1 00:00:02,200 --> 00:00:06,320 For centuries, the best clues to ancient life 2 00:00:06,320 --> 00:00:09,120 have come from fossils - 3 00:00:09,120 --> 00:00:13,200 but now a new window on the past is opening. 4 00:00:13,200 --> 00:00:15,400 How can we travel back in time? 5 00:00:15,400 --> 00:00:17,160 Is there a time machine? 6 00:00:18,280 --> 00:00:21,120 Yes. It's DNA. 7 00:00:22,200 --> 00:00:24,160 It's ancient DNA. 8 00:00:25,280 --> 00:00:28,760 These are fragile molecules that fall apart outside the body. 9 00:00:28,760 --> 00:00:31,440 How long can DNA survive? 10 00:00:31,440 --> 00:00:34,120 With ancient DNA, we're trying to go back in time... 11 00:00:35,440 --> 00:00:38,440 ..but time is the enemy. 12 00:00:41,600 --> 00:00:43,440 A dramatic breakthrough 13 00:00:43,440 --> 00:00:47,480 is transporting us millions of years back into the past, 14 00:00:47,480 --> 00:00:50,080 to before the last Ice Age... 15 00:00:52,520 --> 00:00:55,320 ..revealing surprising creatures that thrived 16 00:00:55,320 --> 00:00:58,680 when our planet was far warmer than it is today. 17 00:01:03,200 --> 00:01:06,080 Could ancient genes from this lost world 18 00:01:06,080 --> 00:01:08,760 help us adapt to a changing planet? 19 00:01:10,360 --> 00:01:13,600 We are stealing genetic secrets of the past... 20 00:01:15,200 --> 00:01:17,440 ..so we can rescue the future. 21 00:01:33,280 --> 00:01:35,840 Buried beneath Greenland's ice sheet 22 00:01:35,840 --> 00:01:39,160 are the remains of a living world that ended 23 00:01:39,160 --> 00:01:42,800 when the Ice Age began over two million years ago. 24 00:01:44,280 --> 00:01:48,000 One scientist is on a quest to reveal that lost world 25 00:01:48,000 --> 00:01:50,040 with ancient DNA. 26 00:01:52,480 --> 00:01:55,040 When I look at this place, 27 00:01:55,040 --> 00:01:58,520 I see one huge cold storage room for ancient DNA. 28 00:02:00,400 --> 00:02:03,720 I spent my life trying to find older and older DNA - 29 00:02:03,720 --> 00:02:07,120 and this is the limit of the possible. 30 00:02:07,120 --> 00:02:09,160 And maybe it's impossible. 31 00:02:10,640 --> 00:02:14,640 What we are trying to recover is DNA millions of years older 32 00:02:14,640 --> 00:02:17,840 than any DNA ever recovered. 33 00:02:17,840 --> 00:02:21,080 So we are trying to reach back before the last Ice Age. 34 00:02:22,640 --> 00:02:26,120 Once, fossils were our only hope 35 00:02:26,120 --> 00:02:29,200 of shedding light on life in the distant past - 36 00:02:29,200 --> 00:02:32,520 but ever since scientists first recovered DNA 37 00:02:32,520 --> 00:02:35,120 from an extinct animal 40 years ago, 38 00:02:35,120 --> 00:02:38,320 fossil hunters have been sharing the stage with gene hunters. 39 00:02:40,360 --> 00:02:43,960 We've peered into a fascinating world of extinct species, 40 00:02:43,960 --> 00:02:48,160 Ice Age beasts, even our Neanderthal cousins. 41 00:02:48,160 --> 00:02:50,160 When I look back in time, 42 00:02:50,160 --> 00:02:52,480 the sharpest tool I have is DNA - 43 00:02:52,480 --> 00:02:55,440 the genes of long dead plants and animals. 44 00:02:55,440 --> 00:02:57,840 This is a far more detailed record of the past 45 00:02:57,840 --> 00:02:59,800 than the fossils alone can ever give us. 46 00:02:59,800 --> 00:03:02,000 But the older DNA gets, 47 00:03:02,000 --> 00:03:03,920 the fainter the signal. 48 00:03:03,920 --> 00:03:08,760 The moment a living thing dies, its DNA starts falling apart. 49 00:03:08,760 --> 00:03:11,680 Of course, we are never going to stop wondering, 50 00:03:11,680 --> 00:03:14,120 "Exactly how far back can we go?" 51 00:03:14,120 --> 00:03:17,000 What is the limit of DNA preservation? 52 00:03:17,000 --> 00:03:20,920 You know what people mean when they say mission impossible, right? 53 00:03:20,920 --> 00:03:23,600 They actually mean it might be possible. 54 00:03:23,600 --> 00:03:27,080 No-one has ever succeeded in getting DNA 55 00:03:27,080 --> 00:03:29,360 older than one million years. 56 00:03:29,360 --> 00:03:31,120 But our tools are getting better. 57 00:03:32,200 --> 00:03:34,920 And as the technology gets more powerful, 58 00:03:34,920 --> 00:03:38,400 these scientists are chasing a new discovery. 59 00:03:38,400 --> 00:03:40,720 To everyone's surprise, 60 00:03:40,720 --> 00:03:43,040 the secret to smashing the limit 61 00:03:43,040 --> 00:03:46,000 could be lying right beneath our feet. 62 00:03:46,000 --> 00:03:49,480 Now, we're on the verge of recovering genetic traces 63 00:03:49,480 --> 00:03:54,520 of a lost world from before the Ice Age. 64 00:03:54,520 --> 00:03:58,600 This ancient DNA, forged in a hotter climate, 65 00:03:58,600 --> 00:04:02,720 might even help us survive our own warming world. 66 00:04:12,960 --> 00:04:15,960 When I was in school, if you had said to my teacher, 67 00:04:15,960 --> 00:04:18,400 "Someday, Eske will be a scientist," 68 00:04:18,400 --> 00:04:20,640 they would have laughed. 69 00:04:20,640 --> 00:04:23,240 I mean, I would have laughed too. 70 00:04:23,240 --> 00:04:25,400 I was a rebel, a troublemaker. 71 00:04:27,360 --> 00:04:30,600 I wasn't good at the typical things 72 00:04:30,600 --> 00:04:33,760 that people connect to being a scientist. 73 00:04:35,920 --> 00:04:39,360 I was a school failure. 74 00:04:39,360 --> 00:04:41,160 That's the truth. 75 00:04:43,680 --> 00:04:48,160 But I think I have one capability 76 00:04:48,160 --> 00:04:54,680 which has proven super valuable - I have a very good imagination. 77 00:05:00,320 --> 00:05:03,320 I used to think I was born too late, 78 00:05:03,320 --> 00:05:06,920 when I realised there's no frontiers left, 79 00:05:06,920 --> 00:05:09,480 everything is mapped - 80 00:05:09,480 --> 00:05:11,360 but there is a frontier. 81 00:05:12,720 --> 00:05:16,240 Our frontier is the deep past. 82 00:05:16,240 --> 00:05:19,000 That is where we can still be explorers. 83 00:05:31,640 --> 00:05:34,560 is pulling mud from the bottom of frozen lakes - 84 00:05:34,560 --> 00:05:37,840 mud laced with DNA from a long-gone world. 85 00:05:40,880 --> 00:05:42,960 WHIRRING 86 00:05:49,280 --> 00:05:52,160 DNA is a blueprint, right? 87 00:05:52,160 --> 00:05:54,800 It's the code that makes you who you are. 88 00:05:56,680 --> 00:05:59,680 Different individuals have different DNA codes. 89 00:05:59,680 --> 00:06:02,360 Different species have different DNA codes. 90 00:06:02,360 --> 00:06:06,880 So, it means if you can pull out a piece of the DNA code, 91 00:06:06,880 --> 00:06:10,080 you can actually map it to all known DNA codes, 92 00:06:10,080 --> 00:06:12,360 all known blueprints - 93 00:06:12,360 --> 00:06:14,280 and then you can identify, well, 94 00:06:14,280 --> 00:06:16,520 what organism are we talking about here? 95 00:06:17,920 --> 00:06:21,760 On this expedition, Eske's team is hunting for DNA 96 00:06:21,760 --> 00:06:26,000 from before the Vikings settled Iceland, about 1,200 years ago. 97 00:06:27,680 --> 00:06:31,280 1,200 years is nothing in ancient DNA research - 98 00:06:31,280 --> 00:06:34,160 especially in the Arctic, where it's cold. 99 00:06:34,160 --> 00:06:37,520 Still, at a certain point, DNA becomes too difficult to read, 100 00:06:37,520 --> 00:06:39,160 so there is a limit. 101 00:06:41,400 --> 00:06:43,120 And I would say, 102 00:06:43,120 --> 00:06:46,760 I've always been obsessed with this limit, to push this limit. 103 00:06:46,760 --> 00:06:48,840 How far can we go? 104 00:06:48,840 --> 00:06:51,920 I still haven't got an answer to that question. 105 00:06:53,640 --> 00:06:56,680 But I'm sure it's further than what we think. 106 00:06:58,040 --> 00:07:00,360 So, what is the limit? 107 00:07:00,360 --> 00:07:04,040 Back in the '90s, some scientists got a little carried away. 108 00:07:05,120 --> 00:07:07,600 "Jurassic Park" was not a documentary. 109 00:07:10,160 --> 00:07:13,560 The early days of ancient DNA were a bit of a disaster. 110 00:07:13,560 --> 00:07:17,560 Unless you were in PR, in which case, it was fantastic. 111 00:07:17,560 --> 00:07:20,480 There was a whole bunch of what we now know 112 00:07:20,480 --> 00:07:24,400 is complete nonsense that was published with just abandon, 113 00:07:24,400 --> 00:07:28,240 just excitement and enthusiasm rather than actual science. 114 00:07:28,240 --> 00:07:31,920 I mean, everybody wants there to be dinosaur DNA. 115 00:07:31,920 --> 00:07:34,000 And so somebody who says, "Hey, 116 00:07:34,000 --> 00:07:36,120 "I got this really well-preserved dinosaur. 117 00:07:36,120 --> 00:07:37,640 "And guess what? There's DNA in it!" 118 00:07:37,640 --> 00:07:40,320 Of course the media are going to be super excited about this! 119 00:07:45,120 --> 00:07:47,440 And Hollywood couldn't resist. 120 00:07:52,120 --> 00:07:54,880 So, let's reconstruct Jurassic Park. 121 00:07:54,880 --> 00:07:58,320 Scientists go somewhere hot, because amber forms in hot places, 122 00:07:58,320 --> 00:08:01,320 and they find a really beautiful piece of amber, 123 00:08:01,320 --> 00:08:04,680 inside of which they can see this fantastic insect 124 00:08:04,680 --> 00:08:06,760 that looks perfectly preserved. 