WEBVTT - Cambrian Monster Mash 0:00:04.680 --> 0:00:13.600 Hello, Dr Jessup. Anybody here? Well, hello, good sir. I'm 0:00:13.640 --> 0:00:17.200 glad to see you have arrived. I apologize I can't 0:00:17.239 --> 0:00:19.920 be there to greet you in person, but please know 0:00:20.040 --> 0:00:23.400 that I have most appreciative of your attendance. It's so 0:00:23.480 --> 0:00:26.880 hard to find good volunteers these days. It's it's just 0:00:26.880 --> 0:00:30.160 just every undergraduate with even a bit of backbone and 0:00:30.240 --> 0:00:35.400 simply vanished in the past six months. Uh huh okay, 0:00:35.560 --> 0:00:38.600 So am I in the right place? Ah? Well, well, 0:00:38.600 --> 0:00:41.400 perhaps instead you should ask whether you were in the 0:00:41.520 --> 0:00:44.960 right time? Uh huh. Well, the flyer said you were 0:00:44.960 --> 0:00:51.479 doing six for test subjects in something called Middle Cambrian exposure. 0:00:52.120 --> 0:00:54.720 I'm not sure what that is, but if you're paying cash, 0:00:54.760 --> 0:00:58.160 I'm still on board. Excellent. Now tell me do you 0:00:58.200 --> 0:01:03.400 have any experience with time displacement? I don't think so, 0:01:03.760 --> 0:01:06.560 of course, not, of course not. You can tell me. 0:01:07.319 --> 0:01:09.920 Can you swim? You know I can, but it's one 0:01:09.959 --> 0:01:13.479 of those things I wouldn't say I'm a great swimmer. Okay, 0:01:14.000 --> 0:01:18.880 nobody's perfect. Do you see the throbbing lightness of the 0:01:18.880 --> 0:01:23.119 world text in the center of the room there, Well, yeah, yeah, 0:01:23.120 --> 0:01:30.360 I do, except go to it right, Yes, yes, closer, 0:01:30.520 --> 0:01:36.000 closer doesn't feel right? What's that feeling? What's the matter, 0:01:36.080 --> 0:01:39.480 my little vertebrate? Haven't you ever wanted to feel? Five 0:01:39.760 --> 0:01:45.039 hundred miran years loved? What is that? Is? That? Is 0:01:45.040 --> 0:01:48.800 that an ocean? Oh? My god, It's like the whole 0:01:48.840 --> 0:01:59.320 planet's an ocean. It's full of monsters. Welcome to Stuff 0:01:59.360 --> 0:02:08.760 to blow your Mind from housework dot com. Hey, welcome 0:02:08.800 --> 0:02:10.680 to stuff to blow your mind. My name is Robert 0:02:10.760 --> 0:02:13.359 Lamb and I'm Joe McCormick and Robert. That was obviously 0:02:13.360 --> 0:02:15.760 a reference to some kind of journey we may be 0:02:15.919 --> 0:02:18.840 taking to the Cambrian period. That's right. Yeah, we had 0:02:18.840 --> 0:02:23.280 a little cameo by the late great Anton Jess late 0:02:23.320 --> 0:02:25.160 did he die? I don't know. I mean there are 0:02:25.200 --> 0:02:27.959 there are rumors of his death, but who knows for sure? 0:02:28.120 --> 0:02:30.720 They always exaggerated. Is well? Anyway, today I've got a 0:02:30.720 --> 0:02:32.400 little story I want to tell the lead us into 0:02:32.440 --> 0:02:35.720 our topic. Now. Obviously it is October. It's our favorite 0:02:35.720 --> 0:02:37.760 time of year to talk about monsters. We talked about 0:02:37.760 --> 0:02:39.880 monsters anyway, but this is the time where we really 0:02:39.880 --> 0:02:43.280 double down. Its clear mandate for monsters, and I got 0:02:43.280 --> 0:02:47.320 to take a monster science adventure this past month. So 0:02:47.560 --> 0:02:50.600 this this past month, early on one Sunday morning, my 0:02:50.680 --> 0:02:53.280 wife Rachel and I were in Canada and we woke 0:02:53.360 --> 0:02:55.639 up before dawn on this Sunday morning in the town 0:02:55.639 --> 0:02:59.840 of Golden British Columbia. It's in western Canada, the Canadian Rockies, 0:03:00.760 --> 0:03:02.720 and we had some coffee and bagels, and we filled 0:03:02.760 --> 0:03:05.240 up our backpacks with a bunch of layers of warm clothes, 0:03:05.320 --> 0:03:08.320 bottles of water, all that hiking stuff, and we drove 0:03:08.400 --> 0:03:11.360 along the steep mountain sides to this tiny town called 0:03:11.600 --> 0:03:15.600 Field in British Columbia. And there we parked beside a 0:03:15.600 --> 0:03:18.840 gas station and we waited to meet our guide and 0:03:18.880 --> 0:03:22.280 the rest of this tour group. So the guide was 0:03:22.320 --> 