1 00:00:06,180 --> 00:00:08,146 [woman chanting] 2 00:00:10,387 --> 00:00:14,594 [Narrator] In every corner of the world today are humans. 3 00:00:15,284 --> 00:00:17,801 Seven billion of us. 4 00:00:17,939 --> 00:00:21,215 How did we come to so dominate our planet? 5 00:00:21,353 --> 00:00:24,146 It's one of science's greatest mysteries. 6 00:00:25,974 --> 00:00:27,560 Amazing new evidence suggests 7 00:00:27,698 --> 00:00:30,905 it began with a single tiny group of people 8 00:00:31,043 --> 00:00:34,525 who left Africa on an incredible journey. 9 00:00:38,732 --> 00:00:41,732 With the help of bones, stones and genes 10 00:00:41,870 --> 00:00:44,594 we'll uncover the trials their descendants left 11 00:00:44,732 --> 00:00:46,767 across the world, 12 00:00:46,905 --> 00:00:50,387 and find out how their journeys transformed our species 13 00:00:50,525 --> 00:00:52,870 into the people we are today. 14 00:00:53,974 --> 00:00:57,043 This time the final frontier, 15 00:00:57,905 --> 00:00:59,249 the Americas 16 00:00:59,387 --> 00:01:03,284 cut off from the world by mountains of ice. 17 00:01:03,422 --> 00:01:05,870 [Jim] Ooh. Certainly don't want to go down there. 18 00:01:06,008 --> 00:01:08,215 [Narrator] This is a story of ingenuity. 19 00:01:09,284 --> 00:01:10,801 And danger. 20 00:01:12,491 --> 00:01:15,939 Just how did we reach the Americas? 21 00:01:27,111 --> 00:01:28,456 The Americas today 22 00:01:28,594 --> 00:01:31,318 are home to almost a billion people, 23 00:01:31,456 --> 00:01:33,732 living in nearly 50 different countries 24 00:01:33,870 --> 00:01:37,180 and speaking over 700 different languages. 25 00:01:40,077 --> 00:01:42,698 But of course, it wasn't always like this. 26 00:01:47,698 --> 00:01:49,146 Not so long ago 27 00:01:49,284 --> 00:01:53,284 no human had ever set foot in North or South America. 28 00:01:53,422 --> 00:01:54,836 [helicopter whirring] 29 00:01:58,249 --> 00:02:00,456 [Narrator] By the height of the last Ice Age 30 00:02:00,594 --> 00:02:01,801 our species had occupied 31 00:02:01,939 --> 00:02:05,146 Africa, Australia, Europe and Asia 32 00:02:05,284 --> 00:02:07,663 for at least 15,000 years. 33 00:02:09,111 --> 00:02:12,560 But the Americas remained untouched. 34 00:02:13,284 --> 00:02:14,974 [helicopter whirring] 35 00:02:26,801 --> 00:02:29,560 [Narrator] There were three very good reasons for this. 36 00:02:30,629 --> 00:02:33,249 To the east lay the Atlantic, 37 00:02:33,387 --> 00:02:38,146 to the west over 10,000 kilometers of Pacific Ocean 38 00:02:38,284 --> 00:02:41,077 and to the north lay ice. 39 00:02:41,215 --> 00:02:45,111 Almost the whole of Canada and Alaska were covered by it, 40 00:02:45,249 --> 00:02:47,146 up to several kilometers thick. 41 00:02:55,801 --> 00:02:59,111 It was 5,000 kilometers from north to south 42 00:02:59,249 --> 00:03:01,905 and stretched from coast to coast. 43 00:03:05,318 --> 00:03:09,043 It's hard to think of anything more dangerous or forbidding. 44 00:03:13,353 --> 00:03:16,491 So just how much of a barrier would it have been to anyone 45 00:03:16,629 --> 00:03:18,180 attempting to cross it? 46 00:03:20,387 --> 00:03:22,008 [tools clinking] 47 00:03:33,732 --> 00:03:35,836 [Narrator] Jim O'Rather is a mountaineer 48 00:03:35,974 --> 00:03:39,284 who has scaled some of the world's tallest peeks. 49 00:03:39,422 --> 00:03:42,801 He knows first-hand just how dangerous ice can be. 50 00:03:45,974 --> 00:03:47,698 [Jim] It's so easy to break your leg 51 00:03:47,836 --> 00:03:50,111 or to, uh, puncture yourself. 