WEBVTT - The Headless Men, Part 1 0:00:03.040 --> 0:00:07.000 Welcome to Stuff to Blow Your Mind, a production of iHeartRadio. 0:00:12.920 --> 0:00:15.120 Hey, welcome to Stuff to Blow your Mind. 0:00:15.280 --> 0:00:18.480 My name is Robert Lamb and I am Joe McCormick. 0:00:18.640 --> 0:00:21.560 And Hey, it is no longer October. But is this 0:00:21.600 --> 0:00:23.960 still a topic that we planned on doing in October 0:00:23.960 --> 0:00:27.360 and never got to Possibly. We'll let you guess if 0:00:27.400 --> 0:00:28.319 that is the case or not. 0:00:29.000 --> 0:00:31.240 Yeah, And you might be like, I don't know, Joe 0:00:31.280 --> 0:00:33.800 and Robert, I don't know if I wont Halloween content 0:00:33.920 --> 0:00:37.080 and the early part of November, shouldn't we be doing 0:00:37.120 --> 0:00:42.239 Christmas content now? No, absolutely not. There will be Christmas 0:00:42.240 --> 0:00:44.760 content in due time, but it will not be this month. 0:00:45.240 --> 0:00:48.720 It'll barely be next month. So you're getting more Halloween 0:00:48.760 --> 0:00:50.400 content whether you want it or not. 0:00:51.000 --> 0:00:53.120 Are your Halloween decorations still up or do you get 0:00:53.159 --> 0:00:53.760 them down yet? 0:00:54.080 --> 0:00:56.880 We took them down over the weekend, but the jack 0:00:56.920 --> 0:01:00.880 O Landin's are still out there. They haven't turn to 0:01:00.960 --> 0:01:03.120 jelly yet, but I'm having to give them the tap 0:01:03.520 --> 0:01:07.679 test every day. If they jiggle, then it's dangerously close 0:01:07.720 --> 0:01:09.760 and I have to get them to the backyard and 0:01:10.040 --> 0:01:10.800 spill them there. 0:01:11.000 --> 0:01:15.039 I know exactly what you're saying. We have squirrels very 0:01:15.160 --> 0:01:18.319 slowly eating our pumpkins. It's like they take one bite 0:01:18.319 --> 0:01:19.400 out of them every day. 0:01:20.440 --> 0:01:22.280 It's weird. We have plenty of squirrels around here, but 0:01:22.319 --> 0:01:24.640 I don't think they ever messed with the pumpkins. But 0:01:25.600 --> 0:01:28.199 it has been I feel like more people are chronicling 0:01:28.280 --> 0:01:31.160 the decay and or consumption of their jack lanterns and 0:01:31.200 --> 0:01:33.720 pumpkins this year, and it's been nice to watch. 0:01:34.000 --> 0:01:36.840 I'm curious why just the like one bite and run away, 0:01:36.959 --> 0:01:40.000 Like it can't be that delicious if they don't stay 0:01:40.080 --> 0:01:41.360 to take a few more bites. 0:01:42.200 --> 0:01:45.959 Unless it's you know, just gnawing. It's gnawing action. I'm 0:01:45.959 --> 0:01:46.399 not sure. 0:01:46.680 --> 0:01:49.720 But Okay, what was this Halloween related topic that we 0:01:49.760 --> 0:01:51.880 didn't get to in October and they're covering now. 0:01:51.960 --> 0:01:56.120 It's headlessness, Yeah, which ties in nicely with the idea 0:01:56.120 --> 0:01:59.320 of jackal lanterns. I mean, these two concepts are are 0:01:59.400 --> 0:02:02.480 connected in many ways. Yeah, we're going to discuss the 0:02:02.560 --> 0:02:07.800 idea of headless entities, mostly in the human imagination, but 0:02:08.680 --> 0:02:11.360 it probably makes sense to think about what's lacking in 0:02:11.440 --> 0:02:14.040 these fantastic creatures and what we tend to take for granted. 0:02:14.480 --> 0:02:16.720 It's we're going to get into just the concept of 0:02:17.120 --> 0:02:20.160 why do creatures have heads? What is a head? Even 0:02:20.680 --> 0:02:23.040 it's easy to just take that whole idea for granted, 0:02:24.320 --> 0:02:26.760 because I mean, the basics I think are pretty obvious, 0:02:26.919 --> 0:02:29.079 and you know, we have to stop and look them 0:02:29.080 --> 0:02:31.320 in the mirror and realize. A head is the top 0:02:31.400 --> 0:02:35.120 or front part of an organism, the upper or anterior 0:02:35.160 --> 0:02:38.640 division of the animal body that contains the brain, most 0:02:38.639 --> 0:02:41.320 of the sense organs, and the mouth. It is the 0:02:41.360 --> 0:02:45.639 communication array as we've described it many times before. It's 0:02:45.680 --> 0:02:48.359 the matter consumer, and it's also the nerve center of 0:02:48.400 --> 0:02:49.079 the organism. 