0:03:25.960 a paleontologist named David, and the hiking group was mostly 0:03:26.040 --> 0:03:29.400 French speaking families, some really lovely people and some very 0:03:29.480 --> 0:03:35.400 intelligent children with great questions like why do animals die? Uh? 0:03:35.440 --> 0:03:37.920 And so we hiked through the town of Field and 0:03:37.960 --> 0:03:40.840 along this uphill path through the forest up the side 0:03:40.840 --> 0:03:44.040 of Mount Stephen. And as we went on throughout the day, 0:03:44.080 --> 0:03:46.839 the trail got steeper and steeper, and we could see 0:03:46.880 --> 0:03:49.600 through the trees the town. We came from was becoming 0:03:49.640 --> 0:03:52.320 this tiny miniature model in the distance. And then right 0:03:52.360 --> 0:03:55.360 around midday we came out of the tree line and 0:03:55.400 --> 0:03:58.280 we walked up on this bare plane of flat rocks 0:03:58.680 --> 0:04:01.960 and they were pieces of the underlying shale formation that 0:04:02.000 --> 0:04:04.560 had chipped and broken off, and they had gathered in 0:04:04.600 --> 0:04:07.800 this relatively flat part of the mountain side. And on 0:04:07.840 --> 0:04:10.360 this plane of rocks, you walk around and you pick 0:04:10.440 --> 0:04:14.880 up these mineral fragments and they're full of fossils. It's 0:04:14.920 --> 0:04:18.800 just fossils everywhere. Almost every other rock you find has 0:04:18.880 --> 0:04:21.600 the shape of an animal from millions of years ago 0:04:22.040 --> 0:04:26.680 printed into it. You're literally walking on thousands and thousands 0:04:26.720 --> 0:04:31.200 of fossils. So you're in this this mountainous environment and David, 0:04:31.240 --> 0:04:34.039 who by the way, i'm picturing as the Android from 0:04:34.200 --> 0:04:37.440 Prometheus and Alien Covenant, is guiding you and showing you 0:04:37.560 --> 0:04:41.120 these these prehistoric remnants in the rock. David was not 0:04:41.800 --> 0:04:44.240 Michael Fastbender, but David was excellent. He was a really 0:04:44.240 --> 0:04:46.720 really good guide. And this place we came to where 0:04:46.720 --> 0:04:49.840 we were walking on fossils, this was the Mount Stephen 0:04:49.880 --> 0:04:53.440 Trio bite beds. It is a graveyard of organisms from 0:04:53.440 --> 0:04:57.320 the Cambrian period about five hundred million years ago. Now. 0:04:57.400 --> 0:04:59.839 Mount Stephen is in an area that's home to the 0:05:00.040 --> 0:05:03.240 Urgess Shale geological formation, which is one of the most 0:05:03.320 --> 0:05:07.359 important sites of Cambrian Period fossils in the world. And 0:05:07.360 --> 0:05:09.000 if you ever get a chance to do one of 0:05:09.040 --> 0:05:12.120 these hikes, I highly highly recommended. I think it literally 0:05:12.200 --> 0:05:14.680 might be the coolest thing I've ever done. You have 0:05:14.720 --> 0:05:17.400 to book them through this organization called the Burgess Shale 0:05:17.480 --> 0:05:21.120 Geoscience Foundation, and they pair you with a guide. Our guide, David, 0:05:21.160 --> 0:05:24.400 the paleontologist, was an excellent science communicator. He was really 0:05:24.440 --> 0:05:26.080 good with the kids on the group, and he was 0:05:26.080 --> 0:05:28.000 a great hiking guide. So if you get a chance 0:05:28.040 --> 0:05:31.000 to go with David, big thumbs up to him. Be 0:05:31.160 --> 0:05:33.120 warned if you do try to do this, it's a 0:05:33.160 --> 0:05:37.360 tough hike. It's like eight kilometers round trip horizontally with 0:05:37.480 --> 0:05:41.479 a seven hundred and ninety five meter elevation gain, which 0:05:41.560 --> 0:05:44.919 is like two thousand, six hundred feet and uh and 0:05:45.000 --> 0:05:48.640 that's starting at like twelve hundred or th hundred meters 0:05:48.640 --> 0:05:50.880 of elevation at the at the base of the mountain. 0:05:51.400 --> 0:05:53.839 Uh So the air is thin and it's worth doing 0:05:53.880 --> 0:05:56.680 some other hikes at higher elevation to get yourself accustomed 0:05:56.680 --> 0:05:58.880 to the lack of oxygen. But I also don't want 0:05:58.880 --> 0:06:01.840 to scare you too much. Obviously I will. I am 0:06:01.839 --> 0:06:05.520 no kind of athlete or experienced altitude hiker or anything 0:06:05.560 --> 0:06:08.359 like that, and I survived so beer advising listeners to 0:06:08.360 --> 0:06:12.159 wear their best flip flops this particular, just be prepared, 0:06:12.279 --> 0:06:15.440 have some layers, have some water, do a little practice. 