125 00:08:06,760 --> 00:08:07,880 They take a big needle, 126 00:08:07,880 --> 00:08:09,600 and they stick it into the insect, 127 00:08:09,600 --> 00:08:11,800 and they draw out blood, 128 00:08:11,800 --> 00:08:14,160 presumably from a dinosaur. 129 00:08:14,160 --> 00:08:16,840 And then they take that blood to the lab, 130 00:08:16,840 --> 00:08:20,680 and they do some magic that for some reason involves frogs, 131 00:08:20,680 --> 00:08:22,920 even though we already knew at the time 132 00:08:22,920 --> 00:08:25,520 that birds were the closest living ancestor of dinosaurs - 133 00:08:25,520 --> 00:08:27,840 and then more magic happens, 134 00:08:27,840 --> 00:08:30,960 and dinosaurs are back to life! 135 00:08:30,960 --> 00:08:34,240 But we now know a lot more about DNA than we used to, 136 00:08:34,240 --> 00:08:37,280 and everything we know tells us, no question about it, 137 00:08:37,280 --> 00:08:39,960 that this molecule just doesn't stick around 138 00:08:39,960 --> 00:08:42,080 for millions and millions of years. 139 00:08:42,080 --> 00:08:46,960 Dinosaurs have been extinct for more than 65 million years. 140 00:08:46,960 --> 00:08:49,920 We will never get dinosaur DNA. 141 00:08:49,920 --> 00:08:52,680 Jurassic Park is not going to happen. 142 00:08:52,680 --> 00:08:54,400 I'm sorry. 143 00:08:59,200 --> 00:09:02,200 Getting DNA out of things that are alive is easy. 144 00:09:02,200 --> 00:09:05,400 This is because modern DNA, DNA from living organisms, 145 00:09:05,400 --> 00:09:07,680 is in fantastic condition. 146 00:09:07,680 --> 00:09:09,280 Long strands of DNA - 147 00:09:09,280 --> 00:09:12,320 if you can think of it kind of as party streamers. 148 00:09:14,360 --> 00:09:18,040 Ancient DNA is more like confetti. 149 00:09:18,040 --> 00:09:21,080 The reason that modern DNA party streamers 150 00:09:21,080 --> 00:09:24,320 get chopped up into the confetti that is ancient DNA 151 00:09:24,320 --> 00:09:28,080 is because of random processes that happen outside the body. 152 00:09:29,360 --> 00:09:32,600 Mostly things like UV radiation from the sun. 153 00:09:32,600 --> 00:09:35,720 When we walk outside, UV hits our skin 154 00:09:35,720 --> 00:09:38,640 and it gets into our cells, and it damages our DNA. 155 00:09:38,640 --> 00:09:41,800 But when we're alive, we have proofreading enzymes 156 00:09:41,800 --> 00:09:44,600 that will come along and fix those damages. 157 00:09:44,600 --> 00:09:47,680 Otherwise, we would get cancer every time we walked outside. 158 00:09:47,680 --> 00:09:50,080 But proofreading and fixing DNA, 159 00:09:50,080 --> 00:09:53,200 this is an energy-requiring process - 160 00:09:53,200 --> 00:09:55,760 and after you're dead, there is no more energy. 161 00:10:03,240 --> 00:10:04,560 With ancient DNA, 162 00:10:04,560 --> 00:10:06,600 it's always been a needle in the haystack problem. 163 00:10:08,200 --> 00:10:10,520 This is a fragile molecule. 164 00:10:10,520 --> 00:10:12,720 So, even when we first understood 165 00:10:12,720 --> 00:10:15,360 that DNA could stick around after death, 166 00:10:15,360 --> 00:10:18,720 the question was, how much and where? 167 00:10:18,720 --> 00:10:21,840 Early on, we thought only in soft tissue - 168 00:10:21,840 --> 00:10:24,880 so, a human mummy or a frozen mammoth. 169 00:10:26,160 --> 00:10:30,360 In about 1990, we had the huge insight that fossil bones and teeth 170 00:10:30,360 --> 00:10:32,840 could protect DNA like time capsules - 171 00:10:32,840 --> 00:10:35,360 but well-preserved fossils are rare, 172 00:10:35,360 --> 00:10:38,040 and fossils that contain DNA, they're even rarer. 173 00:10:38,040 --> 00:10:42,040 So, in our field, that has been one of the biggest challenges. 174 00:10:42,040 --> 00:10:45,480 We're all chasing these precious time capsules. 175 00:10:48,240 --> 00:10:50,120 Three decades ago, 176 00:10:50,120 --> 00:10:52,640 Eske was determined to join the hunt. 177 00:10:52,640 --> 00:10:55,000 But the odds were against him. 178 00:10:58,200 --> 00:11:01,520 In 1995, I was a biology student 179 00:11:01,520 --> 00:11:05,360 and I wanted to do my research on ancient DNA. 180 00:11:05,360 --> 00:11:07,800 But I had no fossils. 181 00:11:07,800 --> 00:11:11,520 I wasn't famous, so nobody wanted to give me fossils. 182 00:11:11,520 --> 00:11:13,760 That was a bit of a problem. 183 00:11:13,760 --> 00:11:17,120 You want to do ancient DNA, but you have no fossils. 184 00:11:17,120 --> 00:11:19,360 THUNDER RUMBLES 185 00:11:19,360 --> 00:11:22,680 I remember I was in my flat, 186 00:11:22,680 --> 00:11:24,560 it was an awful day. 187 00:11:24,560 --> 00:11:27,000 The rain was just coming down, 188 00:11:27,000 --> 00:11:29,680 and leaves were falling from the trees. 189 00:11:29,680 --> 00:11:34,000 And I saw this woman out walking her dog. 190 00:11:34,000 --> 00:11:36,120 And she stops. 191 00:11:36,120 --> 00:11:39,680 The dog squats, takes a poop. 192 00:11:41,520 --> 00:11:43,400 It's funny, 193 00:11:43,400 --> 00:11:46,720 inspiration sometimes comes out of the strangest times. 194 00:11:46,720 --> 00:11:50,520 I'm looking at this miserable wet dog, 195 00:11:50,520 --> 00:11:53,960 thinking, "Well, there's DNA in the dog. 196 00:11:53,960 --> 00:11:57,200 "So, there's DNA in the dog poop, right? 197 00:11:58,240 --> 00:12:00,080 "But will it survive?" 198 00:12:00,080 --> 00:12:02,520 We know there's DNA in the leaves, 199 00:12:02,520 --> 00:12:05,960 but we also do know that these things will disappear. 200 00:12:05,960 --> 00:12:09,560 After next rainfall, the dog poop will disappear. 201 00:12:09,560 --> 00:12:11,960 After a few years, the leaves will be gone. 202 00:12:11,960 --> 00:12:16,760 The question I asked myself was, "What will happen to the DNA? 203 00:12:16,760 --> 00:12:21,720 "Will that be gone, too? Or will that be preserved in the soil?" 204 00:12:21,720 --> 00:12:24,360 Because if it's preserved in the soil, 205 00:12:24,360 --> 00:12:27,240 we don't need any fossils - problem solved. 206 00:12:29,920 --> 00:12:32,240 So, I remember I went into the coffee room 207 00:12:32,240 --> 00:12:34,360 in the Department of Zoology, 208 00:12:34,360 --> 00:12:36,880 where all the professors were sitting, 209 00:12:36,880 --> 00:12:38,520 you know, having their lunch. 210 00:12:38,520 --> 00:12:40,240 I came with this idea saying, 211 00:12:40,240 --> 00:12:43,240 "Well, what about looking in the soil for DNA of animals and plants?" 212 00:12:43,240 --> 00:12:45,440 And they were laughing. 213 00:12:45,440 --> 00:12:47,560 And my supervisor turned around, 214 00:12:47,560 --> 00:12:49,320 he was head of department, saying... 215 00:12:49,320 --> 00:12:52,320 HE SPEAKS DANISH 216 00:12:52,320 --> 00:12:54,280 THEY LAUGH 217 00:12:54,280 --> 00:12:57,560 .."I never heard anything as stupid in my life." 218 00:12:58,880 --> 00:13:01,600 No-one had ever thought to recover DNA from dirt. 219 00:13:01,600 --> 00:13:02,840 Why would it be there? 220 00:13:02,840 --> 00:13:04,720 The idea is that DNA is kind of known to be 221 00:13:04,720 --> 00:13:06,560 such an unstable molecule in general. 222 00:13:06,560 --> 00:13:08,640 If you're working in a molecular biology lab 223 00:13:08,640 --> 00:13:10,960 and you don't look after your DNA, it's gone very fast. 224 00:13:10,960 --> 00:13:13,240 So, yeah, it was a completely crazy idea 225 00:13:13,240 --> 00:13:15,040 that it would even be found. 226 00:13:15,040 --> 00:13:18,360 I mean, that DNA enters the environment is obvious 227 00:13:18,360 --> 00:13:20,440 if an animal urinates or defecates - 228 00:13:20,440 --> 00:13:23,000 but that DNA stays in the environment, completely crazy. 229 00:13:24,640 --> 00:13:28,480 So, early on, we didn't know how long ancient DNA could survive, 230 00:13:28,480 --> 00:13:30,840 but there was a second really big hole 231 00:13:30,840 --> 00:13:32,960 in our understanding - contamination. 232 00:13:34,960 --> 00:13:38,160 Ancient DNA getting mixed up with modern DNA. 233 00:13:40,440 --> 00:13:42,760 Well, the trouble is that DNA is everywhere. 234 00:13:42,760 --> 00:13:46,800 My DNA is now on this chair and on my hands and on my shirt, 235 00:13:46,800 --> 00:13:50,720 and DNA is coming out of my mouth as I talk, 236 00:13:50,720 --> 00:13:55,080 and there is microbial DNA absolutely everywhere. 237 00:13:55,080 --> 00:13:57,840 So, when people were sequencing these bones, 238 00:13:57,840 --> 00:14:00,160 they were getting DNA. 239 00:14:00,160 --> 00:14:02,640 And they were saying, "Wow, there's DNA in these bones. 240 00:14:02,640 --> 00:14:04,440 "It must be dinosaur DNA." 241 00:14:04,440 --> 00:14:07,440 I think there was some dinosaur DNA that was published 242 00:14:07,440 --> 00:14:10,560 that they were really excited about because it closely matched a bird. 243 00:14:10,560 --> 00:14:13,240 Well, turns out the field excavation team 244 00:14:13,240 --> 00:14:15,240 was having a chicken dinner one night. 