1 00:00:00,000 --> 00:00:02,940 Close your eyes and imagine Earth, 2 00:00:02,940 --> 00:00:04,620 but not the one we know today. 3 00:00:04,620 --> 00:00:05,460 Okay. 4 00:00:05,460 --> 00:00:08,280 Instead of the familiar continents and bustling cities, 5 00:00:08,280 --> 00:00:10,940 picture a world where land masses are jammed together 6 00:00:10,940 --> 00:00:13,280 in a giant supercontinent. 7 00:00:13,280 --> 00:00:16,220 Volcanoes spew molten rock, 8 00:00:16,220 --> 00:00:19,100 and the air is thick with unfamiliar gases. 9 00:00:19,100 --> 00:00:20,280 Wow. 10 00:00:20,280 --> 00:00:22,620 It's a world where the first whispers of life 11 00:00:22,620 --> 00:00:24,460 are emerging in the vast oceans. 12 00:00:24,460 --> 00:00:25,300 Oh, wow. 13 00:00:25,300 --> 00:00:27,180 Setting the stage for an incredible journey 14 00:00:27,180 --> 00:00:30,220 that will ultimately lead to us. 15 00:00:30,220 --> 00:00:33,460 Welcome to Cosmos in a Pod, Space and Astronomy series. 16 00:00:33,460 --> 00:00:36,020 Today we're taking a deep dive into that epic story, 17 00:00:36,020 --> 00:00:37,700 the history of life on Earth. 18 00:00:37,700 --> 00:00:39,300 We'll journey through billions of years 19 00:00:39,300 --> 00:00:42,140 from those humble beginnings in the primordial oceans 20 00:00:42,140 --> 00:00:43,580 to the reign of dinosaurs. 21 00:00:43,580 --> 00:00:44,420 Oh. 22 00:00:44,420 --> 00:00:46,420 The rise of mammals and finally the emergence 23 00:00:46,420 --> 00:00:47,580 of our own species. 24 00:00:47,580 --> 00:00:51,620 It's a story that spans an almost unimaginable time scale. 25 00:00:51,620 --> 00:00:52,460 Right. 26 00:00:52,460 --> 00:00:54,420 We're talking about events that unfolded over millions 27 00:00:54,420 --> 00:00:55,860 and even billions of years. 28 00:00:55,860 --> 00:00:56,700 Wow. 29 00:00:56,700 --> 00:00:58,300 It's really hard to wrap our minds around 30 00:00:58,300 --> 00:01:00,060 that kind of deep time. 31 00:01:00,060 --> 00:01:00,900 Absolutely. 32 00:01:00,900 --> 00:01:03,380 It's like trying to grasp the concept of infinity. 33 00:01:03,380 --> 00:01:04,420 Let's start at the beginning. 34 00:01:04,420 --> 00:01:06,940 What were those first glimmers of life like? 35 00:01:06,940 --> 00:01:09,020 We're talking about incredibly simple 36 00:01:09,020 --> 00:01:10,740 single-celled organisms. 37 00:01:10,740 --> 00:01:11,980 They were the pioneers. 38 00:01:11,980 --> 00:01:12,820 Right. 39 00:01:12,820 --> 00:01:14,700 The ultimate survivors enduring conditions 40 00:01:14,700 --> 00:01:16,740 that would be instantly lethal to us. 41 00:01:16,740 --> 00:01:17,580 Oh, wow. 42 00:01:17,580 --> 00:01:20,220 I think scorching temperatures, volcanic eruptions, 43 00:01:20,220 --> 00:01:22,900 and an atmosphere that would be toxic to breathe. 44 00:01:22,900 --> 00:01:25,540 So not exactly a welcoming environment. 45 00:01:25,540 --> 00:01:26,380 No. 46 00:01:26,380 --> 00:01:29,580 Somehow life found a way to not only survive, 47 00:01:29,580 --> 00:01:31,260 but to thrive and diversify. 48 00:01:31,260 --> 00:01:32,100 Exactly. 49 00:01:32,100 --> 00:01:32,940 Okay. 50 00:01:32,940 --> 00:01:35,540 These early life forms had a remarkable ability 51 00:01:35,540 --> 00:01:37,020 to adapt and evolve. 52 00:01:37,020 --> 00:01:39,620 Over millions of years, they gradually transformed 53 00:01:39,620 --> 00:01:42,860 the planet, releasing oxygen into the atmosphere, 54 00:01:42,860 --> 00:01:46,060 and paving the way for more complex life to emerge. 55 00:01:46,060 --> 00:01:48,620 This brings us to a pivotal moment in Earth's history. 56 00:01:48,620 --> 00:01:49,460 Okay. 57 00:01:49,460 --> 00:01:53,420 The Cambrian explosion about 542 million years ago. 58 00:01:53,420 --> 00:01:54,540 It sounds pretty dramatic. 59 00:01:54,540 --> 00:01:55,740 What exactly happened? 60 00:01:55,740 --> 00:01:58,140 Imagine a world where most life is microscopic 61 00:01:58,140 --> 00:01:59,300 and relatively simple. 62 00:01:59,300 --> 00:02:01,340 Then suddenly in a geological blink of an eye, 63 00:02:01,340 --> 00:02:03,300 there's an explosion of diversity. 