0:06:15.920 --> 0:06:18.640 If you can make the trip, it is absolutely worth 0:06:18.640 --> 0:06:21.160 it to see these fossils firsthand. You can pick them up, 0:06:21.240 --> 0:06:25.000 you can feel the ribs of these Cambrian organisms. You 0:06:25.040 --> 0:06:27.640 can you can feel the contours of their bodies as 0:06:27.680 --> 0:06:31.360 they printed on this ancient shale. But also it's really 0:06:31.360 --> 0:06:33.880 cool to be there, just because the area around field, 0:06:33.880 --> 0:06:37.440 including Mount Stephen, trial By Beds and the Burgess Shale 0:06:37.480 --> 0:06:41.360 quarry quarries, are just arguably the most important Cambrian fossil 0:06:41.440 --> 0:06:45.120 sites in the world. They are a geological window into 0:06:46.600 --> 0:06:50.200 a time stranger, I would argue than any alien planet 0:06:50.320 --> 0:06:53.719 in any movie, any book, any video game, any Star 0:06:53.760 --> 0:06:57.839 Trek episode. I think the real alien monsters h And 0:06:57.920 --> 0:06:59.719 of course, as you if you know the show, you 0:06:59.720 --> 0:07:03.280 know use the term monster affectionately. It's not a pejorative. 0:07:03.680 --> 0:07:06.440 The real alien monsters are not out there on some 0:07:06.520 --> 0:07:10.640 exo planet. They were right here five million years ago, 0:07:11.040 --> 0:07:13.000 and in this one amazing place you can sort of 0:07:13.040 --> 0:07:17.360 crunch through their frozen graveyard and it's awesome. Now, Joe, 0:07:17.400 --> 0:07:21.320 do you find yourself falling into the same admittedly dumb 0:07:21.360 --> 0:07:23.760 trap that I do when I when I think about 0:07:24.520 --> 0:07:29.360 about the nationalities that are sort of overlaid regarding a 0:07:29.400 --> 0:07:35.120 fossil uh findes like these are Canadian Cambrian monsters and 0:07:35.240 --> 0:07:37.960 stuff like that. Like, yeah, because I was recently reading 0:07:37.960 --> 0:07:40.520 to my son about Terra saurs and was reading about 0:07:40.600 --> 0:07:45.080 the about about Bavarian fossils of Terra saurs, and is 0:07:45.760 --> 0:07:48.679 as silly as it is, I couldn't help but think 0:07:48.720 --> 0:07:54.360 of of Bavarian Terra stars thinking about the Varian rhistoric creature, 0:07:54.440 --> 0:07:57.720 like wearing later hosen the big big stein of beer, 0:07:57.880 --> 0:07:59.800 And it's so unfair. You know, I've done the same 0:07:59.840 --> 0:08:03.520 thing thinking of Mongolian fossil finds. In our previous episode 0:08:03.520 --> 0:08:06.880 we talked about various raptors I believe remember it was 0:08:06.920 --> 0:08:11.280 the velociraptor or Dononicus. But I could not help but 0:08:11.320 --> 0:08:14.400 then think about them in terms of like human history 0:08:14.440 --> 0:08:22.120 regarding that area and part of his pack. Uh yeah, yeah, 0:08:22.120 --> 0:08:24.280 I know exactly what you're talking about. And that does 0:08:24.360 --> 0:08:27.680 highlight the need to sort of explain how the Cambrian 0:08:27.720 --> 0:08:30.720 world was so different than our world, not just that 0:08:30.760 --> 0:08:33.240 it had different animals in it, but that planet Earth 0:08:33.360 --> 0:08:34.880 was different then. So when I say it was an 0:08:34.880 --> 0:08:38.360 alien planet, I mean that quite literally. It's not just 0:08:38.640 --> 0:08:41.480 that it had different fauna, it was a It was 0:08:41.520 --> 0:08:44.880 a totally different place to live. And so before we 0:08:45.040 --> 0:08:48.719 get into exploring these monsters of the Cambrian Period, these 0:08:48.760 --> 0:08:51.920 beautiful and bizarre creatures that you couldn't even dream up 0:08:51.960 --> 0:08:54.280 if you tried, I think we should take a look 0:08:54.320 --> 0:08:57.240 at the Cambrian Period itself and explain what it was 0:08:57.320 --> 0:09:02.280 like to be Terra five hundred million years ago. So 0:09:02.320 --> 0:09:05.319 the Cambrian Period lasted