245 00:14:15,240 --> 00:14:16,840 CHICKEN CLUCKS 246 00:14:18,080 --> 00:14:20,880 In those early days, when I was still a student, 247 00:14:20,880 --> 00:14:25,800 we were all struggling with the problem of contamination, 248 00:14:25,800 --> 00:14:30,520 which was the big downfall of the dinosaur DNA guys of the '90s - 249 00:14:30,520 --> 00:14:35,960 and I decided, well, somehow, we are going to solve that problem. 250 00:14:35,960 --> 00:14:40,080 I was working on this with another student, Anders Hansen. 251 00:14:40,080 --> 00:14:45,760 So, we had this room, basically, our clean laboratory. 252 00:14:45,760 --> 00:14:50,000 But we had a problem with a mould contamination. 253 00:14:50,000 --> 00:14:53,760 And in the end, we became so desperate, 254 00:14:53,760 --> 00:14:58,440 we decided, OK, we will basically clean the entire room down 255 00:14:58,440 --> 00:15:00,480 with very strong bleach. 256 00:15:03,560 --> 00:15:05,720 We knew, well, it wasn't really allowed, 257 00:15:05,720 --> 00:15:07,640 and we didn't have money for gas masks. 258 00:15:10,840 --> 00:15:14,040 Anders got dizzy and threw up. 259 00:15:18,000 --> 00:15:21,240 And the security guard was coming, 260 00:15:21,240 --> 00:15:24,040 saying, "What the BLEEP is going on here? 261 00:15:24,040 --> 00:15:27,360 "It's smelling like a swimming pool in the entire building." 262 00:15:27,360 --> 00:15:30,680 And Monday morning, we had to stand in front 263 00:15:30,680 --> 00:15:33,440 of the professor and the lab director. 264 00:15:33,440 --> 00:15:35,240 And they were furious, right? 265 00:15:35,240 --> 00:15:37,120 I mean, "What are you guys doing? 266 00:15:37,120 --> 00:15:40,120 "Do you know this is totally illegal?" 267 00:15:40,120 --> 00:15:43,840 But the good news was, even though we got all this heat, 268 00:15:43,840 --> 00:15:46,520 the fungi contamination were gone! 269 00:15:47,880 --> 00:15:50,840 Finally, Eske had a mould-free lab. 270 00:15:52,880 --> 00:15:56,800 He first tried getting DNA out of 2,000-year-old ice. 271 00:15:58,480 --> 00:16:00,680 We got ice cores from Greenland, 272 00:16:00,680 --> 00:16:04,120 and we showed we could recover ancient fungi DNA 273 00:16:04,120 --> 00:16:07,240 trapped in the ice without contamination. 274 00:16:07,240 --> 00:16:09,080 And that was big. 275 00:16:10,160 --> 00:16:14,840 So, then we knew we were ready to move to the next step - 276 00:16:14,840 --> 00:16:17,560 searching for DNA in the dirt. 277 00:16:18,680 --> 00:16:23,200 But there were still so many things I didn't understand, 278 00:16:23,200 --> 00:16:26,800 so, I went to Oxford... 279 00:16:26,800 --> 00:16:30,920 ..to one of the most exciting ancient DNA labs on the planet. 280 00:16:33,960 --> 00:16:35,400 Beth Shapiro was there, too. 281 00:16:38,240 --> 00:16:42,120 When I walked into Oxford I knew the field was an absolute hot mess, 282 00:16:42,120 --> 00:16:44,360 but I also understood the potential. 283 00:16:44,360 --> 00:16:49,480 The ability to recover DNA from bones was so powerful. 284 00:16:51,800 --> 00:16:53,640 Eventually, while I was still there, 285 00:16:53,640 --> 00:16:56,320 Eske Willerslev joined us. 286 00:16:56,320 --> 00:16:59,520 Those very first few years where it was just a few of us, 287 00:16:59,520 --> 00:17:01,760 they were probably the most exciting. 288 00:17:01,760 --> 00:17:04,080 We felt like everything was just at our fingertips, 289 00:17:04,080 --> 00:17:05,640 if we could break through, 290 00:17:05,640 --> 00:17:08,320 if we could figure out how to really get DNA out of these things, 291 00:17:08,320 --> 00:17:09,960 that we could believe, that we could trust. 292 00:17:11,200 --> 00:17:13,760 I recognised that it was going to be difficult, 293 00:17:13,760 --> 00:17:16,520 but I also didn't think it was going to be impossible 294 00:17:16,520 --> 00:17:20,880 and I felt we were really at a turning point for the field. 295 00:17:20,880 --> 00:17:26,520 Beth and I worked on some important papers. She was a powerhouse. 296 00:17:26,520 --> 00:17:32,560 I mean, she was one of the few pioneers really pushing the limits 297 00:17:32,560 --> 00:17:34,520 of ancient DNA. 298 00:17:34,520 --> 00:17:37,720 And apart from Beth, it was all men, 299 00:17:37,720 --> 00:17:40,840 so she was a pioneer in that way, too. 300 00:17:43,560 --> 00:17:46,000 If today I were looking back at myself 301 00:17:46,000 --> 00:17:48,640 as I walked into Oxford on that first day, 302 00:17:48,640 --> 00:17:52,080 I think I would say, "Watch out. 303 00:17:52,080 --> 00:17:54,920 "There are going to be some bumps along the way 304 00:17:54,920 --> 00:17:57,480 "but ancient DNA is it - go for it." 305 00:17:59,040 --> 00:18:00,960 In fact, I felt so strongly 306 00:18:00,960 --> 00:18:04,320 that ancient DNA was going to become really, really big, 307 00:18:04,320 --> 00:18:06,040 I devoted my life to it. 308 00:18:16,040 --> 00:18:19,080 So, I really believed in this idea 309 00:18:19,080 --> 00:18:21,880 of environmental DNA, or dirt DNA - 310 00:18:21,880 --> 00:18:23,760 and more than that, 311 00:18:23,760 --> 00:18:27,960 that it could survive in the environment as ancient DNA. 312 00:18:27,960 --> 00:18:29,240 But I had to prove it. 313 00:18:30,520 --> 00:18:35,200 So, I set out to retrieve ancient DNA from the dirt. 314 00:18:35,200 --> 00:18:37,920 And, at that point, no-one had done that. 315 00:18:39,320 --> 00:18:42,480 Eske was searching for DNA from the Ice Age, 316 00:18:42,480 --> 00:18:45,920 which ended 12,000 years ago. 317 00:18:45,920 --> 00:18:48,400 It kept our planet in a frigid grip 318 00:18:48,400 --> 00:18:50,080 for about 2.5 million years. 319 00:18:51,880 --> 00:18:54,720 The Ice Age, it's an amazing period. 320 00:18:54,720 --> 00:18:57,760 It's the time of the big mammals. 321 00:18:57,760 --> 00:19:01,400 You have giant wolves, giant beavers, 322 00:19:01,400 --> 00:19:03,560 mammoth, mastodons, right? 323 00:19:06,080 --> 00:19:08,200 So, I thought, 324 00:19:08,200 --> 00:19:11,440 imagine how much poop and urine 325 00:19:11,440 --> 00:19:15,120 these big mammals had been producing over time, right, 326 00:19:15,120 --> 00:19:18,000 that is in the soil, in the surrounding, 327 00:19:18,000 --> 00:19:20,240 frozen in time in the Arctic. 328 00:19:21,520 --> 00:19:25,480 So, my idea was to bring back that Ice Age world 329 00:19:25,480 --> 00:19:29,360 by retrieving DNA directly from the permafrost - 330 00:19:29,360 --> 00:19:31,800 and that permafrost I got from Siberia. 331 00:19:35,720 --> 00:19:39,040 So, while everyone else was looking for DNA 332 00:19:39,040 --> 00:19:41,240 in fossil bone and teeth, 333 00:19:41,240 --> 00:19:44,480 and discovering one species at a time, 334 00:19:44,480 --> 00:19:47,400 I was looking in the dirt for everything. 335 00:19:50,240 --> 00:19:53,680 It's one thing to recover ancient DNA, 336 00:19:53,680 --> 00:19:56,240 but it's a far more daunting challenge 337 00:19:56,240 --> 00:19:59,640 to read those tiny fragments of genetic confetti. 338 00:19:59,640 --> 00:20:04,600 That is, to decode what kind of ancient life they come from. 339 00:20:04,600 --> 00:20:06,960 The shorter the fragment, 340 00:20:06,960 --> 00:20:09,400 the harder it is to identify. 341 00:20:09,400 --> 00:20:12,400 A genome is like a twisted ladder. 342 00:20:12,400 --> 00:20:14,640 So, if you think of a long ladder, 343 00:20:14,640 --> 00:20:17,560 every rung is a base pair. 344 00:20:17,560 --> 00:20:20,160 And a base is a single molecule - 345 00:20:20,160 --> 00:20:23,680 A, T, G and C. 346 00:20:23,680 --> 00:20:27,160 A human genome is incredibly long. 347 00:20:27,160 --> 00:20:29,880 It has three billion base pairs. 348 00:20:29,880 --> 00:20:32,600 So, that's three billion rungs on the ladder. 349 00:20:32,600 --> 00:20:34,000 That's a big number. 350 00:20:35,400 --> 00:20:38,080 But when we're working with ancient DNA, 351 00:20:38,080 --> 00:20:40,120 we're working with short pieces, 352 00:20:40,120 --> 00:20:42,600 pieces just a few rungs long. 353 00:20:42,600 --> 00:20:45,920 And we have to hope that those little pieces 354 00:20:45,920 --> 00:20:51,240 contain enough unique information that we can match them to known DNA. 355 00:20:52,560 --> 00:20:58,040 Some of Eske's Siberian permafrost was 400,000 years old. 356 00:20:58,040 --> 00:21:02,360 If he could identify species from ancient DNA frozen inside it, 357 00:21:02,360 --> 00:21:05,040 he would set a new record. 358 00:21:06,320 --> 00:21:10,880 So, it's Christmas Eve, and I'm sitting alone in the lab, 359 00:21:10,880 --> 00:21:14,600 everybody has already gone home for Christmas, 360 00:21:14,600 --> 00:21:18,760 and I'm basically checking the DNA sequences 361 00:21:18,760 --> 00:21:20,600 that we got out of the dirt 362 00:21:20,600 --> 00:21:24,880 and comparing those to all known DNA sequences in the world. 