64 00:02:03,300 --> 00:02:06,820 New and more complex creatures appear in the fossil record, 65 00:02:06,820 --> 00:02:09,580 many with hard shells and skeletons. 66 00:02:09,580 --> 00:02:12,020 It's like life suddenly decided to experiment 67 00:02:12,020 --> 00:02:14,780 with a whole new toolkit of possibilities. 68 00:02:14,780 --> 00:02:16,580 It's fascinating to think that so many 69 00:02:16,580 --> 00:02:19,580 of the basic body plans we see in animals today, 70 00:02:19,580 --> 00:02:23,380 from insects to vertebrates, originated during this period. 71 00:02:23,380 --> 00:02:24,220 It's true. 72 00:02:24,220 --> 00:02:28,100 The Cambrian explosion was a time of incredible innovation 73 00:02:28,100 --> 00:02:29,580 and experimentation. 74 00:02:29,580 --> 00:02:32,220 It's when we first see creatures like trilobites, 75 00:02:32,220 --> 00:02:35,100 those iconic armored arthropods that are now found 76 00:02:35,100 --> 00:02:36,860 as fossils all over the world. 77 00:02:36,860 --> 00:02:38,020 Trilobites are pretty cool. 78 00:02:38,020 --> 00:02:38,860 Yeah. 79 00:02:38,860 --> 00:02:40,220 But weren't there also some early predators 80 00:02:40,220 --> 00:02:42,020 lurking in those ancient seas? 81 00:02:42,020 --> 00:02:42,860 Absolutely. 82 00:02:42,860 --> 00:02:45,980 The Cambrian saw the rise of some of the first big predators 83 00:02:45,980 --> 00:02:47,300 like an Amalocaris. 84 00:02:47,300 --> 00:02:48,980 This creature was like a giant shrimp 85 00:02:48,980 --> 00:02:52,620 up to 60 centimeters long with powerful grasping appendages 86 00:02:52,620 --> 00:02:54,180 and sharp mandibles. 87 00:02:54,180 --> 00:02:56,380 It was the apex predator of its time. 88 00:02:56,380 --> 00:02:57,700 It sounds terrifying. 89 00:02:57,700 --> 00:02:59,900 So we've got this burst of life in the oceans 90 00:02:59,900 --> 00:03:02,580 with new creatures evolving and interacting 91 00:03:02,580 --> 00:03:04,580 in increasingly complex ways. 92 00:03:04,580 --> 00:03:06,180 It must have been an incredible sight. 93 00:03:06,180 --> 00:03:07,380 But what about life on land? 94 00:03:07,380 --> 00:03:08,740 What did that start to happen? 95 00:03:08,740 --> 00:03:11,780 That's a transition that took millions of years 96 00:03:11,780 --> 00:03:14,500 and involved overcoming some incredible challenges 97 00:03:14,500 --> 00:03:16,820 and got a completely different environment. 98 00:03:16,820 --> 00:03:20,260 Exposure to sunlight, the need to breathe air and gravity 99 00:03:20,260 --> 00:03:21,820 playing a much larger role. 100 00:03:21,820 --> 00:03:23,140 It was a huge leap. 101 00:03:23,140 --> 00:03:24,100 I can only imagine. 102 00:03:24,100 --> 00:03:24,740 Yeah. 103 00:03:24,740 --> 00:03:29,420 So who were the brave pioneers that first ventured onto land? 104 00:03:29,420 --> 00:03:31,940 Think small but mighty. 105 00:03:31,940 --> 00:03:36,420 In the Silurian period, roughly 419 million years ago, 106 00:03:36,420 --> 00:03:39,260 simple plants like mosses and fungi 107 00:03:39,260 --> 00:03:40,860 started colonizing the land. 108 00:03:40,860 --> 00:03:41,340 Right. 109 00:03:41,340 --> 00:03:43,340 They were the real trailblazers, gradually 110 00:03:43,340 --> 00:03:45,860 transforming a rocky barren landscape 111 00:03:45,860 --> 00:03:47,420 into something more hospitable. 112 00:03:47,420 --> 00:03:50,060 It's amazing to think that these tiny plants were laying 113 00:03:50,060 --> 00:03:53,140 the foundation for entire ecosystems. 114 00:03:53,140 --> 00:03:55,260 Were they the only ones making the move onto land? 115 00:03:55,260 --> 00:03:55,980 Not for long. 116 00:03:55,980 --> 00:03:56,480 OK. 117 00:03:56,480 --> 00:03:58,820 Once you have plants creating a basic ecosystem, 118 00:03:58,820 --> 00:04:00,980 you start to see the first animals venturing out 119 00:04:00,980 --> 00:04:02,260 of the water. 120 00:04:02,260 --> 00:04:05,340 Among the earliest pioneers were arthropods, the ancestors 121 00:04:05,340 --> 00:04:06,700 of insects and spiders. 