from about five hundred forty to 0:09:05.400 --> 0:09:08.120 about four hundred and eighty five million years ago, and 0:09:08.160 --> 0:09:12.400 if you were dropped from today straight into the Cambrian period, 0:09:12.800 --> 0:09:15.880 you would not recognize planet Earth. The Earth, for one thing, 0:09:16.040 --> 0:09:19.600 revolved faster than it does now, So days were only 0:09:19.640 --> 0:09:22.560 about twenty one hours long, and there were about four 0:09:22.640 --> 0:09:25.720 hundred and twenty of them in a year. The air 0:09:25.760 --> 0:09:29.200 would be hot, so the average global surface temperature would 0:09:29.200 --> 0:09:32.120 have been about ten degrees celsius hotter than today. That's 0:09:32.120 --> 0:09:35.160 a good bit hotter. The atmosphere, while it did have 0:09:35.320 --> 0:09:38.280 significant free oxygen, at this point, was not quite what 0:09:38.320 --> 0:09:39.920 it is today. It would have felt a little bit 0:09:39.960 --> 0:09:44.160 thick with carbon dioxide in your lungs. If you happen 0:09:44.240 --> 0:09:47.360 to see dry land, it would probably look more like 0:09:47.440 --> 0:09:51.360 the surface of Mars than Earth today. Because land dwelling 0:09:51.480 --> 0:09:55.480 plants didn't exist yet. It's kind of hard to imagine 0:09:55.520 --> 0:09:58.680 Earth that way. And without plant roots to hold the 0:09:58.720 --> 0:10:02.200 soil in place, lands surfaces eroded very easily in the 0:10:02.240 --> 0:10:05.800 wind and the churning water. So you know, the continents 0:10:05.800 --> 0:10:08.920 are constantly just kind of burning away into the oceans 0:10:08.960 --> 0:10:11.600 and being reformed. So to call back to a previous 0:10:11.679 --> 0:10:15.080 episode we did, was this was definitely a world before fire. 0:10:15.360 --> 0:10:18.280 Oh yeah, because what would it what would it burn? Right? Yeah, 0:10:18.320 --> 0:10:21.400 I mean I can't be sure it was totally without fire, 0:10:21.440 --> 0:10:23.880 but I mean, yeah, obviously not fire on the scale 0:10:23.920 --> 0:10:26.600 we see of wildfires in forests today. Because there was 0:10:26.640 --> 0:10:29.600 oxygen in the atmosphere at this point, but yeah, what 0:10:29.600 --> 0:10:32.640 what would burn? What would the fuel be? All Right, 0:10:32.679 --> 0:10:36.480 So we have this alien world with just a barren 0:10:36.640 --> 0:10:39.600 land when visible, and then we have this this ocean, 0:10:39.760 --> 0:10:43.520 this strange ocean, and the Cambrians Earth that that's not 0:10:43.600 --> 0:10:45.439 a story about land at all. That is a story 0:10:45.480 --> 0:10:48.320 about ocean. It was the ocean planet at that point. 0:10:48.920 --> 0:10:51.120 You could probably make the argument it's the ocean planet 0:10:51.200 --> 0:10:54.560 right now, but it definitely was then. According to Cambrian 0:10:54.640 --> 0:10:57.959 Ocean World Ancient Sea Life of North America by John 0:10:58.000 --> 0:11:01.800 Foster uh the love all of the seas rose steadily 0:11:01.840 --> 0:11:04.480 in this saw tooth rise and fall pattern throughout the 0:11:04.480 --> 0:11:06.920 Cambrian period. So at the beginning of the period sea 0:11:07.000 --> 0:11:09.880 level was actually a little bit lower than it is today, 0:11:09.920 --> 0:11:12.800 But by the end of the Late Cambrian sea level 0:11:12.920 --> 0:11:15.920 was about a hundred and sixty meters or five and 0:11:16.000 --> 0:11:19.320 thirty feet higher than it is today. So in today's terms, 0:11:19.360 --> 0:11:26.080 New York underwater, Rome underwater, Paris underwater, Baghdad underwater, even 0:11:26.120 --> 0:11:29.720 parts of Moscow underwater, and the high sea level in 0:11:29.760 --> 0:11:33.280 the Cambrian led to flooding of about forty percent of 0:11:33.320 --> 0:11:36.680 the area of Earth's continental masses. Compared that to today, 0:11:36.760 --> 0:11:39.640 we're only about five percent of that continental area is 0:11:39.720 --> 0:11:43.199 covered in water, so most of our planets dry land 0:11:43.280 --> 0:11:46.880 mass was gathered together closer to the south pole, and 0:11:46.920 --> 0:11:50.400 the continent that became North America was then called Laurentia, 0:11:50.520 --> 0:11:54.040 not then called by people who have been people today 0:11:54.160 --> 0:11:57.240 called that continent than Laurentia, and you sort of have 0:11:57.320 --> 0:12:03.000 to imagine North America turned sideways, mostly flooded, straddling the equator. 