363 00:21:24,880 --> 00:21:26,960 And when I see the results, 364 00:21:26,960 --> 00:21:31,080 the hairs on my back are just rising. 365 00:21:31,080 --> 00:21:33,080 It was - bang! - woolly mammoth. 366 00:21:33,080 --> 00:21:34,840 It was - bang! - bison. 367 00:21:34,840 --> 00:21:37,120 It was - bang! - reindeer. 368 00:21:37,120 --> 00:21:39,320 It was - bang! - hare. 369 00:21:39,320 --> 00:21:43,200 It was - bang, bang, bang! - different types of plants. 370 00:21:45,520 --> 00:21:48,720 It worked better than I could even have imagined. 371 00:21:50,800 --> 00:21:54,440 Eske had matched the ancient DNA in his Siberian dirt 372 00:21:54,440 --> 00:21:57,840 to known species, whose genetic sequences 373 00:21:57,840 --> 00:22:00,560 were collected in a vast catalogue - 374 00:22:00,560 --> 00:22:03,480 and sure enough, there were dozens of matches, 375 00:22:03,480 --> 00:22:06,880 including extinct species. 376 00:22:06,880 --> 00:22:10,840 Eske was the first to show that enough DNA can survive in the dirt 377 00:22:10,840 --> 00:22:13,280 to paint a picture of the past. 378 00:22:13,280 --> 00:22:15,120 Still a student, 379 00:22:15,120 --> 00:22:17,880 he'd just sparked a new field of science - 380 00:22:17,880 --> 00:22:20,800 ancient environmental DNA. 381 00:22:22,280 --> 00:22:25,080 The reason the technique of environmental DNA works 382 00:22:25,080 --> 00:22:27,400 is that DNA is everywhere. 383 00:22:27,400 --> 00:22:29,960 It is raining DNA. 384 00:22:29,960 --> 00:22:32,840 The very problem we had with DNA contaminating samples - 385 00:22:32,840 --> 00:22:36,040 that DNA is falling off of me and coming out of my mouth 386 00:22:36,040 --> 00:22:38,040 and floating in the air around me - 387 00:22:38,040 --> 00:22:41,640 that is exactly the opportunity we have with environmental DNA. 388 00:22:41,640 --> 00:22:45,960 So I realised, it's not the scarcity of DNA that is limiting us. 389 00:22:45,960 --> 00:22:48,680 Environmental DNA is everywhere. 390 00:22:48,680 --> 00:22:50,720 The limit is time. 391 00:22:50,720 --> 00:22:53,360 And this is really when I started thinking, 392 00:22:53,360 --> 00:22:57,280 "Well, how far back in time can we really push this?" 393 00:23:08,520 --> 00:23:11,000 So, today we are in the Holocene. 394 00:23:12,480 --> 00:23:15,400 That's about the last 12,000 years. 395 00:23:17,760 --> 00:23:20,040 Before that, it was the Pleistocene, 396 00:23:20,040 --> 00:23:22,640 a period of lots of ice ages, more than 20, 397 00:23:22,640 --> 00:23:25,680 lasted about 2.5 million years. 398 00:23:25,680 --> 00:23:28,840 And before that was the Pliocene, 399 00:23:28,840 --> 00:23:31,240 when it was much warmer than the Pleistocene. 400 00:23:31,240 --> 00:23:33,200 LOW GROWL 401 00:23:33,200 --> 00:23:35,400 Yeah, it was a really weird place, 402 00:23:35,400 --> 00:23:37,000 you would not recognise that world. 403 00:23:39,760 --> 00:23:41,840 When you go back three million years, 404 00:23:41,840 --> 00:23:43,240 you're in a way warmer climate. 405 00:23:43,240 --> 00:23:45,640 Earth was just hotter. 406 00:23:45,640 --> 00:23:47,640 INSECTS BUZZ 407 00:23:47,640 --> 00:23:50,360 And it had been that way for a very long time, 408 00:23:50,360 --> 00:23:53,800 since before the extinction of the dinosaurs 65 million years ago. 409 00:23:56,760 --> 00:23:58,960 I'm a vertebrate palaeontologist. 410 00:23:58,960 --> 00:24:02,600 I study the animals that lived in the Arctic before the Ice Age. 411 00:24:02,600 --> 00:24:05,280 Mammals of the Pliocene Arctic. 412 00:24:05,280 --> 00:24:08,360 The reality is, we don't know very much. 413 00:24:08,360 --> 00:24:11,160 The time before the Ice Age began, the Pliocene, 414 00:24:11,160 --> 00:24:12,960 it's kind of a lost world. 415 00:24:15,040 --> 00:24:18,360 We don't have full skeletons of any Pliocene mammals. 416 00:24:18,360 --> 00:24:21,240 We just have fragments, shards of bone, 417 00:24:21,240 --> 00:24:23,760 evidence of maybe 13 species. 418 00:24:26,600 --> 00:24:28,640 I still have so many questions. 419 00:24:30,600 --> 00:24:34,280 For a palaeontologist like me, it's really frustrating. 420 00:24:34,280 --> 00:24:39,200 So, where fossils are lacking, could DNA help us? 421 00:24:39,200 --> 00:24:43,400 Could genetic traces really endure for millions of years? 422 00:24:43,400 --> 00:24:48,440 Everything we knew about DNA had told us that was impossible. 423 00:24:49,840 --> 00:24:53,160 The oldest DNA is the coldest DNA. 424 00:24:55,360 --> 00:24:57,280 DNA is fragile, 425 00:24:57,280 --> 00:24:59,880 so it falls apart over time, 426 00:24:59,880 --> 00:25:02,600 but cold slows that process down. 427 00:25:06,600 --> 00:25:09,240 No-one has ever succeeded 428 00:25:09,240 --> 00:25:12,320 in getting DNA older than one million years... 429 00:25:13,680 --> 00:25:16,640 ..but our tools are getting better, 430 00:25:16,640 --> 00:25:20,040 so I think the limits might change. 431 00:25:20,040 --> 00:25:24,360 20 years ago, recovering 400,000-year-old DNA 432 00:25:24,360 --> 00:25:29,520 from Siberian permafrost was an impressive leap back in time. 433 00:25:29,520 --> 00:25:34,000 The student was suddenly a professor - 434 00:25:34,000 --> 00:25:36,400 the youngest in Denmark - 435 00:25:36,400 --> 00:25:42,040 but Eske's quest to recover even older DNA had just begun. 436 00:25:42,040 --> 00:25:44,800 I just happened to get this invitation 437 00:25:44,800 --> 00:25:46,760 from a group of geologists 438 00:25:46,760 --> 00:25:49,800 to go up to northeastern Greenland, 439 00:25:49,800 --> 00:25:52,680 and this is a remarkable place. 440 00:25:52,680 --> 00:25:56,880 I mean, there you have something called the Kap Kobenhavn Formation, 441 00:25:56,880 --> 00:26:00,800 and it's a super dry and a super cold place. 442 00:26:00,800 --> 00:26:05,680 Naturally, I thought northern Greenland would hold the answer. 443 00:26:07,560 --> 00:26:12,440 If really old DNA is going to be preserved anywhere, it's here. 444 00:26:17,320 --> 00:26:19,120 Northeastern Greenland, 445 00:26:19,120 --> 00:26:24,520 it's one of the most hostile places on Earth, extremely cold - 446 00:26:24,520 --> 00:26:28,640 but even more important, this is an Arctic desert. 447 00:26:30,680 --> 00:26:34,240 It was too dry for glaciers to form. 448 00:26:34,240 --> 00:26:37,720 No glaciers to grind away the landscape. 449 00:26:37,720 --> 00:26:42,000 The sediments up there are perfectly preserved. 450 00:26:42,000 --> 00:26:44,560 In Kap Kobenhavn, 451 00:26:44,560 --> 00:26:48,240 you're literally walking on dirt from before the Ice Age. 452 00:26:50,120 --> 00:26:51,640 It's incredible. 453 00:26:51,640 --> 00:26:55,240 This place that is almost barren ground today, 454 00:26:55,240 --> 00:26:59,800 in the sediments, we discovered chunks of trees of wood 455 00:26:59,800 --> 00:27:02,400 that are three million years old 456 00:27:02,400 --> 00:27:05,040 but is still preserved there. 457 00:27:05,040 --> 00:27:07,200 I mean, you can basically take them up 458 00:27:07,200 --> 00:27:09,440 and use them as fuel in your campfire. 459 00:27:09,440 --> 00:27:12,040 So this told me two things. 460 00:27:12,040 --> 00:27:16,080 First, Kap Kobenhavn must have looked very different in the past, 461 00:27:16,080 --> 00:27:21,160 and secondly, this must be among the best places in the world 462 00:27:21,160 --> 00:27:23,160 for long-term preservation of DNA. 463 00:27:25,880 --> 00:27:27,840 This gave me an idea. 464 00:27:29,080 --> 00:27:30,880 A naughty idea. 465 00:27:36,360 --> 00:27:39,200 What if we could just dig in the dirt 466 00:27:39,200 --> 00:27:42,240 and recover DNA millions of years old? 467 00:27:44,280 --> 00:27:48,080 If your goal is to get the oldest sample, 468 00:27:48,080 --> 00:27:51,480 then you go where that oldest sample is likely to be. 469 00:27:51,480 --> 00:27:54,040 It reckons back to the age of exploration, right? 470 00:27:54,040 --> 00:27:57,040 I mean, think about - my kids are in fourth grade, 471 00:27:57,040 --> 00:27:58,880 so they're learning about the explorers 472 00:27:58,880 --> 00:28:00,320 that went around the world, 473 00:28:00,320 --> 00:28:03,880 and this is kind of, I think, how Eske sees himself, a bit. 474 00:28:03,880 --> 00:28:06,160 He's like, "Oh, you know what? There's an Arctic desert. 475 00:28:06,160 --> 00:28:08,720 "I'm going to go there, and I'm going to get DNA from that," 476 00:28:08,720 --> 00:28:11,680 and he will - because he's Eske, and that's how Eske works. 477 00:28:13,480 --> 00:28:16,400 In 2005, I published this review paper 478 00:28:16,400 --> 00:28:20,880 where we basically claimed, well, ancient DNA cannot survive 479 00:28:20,880 --> 00:28:23,040 for more than one million years. 480 00:28:23,040 --> 00:28:25,120 That's the absolute limit. 481 00:28:25,120 --> 00:28:27,600 But in the back of my head, 482 00:28:27,600 --> 00:28:30,600 I was still wondering is that really true, right? 