122 00:04:06,700 --> 00:04:07,220 Oh, wow. 123 00:04:07,220 --> 00:04:10,260 They already had exoskeletons, which provided some protection 124 00:04:10,260 --> 00:04:11,500 from drying out. 125 00:04:11,500 --> 00:04:14,380 And their jointed limbs were well-suited for moving on land. 126 00:04:14,380 --> 00:04:16,660 It's like they were pre-adapted for this new terrestrial 127 00:04:16,660 --> 00:04:17,220 lifestyle. 128 00:04:17,220 --> 00:04:17,860 Yeah. 129 00:04:17,860 --> 00:04:20,980 But what about creatures with backbones of the vertebrates? 130 00:04:20,980 --> 00:04:22,620 When did they enter the picture? 131 00:04:22,620 --> 00:04:25,380 That brings us to the Devonian period, sometimes 132 00:04:25,380 --> 00:04:26,780 called the Age of Fishes. 133 00:04:26,780 --> 00:04:27,380 Right. 134 00:04:27,380 --> 00:04:31,140 This was a time of incredible diversification in the oceans. 135 00:04:31,140 --> 00:04:33,860 But it also saw the beginnings of the transition 136 00:04:33,860 --> 00:04:38,900 from fins to limbs, a key step in the evolution of amphibians 137 00:04:38,900 --> 00:04:41,700 and ultimately all land-dwelling vertebrates, 138 00:04:41,700 --> 00:04:43,100 including ourselves. 139 00:04:43,100 --> 00:04:45,640 So are we talking about fish walking on land? 140 00:04:45,640 --> 00:04:48,820 Not exactly walking, but definitely moving around. 141 00:04:48,820 --> 00:04:51,020 One of the most fascinating creatures from this time 142 00:04:51,020 --> 00:04:52,060 is Tiktaalik. 143 00:04:52,060 --> 00:04:52,700 OK. 144 00:04:52,700 --> 00:04:55,700 It lived about 375 million years ago, 145 00:04:55,700 --> 00:04:57,580 and it had some very unique features. 146 00:04:57,580 --> 00:04:59,460 What made Tiktaalik so special? 147 00:04:59,460 --> 00:05:02,180 It still had gills and scales like a fish, 148 00:05:02,180 --> 00:05:04,720 but it also had strong limb-like fins 149 00:05:04,720 --> 00:05:07,300 with bones that resembled those in our arms and legs. 150 00:05:07,300 --> 00:05:07,940 Wow. 151 00:05:07,940 --> 00:05:10,520 It could use those fins to prop itself up and move around 152 00:05:10,520 --> 00:05:13,700 in shallow water or even on land for short periods. 153 00:05:13,700 --> 00:05:16,420 It also had a more mobile neck than most fish 154 00:05:16,420 --> 00:05:18,460 and a flat head with eyes on top, 155 00:05:18,460 --> 00:05:20,540 suggesting it was adapted to looking around 156 00:05:20,540 --> 00:05:22,140 above the water's surface. 157 00:05:22,140 --> 00:05:25,060 So Tiktaalik was a real transitional fossil. 158 00:05:25,060 --> 00:05:25,740 Exactly. 159 00:05:25,740 --> 00:05:29,220 Showing us a snapshot of that incredible evolutionary journey 160 00:05:29,220 --> 00:05:30,300 from water to land. 161 00:05:30,300 --> 00:05:31,100 Exactly. 162 00:05:31,100 --> 00:05:33,700 It highlights the incredible power of natural selection 163 00:05:33,700 --> 00:05:38,300 to shape life in response to new challenges and opportunities. 164 00:05:38,300 --> 00:05:41,620 What stands out to you so far about this journey 165 00:05:41,620 --> 00:05:42,820 through deep time? 166 00:05:42,820 --> 00:05:44,380 What has you hooked? 167 00:05:44,380 --> 00:05:47,660 It's mind-blowing to think about those seemingly small steps 168 00:05:47,660 --> 00:05:50,420 from single-celled organisms to the first creatures 169 00:05:50,420 --> 00:05:52,100 venturing onto land. 170 00:05:52,100 --> 00:05:55,300 It just shows how these tiny changes over millions of years 171 00:05:55,300 --> 00:05:58,180 can lead to huge transformations in the history of life. 172 00:05:58,180 --> 00:05:58,780 Right. 173 00:05:58,780 --> 00:06:00,900 But I have to admit, I'm ready for some bigger players 174 00:06:00,900 --> 00:06:01,540 to enter the scene. 175 00:06:01,540 --> 00:06:02,460 What about the dinosaurs? 176 00:06:02,460 --> 00:06:03,260 OK, buckle up. 177 00:06:03,260 --> 00:06:05,060 We're about to enter the Mesozoic era, 178 00:06:05,060 --> 00:06:07,100 a time when dinosaurs roamed the Earth 179 00:06:07,100 --> 00:06:09,620 and the planet looked very different from what we know today. 180 00:06:09,620 --> 00:06:11,540 Let's dive into the age of dinosaurs. 181 00:06:11,540 --> 00:06:14,580 So we're entering the Mesozoic era, the age of dinosaurs. 