0:02:49.320 --> 0:02:52.639 Now, most of the animals you can probably think of 0:02:52.639 --> 0:02:56.080 off the top of your head do have heads, but 0:02:56.240 --> 0:02:59.720 actually a head is not a necessary part of what 0:02:59.760 --> 0:03:02.840 it means to be an animal. There are animals without heads, 0:03:03.120 --> 0:03:06.519 So that raises the question of why do certain animals 0:03:06.560 --> 0:03:09.320 have heads and not others? What causes this difference? 0:03:10.240 --> 0:03:12.919 Yeah, we have to realize that heads emerge in organisms 0:03:12.960 --> 0:03:15.639 over the course of evolutionary time and a process referred 0:03:15.680 --> 0:03:20.160 to as cephalization, during which the mouth, sense organs and 0:03:20.240 --> 0:03:23.240 nerve ganglia moved toward the front or what would we 0:03:23.280 --> 0:03:25.240 would come to think of at the front of the creatures, 0:03:25.480 --> 0:03:29.720 resulting in head morphology and the emergence of complex brains 0:03:30.160 --> 0:03:36.560 and arthropods, cephalopod mollus and invertebrates. So these organisms tend 0:03:36.560 --> 0:03:42.320 to be cephalized or semi cephalized. And would that mean 0:03:42.360 --> 0:03:45.000 that a creature in fantasy that has lost its head 0:03:45.000 --> 0:03:51.640 and continues to move around and act and behave is decephalized. 0:03:52.200 --> 0:03:54.040 Well, I think that would be the term. The head 0:03:54.080 --> 0:03:57.680 is removed, a thing is decephalized. But whether or not 0:03:57.720 --> 0:04:00.040 a thing can continue to act without its head, it 0:04:00.200 --> 0:04:04.200 probably depends on the degree to which it was originally 0:04:04.400 --> 0:04:09.160 cephalized as a matter of its innate anatomy. I'll get 0:04:09.200 --> 0:04:12.240 back to that in a few minutes. Actually, So I 0:04:12.280 --> 0:04:14.920 was thinking about this, and it probably helps to put 0:04:15.080 --> 0:04:22.680 cephalization within the broader evolutionary history of bilateral animals or bilatarians. 0:04:22.839 --> 0:04:25.720 These are animals that have a left side and a 0:04:25.839 --> 0:04:29.240 right side of the body that are roughly symmetrical, that 0:04:29.360 --> 0:04:32.560 are mirror images of each other. So we are bilatarians, 0:04:32.800 --> 0:04:35.279 and again, most of the animals you can think of off 0:04:35.160 --> 0:04:38.360 the top of your head are bilatarians. The symmetry does 0:04:38.400 --> 0:04:41.919 not have to be exact. It refers to the overall 0:04:42.040 --> 0:04:45.679 body plan and how the animal develops in its earliest 0:04:45.680 --> 0:04:48.520 phases of growth. So even in the case of animals 0:04:48.520 --> 0:04:53.040 that happen to have evolved wildly asymmetrical features. One example 0:04:53.080 --> 0:04:55.920 we've talked about on the show before is male fiddler crabs, 0:04:56.000 --> 0:04:59.279 which have one claw that's much bigger than the other, 0:04:59.320 --> 0:05:02.000 in some cases half of the crab's body weight, So 0:05:02.600 --> 0:05:04.800 you know, roughly on the scale of a human with 0:05:04.880 --> 0:05:08.000 one regular sized hand and then another hand that's four 0:05:08.040 --> 0:05:11.880 feet in diameter and weighs eighty pounds, even that animal 0:05:12.120 --> 0:05:15.600 is a bilatarian because the animal's body plan has bilateral 0:05:15.640 --> 0:05:19.120 symmetry overall, with the exception of the claw, And it's 0:05:19.160 --> 0:05:22.920 also a question of its evolutionary clade. It is descended 0:05:23.080 --> 0:05:28.160 from the evolutionary clade of bilateral animals. So bilateral symmetry 0:05:28.240 --> 0:05:30.919 is not just a feature of an animal body, but 0:05:31.000 --> 0:05:34.440 a particular branch on the evolutionary tree, going back to 0:05:34.480 --> 0:05:37.640 a common ancestor. As I was saying a minute ago, 0:05:38.080 --> 0:05:41.480 though most of the animals you can think of are bilateral, 0:05:41.680 --> 0:05:44.440 not all animals are. There are lots of