0:12:03.720 --> 0:12:07.559 Also adding to the alien quality in the Cambrian astronomy 0:12:07.600 --> 0:12:09.560 would have been a little bit different. So the Moon 0:12:10.280 --> 0:12:13.839 was more than twenty kilometers closer to Earth than meaning 0:12:13.880 --> 0:12:16.840 that its gravity was stronger, meaning the high and low 0:12:16.880 --> 0:12:20.720 tides on Earth were higher and lower. Okay, you know 0:12:20.960 --> 0:12:22.720 my son was just talking to him to me the 0:12:22.720 --> 0:12:26.120 other day about the size of the moon and prehistoric times. 0:12:26.320 --> 0:12:29.160 Oh yeah, like he knew that the moon was bigger 0:12:29.160 --> 0:12:31.719 in prehistoric times. Yeah, and uh, and knows that it 0:12:31.760 --> 0:12:35.040 will be it will be smaller in future times. Did 0:12:35.040 --> 0:12:37.280 he into it that or did he find that out somewhere? 0:12:37.360 --> 0:12:42.920 He consumes a lot of dinosaur train and he really 0:12:42.960 --> 0:12:45.240 likes this podcast, Wow in the World. That's a great 0:12:45.280 --> 0:12:48.040 science podcast for for kids. So and then you know, 0:12:48.720 --> 0:12:50.760 we talked to him a lot about science. Man, I 0:12:50.800 --> 0:12:53.200 wish I was that cool when I was, I probably 0:12:53.200 --> 0:12:55.280 just would have told you about like which ninja turtle 0:12:55.400 --> 0:12:58.199 was bigger in prehistoric times. Yeah, so far ninja turtles 0:12:58.200 --> 0:12:59.600 will probably come in and wash it all the way. 0:13:00.200 --> 0:13:02.720 But for now, he's really really into the thing, like 0:13:02.840 --> 0:13:06.400 an alien ocean driving away the continents. Okay, So if 0:13:06.400 --> 0:13:10.000 we looked under that ancient ocean, that's where the real 0:13:10.080 --> 0:13:13.920 craziness comes in, because we would find this vast realm 0:13:14.000 --> 0:13:20.000 of gorgeous, terrifying, surreal monsters that would look completely unlike 0:13:20.040 --> 0:13:23.079 the kind of Earth life we're familiar with today. Because 0:13:23.120 --> 0:13:25.719 the Cambrian period is the geological layer where we see 0:13:25.760 --> 0:13:28.800 evidence of one of the most fascinating and mysterious events 0:13:28.800 --> 0:13:31.480 in the history of life on Earth, known as the 0:13:31.520 --> 0:13:36.160 Cambrian Explosion. So explosion. What exploded? Was this like a 0:13:36.160 --> 0:13:40.360 bunch of volcanoes or something? No, the Cambrian explosion is 0:13:40.360 --> 0:13:45.600 a story about biodiversity. So, Robert, how old is the Earth? Oh, 0:13:45.720 --> 0:13:47.920 it's so at four and a half billion years old. Yeah, 0:13:48.000 --> 0:13:50.920 that's the general astronomical idea. So four and a half 0:13:50.960 --> 0:13:53.960 billion years old. We've had this planet roughly, and we 0:13:54.000 --> 0:13:56.679 know there's been single celled life on the planet for 0:13:56.720 --> 0:13:59.320 at least maybe three and a half billion years or so, 0:13:59.440 --> 0:14:03.480 based on fossil traces left behind by these organisms. And 0:14:03.559 --> 0:14:07.319 new findings keep pushing the debatable frontier of earliest life 0:14:07.360 --> 0:14:10.120 farther and farther back into the darkness of Earth time. 0:14:10.480 --> 0:14:13.160 One example, I just came across So the other day, 0:14:13.320 --> 0:14:15.920 just earlier this year, in March seventeen, there was an 0:14:16.000 --> 0:14:20.080 article published in Nature arguing that apparent microbe fossils in 0:14:20.120 --> 0:14:23.920 the New Vue Agatuck Belt in Quebec are about three 0:14:24.040 --> 0:14:28.360 point eight billion and possibly four point three billion years old, 0:14:28.480 --> 0:14:32.200 somewhere in that range, and these single celled life forms 0:14:32.400 --> 0:14:35.400 would have been surviving around hydrothermal vents and had this 0:14:35.480 --> 0:14:42.000 biochemistry based on eating and excreting iron. That's that's like 0:14:42.040 --> 0:14:45.480 a comic book film, right, yeah, the iron eater. And 0:14:45.520 --> 0:14:48.000 the crazy thing is that if these findings are correct, 0:14:48.080 --> 0:14:50.760 life on Earth would have began within just a few 0:14:50.920 --> 0:14:55.000 hundred million years of the planet first accreting together in space. 