182 00:06:14,580 --> 00:06:19,820 This era spans from about 252 million to 66 million years ago. 183 00:06:19,820 --> 00:06:24,220 And it's divided into three periods, the Triassic, Jurassic, 184 00:06:24,220 --> 00:06:25,260 and Cretaceous. 185 00:06:25,260 --> 00:06:27,700 All right, so we're stepping into the Mesozoic era, 186 00:06:27,700 --> 00:06:29,260 the age of dinosaurs. 187 00:06:29,260 --> 00:06:35,020 This era spans from about 252 million to 66 million years ago. 188 00:06:35,020 --> 00:06:39,100 And it's divided into three periods, the Triassic, Jurassic, 189 00:06:39,100 --> 00:06:40,540 and Cretaceous. 190 00:06:40,540 --> 00:06:42,780 Before we get to the T-rex and Triceratops, 191 00:06:42,780 --> 00:06:46,380 can you paint a picture of what the world looked like back then? 192 00:06:46,380 --> 00:06:49,380 Imagine this supercontinent pangaea, 193 00:06:49,380 --> 00:06:52,140 which we talked about earlier, starting to break apart. 194 00:06:52,140 --> 00:06:54,860 As these massive land masses drift apart, 195 00:06:54,860 --> 00:06:57,900 new oceans form and climates change. 196 00:06:57,900 --> 00:07:01,220 The climate during much of the Mesozoic was warmer than today, 197 00:07:01,220 --> 00:07:03,860 and there was more carbon dioxide in the atmosphere. 198 00:07:03,860 --> 00:07:07,340 This created ideal conditions for lush vegetation to flourish, 199 00:07:07,340 --> 00:07:09,540 supporting a huge diversity of life. 200 00:07:09,540 --> 00:07:11,340 So we're talking about a world in transition, 201 00:07:11,340 --> 00:07:13,660 both geographically and climatically. 202 00:07:13,660 --> 00:07:16,580 What were the first dinosaurs like in this dynamic world? 203 00:07:16,580 --> 00:07:19,540 The Triassic period saw the emergence of the first dinosaurs. 204 00:07:19,540 --> 00:07:21,100 They were relatively small compared 205 00:07:21,100 --> 00:07:22,540 to their later relatives, but they already 206 00:07:22,540 --> 00:07:25,460 had some of the features that would make them so successful. 207 00:07:25,460 --> 00:07:27,660 Many early dinosaurs were bipedal, 208 00:07:27,660 --> 00:07:29,540 meaning they walked on two legs. 209 00:07:29,540 --> 00:07:33,740 This freed up their forelimbs for grasping and manipulating 210 00:07:33,740 --> 00:07:34,940 objects. 211 00:07:34,940 --> 00:07:38,220 Some had already developed powerful jaws and sharp teeth, 212 00:07:38,220 --> 00:07:40,220 making them formidable predators. 213 00:07:40,220 --> 00:07:42,540 It sounds like the blueprint for dinosaur domination 214 00:07:42,540 --> 00:07:44,780 was already being laid out. 215 00:07:44,780 --> 00:07:47,060 When did the really iconic dinosaurs 216 00:07:47,060 --> 00:07:48,100 come into the picture? 217 00:07:48,100 --> 00:07:49,940 As we move into the Jurassic period, 218 00:07:49,940 --> 00:07:53,540 we see dinosaurs really hitting their stride, 219 00:07:53,540 --> 00:07:56,940 evolving into a spectacular array of shapes and sizes. 220 00:07:56,940 --> 00:07:57,540 Wow. 221 00:07:57,540 --> 00:08:01,380 Think giants like Brachiosaurus and Diplodocus, 222 00:08:01,380 --> 00:08:04,100 those long-necked behemoths that roamed the Earth. 223 00:08:04,100 --> 00:08:06,420 Those are the ones that always capture the imagination. 224 00:08:06,420 --> 00:08:06,940 Yeah. 225 00:08:06,940 --> 00:08:08,420 Can you give me a sense of scale? 226 00:08:08,420 --> 00:08:10,340 How big were these sauropods? 227 00:08:10,340 --> 00:08:13,300 Brachiosaurus, for example, could reach over 40 feet tall 228 00:08:13,300 --> 00:08:15,140 and weigh as much as 50 tons. 229 00:08:15,140 --> 00:08:15,740 Wow. 230 00:08:15,740 --> 00:08:19,060 Imagine its long neck stretching above the treetops 231 00:08:19,060 --> 00:08:22,060 like a prehistoric giraffe browsing on leaves 232 00:08:22,060 --> 00:08:23,740 that other dinosaurs couldn't reach. 233 00:08:23,740 --> 00:08:27,700 It's mind-boggling to think about creatures that massive. 234 00:08:27,700 --> 00:08:29,620 But it wasn't just about size, right? 235 00:08:29,620 --> 00:08:30,620 What about the predators? 236 00:08:30,620 --> 00:08:31,260 Of course. 