sea creatures 0:05:44.520 --> 0:05:50.039 like sponges, jellyfish, hydri and corals, that are animals but 0:05:50.120 --> 0:05:55.440 are not Bilatarians. We don't know for sure when exactly 0:05:55.480 --> 0:05:58.680 this split took place, when the last common ancestor of 0:05:58.760 --> 0:06:02.600 all bilatarians split off from the ancestors of other animals, 0:06:02.600 --> 0:06:04.960 but based on what I've been reading, I think it's 0:06:05.040 --> 0:06:08.560 probably sometime between roughly five hundred and fifty and six 0:06:08.680 --> 0:06:11.880 hundred million years ago. Is clearly it pre dates the 0:06:12.400 --> 0:06:16.920 Cambrian Explosion, because in the Cambrian era, starting around five 0:06:17.000 --> 0:06:20.679 hundred and fifty million years ago, you see a great 0:06:20.839 --> 0:06:26.039 diffusion or profusion of different animal body plans that exhibit 0:06:26.080 --> 0:06:30.400 bilateral symmetry. So clearly their last common ancestor was before that. 0:06:31.240 --> 0:06:34.760 There's still debate about exactly what that animal was like, 0:06:35.000 --> 0:06:39.480 but whatever its exact features were, it is mind boggling 0:06:39.520 --> 0:06:47.600 to imagine the common ancestor of all of the world's fish, crabs, cats, squid, slugs, 0:06:47.920 --> 0:06:50.719 barnacles and worms all in one body. 0:06:51.160 --> 0:06:53.120 Yeah, you can't just combine all those things in your 0:06:53.160 --> 0:06:54.960 head and say, like, all right, a little bit of 0:06:54.520 --> 0:06:56.839 the cat, a little bit of the squid. It's a 0:06:56.920 --> 0:06:58.679 different sort of arithmetic in play. 0:06:59.320 --> 0:07:02.320 But one of the things, apart from bilateral symmetry that 0:07:02.480 --> 0:07:08.280 makes Bilatarians unique is their degree of cephalization. That they 0:07:08.480 --> 0:07:12.200 these animals really started to develop heads in ways that 0:07:12.320 --> 0:07:16.520 non biletarian animals did not. And the authors of a 0:07:16.520 --> 0:07:19.920 paper I was looking at, they they define cephalization as 0:07:20.040 --> 0:07:25.080 quote anterior concentration, and remember anterior means front, so front 0:07:25.120 --> 0:07:30.640 facing concentration of nervous tissue, sensory organs, and the appearance 0:07:30.680 --> 0:07:35.960 of dedicated feeding structures surrounding the mouth. Now, one question 0:07:36.040 --> 0:07:38.800 I was wondering about was how to even decide which 0:07:39.000 --> 0:07:42.760 is the anterior part of an animal that doesn't already 0:07:42.840 --> 0:07:45.520 have a head. I think the answer is it's where 0:07:45.560 --> 0:07:49.240 the mouth is. Makes sense. Yeah, Now to get some 0:07:49.280 --> 0:07:53.920 more perspective on why and how a head developed in Bilatarians, 0:07:54.080 --> 0:07:57.400 I was reading a few chapters from a book. It 0:07:57.560 --> 0:08:00.960 was a book called Creatures of acxis The Rise of 0:08:01.000 --> 0:08:03.920 the Animal Kingdom, published by Hill and Wang two thousand 0:08:03.920 --> 0:08:07.440 and seven by an author named Wallace Arthur. 0:08:07.880 --> 0:08:07.960 So. 0:08:08.040 --> 0:08:11.080 The author of this book, Wallace Arthur is an evolutionary 0:08:11.120 --> 0:08:14.440 biologist who was a professor at the University of Galway 0:08:14.520 --> 0:08:17.080 in Ireland. I looked him up and it seems like 0:08:17.120 --> 0:08:19.720 his work focused a lot on the interplay between evolution 0:08:19.840 --> 0:08:23.360 and development and the emergence of animal body plans, which 0:08:23.360 --> 0:08:25.800 is what we're talking about here, And in a couple 0:08:25.880 --> 0:08:29.000 of chapters of this book he has a very nice, 0:08:29.000 --> 0:08:33.720 plain language summary of the likely pressures leading early by 0:08:33.800 --> 0:08:38.959 leetarians to acquire ahead. So one interesting thing to think 0:08:38.960 --> 0:08:42.680 about here is that the early evolution of the animal 0:08:42.679 --> 0:08:47.160 lineage found different types of symmetries. So the first animals 0:08:47.200 --> 0:08:50.400 were not symmetrical, and there are animals today that