0:14:55.160 --> 0:14:57.800 It's kind of hard to believe, but whether life on 0:14:57.800 --> 0:15:00.640 Earth began like four point two billion years go or 0:15:00.800 --> 0:15:03.640 more recently. We know that for a long long time, 0:15:04.360 --> 0:15:08.160 life on Earth wasn't becoming much more complex, right. There 0:15:08.240 --> 0:15:12.680 was no serious multicellular life, So no animals, no fish 0:15:12.720 --> 0:15:17.120 and reptiles, no birds, no plants, no mushrooms, just microbial 0:15:17.240 --> 0:15:21.440 organisms like bacteria and archaea floating around in the oceans, 0:15:21.480 --> 0:15:26.080 forming mats and films and occasionally occasionally building these giant 0:15:26.160 --> 0:15:30.160 mineral brains in the surf called strummtallites. So this would 0:15:30.200 --> 0:15:32.480 be if this were a science fiction film, this would 0:15:32.480 --> 0:15:37.680 be the least cinematic alien life form encounter unless it 0:15:37.720 --> 0:15:40.560 made people like, you know, horribly sick obviously, or possessed them. 0:15:41.280 --> 0:15:44.480 Biofilm planet, yeah, yeah, the planet of slime. Yeah, it 0:15:44.600 --> 0:15:46.920 was would be the episode of of Star Trek that 0:15:47.160 --> 0:15:50.800 that does not does not make it to the series. Yeah, 0:15:50.840 --> 0:15:52.960 and that's you know, that would have been the story 0:15:53.000 --> 0:15:56.440 of Earth for most of Earth's history, not having any 0:15:56.520 --> 0:15:58.960 kind of interesting animals or anything like that. Not to 0:15:59.000 --> 0:16:01.680 say that microbes aren't interesting in themselves, but maybe less 0:16:01.720 --> 0:16:04.760 interesting to look at. It would have been slime planet. Yeah. Generally, 0:16:04.760 --> 0:16:07.880 this is the stuff that occupies one, maybe two pages 0:16:08.000 --> 0:16:11.160 of a of a large prehistoric life book before you 0:16:11.200 --> 0:16:14.560 get onto the more exciting things, the things that children 0:16:14.600 --> 0:16:16.880 can imagine fighting each other. But it's most of the 0:16:16.920 --> 0:16:21.440 life that's ever happened. And then billions of years later, 0:16:21.560 --> 0:16:25.720 at the beginning of the Cambrian Period, something happens very suddenly. 0:16:26.560 --> 0:16:30.160 Loads of insane animals show up. And when I say suddenly, 0:16:30.240 --> 0:16:32.960 I have to qualify that that's suddenly from a geological 0:16:33.040 --> 0:16:36.119 point of view, which in reality means it took millions 0:16:36.120 --> 0:16:38.640 of years about five hundred and forty million years ago 0:16:38.720 --> 0:16:41.480 to about five hundred million years ago. But that's still 0:16:41.520 --> 0:16:44.280 pretty suddenly compared to the age of the Earth. And 0:16:44.320 --> 0:16:49.600 this geologically rapid spike in animal diversity delivers creatures with 0:16:49.720 --> 0:16:56.320 bilateral symmetry, with large bodies, with eyes, with legs, with shells, 0:16:56.320 --> 0:17:00.400 with segmented body parts. You've got all of these crazy 0:17:00.440 --> 0:17:04.240 different types of creatures suddenly showing up, and it's like 0:17:04.680 --> 0:17:07.000 where did they all come from? Yeah, it's like all 0:17:07.080 --> 0:17:09.280 these prototypes are rolled out at once. It's like the 0:17:09.320 --> 0:17:11.480 segment in is it is a RoboCop one or two 0:17:11.480 --> 0:17:15.080 where we get all the crazy prototypes that, oh, that's 0:17:15.080 --> 0:17:17.760 a RoboCop two. Yes, yeah, it's one of our favorite 0:17:17.760 --> 0:17:21.360 points of comparison on the show for biology. Uh yeah, 0:17:21.440 --> 0:17:25.120 you have suddenly all these different, you know, seemingly crazy 0:17:25.280 --> 0:17:28.800 examples of life, and many of many of which don't 0:17:28.800 --> 0:17:32.120 seem to to fall in easily into that category of well, 0:17:32.160 --> 0:17:34.520 