237 00:08:31,260 --> 00:08:34,260 The Jurassic period was also home to fearsome predators 238 00:08:34,260 --> 00:08:35,540 like Allosaurus. 239 00:08:35,540 --> 00:08:39,980 This powerful carnivore could reach lengths of over 30 feet. 240 00:08:39,980 --> 00:08:43,380 It had powerful legs, sharp claws, and a mouthful 241 00:08:43,380 --> 00:08:45,500 of serrated teeth, making it more 242 00:08:45,500 --> 00:08:48,620 than capable of taking down even large prey. 243 00:08:48,620 --> 00:08:52,260 So the Jurassic was a time of giants, both plant eaters 244 00:08:52,260 --> 00:08:53,620 and meat eaters. 245 00:08:53,620 --> 00:08:56,060 But dinosaurs weren't the only ones ruling the Earth 246 00:08:56,060 --> 00:08:57,780 during the Mesozeric, were they? 247 00:08:57,780 --> 00:08:59,300 Absolutely not. 248 00:08:59,300 --> 00:09:01,020 While dinosaurs dominated the land, 249 00:09:01,020 --> 00:09:04,300 the oceans were teeming with equally incredible creatures. 250 00:09:04,300 --> 00:09:07,460 Marine reptiles like Ichthyosaurs and Plesiosaurs 251 00:09:07,460 --> 00:09:08,340 ruled the waves. 252 00:09:08,340 --> 00:09:09,140 Wow. 253 00:09:09,140 --> 00:09:11,860 They had streamlined bodies and powerful flippers, 254 00:09:11,860 --> 00:09:14,380 perfectly adapted for life in the water. 255 00:09:14,380 --> 00:09:17,180 Imagine sleek dolphin-like Ichthyosaurs 256 00:09:17,180 --> 00:09:19,740 darting through the water, hunting fish and squid, 257 00:09:19,740 --> 00:09:21,460 while the long-necked Plesiosaurs 258 00:09:21,460 --> 00:09:23,780 with their paddle-like limbs patrolled the depths. 259 00:09:23,780 --> 00:09:25,820 It sounds like an underwater Jurassic park. 260 00:09:25,820 --> 00:09:27,820 Were there any familiar creatures like mammals 261 00:09:27,820 --> 00:09:28,900 around during this time? 262 00:09:28,900 --> 00:09:30,660 Believe it or not, during the Mesozoic, 263 00:09:30,660 --> 00:09:33,540 our distant mammalian ancestors were already evolving. 264 00:09:33,540 --> 00:09:35,860 They were mostly small, nocturnal creatures, 265 00:09:35,860 --> 00:09:37,620 probably scurrying around in the undergrowth, 266 00:09:37,620 --> 00:09:40,060 trying to avoid becoming dinosaur snacks. 267 00:09:40,060 --> 00:09:41,940 They weren't the dominant life forms yet, 268 00:09:41,940 --> 00:09:44,060 but they were there biding their time. 269 00:09:44,060 --> 00:09:46,380 It's fascinating to think about our own lineage 270 00:09:46,380 --> 00:09:50,300 going back that far existing in the shadows 271 00:09:50,300 --> 00:09:52,340 of those giant reptiles. 272 00:09:52,340 --> 00:09:53,940 Did the reign of the dinosaurs last 273 00:09:53,940 --> 00:09:55,460 until the end of the Mesozoic? 274 00:09:55,460 --> 00:09:59,380 Well, the Mesozoic wasn't all sunshine and giant dinosaurs. 275 00:09:59,380 --> 00:10:02,380 There were periods of intense volcanic activity shifts 276 00:10:02,380 --> 00:10:04,780 in sea levels and even asteroid impacts 277 00:10:04,780 --> 00:10:07,020 that caused mass extinctions. 278 00:10:07,020 --> 00:10:08,980 And as you hinted at, one of those events 279 00:10:08,980 --> 00:10:12,220 brought the age of dinosaurs to a dramatic end. 280 00:10:12,220 --> 00:10:13,540 You're talking about the asteroid impact 281 00:10:13,540 --> 00:10:14,940 at the end of the Cretaceous period. 282 00:10:14,940 --> 00:10:15,780 Yeah, that's right. 283 00:10:15,780 --> 00:10:16,980 The one that wiped out the dinosaurs. 284 00:10:16,980 --> 00:10:17,780 That's right. 285 00:10:17,780 --> 00:10:21,260 About 66 million years ago, a massive asteroid 286 00:10:21,260 --> 00:10:23,580 estimated to be about six miles wide 287 00:10:23,580 --> 00:10:26,300 slammed into the Earth near the Yucatan Peninsula 288 00:10:26,300 --> 00:10:27,980 in what is now Mexico. 289 00:10:27,980 --> 00:10:30,100 The impact was catastrophic. 290 00:10:30,100 --> 00:10:33,900 It triggered earthquake tsunamis and widespread wildfires. 291 00:10:33,900 --> 00:10:36,140 Huge amounts of dust and debris were thrown 292 00:10:36,140 --> 00:10:38,100 into the atmosphere, blocking out the sun 293 00:10:38,100 --> 00:10:41,940 and causing a global cooling effect that lasted for years. 