are 0:08:50.440 --> 0:08:54.080 not symmetrical in their bodies, like sponges. You know, you 0:08:54.160 --> 0:08:56.640 can't cut them down the middle and get a mirror 0:08:56.679 --> 0:09:01.559 image in any direction. Then there came animals with radial symmetry, 0:09:02.040 --> 0:09:06.240 where the body is symmetrically reproduced around an axis in 0:09:06.280 --> 0:09:09.880 the middle. And a great example here would be a jellyfish. Jellyfish, 0:09:10.280 --> 0:09:14.400 they're not bilaterally symmetrical, but they're radially symmetrical. Finally, there 0:09:14.400 --> 0:09:18.000 came animals with bilateral symmetry, tracing back to a common 0:09:18.040 --> 0:09:21.760 ancestor that is known in the literature as the ur bileatarian, 0:09:22.000 --> 0:09:26.040 so biletarian with the letters you are in front of it, 0:09:26.080 --> 0:09:29.320 you are meaning like original or first. And again we 0:09:29.360 --> 0:09:31.640 don't know exactly what this animal was like, but Arthur 0:09:31.720 --> 0:09:34.560 thinks the best guess is that it was somewhat similar 0:09:34.960 --> 0:09:39.560 to modern flatworms. This, he acknowledges this is debatable, and 0:09:39.600 --> 0:09:41.440 I was reading a bit about the modern debate here 0:09:41.480 --> 0:09:45.079 it seems like this is still one of the one 0:09:45.160 --> 0:09:47.560 of the possible pictures of what this creature was like. 0:09:48.240 --> 0:09:52.000 So Arthur asks a question, if you compare a bilaterally 0:09:52.040 --> 0:09:56.920 symmetrical flatworm with a radially symmetrical animal like a jellyfish, 0:09:57.280 --> 0:10:00.640 can we really say that one is more complex than 0:10:00.679 --> 0:10:04.559 the other? He writes, quote, does a flatworm have more 0:10:04.640 --> 0:10:08.960 different types of parts than a jellyfish? Well, not really. Yes, 0:10:09.000 --> 0:10:11.800 it has left and right sides, which a jellyfish does not, 0:10:12.040 --> 0:10:15.440 but that's about it. Although the flatworm has head and 0:10:15.520 --> 0:10:18.720 tail ends while the jellyfish does not, The jellyfish has 0:10:18.720 --> 0:10:21.800 a top side and an underside, the latter having the mouth, 0:10:22.160 --> 0:10:24.800 which pretty much amount to the same thing. And the 0:10:24.880 --> 0:10:29.640 jellyfish has tentacles while the flatworm does not. And yet 0:10:29.640 --> 0:10:32.200 despite this basic parity, or maybe you might even say 0:10:32.200 --> 0:10:35.240 that the jellyfish seems more complex, we do tend to 0:10:35.320 --> 0:10:40.280 think of bilaterally symmetrical animals as more complex than animals 0:10:40.280 --> 0:10:42.880 with radial symmetry. Why do we think of them that way. Well, 0:10:43.400 --> 0:10:46.160 Arthur says that there could be a good reason for this, 0:10:46.200 --> 0:10:50.800 and it's that bilateral symmetry led to subsequent steps of 0:10:50.880 --> 0:10:56.440 increasing complexity. Bilateral symmetry was not itself necessarily more complex, 0:10:56.840 --> 0:11:01.760 but it became a platform for future complexity to emerge, 0:11:02.160 --> 0:11:05.400 making the point that some changes in evolution can seem 0:11:05.440 --> 0:11:09.360 really important to us because they are necessary precursors to 0:11:09.559 --> 0:11:13.080 other developments, maybe millions of years down the line, and 0:11:13.160 --> 0:11:16.800 you couldn't always necessarily predict what those future developments would 0:11:16.800 --> 0:11:19.480 be at the time. Like if we were standing there 0:11:19.480 --> 0:11:22.760 in the pre Cambrian era looking at the orbilatarian, you 0:11:22.760 --> 0:11:26.000 wouldn't necessarily be able to look at this little flatworm 0:11:26.120 --> 0:11:28.040 like creature or whatever it was that it looked like 0:11:28.040 --> 0:11:31.080 some kind of little little organism that has left and 0:11:31.160 --> 0:11:34.760 right sides that roughly mirror each other and think, well, yes, 0:11:35.240 --> 0:11:37.520 this is going to be big, This will turn into 0:11:37.520 --> 0:11:39.559 spiders and cats and octopuses. 