this is a precursor to something we have later on. 0:17:34.600 --> 0:17:37.720 It's a precursor to something we have today now. Of course, 0:17:37.760 --> 0:17:41.000 for some people with negative attitudes towards evolutionary science, this 0:17:41.080 --> 0:17:44.280 provides some kind of rhetorical ammunition, right indeed, I mean 0:17:44.280 --> 0:17:47.840 the explosion is often exploited by evolution of niers, even Darwin, 0:17:48.240 --> 0:17:50.560 we have to note thought that the explosion was at 0:17:50.600 --> 0:17:53.960 odds with the normal evolutionary process, which in a funny 0:17:53.960 --> 0:17:55.959 way could be true, but not in the way an 0:17:55.960 --> 0:17:59.960 evolution denier would mean. A couple of thoughts. Evolution is 0:18:00.040 --> 0:18:02.800 we're familiar with it today, tends to take place within 0:18:03.000 --> 0:18:07.440 ecosystems in which every niche is already filled. So basically, 0:18:07.480 --> 0:18:09.760 every way there is for a creature to make a living, 0:18:09.800 --> 0:18:12.080 there's already something trying to do that. So if you 0:18:12.119 --> 0:18:15.200 want to compete, you've got to outcompete these other organisms. 0:18:15.760 --> 0:18:17.880 The global ocean of the Cambrian on the other hand, 0:18:17.920 --> 0:18:20.720 represented a world in which it seems like there was 0:18:20.760 --> 0:18:26.280 still tremendous ecological opportunity to occupy, Like there was territory 0:18:26.440 --> 0:18:30.800 in the ecology that didn't have any existing competition. So 0:18:30.840 --> 0:18:33.080 it was a time in which an animal could start 0:18:33.200 --> 0:18:36.520 doing something to eat or to otherwise survive, and no 0:18:36.600 --> 0:18:39.879 other species was already doing that thing. There was just 0:18:39.960 --> 0:18:42.560 sort of like free land to grab. Yeah, like yeah, 0:18:42.720 --> 0:18:46.680 land grab call the frontier, except without other organisms already 0:18:46.720 --> 0:18:49.960 occupying it. So that there could be one explanation for 0:18:50.200 --> 0:18:53.080 why evolution seems to be working differently at this one 0:18:53.200 --> 0:18:57.399 period in history than it has since. But also the 0:18:57.480 --> 0:19:01.080 Young Earth creationist who exploits ongoing abates in biology to 0:19:01.200 --> 0:19:05.960 sort of resort to the supernatural. They're employing a fallacy 0:19:06.000 --> 0:19:09.080 in rhetoric known as the argument from ignorance fallacy, which 0:19:09.160 --> 0:19:12.159 means like, I don't know what caused something, therefore the 0:19:12.240 --> 0:19:17.040 cause is x uh. Example, you don't know who committed 0:19:17.040 --> 0:19:21.880 the Jack the Ripper murders, therefore it was interdimensional sasquatches. Now, 0:19:22.119 --> 0:19:24.680 the version employed here, of course, says, you can't all 0:19:24.720 --> 0:19:27.359 agree we don't know on what caused the sudden or 0:19:27.400 --> 0:19:31.480 geologically sudden biodiversity of the Cambrian explosion. Therefore, the cause 0:19:31.600 --> 0:19:35.280 is supernatural. Now, this line of thinking obviously doesn't get 0:19:35.359 --> 0:19:38.399 you anywhere once you examine it, but the disagreement and 0:19:38.480 --> 0:19:41.679 debate over the cause is a fascinating, outstanding question, and 0:19:41.720 --> 0:19:43.840 it's something I think we want to entertain a few 0:19:44.080 --> 0:19:48.159 answers to today. Now, some of the hypotheses are primarily 0:19:48.480 --> 0:19:52.439 environmental and chemical. Right, so some scientists have proposed that 0:19:52.480 --> 0:19:55.199 the cause of the camera and explosion could be a 0:19:55.320 --> 0:19:58.680 rise in the content of oxygen in the atmosphere, which 0:19:58.760 --> 0:20:01.960 leads to an increase in the level of dissolved oxygen 0:20:02.000 --> 0:20:05.240 and the oceans. Now, of course, remember that Earth's original 0:20:05.240 --> 0:20:08.320 atmosphere did not have free oxygen, right, That was added 0:20:08.359 --> 0:20:12.119 to the atmosphere gradually as a waste product of photosynthesis. 