483 00:28:30,600 --> 00:28:33,600 Could DNA survive longer than one million years 484 00:28:33,600 --> 00:28:36,200 in a place like the Kap Kobenhavn Formation? 485 00:28:38,080 --> 00:28:41,040 So, on that same expedition, I thought, 486 00:28:41,040 --> 00:28:44,800 "Hey! I mean, we're here! Why not sample the sediments? 487 00:28:44,800 --> 00:28:49,440 "You never know, we just might be able to find DNA." 488 00:28:51,280 --> 00:28:55,680 I remember it was pretty miserable up there. 489 00:28:55,680 --> 00:28:58,400 We were working in the freezing Arctic desert, 490 00:28:58,400 --> 00:29:01,280 where it rained anyway. 491 00:29:01,280 --> 00:29:03,960 Still, we cored into the frozen ground, 492 00:29:03,960 --> 00:29:06,040 and I got my crazy samples. 493 00:29:09,440 --> 00:29:13,920 So, I took the sediment samples back to my lab in Copenhagen. 494 00:29:13,920 --> 00:29:16,480 To be honest, 495 00:29:16,480 --> 00:29:20,040 this was the beginning of a very frustrating project. 496 00:29:21,960 --> 00:29:26,040 Those Greenland samples would tease and torment Eske and his team 497 00:29:26,040 --> 00:29:27,920 for the next 15 years. 498 00:29:30,640 --> 00:29:34,240 In the early days, Astrid Schmidt was a doctoral student 499 00:29:34,240 --> 00:29:36,160 in Eske's lab. 500 00:29:36,160 --> 00:29:38,960 When Eske offered her the Greenland samples, 501 00:29:38,960 --> 00:29:40,880 she jumped on them. 502 00:29:43,240 --> 00:29:44,960 At that time, 503 00:29:44,960 --> 00:29:47,280 Eske was a star in the scientific community, 504 00:29:47,280 --> 00:29:49,800 and I was inspired by Eske's enthusiasm. 505 00:29:51,800 --> 00:29:55,880 We had a hypothesis that, if the environment had been kept cold, 506 00:29:55,880 --> 00:29:59,080 and the temperatures had not been moving up and down, 507 00:29:59,080 --> 00:30:02,240 fluctuated, then we would have had at least a possibility 508 00:30:02,240 --> 00:30:05,040 of finding ancient DNA. 509 00:30:05,040 --> 00:30:08,080 So, we were being optimistic, 510 00:30:08,080 --> 00:30:09,800 knowing it was a long shot, 511 00:30:09,800 --> 00:30:13,400 but also knowing that we could get ground-breaking results from this. 512 00:30:14,800 --> 00:30:16,680 And there was DNA in the samples. 513 00:30:16,680 --> 00:30:19,520 We could see it - but it was super degraded. 514 00:30:21,640 --> 00:30:25,200 It's not enough to see that your samples contain ancient DNA. 515 00:30:25,200 --> 00:30:28,040 You have to be able to identify that DNA 516 00:30:28,040 --> 00:30:31,080 and to know what forms of life it came from. 517 00:30:31,080 --> 00:30:34,200 To do that, the fragments need to be long enough. 518 00:30:34,200 --> 00:30:37,320 You need a certain number of base pairs in a fragment. 519 00:30:37,320 --> 00:30:39,120 You need enough rungs on your ladder. 520 00:30:40,720 --> 00:30:42,520 When Astrid started, 521 00:30:42,520 --> 00:30:45,880 scientists needed at least 100 base pairs. 522 00:30:45,880 --> 00:30:49,880 We did everything we could with the technology that existed, 523 00:30:49,880 --> 00:30:52,760 but we just couldn't overcome the central problem. 524 00:30:52,760 --> 00:30:55,400 The Greenland DNA was just too old, 525 00:30:55,400 --> 00:30:57,800 the fragments were too short. 526 00:30:57,800 --> 00:30:59,960 It was very frustrating. 527 00:30:59,960 --> 00:31:04,000 The DNA, after one million year, was just total garbage. 528 00:31:04,000 --> 00:31:07,400 With, you can say, the technology in hand at the time, 529 00:31:07,400 --> 00:31:10,520 the DNA was completely unreadable. 530 00:31:10,520 --> 00:31:16,640 Well, Astrid, was one of many people in my lab 531 00:31:16,640 --> 00:31:20,720 that tried the Kap Kobenhavn samples and basically failed. 532 00:31:20,720 --> 00:31:22,440 In retrospect... 533 00:31:24,080 --> 00:31:27,240 ..I was probably not a very good supervisor, right? 534 00:31:27,240 --> 00:31:31,560 Because I kind of pushed for people to do these samples 535 00:31:31,560 --> 00:31:35,440 every time we had improvements of our methodology, 536 00:31:35,440 --> 00:31:38,640 in a hope, "Well, this time, they will work." 537 00:31:38,640 --> 00:31:42,120 If that happened, it would be a career booster - 538 00:31:42,120 --> 00:31:48,040 but the...risk associated with this project was huge, right? 539 00:31:48,040 --> 00:31:51,160 So it was failure after failure. 540 00:31:51,160 --> 00:31:56,400 Kap Kobenhavn project was, um, yeah, a bit sensitive. 541 00:31:56,400 --> 00:32:00,080 As a postdoc, if you decided to invest your time in this, 542 00:32:00,080 --> 00:32:03,920 it was the case of having only so many years 543 00:32:03,920 --> 00:32:06,680 to be able to produce excellent research. 544 00:32:06,680 --> 00:32:08,520 If you're not able to produce research 545 00:32:08,520 --> 00:32:10,280 because the technology doesn't allow it, 546 00:32:10,280 --> 00:32:12,480 not because you're a bad researcher, 547 00:32:12,480 --> 00:32:15,040 you still end up with nothing to show for it. 548 00:32:16,240 --> 00:32:18,760 In 2013, I left research science, 549 00:32:18,760 --> 00:32:22,440 and I didn't pursue science since then. 550 00:32:22,440 --> 00:32:25,400 I took a big risk and I paid a price. 551 00:32:25,400 --> 00:32:30,720 So, Astrid, she suffered the curse of the Greenland samples. 552 00:32:30,720 --> 00:32:32,720 And she was not the last one. 553 00:32:32,720 --> 00:32:36,680 You have to take a risk to make a scientific career, 554 00:32:36,680 --> 00:32:38,560 and you also have to take a risk 555 00:32:38,560 --> 00:32:41,280 if you want to make ground-breaking science. 556 00:32:45,880 --> 00:32:48,960 If you had asked one of my teachers, 557 00:32:48,960 --> 00:32:52,160 "Well, what do you think will become of Eske?", 558 00:32:52,160 --> 00:32:54,040 I'm pretty sure they would have said, 559 00:32:54,040 --> 00:32:57,680 "Well, worst-case scenario, he will be a criminal. 560 00:32:57,680 --> 00:33:01,600 "Best-case scenario, he will be a societal burden, a loser." 561 00:33:06,720 --> 00:33:11,880 I mean, I remember in school, we were all asked to go up to the board 562 00:33:11,880 --> 00:33:15,040 and write a word, right? Spell a word. 563 00:33:15,040 --> 00:33:17,960 And there was one of the students who said, 564 00:33:17,960 --> 00:33:20,520 "Well, has Eske been up to the board yet?" 565 00:33:20,520 --> 00:33:22,920 And then the teacher looked at the board - 566 00:33:22,920 --> 00:33:24,760 "No, because there's no mistakes." 567 00:33:27,800 --> 00:33:29,040 So... 568 00:33:31,760 --> 00:33:37,040 I always was told as a kid, both by my family - 569 00:33:37,040 --> 00:33:41,600 by my parents, basically, my father - but also my teachers, 570 00:33:41,600 --> 00:33:47,200 "Well, you're not too smart, right? So you have to somehow compensate." 571 00:33:47,200 --> 00:33:48,760 And, well, how can you compensate? 572 00:33:48,760 --> 00:33:51,320 Well, you can compensate by hard work. 573 00:33:51,320 --> 00:33:53,760 There's a lot we can do, right? You can already see it now... 574 00:33:53,760 --> 00:33:55,880 He is not afraid to call you in the middle of the night 575 00:33:55,880 --> 00:33:57,720 and remind you that you told him a few hours ago 576 00:33:57,720 --> 00:34:01,320 you were going to do something for him. He is that personality! 577 00:34:01,320 --> 00:34:04,400 I like working with Eske, but I also hate working with Eske. 578 00:34:04,400 --> 00:34:07,560 It's exciting to work with Eske because he's so driven - 579 00:34:07,560 --> 00:34:09,440 it's just, drive, drive, drive all the time - 580 00:34:09,440 --> 00:34:14,360 but it's also exhausting and kind of scary and infuriating at times, 581 00:34:14,360 --> 00:34:15,920 because you're like, "Yeah, this is cool stuff, 582 00:34:15,920 --> 00:34:18,080 "but, Eske, I also have to sleep!" 583 00:34:19,680 --> 00:34:24,640 Despite the curse, Eske and his team kept returning to Greenland, 584 00:34:24,640 --> 00:34:27,320 hoping to find DNA in better condition. 585 00:34:28,440 --> 00:34:32,760 Meanwhile, students continued to suffer under the curse, 586 00:34:32,760 --> 00:34:36,840 failing to recover DNA long enough to identify. 587 00:34:36,840 --> 00:34:39,440 They all changed careers. 588 00:34:39,440 --> 00:34:43,560 But as they left, new ones stepped into their shoes. 589 00:34:46,160 --> 00:34:49,960 So, you can imagine what I felt when these samples landed on my table. 590 00:34:52,280 --> 00:34:55,720 So, I was a PhD student in Eske Willerslev's lab. 591 00:34:55,720 --> 00:34:58,560 This was my last option also to succeed in a project 592 00:34:58,560 --> 00:35:01,760 that I was given as a PhD student. I was coming to... 593 00:35:01,760 --> 00:35:03,720 HE LAUGHS 594 00:35:03,720 --> 00:35:08,360 ..the final tries of actually making this a success. 595 00:35:08,360 --> 00:35:12,720 Back in the day, we needed almost 100 base pair fragments 596 00:35:12,720 --> 00:35:18,520 to survive in a sample in order to retrieve any DNA whatsoever. 