0:11:41.440 --> 0:11:42.160 But that is. 0:11:42.120 --> 0:11:45.520 Exactly what happened. It became this sort of platform for 0:11:45.840 --> 0:11:49.640 future development. But to come back to the question, what 0:11:50.040 --> 0:11:54.400 is it about these early Bilatarians that favors the evolution 0:11:54.559 --> 0:11:57.920 of a head. Well, Arthur argues that it is the 0:11:57.960 --> 0:12:02.800 peculiarities of pre cam animal movement. It had to do 0:12:02.840 --> 0:12:07.439 with how animals move. So he says, you know, jellyfish, 0:12:07.480 --> 0:12:11.800 this animal with radial symmetry swims around in the open sea. 0:12:11.920 --> 0:12:13.880 You know, it floats in the water column. It kind 0:12:13.880 --> 0:12:16.280 of pulses to swim where it wants. And then you 0:12:16.360 --> 0:12:18.760 might have other animals that have radial symmetry, like the 0:12:18.800 --> 0:12:22.320 sea anemone. This lives it's a sessile organism, so it 0:12:22.360 --> 0:12:24.600 lives most of its life by sticking itself to a 0:12:24.640 --> 0:12:30.360 surface and staying there, you know, grabbing things from the water. Flatworms, however, 0:12:31.160 --> 0:12:36.120 creep across the two dimensional surfaces of solid objects like 0:12:36.280 --> 0:12:39.800 rocks in the water. So you can imagine what he 0:12:39.880 --> 0:12:43.920 thinks is likely the form of the orbiletarian traversing the 0:12:43.920 --> 0:12:47.920 face of a flat boulder in an archaic lagoon. And 0:12:47.960 --> 0:12:50.680 so he zeros in on the different ways that these 0:12:50.720 --> 0:12:54.840 creatures move. For the jellyfish with radial symmetry floating in 0:12:54.880 --> 0:12:57.880 the water, Arthur says, there is little reason to think 0:12:57.920 --> 0:13:01.320 of any direction as forward or backward. All directions are 0:13:01.360 --> 0:13:05.240 basically the same. The sessile sea an enemy doesn't generally 0:13:05.280 --> 0:13:07.719 travel around, so travel isn't a big issue for it. 0:13:07.800 --> 0:13:11.960 But for the flatworm like or biltarian, there is a 0:13:12.200 --> 0:13:17.080 very definite forward and backward regime in the way that 0:13:17.120 --> 0:13:19.600 this animal moves. You can think of the difference between 0:13:19.920 --> 0:13:23.439 a car and an aerial drone. You know, the jellyfish 0:13:23.480 --> 0:13:25.400 might be more like the aerial drone. It can kind 0:13:25.400 --> 0:13:28.280 of go in whatever direction a car has to like 0:13:28.480 --> 0:13:32.679 aim its movement. It crawls, it creeps along on a 0:13:32.720 --> 0:13:33.680 forward path. 0:13:34.080 --> 0:13:36.320 That's a good way of putting it. Yeah, yeah, drones 0:13:37.000 --> 0:13:37.760 versus cars. 0:13:37.840 --> 0:13:41.600 Yeah, now, no, there's absolutely nothing wrong with moving like 0:13:41.640 --> 0:13:44.560 a drone, you know, the jellyfish, and there's nothing wrong 0:13:44.600 --> 0:13:48.480 with these other lineages. Jellyfish can be highly successful without 0:13:48.480 --> 0:13:51.720 a brain and with limited range of behaviors. They're doing 0:13:51.800 --> 0:13:54.080 just find how they are, and this leads to what 0:13:54.240 --> 0:13:57.840 Arthur calls an evolutionary cul de sac. You know, they're 0:13:57.960 --> 0:14:00.880 just successful in the way they already are. But for 0:14:00.920 --> 0:14:06.200 the orbiletarian, with a definite bias for forward movement, there 0:14:06.360 --> 0:14:09.480 is a lot of reason to differentiate the front of 0:14:09.520 --> 0:14:12.080 the body from the back. There are reasons this animal 0:14:12.160 --> 0:14:15.920 needs to change based on the way it moves. Arthur writes, quote, 0:14:16.280 --> 0:14:18.679 it is more important to be able to detect the 0:14:18.720 --> 0:14:21.640 features of the area you are moving into than the 0:14:21.640 --> 0:14:24.880 one you're leaving behind. So it is to be expected 0:14:24.920 --> 0:14:28.440 that natural selection will favor variants that have more of 0:14:28.480 --> 0:14:32.400 their nerve net upfront. As part of this concentration of 0:14:32.440 --> 0:14:35.480 perceptive powers at the front of the animal, in the 0:14:35.520 --> 0:14:38.360 region that