294 00:10:41,940 --> 00:10:42,420 Really? 295 00:10:42,420 --> 00:10:44,380 This dramatic change in climate, along 296 00:10:44,380 --> 00:10:47,500 with other devastating consequences of the impact, 297 00:10:47,500 --> 00:10:50,100 led to the extinction of about 75% 298 00:10:50,100 --> 00:10:52,740 of all plant and animal species on Earth, 299 00:10:52,740 --> 00:10:55,220 including the non-avian dinosaurs. 300 00:10:55,220 --> 00:10:57,220 It's incredible to think that a single event could 301 00:10:57,220 --> 00:11:00,180 have such a profound impact on the history of life. 302 00:11:00,180 --> 00:11:01,620 What happened to those small mammals 303 00:11:01,620 --> 00:11:03,740 that were living in the shadow of the dinosaurs? 304 00:11:03,740 --> 00:11:06,260 That's where the story takes a really interesting turn. 305 00:11:06,260 --> 00:11:07,780 While the dinosaurs couldn't adapt 306 00:11:07,780 --> 00:11:10,260 to the sudden and dramatic environmental changes brought 307 00:11:10,260 --> 00:11:12,820 about by the asteroid impact, many mammals 308 00:11:12,820 --> 00:11:15,220 with their smaller size adaptable diets 309 00:11:15,220 --> 00:11:17,460 and the ability to regulate their body temperature 310 00:11:17,460 --> 00:11:18,540 managed to survive. 311 00:11:18,540 --> 00:11:20,300 So in a way, the extinction of the dinosaurs 312 00:11:20,300 --> 00:11:23,260 opened up a whole new world of possibilities for mammals. 313 00:11:23,260 --> 00:11:24,100 Exactly. 314 00:11:24,100 --> 00:11:27,540 And that brings us to the Cenozoic era, the age of mammals, 315 00:11:27,540 --> 00:11:30,420 and the eventual emergence of our own species. 316 00:11:30,420 --> 00:11:34,420 What stands out to you the most about the reign of the dinosaurs? 317 00:11:34,420 --> 00:11:36,020 What has you captivated? 318 00:11:36,020 --> 00:11:38,620 For me, it's the sheer scale of these creatures 319 00:11:38,620 --> 00:11:40,860 and the drama of their world. 320 00:11:40,860 --> 00:11:43,900 Giant herbivores, fearsome predators, 321 00:11:43,900 --> 00:11:45,900 and then that sudden catastrophic ending. 322 00:11:45,900 --> 00:11:49,860 It really makes you realize how powerful the forces of nature 323 00:11:49,860 --> 00:11:50,700 can be. 324 00:11:50,700 --> 00:11:52,140 But I'm also curious to learn more 325 00:11:52,140 --> 00:11:54,020 about how our own lineage emerged 326 00:11:54,020 --> 00:11:55,340 after the dinosaurs were gone. 327 00:11:55,340 --> 00:11:57,300 That's a journey full of twists and turns 328 00:11:57,300 --> 00:12:00,100 as mammals diversified and spread across the globe. 329 00:12:00,100 --> 00:12:02,820 Are you ready to explore the world after the dinosaurs? 330 00:12:02,820 --> 00:12:03,660 Absolutely. 331 00:12:03,660 --> 00:12:06,900 Let's see how our furry ancestors took over the planet. 332 00:12:06,900 --> 00:12:08,700 So we're entering the Cenozoic era, which 333 00:12:08,700 --> 00:12:12,740 began about 66 million years ago and continues to this day. 334 00:12:12,740 --> 00:12:14,220 This is the age of mammals, right? 335 00:12:14,220 --> 00:12:14,700 That's right. 336 00:12:14,700 --> 00:12:16,140 It's the era where mammals really 337 00:12:16,140 --> 00:12:17,540 get their chance to shine. 338 00:12:17,540 --> 00:12:19,140 After the extinction of the dinosaurs, 339 00:12:19,140 --> 00:12:21,980 they diversified rapidly, filling the ecological niches 340 00:12:21,980 --> 00:12:23,060 that were left vacant. 341 00:12:23,060 --> 00:12:25,340 It's like the planet was a blank canvas, 342 00:12:25,340 --> 00:12:29,260 and mammals were the artists ready to create something new. 343 00:12:29,260 --> 00:12:30,780 What were the early mammals like? 344 00:12:30,780 --> 00:12:32,940 In the Paleogene period, which immediately followed 345 00:12:32,940 --> 00:12:36,580 the extinction event, mammals were still relatively small, 346 00:12:36,580 --> 00:12:38,820 but they were evolving quickly, experimenting 347 00:12:38,820 --> 00:12:41,300 with different lifestyles and diets. 348 00:12:41,300 --> 00:12:44,580 Picture early primates, the ancestors of monkeys and apes 349 00:12:44,580 --> 00:12:46,380 swinging through the trees. 