597 00:35:18,520 --> 00:35:20,600 But the technology was changing. 598 00:35:20,600 --> 00:35:24,720 And I had a student, Mikkel, who came to me with an idea. 599 00:35:24,720 --> 00:35:26,600 I was immediately excited. 600 00:35:26,600 --> 00:35:28,720 I thought, "Yes, this could work." 601 00:35:30,280 --> 00:35:33,600 Mikkel suggested we use a powerful technique 602 00:35:33,600 --> 00:35:36,680 called shotgun sequencing. 603 00:35:36,680 --> 00:35:39,760 Shotgun sequencing itself wasn't new, 604 00:35:39,760 --> 00:35:43,120 but no-one had ever used it on dirt DNA. 605 00:35:43,120 --> 00:35:46,960 I don't know why, in retrospect. It seemed kind of obvious. 606 00:35:48,400 --> 00:35:51,320 First, Mikkel proved that the shotgun technique 607 00:35:51,320 --> 00:35:55,320 could work on dirt DNA several thousand years old. 608 00:35:55,320 --> 00:35:57,760 It really showed us that we could actually 609 00:35:57,760 --> 00:36:02,680 get ancient environmental DNA even from the very shortest threads 610 00:36:02,680 --> 00:36:05,440 that were preserving in the samples. 611 00:36:05,440 --> 00:36:08,360 And the obvious next step would actually be 612 00:36:08,360 --> 00:36:10,600 to take on the most challenging project of them all, 613 00:36:10,600 --> 00:36:15,600 what we refer to as the curse, the Kap Kobenhavn Formation. 614 00:36:18,080 --> 00:36:19,920 In the early years of ancient DNA, 615 00:36:19,920 --> 00:36:23,120 we had to decide which part of the genome to look at. 616 00:36:23,120 --> 00:36:27,520 Those are the giveaway parts of the genome that we call barcodes. 617 00:36:27,520 --> 00:36:30,560 They reveal the identity of an organism. 618 00:36:30,560 --> 00:36:32,080 We matched those barcodes 619 00:36:32,080 --> 00:36:33,880 to our reference catalogue - 620 00:36:33,880 --> 00:36:36,480 but those barcode fragments had to be long enough. 621 00:36:37,760 --> 00:36:41,080 We know that DNA fragments over a hundred base pairs 622 00:36:41,080 --> 00:36:43,240 just don't survive millions of years, 623 00:36:43,240 --> 00:36:46,640 even frozen, high up in the Arctic. 624 00:36:46,640 --> 00:36:50,320 So, shotgun sequencing was a revolution. 625 00:36:50,320 --> 00:36:54,440 Now, instead of targeting a specific part of the genome with precision, 626 00:36:54,440 --> 00:36:57,640 like with a rifle, we're using a shotgun. 627 00:36:57,640 --> 00:37:00,440 A shotgun hits everything. 628 00:37:00,440 --> 00:37:05,240 With the shotgun method, we just sequence all the DNA we can find. 629 00:37:05,240 --> 00:37:09,680 Then we look for matches with every genome sequence 630 00:37:09,680 --> 00:37:13,240 for every organism that we know of. 631 00:37:13,240 --> 00:37:15,520 It takes immense computing power, 632 00:37:15,520 --> 00:37:17,240 billions of operations, 633 00:37:17,240 --> 00:37:20,600 and only now are computers powerful enough 634 00:37:20,600 --> 00:37:23,320 to work with fragments down to 30 base pairs. 635 00:37:25,960 --> 00:37:29,160 Imagine shredding War and Peace. 636 00:37:29,160 --> 00:37:33,360 All you have are short phrases, not even sentences. 637 00:37:33,360 --> 00:37:36,000 And you walk into the Library of Congress, 638 00:37:36,000 --> 00:37:41,280 and you start looking for a match for each one of those phrases, 639 00:37:41,280 --> 00:37:44,320 book by book by book. 640 00:37:44,320 --> 00:37:46,880 There's another War and Peace in there somewhere, 641 00:37:46,880 --> 00:37:50,800 but you need to work through millions of other books 642 00:37:50,800 --> 00:37:52,440 before you find a match. 643 00:37:52,440 --> 00:37:56,640 And once you do, your job is to reconstruct 644 00:37:56,640 --> 00:38:00,520 as many pages of that novel as you can. 645 00:38:04,160 --> 00:38:08,040 So we were the first to use shotgun sequencing on dirt. 646 00:38:08,040 --> 00:38:13,000 And when we did, man, it was powerful. 647 00:38:13,000 --> 00:38:18,280 In science, moments like this actually feels like magic. 648 00:38:18,280 --> 00:38:20,400 I have no other way of putting it. 649 00:38:20,400 --> 00:38:25,040 It was just like that Christmas Eve 25 years ago. 650 00:38:25,040 --> 00:38:28,280 As if by magic, we were seeing the genetic signatures 651 00:38:28,280 --> 00:38:31,360 of these plants and animals appear - 652 00:38:31,360 --> 00:38:33,640 bang, bang, bang! 653 00:38:33,640 --> 00:38:35,320 But it's different this time. 654 00:38:35,320 --> 00:38:37,720 Now, there's hundreds - 655 00:38:37,720 --> 00:38:41,840 fleas, lemmings, Arctic hare, geese, caribou - 656 00:38:41,840 --> 00:38:44,640 a whole forest ecosystem - 657 00:38:44,640 --> 00:38:50,160 larch, poplar, willow, spruce, ash, cedar trees. 658 00:38:50,160 --> 00:38:53,440 We're looking at a long list of organisms 659 00:38:53,440 --> 00:38:57,400 from a place that today is an Arctic desert. 660 00:39:02,480 --> 00:39:04,280 Eske's team had recovered 661 00:39:04,280 --> 00:39:08,040 the genetic fingerprints of a lost world - 662 00:39:08,040 --> 00:39:10,480 nine land and sea animals, 663 00:39:10,480 --> 00:39:13,920 from horseshoe crabs to big mammals, 664 00:39:13,920 --> 00:39:18,920 over 100 plants, from mosses to forest trees, 665 00:39:18,920 --> 00:39:24,000 and nearly 2,000 other organisms, from bacteria to plankton... 666 00:39:25,640 --> 00:39:27,720 ..some of them extinct, 667 00:39:27,720 --> 00:39:30,680 and many of them never detected in the Arctic. 668 00:39:30,680 --> 00:39:34,640 But this incredible breakthrough created another problem. 669 00:39:35,960 --> 00:39:39,880 If you're claiming to have recovered the world's oldest DNA, 670 00:39:39,880 --> 00:39:42,800 you had better be very sure about the date. 671 00:39:44,520 --> 00:39:47,440 We knew we were going to get hammered. 672 00:39:47,440 --> 00:39:52,720 Extraordinary claims demand extraordinary evidence, right? 673 00:39:52,720 --> 00:39:57,160 We had to be very sure about the dates from Kap Kobenhavn. 674 00:39:57,160 --> 00:40:01,520 That took two more years of hard work. 675 00:40:05,080 --> 00:40:08,800 We used a whole set of different methods. 676 00:40:08,800 --> 00:40:10,880 We looked for organisms in the sediments 677 00:40:10,880 --> 00:40:14,600 that we knew lived on Earth for a known period of the past. 678 00:40:14,600 --> 00:40:20,000 We used the biological clock based on how DNA mutates over time. 679 00:40:20,000 --> 00:40:22,680 And Eske's team used three more independent methods 680 00:40:22,680 --> 00:40:25,280 to date the sediment from Greenland. 681 00:40:25,280 --> 00:40:30,200 When their work was done, they had made a remarkable discovery - 682 00:40:30,200 --> 00:40:36,400 the Cape Copenhagen DNA is at least two million years old. 683 00:40:36,400 --> 00:40:41,280 It's important to understand that this is the minimum possible age. 684 00:40:41,280 --> 00:40:46,320 Taking all the lines of the dating evidence as a whole, 685 00:40:46,320 --> 00:40:50,280 the most likely age of the Kap Kobenhavn DNA 686 00:40:50,280 --> 00:40:52,720 is actually 2.5 million years. 687 00:40:52,720 --> 00:40:55,400 This puts us into the late Pliocene, 688 00:40:55,400 --> 00:41:00,320 which is the period just before we start having glaciations. 689 00:41:00,320 --> 00:41:03,960 If Eske's DNA is that old, if it is Pliocene, 690 00:41:03,960 --> 00:41:06,200 then that is huge. 691 00:41:06,200 --> 00:41:11,800 Eske had his hands on DNA from before the last Ice Age. 692 00:41:11,800 --> 00:41:14,840 Finally, we are catching sight of the living world 693 00:41:14,840 --> 00:41:19,400 that existed in Greenland before the world grew cold. 694 00:41:20,960 --> 00:41:22,760 That was the moment. 695 00:41:22,760 --> 00:41:27,680 That was when we knew we had something to tell the world. 696 00:41:27,680 --> 00:41:32,560 16 years after Eske began collecting dirt in Greenland, 697 00:41:32,560 --> 00:41:35,960 the breakthrough was published in Nature magazine. 698 00:41:35,960 --> 00:41:40,320 It was covered by over 400 newspapers around the world. 699 00:41:40,320 --> 00:41:44,160 It even landed on the front page of the New York Times. 700 00:41:44,160 --> 00:41:48,600 This was one of the biggest science stories of the year. 701 00:41:48,600 --> 00:41:51,880 Until this day, the record for the oldest DNA 702 00:41:51,880 --> 00:41:55,160 was from a fossil of a single species, 703 00:41:55,160 --> 00:42:00,120 a mammoth that lived one million years ago, during the Ice Age. 704 00:42:00,120 --> 00:42:05,480 Using dirt DNA instead of fossils, Eske's team shattered that record, 705 00:42:05,480 --> 00:42:08,960 opening a window on an unknown living world 706 00:42:08,960 --> 00:42:11,480 more than twice as old as that mammoth. 707 00:42:11,480 --> 00:42:13,160 It feels almost magical 708 00:42:13,160 --> 00:42:15,880 to be able to infer such a complete picture 709 00:42:15,880 --> 00:42:17,600 of an ancient ecosystem 710 00:42:17,600 --> 00:42:20,480 from tiny fragments of preserved DNA. 711 00:42:22,680 --> 00:42:26,040 When I first heard about the results from Kap Kobenhavn... 