will one day merit the term head, there 0:14:38.360 --> 0:14:43.160 may be rudimentary forward pointing outgrowths densely populated with sensory 0:14:43.240 --> 0:14:48.040 nerves primitive antennae. And I was thinking about this. Maybe 0:14:48.040 --> 0:14:50.040 this is getting a little too philosophical about it, but 0:14:50.160 --> 0:14:53.160 you could argue that the evolution of the head in 0:14:53.240 --> 0:14:57.160 animals is related to the nature of time. For an 0:14:57.280 --> 0:15:01.360 organism that specializes in moving in one direction, moving like 0:15:01.400 --> 0:15:05.360 a car, or like a flatworm moving forward along varied terrain, 0:15:06.040 --> 0:15:08.680 the gathering of nerve cells and sensory organs in the 0:15:08.720 --> 0:15:12.840 front reflects the fact of reality that it is more 0:15:12.880 --> 0:15:16.000 important to sense and react to the future where you 0:15:16.080 --> 0:15:18.800 are headed than to the past where you've just been. 0:15:19.240 --> 0:15:22.280 The past can't hurt you anymore, but the future can no. 0:15:22.400 --> 0:15:24.240 I think that's a good way of looking at it. 0:15:24.080 --> 0:15:27.360 And it reminds me of some accounts. Off the top 0:15:27.400 --> 0:15:29.800 of my head. I can't recall how accurate these are 0:15:29.800 --> 0:15:32.200 held up to be, but there was at least an 0:15:32.200 --> 0:15:37.120 idea that was put forward in Western writing that certain 0:15:37.240 --> 0:15:42.680 members of Native Arctic groups kind of referred linguistically to 0:15:44.040 --> 0:15:49.440 something in the distance as being tomorrow, like this relationship 0:15:49.520 --> 0:15:53.880 between where you will be and how you think about 0:15:54.000 --> 0:15:57.360 what is ahead of you. And yeah, I can sort 0:15:57.360 --> 0:15:59.480 of see that reflected in what we're talking about here. 0:16:00.040 --> 0:16:02.640 Oh, this came up when we were talking about the 0:16:02.720 --> 0:16:07.480 cultural spatialization of time. Yeah, how people represent time in 0:16:07.640 --> 0:16:10.280 as a type of physical space or the metaphor of 0:16:10.320 --> 0:16:13.120 the space around them. And I don't remember if that 0:16:13.320 --> 0:16:16.120 example in particular was thought to be valid, but that 0:16:16.160 --> 0:16:19.720 there are cultural differences in the spatial metaphors people used 0:16:19.800 --> 0:16:22.880 to describe, like the future in the past and so forth. 0:16:23.520 --> 0:16:27.120 Yeah, yeah, but even today, you know, we can easily 0:16:27.280 --> 0:16:31.640 think about everything that's coming into us is like our future. 0:16:32.000 --> 0:16:34.400 You know, it's the future of our body in that 0:16:34.640 --> 0:16:36.880 in what we are consuming the you know, the future 0:16:36.920 --> 0:16:40.000 of our thoughts based on the sense data that's entering 0:16:40.480 --> 0:16:44.440 entering our body and our mind and so forth. So 0:16:44.920 --> 0:16:47.120 uh yeah, I can see this this holding up. Whereas 0:16:47.200 --> 0:16:50.160 what is it like? I mean, to the limited extent 0:16:50.200 --> 0:16:52.160 you can even ask this question, what is it like then? 0:16:52.520 --> 0:16:56.000 For the creature that is not farward loaded, that is, 0:16:56.080 --> 0:16:58.040 you know, it's kind of like an a nowness. It's 0:16:58.120 --> 0:17:02.320 kind of perhaps something at least distantly comparable to that 0:17:02.960 --> 0:17:07.520 state of calmness and serenity that we aspire to, you know, 0:17:08.040 --> 0:17:09.679 or so many of us aspire to to try and 0:17:09.720 --> 0:17:14.840 get out of that forward headlong you know, sprint into 0:17:14.880 --> 0:17:15.880 the future. 0:17:15.760 --> 0:17:29.200 Assume the mind of a jellyfish. Yeah yeah, okay. Next 0:17:29.320 --> 0:17:34.240 ecological consideration pressure on the creation of a head in 0:17:34.600 --> 0:17:39.760 the early piletarians. Arthur says that forward movement also favors 0:17:39.800 --> 0:17:42.879 the evolution of a front facing mouth. If you think 0:17:42.920 --> 0:17:45.440 about this, this will make sense. It's kind of obvious. 