52 00:03:51,905 --> 00:03:53,629 It's quite rotten here, isn't it? 53 00:03:55,043 --> 00:03:57,215 [Narrator] A fall would easily be fatal. 54 00:03:58,629 --> 00:04:01,801 [Jim] I've been on rope and fallen into crevasses 55 00:04:01,939 --> 00:04:03,043 in White Oaks. 56 00:04:03,180 --> 00:04:04,698 And hung hundreds of feet 57 00:04:04,836 --> 00:04:06,767 without even seeing the bottom of the crevasse, 58 00:04:06,905 --> 00:04:11,008 and looked down between my legs and just quivered hanging there. 59 00:04:11,146 --> 00:04:12,905 [Narrator] Even with modern equipment, 60 00:04:13,043 --> 00:04:16,008 hyperthermia, frost bite and dehydration 61 00:04:16,146 --> 00:04:17,836 are serious risks. 62 00:04:17,974 --> 00:04:20,974 So imagine what it would have been like in the ice age, 63 00:04:21,111 --> 00:04:25,111 without the gear carrying all your food for the journey. 64 00:04:25,249 --> 00:04:28,180 [Jim] Stand on it, and then it disappears on you. 65 00:04:28,318 --> 00:04:30,905 [Narrator]But would have simply been impossible. 66 00:04:32,801 --> 00:04:35,870 But what's extraordinary and baffling 67 00:04:36,008 --> 00:04:40,836 is that somehow Stone Age people did make it to the Americas. 68 00:04:40,974 --> 00:04:44,111 To a land that was, to all intense and purposes, 69 00:04:44,249 --> 00:04:45,905 totally unreachable. 70 00:04:46,043 --> 00:04:47,111 [Jim] Whoa! 71 00:04:49,525 --> 00:04:51,043 [grandiose music] 72 00:05:05,180 --> 00:05:08,629 [Narrator] Our quest is to find out how they did it. 73 00:05:09,732 --> 00:05:11,801 -[chanting indistinctly] -[drum banging] 74 00:05:26,836 --> 00:05:29,491 [Narrator] In Calgary in modern day Canada 75 00:05:29,629 --> 00:05:32,594 the native American Tsuu T'ina first nation 76 00:05:32,732 --> 00:05:36,698 has gathered for one of the most important events in their year. 77 00:05:36,836 --> 00:05:39,111 They're hosting their annual powwow. 78 00:05:42,249 --> 00:05:44,525 [man] All right, give them a round of applause, 79 00:05:44,663 --> 00:05:45,905 ladies and gentlemen. 80 00:05:46,043 --> 00:05:47,732 [Narrator] The Tsuu T'ina are descendants 81 00:05:47,870 --> 00:05:51,043 of some of the first people to reach to America. 82 00:05:51,180 --> 00:05:53,974 They're our proof that human kind made it here. 83 00:05:55,732 --> 00:05:57,353 But the question for us 84 00:05:57,491 --> 00:05:59,491 is did they arrive before or after 85 00:05:59,629 --> 00:06:02,215 the North American ice sheets disappeared? 86 00:06:03,767 --> 00:06:05,594 Like most native Americans 87 00:06:05,732 --> 00:06:06,732 the Tsuu T'ina believe 88 00:06:06,870 --> 00:06:09,077 they have always lived in this land. 89 00:06:11,387 --> 00:06:12,353 But maybe there's something 90 00:06:12,491 --> 00:06:14,525 in their own story of their origins 91 00:06:14,663 --> 00:06:16,180 which can give us hints about the world 92 00:06:16,318 --> 00:06:18,008 their ancestors lived in. 93 00:06:19,629 --> 00:06:22,111 The story begins in the north. 94 00:06:22,249 --> 00:06:25,525 [Bigplume] Well, what was told to us by our ancestors, 95 00:06:25,663 --> 00:06:27,180 [...], the old people, 96 00:06:27,318 --> 00:06:29,146 was that thousands of years ago, 97 00:06:29,284 --> 00:06:32,318 we were one huge tribe, the Dené. 98 00:06:32,456 --> 00:06:34,905 We were mitigating south because the ice. 99 00:06:36,111 --> 00:06:38,836 The legend goes on to say that, 100 00:06:38,974 --> 00:06:42,801 um, there was a grandmother with one of her grandchildren 101 00:06:42,939 --> 00:06:45,801 who spotted a horn in the ice 102 00:06:45,939 --> 00:06:49,180 as we crossed over the Great Lakes up north. 