712 00:42:27,400 --> 00:42:30,200 ..I just said to myself, "What?!" 713 00:42:30,200 --> 00:42:33,440 What we're talking about is pushing the record back 714 00:42:33,440 --> 00:42:37,240 to at least two million years, and I believe much longer than that. 715 00:42:37,240 --> 00:42:39,480 It was a complete tour de force. 716 00:42:39,480 --> 00:42:43,320 "What are my feelings when I first saw this paper?", is...stunned. 717 00:42:43,320 --> 00:42:46,400 I think we just never really thought it would be possible, 718 00:42:46,400 --> 00:42:51,040 after years of trying, to get DNA from these ancient ecosystems. 719 00:42:51,040 --> 00:42:54,360 We never thought we'd see such a rich and diverse ecosystem 720 00:42:54,360 --> 00:42:55,440 in Greenland. 721 00:42:57,040 --> 00:42:59,360 We're seeing the very last Arctic forests 722 00:42:59,360 --> 00:43:02,680 from a hotter world before the Ice Age. 723 00:43:02,680 --> 00:43:05,760 And these forests are unique. We have nothing like them today. 724 00:43:12,680 --> 00:43:17,200 I always knew that there was forest in the High Arctic. 725 00:43:17,200 --> 00:43:20,240 I touched the wood of ancient trees up there. 726 00:43:21,520 --> 00:43:25,080 But when we looked at the sequences from Greenland, 727 00:43:25,080 --> 00:43:31,080 there was one that completely shocked me, shocked everyone. 728 00:43:35,000 --> 00:43:39,800 To hear that there was mastodon DNA from Kap Kobenhavn, 729 00:43:39,800 --> 00:43:43,520 this just struck me as, "Whoa! How can that be? 730 00:43:43,520 --> 00:43:45,240 "That is so far north." 731 00:43:45,240 --> 00:43:47,720 Relatives of the modern elephant, 732 00:43:47,720 --> 00:43:52,320 mastodons were forest creatures that died out at the end of the Ice Age. 733 00:43:52,320 --> 00:43:55,640 The closest to Kap Kobenhavn their remains have been found 734 00:43:55,640 --> 00:44:00,080 is almost 3,000 miles to the south, in North America. 735 00:44:00,080 --> 00:44:01,840 It comes completely out of the blue, 736 00:44:01,840 --> 00:44:03,600 and it was the first time 737 00:44:03,600 --> 00:44:06,880 that we found such a large animal in Greenland. 738 00:44:20,280 --> 00:44:23,720 So, after all those years, 739 00:44:23,720 --> 00:44:27,720 we broke the curse of the Greenland samples. 740 00:44:27,720 --> 00:44:30,720 I guess you can say it was a breakthrough 741 00:44:30,720 --> 00:44:33,600 that immediately became a problem. 742 00:44:33,600 --> 00:44:35,440 The big question, of course, 743 00:44:35,440 --> 00:44:42,160 is, "How do such DNA survive beyond the one-million-year-old limit?" 744 00:44:42,160 --> 00:44:44,800 That was the mystery we had to solve. 745 00:44:48,000 --> 00:44:53,320 It turns out, DNA survived such an incredible long time 746 00:44:53,320 --> 00:44:56,280 because of minerals in the soil. 747 00:44:58,280 --> 00:45:00,920 DNA is electrically charged, 748 00:45:00,920 --> 00:45:04,360 and many mineral particles that you find in the soil 749 00:45:04,360 --> 00:45:07,240 is also electrically charged. 750 00:45:07,240 --> 00:45:11,280 So, therefore, DNA fragments will basically bind itself 751 00:45:11,280 --> 00:45:15,320 around such sediment particles. 752 00:45:15,320 --> 00:45:18,920 And this will reduce the rate of degradation, 753 00:45:18,920 --> 00:45:22,800 of the spontaneous reaction that are attacking the DNA 754 00:45:22,800 --> 00:45:24,640 and breaking it up. 755 00:45:24,640 --> 00:45:29,080 So, yes, it will still be degraded, it will still be destroyed, 756 00:45:29,080 --> 00:45:33,920 but the rate by which this is happening is heavily reduced. 757 00:45:35,880 --> 00:45:41,800 It turned out that particularly certain minerals of clay and quartz 758 00:45:41,800 --> 00:45:44,120 binds the DNA very strong. 759 00:45:44,120 --> 00:45:49,120 If bound to clay and quartz, DNA is basically frozen in time. 760 00:45:50,720 --> 00:45:53,480 What is super cool about the Greenland breakthrough 761 00:45:53,480 --> 00:45:58,520 is the discovery that certain minerals can freeze DNA in time - 762 00:45:58,520 --> 00:46:01,480 because this means that everything we thought 763 00:46:01,480 --> 00:46:05,600 about the limits of DNA preservation are out the window. 764 00:46:05,600 --> 00:46:08,080 Not back to the age of dinosaurs, 765 00:46:08,080 --> 00:46:10,720 but far beyond the old one-million-year limit. 766 00:46:13,000 --> 00:46:15,200 So, these cores that no-one believed in 767 00:46:15,200 --> 00:46:19,120 turned out to contain the most amazing treasure. 768 00:46:19,120 --> 00:46:22,640 It just took us 15 years to find out how to get it out. 769 00:46:24,600 --> 00:46:27,520 To be honest, I never really lost faith - 770 00:46:27,520 --> 00:46:32,200 because every limit we have ever set, we broke. 771 00:46:35,840 --> 00:46:38,320 Until now, what we knew of the living world 772 00:46:38,320 --> 00:46:41,840 before the Ice Age, we learned from fossils. 773 00:46:41,840 --> 00:46:44,280 At the Canadian Museum of Nature, 774 00:46:44,280 --> 00:46:48,800 Natalia Rybczynski only has fragments of bone to study - 775 00:46:48,800 --> 00:46:52,400 but with the spectacular discovery of DNA from Greenland, 776 00:46:52,400 --> 00:46:58,000 finally, a detailed portrait of this lost world is emerging. 777 00:46:58,000 --> 00:47:01,000 And it's even stranger than scientists expected. 778 00:47:01,880 --> 00:47:05,200 This was a really weird environment. 779 00:47:05,200 --> 00:47:09,680 You had a forest where, half the year, it was dark. 780 00:47:09,680 --> 00:47:15,080 And the other half of the year, it was sunshine all day around. 781 00:47:15,080 --> 00:47:19,400 This means that all the organisms we are uncovering 782 00:47:19,400 --> 00:47:22,800 had to survive half the year in darkness. 783 00:47:22,800 --> 00:47:24,640 So one of the things I'm really interested in 784 00:47:24,640 --> 00:47:29,520 is how these northern forests, these Arctic forests, 785 00:47:29,520 --> 00:47:33,000 might have shaped the species we see today. 786 00:47:35,600 --> 00:47:38,800 But what if hibernation in some mammals today 787 00:47:38,800 --> 00:47:43,080 actually came from when they were living at these high latitudes, 788 00:47:43,080 --> 00:47:45,720 in these dark winter forests, right? 789 00:47:45,720 --> 00:47:47,880 Maybe this is where hibernation evolved 790 00:47:47,880 --> 00:47:49,640 for some lineages, such as bears. 791 00:47:51,360 --> 00:47:55,560 We actually discovered a Pliocene bear fossil in Arctic Canada, 792 00:47:55,560 --> 00:47:59,440 but the fossil record doesn't give us evidence of hibernation. 793 00:47:59,440 --> 00:48:01,560 In theory, we could find it, but we haven't. 794 00:48:03,360 --> 00:48:05,640 That is where Eske and his DNA could really help us. 795 00:48:05,640 --> 00:48:08,440 What if we could trace the evolution of hibernation 796 00:48:08,440 --> 00:48:10,200 using genetic evidence? 797 00:48:10,200 --> 00:48:11,440 That would be very cool. 798 00:48:24,400 --> 00:48:28,440 I think the thing that really blew our minds from the Pliocene 799 00:48:28,440 --> 00:48:30,200 is the camel. 800 00:48:30,200 --> 00:48:34,040 How could this camel, known only by a few fragments of bone, 801 00:48:34,040 --> 00:48:36,840 survive so far north? 802 00:48:36,840 --> 00:48:40,120 The living world revealed by the Greenland DNA 803 00:48:40,120 --> 00:48:42,000 gives us some clues. 804 00:48:42,000 --> 00:48:45,520 When you think about camels today, it's really easy to imagine 805 00:48:45,520 --> 00:48:47,920 that they evolved to live in the desert, 806 00:48:47,920 --> 00:48:51,840 and this is where the finding of the High Arctic camel 807 00:48:51,840 --> 00:48:55,960 is so mind-blowing, right? Because it's not in a desert. 808 00:48:55,960 --> 00:49:00,040 It's living a complete opposite to a desert. It's in a forest. 809 00:49:01,480 --> 00:49:05,280 Ever notice how huge a camel's eye is? 810 00:49:05,280 --> 00:49:06,880 Well, it turns out they have incredible vision, 811 00:49:06,880 --> 00:49:08,680 including night vision. 812 00:49:08,680 --> 00:49:11,760 That's pretty useful when it's dark six months of the year. 813 00:49:13,720 --> 00:49:18,400 One of the most dramatic features of the camel, it's the hump. 814 00:49:18,400 --> 00:49:21,240 It's actually a specialised fat deposit. 815 00:49:21,240 --> 00:49:24,000 And when you think about the importance of fat, 816 00:49:24,000 --> 00:49:27,120 energy storage, this is something that's also very important 817 00:49:27,120 --> 00:49:31,520 for animals that survive through harsh winters. 818 00:49:31,520 --> 00:49:35,400 The wide feet of camels - you know, it's listed as one of the traits 819 00:49:35,400 --> 00:49:37,360 that helps them walk over sand - 820 00:49:37,360 --> 00:49:39,640 also would function well in soft snow. 821 00:49:41,240 --> 00:49:44,480 We haven't found camel DNA from before the Ice Age. 822 00:49:44,480 --> 00:49:46,520 Not yet. 823 00:49:46,520 --> 00:49:50,440 But we have now recreated the forest world they were living in, 824 00:49:50,440 --> 00:49:53,520 and Natalia's fossils tells us they were there. 