0:17:45.560 --> 0:17:48.840 Like if you feed by taking things into an orifice 0:17:48.840 --> 0:17:51.919 in your body, it's best to be able to aim 0:17:52.040 --> 0:17:56.480 your body movement to engulf food matter with that orifice. 0:17:56.880 --> 0:17:59.239 So like, in the same way that it wouldn't make 0:17:59.280 --> 0:18:02.320 sense to build a combine harvester with its intake on 0:18:02.400 --> 0:18:05.359 the side. Right, you'd want it in the front of 0:18:05.400 --> 0:18:07.640 the vehicle so you can aim it at the thing 0:18:07.680 --> 0:18:09.200 you're trying to harvest. 0:18:09.520 --> 0:18:13.760 Essentially an eat the future approach. Basically we've covered so. 0:18:13.800 --> 0:18:18.080 Far right, So aiming the mouth orifice at food and 0:18:18.160 --> 0:18:22.960 making sure food gets inside also requires extra motor control 0:18:23.359 --> 0:18:26.920 around this region of the body. And this also favors 0:18:27.240 --> 0:18:31.000 nerve cells being concentrated at the anterior or the front 0:18:31.160 --> 0:18:34.200 of the bileatarian body. So nerve cells want to gather 0:18:34.280 --> 0:18:37.240 there not just to sense what is ahead in your 0:18:37.320 --> 0:18:41.400 movement schema, but also to control the mouth to eat 0:18:41.480 --> 0:18:44.560 what is ahead in the movement schema. And you can 0:18:44.600 --> 0:18:47.840 see this, this direct connection between nerve cell density and 0:18:47.880 --> 0:18:52.240 eating behavior in an example that Arthur sites, which are 0:18:52.680 --> 0:18:56.400 modern snails and slugs, some of the simpler bileateian animals 0:18:56.440 --> 0:19:00.680 extant today. These creatures, he writes quote, have a arrangement 0:19:00.760 --> 0:19:03.920 of mouth and nerve cells such that the nerves form 0:19:04.000 --> 0:19:07.600 a ring around the mouth or the esophagus, and at 0:19:07.680 --> 0:19:11.320 various points around this ring are expanded groupings of nerve 0:19:11.400 --> 0:19:15.879 cells called ganglia or mini brains if you like. So 0:19:16.040 --> 0:19:19.520 I love that. Of course, what begins as ganglia for 0:19:19.640 --> 0:19:22.159 control of just like a mouth, you know, the eating 0:19:22.240 --> 0:19:26.520 orifice could well evolve over millions of years into denser 0:19:26.560 --> 0:19:30.200 and more complex structures of neurons, and eventually could even 0:19:30.280 --> 0:19:34.639 become a brain. And so I thought this was fascinating. 0:19:34.680 --> 0:19:38.600 According to Arthur's argument here, so much of the strange 0:19:38.640 --> 0:19:43.959 and complicated and unpredictable evolutionary potential of the bileatarian body 0:19:44.000 --> 0:19:48.040 plan arises out of the simple circumstance that these animals, 0:19:48.080 --> 0:19:52.439 the Orbileatarians, had specific limitations on their range of movement, 0:19:52.760 --> 0:19:56.800 that their world was a world of moving forward. One 0:19:56.800 --> 0:19:58.760 more thing from this book I wanted to mention before 0:19:58.760 --> 0:20:01.800 I move on is something that he talks about in 0:20:01.840 --> 0:20:04.600 the next chapter, which is sort of the idea that 0:20:04.720 --> 0:20:09.040 cephalization is not a binary It's not like you are 0:20:09.119 --> 0:20:13.520 cephalized or not, but a question of degree. Some creatures 0:20:13.560 --> 0:20:17.919 are strongly cephalized, others are more weakly cephalized. And to 0:20:17.960 --> 0:20:21.000 illustrate this, Arthur begins by telling a story about a 0:20:21.000 --> 0:20:23.800 time he was collecting centipedes from an area along the 0:20:23.840 --> 0:20:27.400 coast of northeast England. He says he collected a number 0:20:27.400 --> 0:20:29.800 of centipedes. He brought him back to the lab for examination, 0:20:30.280 --> 0:20:32.880 where they seem to be functioning fine. Some of them 0:20:32.920 --> 0:20:35.920 had injuries, like they might be missing legs or parts 0:20:35.920 --> 0:20:39.600 of legs, but he explains that these centipedes have an 0:20:39.640 --> 0:20:43.840 adaptation where they cover the stumps of their missing appendages 0:20:44.240 --> 0:20:47.840 with a thick black substance that looks like tar, presumably 0:20:47.920 --> 0:20:51.840 to seal off the wound and prevent anything that's on 0:20:51.880 --> 0:20:54.280 the outside from getting in or anything on the inside 0:20:54.280 --> 0:20:55.000 from getting out. 0:20:55.520 --> 0:20:57.760 Seems like a solid approach, some sort of weird black 0:20:57.800 --> 0:20:59.120 centipede sealant. 