103 00:06:51,560 --> 00:06:53,801 The child was asking for that horn 104 00:06:55,284 --> 00:06:57,215 so they proceeded to... 105 00:06:57,353 --> 00:06:59,249 uh, chop away at the ice 106 00:06:59,387 --> 00:07:01,870 to dig out the horn for the child. 107 00:07:03,215 --> 00:07:05,732 It magically separated the ice. 108 00:07:05,870 --> 00:07:07,215 [drum rumbling] 109 00:07:08,387 --> 00:07:10,767 [Bigplume] Cracked and split in two. 110 00:07:10,905 --> 00:07:13,146 So the clans that were on the south side 111 00:07:13,284 --> 00:07:14,870 continued to mitigate south, 112 00:07:15,008 --> 00:07:16,456 the ones who were left on the north 113 00:07:16,594 --> 00:07:18,284 stayed in the north, 114 00:07:18,422 --> 00:07:20,663 that's how the story is always told. 115 00:07:23,111 --> 00:07:26,629 [Narrator]This tale of a great family journey across the ice 116 00:07:26,767 --> 00:07:28,008 seems to give us a clue 117 00:07:28,146 --> 00:07:30,525 to how long the Tsuu T'ina have been here. 118 00:07:31,767 --> 00:07:34,043 Back when this was a land of ice. 119 00:07:36,870 --> 00:07:39,387 [man] Okay, let's hold them into the gate. 120 00:07:39,525 --> 00:07:40,870 Wow, Look at that. 121 00:07:41,491 --> 00:07:43,525 [crowd cheering] 122 00:07:43,663 --> 00:07:45,732 [Narrator] And perhaps just as intriguing 123 00:07:45,870 --> 00:07:48,456 is something visible in their faces. 124 00:07:49,663 --> 00:07:51,629 They have distinctive features, 125 00:07:51,767 --> 00:07:53,077 high cheek bones, 126 00:07:53,215 --> 00:07:56,594 a comparatively flat face and almond shaped eyes. 127 00:07:58,974 --> 00:08:01,801 It's a look we've seen before on the human journey, 128 00:08:01,939 --> 00:08:03,939 though a long way from here. 129 00:08:04,077 --> 00:08:08,663 In Siberia, over 6,000 kilometers west of Calgary. 130 00:08:12,836 --> 00:08:15,525 The Evenki people of northern Siberia 131 00:08:15,663 --> 00:08:17,905 share the same facial characteristics. 132 00:08:20,249 --> 00:08:23,353 And the similarities are not just facial. 133 00:08:23,491 --> 00:08:25,491 The tepee of the Native Americans 134 00:08:25,629 --> 00:08:27,905 bears a striking resemblance to the chume 135 00:08:28,043 --> 00:08:30,663 the Evenki use when on hunting trips. 136 00:08:33,836 --> 00:08:37,146 Could these similarities hold the key to the origins 137 00:08:37,284 --> 00:08:39,043 of the native Americans? 138 00:08:49,974 --> 00:08:53,525 Scientist Tracy Literre from Cambridge University 139 00:08:53,663 --> 00:08:54,732 has a particular reason 140 00:08:54,870 --> 00:08:56,836 to be interested in this question. 141 00:08:58,905 --> 00:09:01,767 She herself is a member of the Colville Indian tribes 142 00:09:01,905 --> 00:09:03,353 of Washington state, 143 00:09:03,491 --> 00:09:07,249 and is studying the history of Native Americans. 144 00:09:07,387 --> 00:09:10,732 One of the tools she uses to find out about her ancestry 145 00:09:10,870 --> 00:09:13,594 is Mitochondrial DNA. 146 00:09:13,732 --> 00:09:17,284 A genetic fingerprint stored within each of our cells 147 00:09:17,422 --> 00:09:19,215 that's passed on through the female line 148 00:09:19,353 --> 00:09:21,284 from mother to child. 149 00:09:21,422 --> 00:09:24,939 It's a science that hasn't always been popular here. 150 00:09:25,077 --> 00:09:26,801 There is some controversy 151 00:09:26,939 --> 00:09:30,525 surrounding genetic research among native communities. 