0:20:12.200 --> 0:20:14.800 You have all these microbes out there and they're eating 0:20:14.800 --> 0:20:18.600 the sunlight and then their geoengineering the atmosphere with their 0:20:18.600 --> 0:20:22.720 waste products, which included oxygen. The gradual natural terraforming of 0:20:22.760 --> 0:20:26.240 our world. Yeah, the microbial terraforming of Earth, which absolutely 0:20:26.280 --> 0:20:28.280 did happen in the past, and that's where we get 0:20:28.280 --> 0:20:31.600 our oxygen. Now, when you think about it. Large, fast 0:20:31.680 --> 0:20:35.399 moving animals need lots of oxygen to feed their energy 0:20:35.480 --> 0:20:38.040 hungry tissues. Like think of the way that when you 0:20:38.160 --> 0:20:41.880 move your muscles a lot, your body starts greedily gulping 0:20:41.960 --> 0:20:45.000 down more and more air. In the same way, if 0:20:45.000 --> 0:20:47.520 you think about these organisms in the past, suddenly you 0:20:47.520 --> 0:20:50.439 wanted to have organisms with large bodies. They would have 0:20:50.480 --> 0:20:54.920 needed access to oxygen. So maybe when that oxygen became available, 0:20:55.040 --> 0:20:57.960 suddenly you could build these big, fast moving bodies and 0:20:58.000 --> 0:21:01.040 you get all this animal biodiversity. So previously the the 0:21:01.119 --> 0:21:04.480 oxygen economy would not support this kind of growth, right, 0:21:04.560 --> 0:21:07.520 But the idea is then it would. So did a 0:21:07.560 --> 0:21:10.600 sudden increase in oxygen drive the explosion? Well, some recent 0:21:10.640 --> 0:21:14.080 studies have cast doubt on this hypothesis, including one published 0:21:14.080 --> 0:21:18.440 in Nature by Spurling at all uh and it basically 0:21:18.520 --> 0:21:22.399 did not find evidence of a significant increase of oxygen 0:21:22.480 --> 0:21:25.000 in ocean water at the beginning of the Cambrian So 0:21:25.080 --> 0:21:28.040 evidence shows that if there was an increase in oxygen 0:21:28.080 --> 0:21:30.560 at the Cambrian transition, it was kind of a small one. 0:21:31.119 --> 0:21:33.440 Al Right, Well, what else do we have? Well, other 0:21:33.520 --> 0:21:38.320 hypotheses are more biological and ecological, like what if there 0:21:38.400 --> 0:21:42.760 was one type of biological innovation, some new way for 0:21:42.840 --> 0:21:46.600 animals to make a living or new thing. Animals could 0:21:46.600 --> 0:21:51.280 do that rapidly accelerated competition with an ecosystems, which would 0:21:51.320 --> 0:21:54.639 speed up natural selection and cause new species to form 0:21:54.720 --> 0:21:59.520 much more rapidly. How about the example of site. Oh yeah, 0:21:59.520 --> 0:22:02.360 this is a big yeah. So previous animals they might 0:22:02.400 --> 0:22:05.960 have had some kind of photosensitive spots or receptors that 0:22:06.000 --> 0:22:09.160 would have allowed them to, for example, move towards the sunlight. 0:22:09.720 --> 0:22:12.720 But the Cambrian is the first period in history where 0:22:12.720 --> 0:22:16.159 we have evidence of complex site organs, you know, eyes. 0:22:16.240 --> 0:22:19.880 It's the age of organisms with compound eyes. So imagine 0:22:19.920 --> 0:22:22.919 how much adaptive pressure would be put on you if 0:22:22.960 --> 0:22:25.879 you lived in a world where all creatures were basically 0:22:25.880 --> 0:22:30.639 blind and then suddenly some of your competitors could see. Yeah, 0:22:30.680 --> 0:22:33.440 this is this is a crazy thing to try to imagine, 0:22:33.440 --> 0:22:36.679 but yeah, just just think of sight coming online in 0:22:36.680 --> 0:22:39.760 a world and all the additional stuff that this entail. 0:22:39.840 --> 0:22:43.119 Suddenly pigmentation begins to matter. I mean, it's hard to 0:22:43.160 --> 0:22:46.520 even apply. You're one is tempted to apply this to 0:22:46.640 --> 0:22:50.040 human arms race um, which is which is often an 0:22:50.040 --> 0:22:53.920 an apt comparison. But I mean, what can we even 0:22:54.000 --> 0:22:58.080 look to in human technology and human weapons systems. I mean, 0:22:58.320 --> 0:23:00.800 I'm just thinking maybe you could apply it. You can 0:23:00.800 --> 0:23:03.720 compare it to flight and say that, well, once, once 0:23:03.800 --> 0:23:06.440 human technology allowed us to take to the air, that 0:23:06.480 --> 0:23:10.919