0:20:58.840 --> 0:21:01.960 Okay, yep, yeap, seal it up. But then he came 0:21:02.000 --> 0:21:05.919 across something weird, he writes, quote to my surprise, I 0:21:06.000 --> 0:21:10.040 found that one specimen had lost its head and had 0:21:10.160 --> 0:21:14.840 used that same black tar technique to seal the wound. Strangely, 0:21:15.119 --> 0:21:18.159 it was moving around in a normal fashion, just like 0:21:18.200 --> 0:21:21.159 all its friends who had retained their heads. It walked 0:21:21.160 --> 0:21:24.040 in the way centipedes do, usually in a forward direction, 0:21:24.400 --> 0:21:28.240 but it was also able to retreat backward from threatening stimulis, 0:21:28.320 --> 0:21:30.960 such as my giving it a tap on its anterior 0:21:31.160 --> 0:21:33.800 end with a pair of tweezers. Not only did it 0:21:33.840 --> 0:21:36.880 do so for a considerable period in the lab hours, 0:21:37.320 --> 0:21:39.639 but it had probably done so for an even longer 0:21:39.680 --> 0:21:43.480 one days in the wild before I found it, because 0:21:43.680 --> 0:21:47.800 the wound looked old. Inasmuch as you can tell these things. Wow, 0:21:48.400 --> 0:21:52.080 So he says that this headless centipede eventually died because 0:21:52.119 --> 0:21:55.560 it probably starved to death. No mouth means it can't eat. 0:21:56.320 --> 0:22:00.439 But that's amazing. It's hard for us, being extremely highly 0:22:00.440 --> 0:22:04.480 cephalized organisms, to imagine that, Like the first problem to 0:22:04.520 --> 0:22:07.199 reach the crisis point with a headless animal would be 0:22:07.240 --> 0:22:10.040 that it starves to death. And the difference here is 0:22:10.119 --> 0:22:13.399 the level of cephalization in each organism. The centipede and 0:22:13.440 --> 0:22:17.159 the human are both cephalized. They both have heads, but 0:22:17.240 --> 0:22:21.280 the human is strongly cephalized and the centipede only weakly so. 0:22:21.320 --> 0:22:25.600 In humans, control of the body functions is strongly localized 0:22:25.600 --> 0:22:27.760 in the brain, which is in the head, and the 0:22:27.800 --> 0:22:31.480 body really can't do anything without the brain. Centipedes, on 0:22:31.520 --> 0:22:33.960 the other hand, they do have a brain of sorts 0:22:34.000 --> 0:22:36.199 in the head. There is a cluster of nervous tissue 0:22:36.240 --> 0:22:39.160 up there, but they also have clusters of nerve cells 0:22:39.160 --> 0:22:42.479 in each body segment that work as a distributed system 0:22:42.520 --> 0:22:46.320 of many secondary brains throughout the body. Even without the 0:22:46.320 --> 0:22:48.679 brain in the head, the body segments can keep on 0:22:48.800 --> 0:22:52.400 living and acting individually. They can make the centipede walk around, 0:22:52.520 --> 0:22:56.080 react to stimuli, and so forth, but not forever. But 0:22:56.359 --> 0:22:59.200 to come back to headlessness in nature, I want to 0:22:59.240 --> 0:23:05.080 emphasize again that not every animal naturally has a head. Jellyfish, 0:23:05.160 --> 0:23:10.240 for example, there's some disagreement to the extent to which 0:23:10.280 --> 0:23:13.240 you should say they are cephalized, but they really don't 0:23:13.240 --> 0:23:16.240 have anything you would normally call ahead. In fact, jellyfish, 0:23:16.240 --> 0:23:19.680 you don't even have brains or hearts, or even blood 0:23:19.760 --> 0:23:22.480 for that matter. They do have a nervous system, but 0:23:22.640 --> 0:23:26.120 it is distributed throughout the body tissues without a central 0:23:26.200 --> 0:23:29.680 like a major command center like a biletarian brain. 0:23:30.359 --> 0:23:34.560 Yeah, it's fascinating and maybe a little treacherous right to 0:23:34.960 --> 0:23:37.280