825 00:49:55,360 --> 00:49:58,680 This is a forest that stretched from Greenland to Canada 826 00:49:58,680 --> 00:50:01,160 on solid land without barriers. 827 00:50:09,360 --> 00:50:11,960 We used to believe that ancient DNA could take you back 828 00:50:11,960 --> 00:50:13,600 a few thousand years. 829 00:50:13,600 --> 00:50:17,240 Today, we know we can see millions of years back in time. 830 00:50:17,240 --> 00:50:21,680 Back to a hotter time, before the Ice Age - 831 00:50:21,680 --> 00:50:25,000 the Pliocene, a long-lost epoch 832 00:50:25,000 --> 00:50:29,440 that climate scientists believe may hold a lesson for us today. 833 00:50:30,880 --> 00:50:33,920 So it's in Cruise 28. 834 00:50:33,920 --> 00:50:35,880 And let's see... 835 00:50:35,880 --> 00:50:37,920 179. Wow! 836 00:50:37,920 --> 00:50:40,320 And you can just tell how much has been sampled. 837 00:50:43,400 --> 00:50:47,000 The Pliocene's a big red flashing light, right? 838 00:50:49,400 --> 00:50:51,360 The Pliocene seems very distant, 839 00:50:51,360 --> 00:50:54,880 filled with strange animals that are now extinct - 840 00:50:54,880 --> 00:50:56,280 but at the same time, 841 00:50:56,280 --> 00:50:58,960 it feels very close to me, as someone who studies climate. 842 00:51:01,520 --> 00:51:04,800 The Pliocene was the last time atmospheric CO2 levels 843 00:51:04,800 --> 00:51:06,240 were the same as today. 844 00:51:06,240 --> 00:51:08,160 You have to go back three million years 845 00:51:08,160 --> 00:51:11,440 to find a climate equivalent to what we're doing right now. 846 00:51:12,600 --> 00:51:14,560 That is a CO2 level 847 00:51:14,560 --> 00:51:19,160 of about 400 parts per million in the atmosphere. 848 00:51:19,160 --> 00:51:22,320 Sometimes people say, "Well, we have the same amount of CO2 849 00:51:22,320 --> 00:51:24,600 "in the atmosphere as the Pliocene, 850 00:51:24,600 --> 00:51:26,840 "but we still have this giant Greenland ice cap, 851 00:51:26,840 --> 00:51:30,320 "and we don't have forests around the Arctic. What gives?" 852 00:51:30,320 --> 00:51:34,280 And the reason for that is cos the ice caps are really slow. 853 00:51:34,280 --> 00:51:37,120 They have this really long response time. 854 00:51:37,120 --> 00:51:42,160 And you could think about it as, you know, you have a frozen lasagne, 855 00:51:42,160 --> 00:51:44,600 you put it in the oven, the oven's really hot, 856 00:51:44,600 --> 00:51:47,920 but it takes a long time for it to defrost. 857 00:51:47,920 --> 00:51:49,560 And that's what's going on right now. 858 00:51:49,560 --> 00:51:52,920 We have the ice sheets, they're in this warm atmosphere 859 00:51:52,920 --> 00:51:56,440 and they're rapidly losing mass. They're melting. 860 00:51:56,440 --> 00:51:58,720 But it's going to take them a long time. 861 00:51:59,840 --> 00:52:03,880 One of the key questions of the Pliocene has always been, 862 00:52:03,880 --> 00:52:06,480 how much of the polar ice sheets will melt? 863 00:52:06,480 --> 00:52:09,880 And by extension, how high will sea level rise? 864 00:52:09,880 --> 00:52:12,720 And this has been a tricky question for a long time. 865 00:52:17,520 --> 00:52:19,880 Well, we've finally found the site that tells us 866 00:52:19,880 --> 00:52:23,080 exactly how high Pliocene sea levels were. 867 00:52:23,080 --> 00:52:25,240 It's in a cave in Spain. 868 00:53:42,160 --> 00:53:44,800 Sea levels were almost 50 feet higher. 869 00:53:46,280 --> 00:53:49,240 16 metres - think about that. 870 00:53:51,720 --> 00:53:54,800 It's a scary number. It's a big number and it's a scary number, 871 00:53:54,800 --> 00:53:57,960 cos you think about standing at the shore today, 872 00:53:57,960 --> 00:54:00,640 think about what 50 feet looks like. 873 00:54:00,640 --> 00:54:06,760 Look up and then imagine how far inland the ocean would be going 874 00:54:06,760 --> 00:54:09,280 with a 50-foot sea level rise. 875 00:54:11,120 --> 00:54:15,800 It's hard to imagine what our world looks like 876 00:54:15,800 --> 00:54:19,960 with even 20 feet of sea level rise. 877 00:54:19,960 --> 00:54:23,640 Even the coastlines around the world would look dramatically different. 878 00:54:25,400 --> 00:54:27,000 Most of the major cities - 879 00:54:27,000 --> 00:54:33,920 Mumbai, Hamburg, London, New York, Los Angeles - everywhere you go... 880 00:54:35,960 --> 00:54:37,560 ..these cities are at risk. 881 00:54:40,800 --> 00:54:42,720 But here's the thing - 882 00:54:42,720 --> 00:54:46,120 if we do nothing and we just keep doing what we're doing, 883 00:54:46,120 --> 00:54:48,800 by the end of the 21st century, 884 00:54:48,800 --> 00:54:51,720 we will have a level of CO2 in the atmosphere, 885 00:54:51,720 --> 00:54:56,240 let's say around 800 parts per million, that now becomes equivalent 886 00:54:56,240 --> 00:54:59,240 to these time periods in the deep, deep past, 887 00:54:59,240 --> 00:55:01,560 like the Eocene 50 million years ago. 888 00:55:05,800 --> 00:55:11,080 The new Pliocene has begun. It's called the Anthropocene. 889 00:55:11,080 --> 00:55:12,840 We've already altered Earth's climate. 890 00:55:12,840 --> 00:55:15,360 We're living in a climate 891 00:55:15,360 --> 00:55:20,520 that is about 1 Celsius warmer globally than it should be. 892 00:55:23,200 --> 00:55:26,200 The climate of the Pliocene is where we're going. 893 00:55:26,200 --> 00:55:28,960 It's like our instruction manual for what's coming. 894 00:55:32,520 --> 00:55:35,080 When the Pliocene ended and the Ice Age began, 895 00:55:35,080 --> 00:55:38,440 that was a big blow - but it didn't end life on Earth. 896 00:55:38,440 --> 00:55:40,880 All life around us has its evolutionary roots 897 00:55:40,880 --> 00:55:43,440 in a hotter world, including us. 898 00:55:43,440 --> 00:55:47,680 And that hotter world could hold lessons for our own survival. 899 00:55:50,280 --> 00:55:53,600 Greenland proves we can go much deeper in time 900 00:55:53,600 --> 00:55:55,120 than what we thought we would. 901 00:55:57,160 --> 00:56:00,320 We now have the technology to go even farther back in time, 902 00:56:00,320 --> 00:56:03,840 potentially many millions of years. 903 00:56:03,840 --> 00:56:06,920 We have access to the genetic codes of plants and animals 904 00:56:06,920 --> 00:56:09,200 that survived in different climates - 905 00:56:09,200 --> 00:56:11,360 hotter climates, drier climates. 906 00:56:11,360 --> 00:56:14,680 If we can sequence the genomes of those ancient organisms, 907 00:56:14,680 --> 00:56:16,160 maybe they can help us. 908 00:56:16,160 --> 00:56:17,920 And I think we're going to need help. 909 00:56:19,000 --> 00:56:22,120 The rescue effort has already started. 910 00:56:22,120 --> 00:56:25,120 Scientists in Copenhagen have identified a gene 911 00:56:25,120 --> 00:56:28,400 from the Greenland DNA that helped poplar trees grow 912 00:56:28,400 --> 00:56:31,640 in the extreme light conditions of the High Arctic... 913 00:56:32,840 --> 00:56:36,520 ..and they've put that gene into a modern barley plant. 914 00:56:37,840 --> 00:56:41,200 One day, when our climate is much warmer, 915 00:56:41,200 --> 00:56:44,560 this barley might thrive at the top of the world, 916 00:56:44,560 --> 00:56:47,160 just as those ancient poplar trees did. 917 00:56:49,640 --> 00:56:54,800 This is a food plant engineered for a hot future. 918 00:56:56,800 --> 00:56:59,560 We are stealing genetic secrets of the past... 919 00:57:00,960 --> 00:57:03,800 ..so we can rescue the future. 920 00:57:05,360 --> 00:57:08,440 I want to do my part to rescue the future. 921 00:57:11,200 --> 00:57:16,440 We are going to sequence thousands, millions of ancient genomes 922 00:57:16,440 --> 00:57:19,840 from sediment samples all over the world. 923 00:57:21,240 --> 00:57:25,320 Because we are now using robots across the entire pipeline, 924 00:57:25,320 --> 00:57:29,240 we can do 200 samples a week. 925 00:57:29,240 --> 00:57:32,960 We are starting an industrial revolution 926 00:57:32,960 --> 00:57:35,160 in ancient DNA sequencing. 927 00:57:39,080 --> 00:57:43,120 Arctic barley could be just the beginning. 928 00:57:43,120 --> 00:57:48,200 Scientists are gearing up to put ancient genes into rice, wheat, 929 00:57:48,200 --> 00:57:52,840 and other foods to help them thrive in a warming world. 930 00:57:55,520 --> 00:57:57,040 Today, we take for granted 931 00:57:57,040 --> 00:58:02,000 that all organisms are shedding DNA around in the environment. 932 00:58:02,000 --> 00:58:05,680 But, once, this was a new idea. 933 00:58:05,680 --> 00:58:11,080 It all started with that dog pooping in the rain. 934 00:58:11,080 --> 00:58:13,560 And that is why we can do this, 935 00:58:13,560 --> 00:58:19,080 where a little bit of dirt contains an entire living world.