350 00:12:46,380 --> 00:12:48,820 The ancestors of whales were starting their transition 351 00:12:48,820 --> 00:12:51,820 from land back to the sea, and the ungulates, 352 00:12:51,820 --> 00:12:54,660 the group that would give rise to horses, deer, and camels 353 00:12:54,660 --> 00:12:57,700 were beginning to graze on the expanding grasslands. 354 00:12:57,700 --> 00:12:59,820 So a lot of the mammal groups we're familiar with today 355 00:12:59,820 --> 00:13:01,740 were starting to take shape. 356 00:13:01,740 --> 00:13:04,500 When did the world start to look more like the one we know? 357 00:13:04,500 --> 00:13:06,300 That's where the Neo-Gene period comes in, 358 00:13:06,300 --> 00:13:09,020 starting about 23 million years ago. 359 00:13:09,020 --> 00:13:11,900 This is when we see the rise of grasslands and savannas, 360 00:13:11,900 --> 00:13:15,020 which played a huge role in shaping mammalian evolution. 361 00:13:15,020 --> 00:13:16,780 What was so special about grasslands? 362 00:13:16,780 --> 00:13:20,100 Grasslands provided a new type of habitat favoring animals 363 00:13:20,100 --> 00:13:22,620 that could graze efficiently and run quickly. 364 00:13:22,620 --> 00:13:25,060 This led to the evolution of fast-running herbivores, 365 00:13:25,060 --> 00:13:27,460 like horses and antelopes with long legs, 366 00:13:27,460 --> 00:13:30,580 and specialized teeth for grinding tough grasses. 367 00:13:30,580 --> 00:13:32,500 Of course, where you have fast-running herbivores, 368 00:13:32,500 --> 00:13:34,740 you also get fast-running predators. 369 00:13:34,740 --> 00:13:38,180 So the grasslands also saw the evolution of big cats, wolves, 370 00:13:38,180 --> 00:13:39,220 and other hunters. 371 00:13:39,220 --> 00:13:40,620 It sounds like the landscape itself 372 00:13:40,620 --> 00:13:44,060 was driving a whole new set of evolutionary adaptations. 373 00:13:44,060 --> 00:13:47,420 Was this also the time when our own lineage began to emerge? 374 00:13:47,420 --> 00:13:49,100 Yes, during the late Neo-Gene, we 375 00:13:49,100 --> 00:13:52,180 see the first hominins, our early human ancestors, 376 00:13:52,180 --> 00:13:53,500 appear in Africa. 377 00:13:53,500 --> 00:13:55,060 They were still very ape-like, but they 378 00:13:55,060 --> 00:13:56,660 had a crucial difference. 379 00:13:56,660 --> 00:13:59,020 They were walking upright on two legs. 380 00:13:59,020 --> 00:14:00,940 This freed up their hands for tool use 381 00:14:00,940 --> 00:14:03,900 and is considered a defining characteristic of our lineage. 382 00:14:03,900 --> 00:14:06,020 So walking upright was a game changer. 383 00:14:06,020 --> 00:14:08,180 But when did those more human-like traits, 384 00:14:08,180 --> 00:14:10,540 like larger brains and more complex tool use, 385 00:14:10,540 --> 00:14:11,460 start to develop? 386 00:14:11,460 --> 00:14:13,760 That takes us into the Pleistocene Epoch, 387 00:14:13,760 --> 00:14:16,420 starting about 2.6 million years ago. 388 00:14:16,420 --> 00:14:18,300 This period is marked by dramatic swings 389 00:14:18,300 --> 00:14:20,540 in climate, with ice ages coming and going, 390 00:14:20,540 --> 00:14:22,420 glaciers advancing and retreating, 391 00:14:22,420 --> 00:14:24,860 and sea levels rising and falling. 392 00:14:24,860 --> 00:14:27,620 These were challenging times demanding adaptability 393 00:14:27,620 --> 00:14:28,980 and ingenuity. 394 00:14:28,980 --> 00:14:30,820 Those ice ages sound brutal. 395 00:14:30,820 --> 00:14:32,620 How did our ancestors cope? 396 00:14:32,620 --> 00:14:34,380 They had to be resourceful. 397 00:14:34,380 --> 00:14:36,260 They developed more sophisticated tools 398 00:14:36,260 --> 00:14:38,460 for hunting and scraping hides, learned 399 00:14:38,460 --> 00:14:40,300 to control fire for warmth and cooking, 400 00:14:40,300 --> 00:14:41,800 and their brains were getting bigger, 401 00:14:41,800 --> 00:14:44,980 allowing for greater problem solving and communication. 402 00:14:44,980 --> 00:14:47,860 Those challenges pushed our ancestors to innovate and become 403 00:14:47,860 --> 00:14:49,060 more intelligent. 