42:32,080 Speaker 1: present episodes. It's all fair game. We read those on 709 00:42:32,120 --> 00:42:34,239 Speaker 1: Mondays on listener mail and the Stuff to Blow Your 710 00:42:34,280 --> 00:42:36,880 Speaker 1: Mind podcast feed We have our core episodes on Tuesdays 711 00:42:36,880 --> 00:42:40,400 Speaker 1: and Thursday's short form artifact or monster fact episode on Wednesdays, 712 00:42:40,800 --> 00:42:43,600 Speaker 1: and on Fridays, we put aside most serious concerns and 713 00:42:43,640 --> 00:42:46,560 Speaker 1: we just watch a weird film on Weird House Cinema. 714 00:42:46,760 --> 00:42:49,800 Speaker 1: Huge thanks as always to our excellent audio producer Seth 715 00:42:49,880 --> 00:42:52,359 Speaker 1: Nicholas Johnson. If you would like to get in touch 716 00:42:52,400 --> 00:42:54,839 Speaker 1: with us with feedback on this episode or any other, 717 00:42:54,960 --> 00:42:57,160 Speaker 1: to suggest a topic for the future, or just to 718 00:42:57,280 --> 00:43:00,000 Speaker 1: say hello, you can email us at contact at stuff 719 00:43:00,000 --> 00:43:09,640 Speaker 1: to Blow your Mind dot com. Stuff to Blow Your 720 00:43:09,680 --> 00:43:12,600 Speaker 1: Mind is production of I Heart Radio. For more podcasts 721 00:43:12,600 --> 00:43:14,680 Speaker 1: for My Heart Radio, visit the I heart Radio app, 722 00:43:14,880 --> 00:43:30,200 Speaker 1: Apple Podcasts, or wherever you listening to your favorite shows.