152 00:09:30,663 --> 00:09:34,905 A lot of times in the past there's been research conducted 153 00:09:35,043 --> 00:09:36,043 without the knowledge 154 00:09:36,180 --> 00:09:37,629 of the tribes that are under study. 155 00:09:37,767 --> 00:09:41,629 Many native communities believe that your biological resources 156 00:09:41,767 --> 00:09:46,801 or their bodily tissues, hairs and fluids are sacred. 157 00:09:46,939 --> 00:09:50,318 [Narrator] But by working with Native American communities, 158 00:09:50,456 --> 00:09:51,939 scientists like Tracey 159 00:09:52,077 --> 00:09:54,318 have been able to discover a surprising amount 160 00:09:54,456 --> 00:09:56,353 from their DNA. 161 00:09:56,491 --> 00:09:58,939 All living Native Americans 162 00:09:59,077 --> 00:10:03,008 from North to South America belong to one of five lineages 163 00:10:03,146 --> 00:10:06,939 and can be traced back to southern Siberia. 164 00:10:07,077 --> 00:10:09,836 For many years scientists have been suggesting 165 00:10:09,974 --> 00:10:12,525 that there is a link based on the physical attributes 166 00:10:12,663 --> 00:10:14,767 and i think genetics now proves that. 167 00:10:19,767 --> 00:10:21,767 [Narrator] The latest genetic research 168 00:10:21,905 --> 00:10:25,180 suggests that we all originate from Africa. 169 00:10:25,318 --> 00:10:27,663 Around 70,000 years ago, 170 00:10:27,801 --> 00:10:30,732 a tiny group of us left the continent. 171 00:10:30,870 --> 00:10:32,698 Their descendants went on to populate 172 00:10:32,836 --> 00:10:36,111 Asia, Australia and Europe. 173 00:10:36,249 --> 00:10:40,905 And genetics now helps us extend the story to America. 174 00:10:41,043 --> 00:10:44,318 It suggests that the ancestors of all Native Americans 175 00:10:44,456 --> 00:10:46,594 originally came from Siberia. 176 00:10:47,491 --> 00:10:48,698 And what's more, 177 00:10:48,836 --> 00:10:50,939 the evidence implies they entered America 178 00:10:51,077 --> 00:10:54,077 sometime during the last Ice Age. 179 00:10:54,215 --> 00:10:58,249 Around 15 to 18,000 years ago. 180 00:10:58,387 --> 00:11:00,008 So it seems like people mitigated 181 00:11:00,146 --> 00:11:04,215 from Siberia into America at a point when North America 182 00:11:04,353 --> 00:11:07,077 was under the impenetrable sheet of ice. 183 00:11:09,525 --> 00:11:11,939 Today Siberia and Alaska 184 00:11:12,077 --> 00:11:14,974 are separated by 80 kilometers of water, 185 00:11:16,180 --> 00:11:17,974 but 20,000 years ago, 186 00:11:18,111 --> 00:11:20,284 what we know as the Bearing Straight 187 00:11:20,422 --> 00:11:23,180 was part of a vast swathe of land, 188 00:11:23,318 --> 00:11:26,560 a long-lost continent known as Beringia 189 00:11:26,698 --> 00:11:29,456 which could have taken people as far as Alaska. 190 00:11:31,836 --> 00:11:35,560 But this doesn't explain how people entered America, 191 00:11:35,698 --> 00:11:37,870 because once they had crossed the land bridge 192 00:11:38,008 --> 00:11:41,043 the way was still blocked by the massive wall of ice 193 00:11:41,180 --> 00:11:43,043 stretching east to west. 194 00:11:44,249 --> 00:11:45,801 So how and when 195 00:11:45,939 --> 00:11:48,525 did the first people enter America, 196 00:11:48,663 --> 00:11:50,732 south of the ice? 197 00:11:50,870 --> 00:11:53,146 It's a question that has puzzled scientists 198 00:11:53,284 --> 00:11:54,629 for decades. 