404 00:14:49,060 --> 00:14:51,020 It's like those harsh conditions were driving 405 00:14:51,020 --> 00:14:52,940 the evolution of our minds. 406 00:14:52,940 --> 00:14:55,340 And all the while, our ancestors were on the move, 407 00:14:55,340 --> 00:14:56,620 spreading across the globe. 408 00:14:56,620 --> 00:14:57,740 Exactly. 409 00:14:57,740 --> 00:15:00,940 By the late Pleistocene, humans had migrated out of Africa 410 00:15:00,940 --> 00:15:03,220 and reached almost every corner of the world. 411 00:15:03,220 --> 00:15:04,800 They were adapting to new environments, 412 00:15:04,800 --> 00:15:07,500 developing new cultures, and continuing to evolve. 413 00:15:07,500 --> 00:15:09,980 This brings us to the Holocene, our current epoch, 414 00:15:09,980 --> 00:15:12,460 which began about 12,000 years ago. 415 00:15:12,460 --> 00:15:13,820 What happened during this period? 416 00:15:13,820 --> 00:15:16,000 The Holocene is marked by a warming trend 417 00:15:16,000 --> 00:15:17,980 and the retreat of the glaciers. 418 00:15:17,980 --> 00:15:20,860 This created more stable and hospitable environments, 419 00:15:20,860 --> 00:15:23,660 allowing humans to settle down and develop agriculture. 420 00:15:23,660 --> 00:15:24,540 Agriculture. 421 00:15:24,540 --> 00:15:27,040 It seems like that was the defining moment for our species. 422 00:15:27,040 --> 00:15:28,980 It was truly revolutionary. 423 00:15:28,980 --> 00:15:31,220 For millions of years, our ancestors 424 00:15:31,220 --> 00:15:33,780 had been nomadic hunter gatherers. 425 00:15:33,780 --> 00:15:36,100 But with agriculture, they could stay in one place, 426 00:15:36,100 --> 00:15:38,940 cultivate crops, and produce a surplus of food. 427 00:15:38,940 --> 00:15:42,020 This led to larger settlements, specialization of labor, 428 00:15:42,020 --> 00:15:44,620 and eventually the rise of civilizations. 429 00:15:44,620 --> 00:15:47,540 It's the foundation of the world we live in today. 430 00:15:47,540 --> 00:15:50,620 What an incredible journey from those single-celled organisms 431 00:15:50,620 --> 00:15:54,340 in the primordial oceans to the rise of human civilizations. 432 00:15:54,340 --> 00:15:57,380 It's mind-blowing to think about the vastness of time 433 00:15:57,380 --> 00:15:59,660 and the interconnectedness of all life on Earth. 434 00:15:59,660 --> 00:16:02,260 It's a story that highlights the resilience of life, 435 00:16:02,260 --> 00:16:04,460 its ability to adapt and evolve in the face 436 00:16:04,460 --> 00:16:06,480 of extraordinary challenges. 437 00:16:06,480 --> 00:16:09,300 Understanding this history gives us a deeper appreciation 438 00:16:09,300 --> 00:16:12,100 for the complexity and fragility of our planet, 439 00:16:12,100 --> 00:16:14,380 and it underscores the importance of protecting it 440 00:16:14,380 --> 00:16:15,980 for future generations. 441 00:16:15,980 --> 00:16:17,380 I couldn't agree more. 442 00:16:17,380 --> 00:16:19,500 Well, our deep dive through Earth's history 443 00:16:19,500 --> 00:16:21,340 comes to an end here. 444 00:16:21,340 --> 00:16:23,900 Thank you for joining us on this incredible adventure. 445 00:16:23,900 --> 00:16:26,700 We hope you've enjoyed exploring the epic story of life 446 00:16:26,700 --> 00:16:27,660 on Earth. 447 00:16:27,660 --> 00:16:29,740 We've journeyed through billions of years, 448 00:16:29,740 --> 00:16:32,700 witnessed the rise and fall of incredible creatures, 449 00:16:32,700 --> 00:16:34,380 and seen how the forces of nature 450 00:16:34,380 --> 00:16:37,500 have shaped our planet and the life it sustains. 451 00:16:37,500 --> 00:16:39,580 It's a story that continues to unfold, 452 00:16:39,580 --> 00:16:40,980 and we're all part of it. 453 00:16:40,980 --> 00:16:43,540 Thanks for joining us on this deep dive into Earth's history 454 00:16:43,540 --> 00:16:46,740 here on Cosmos in a Pod, Space, and Astronomy series. 455 00:16:46,740 --> 00:16:48,480 Don't forget to subscribe to the podcast 456 00:16:48,480 --> 00:16:51,220 and check out our YouTube channel for more deep dives. 457 00:16:51,220 --> 00:17:19,220 Until next time, keep exploring.