199 00:11:58,353 --> 00:11:59,905 In 1933, 200 00:12:00,043 --> 00:12:02,939 archaeologists working in the western United States 201 00:12:03,077 --> 00:12:05,525 unearthed a beautiful stone object. 202 00:12:06,525 --> 00:12:08,077 It was an ancient tool 203 00:12:08,215 --> 00:12:12,663 later dated to some 13,000 years ago. 204 00:12:12,801 --> 00:12:15,077 The stone tool was one of the first of many 205 00:12:15,215 --> 00:12:16,629 almost identical 206 00:12:16,767 --> 00:12:19,629 to be uncovered across the United States. 207 00:12:20,491 --> 00:12:21,870 They were given a name 208 00:12:22,008 --> 00:12:24,767 after the place where several of them were found, 209 00:12:24,905 --> 00:12:26,732 Clovis. 210 00:12:26,870 --> 00:12:28,525 They were the earliest known evidence 211 00:12:28,663 --> 00:12:30,491 of people living in America. 212 00:12:33,525 --> 00:12:36,491 But no one knew how these people had got there. 213 00:12:36,629 --> 00:12:38,663 [wind howling] 214 00:12:38,801 --> 00:12:41,008 [Narrator] Today, modern climatologists 215 00:12:41,146 --> 00:12:42,284 can look back in time 216 00:12:42,422 --> 00:12:43,939 and stimulate the weather conditions 217 00:12:44,077 --> 00:12:45,111 of the past. 218 00:12:46,870 --> 00:12:49,146 Maybe this can help us find out 219 00:12:49,284 --> 00:12:52,008 how people could have made it past the ice. 220 00:12:53,698 --> 00:12:55,698 But 22,000 years ago, 221 00:12:55,836 --> 00:12:58,180 we can see the vast sheet of ice. 222 00:12:59,870 --> 00:13:04,111 But around 13 and half thousand years ago, it parts 223 00:13:04,249 --> 00:13:05,939 and a corridor emerges, 224 00:13:06,077 --> 00:13:07,180 from northern Canada 225 00:13:07,318 --> 00:13:09,663 to the heart of the United States. 226 00:13:12,284 --> 00:13:17,111 Perhaps people entered America through the ice sheets. 227 00:13:17,249 --> 00:13:19,077 It would certainly fit with the appearance 228 00:13:19,215 --> 00:13:21,043 of the early stone tools. 229 00:13:22,801 --> 00:13:26,525 So what do we know about these Clovis pioneers? 230 00:13:27,525 --> 00:13:29,146 One way to find out about them 231 00:13:29,284 --> 00:13:31,836 is to look at what they left behind. 232 00:13:36,836 --> 00:13:38,491 Archaeologist Andy Hemmings 233 00:13:38,629 --> 00:13:41,111 is an expert on prehistoric stone tools 234 00:13:41,249 --> 00:13:44,732 and today he's recreating one of the Clovis tools. 235 00:13:46,215 --> 00:13:48,491 [Andy] I've got a modern replica of a clovis point 236 00:13:48,629 --> 00:13:50,215 that I'm in the process of hafting up 237 00:13:50,353 --> 00:13:51,801 on a seven-foot spear. 238 00:13:53,318 --> 00:13:55,629 There's a little groove cut in the end of the dart 239 00:13:56,801 --> 00:13:58,077 and... 240 00:13:58,215 --> 00:14:00,353 the spear fits inside it 241 00:14:00,491 --> 00:14:02,111 and then we'll take some sinew 242 00:14:03,698 --> 00:14:06,111 and... and just start wrapping it 243 00:14:06,249 --> 00:14:07,836 snugly and firmly in there. 244 00:14:07,974 --> 00:14:09,525 [Narrator] When attached to a shaft 245 00:14:09,663 --> 00:14:13,146 these stone tools become lethal spears. 246 00:14:13,284 --> 00:14:15,456 In Southeast Arizona there were eight Clovis points 247 00:14:15,594 --> 00:14:17,111 found with one mammoth, 248 00:14:17,249 --> 00:14:19,353 five of them were behind the back of the skull 249 00:14:19,491 --> 00:14:21,215 and the front of the shoulder blades, 250 00:14:21,353 --> 00:14:24,663 any one of which would probably have been a lethal wound. 251 00:14:24,801 --> 00:14:28,111 At Clovis, they were found in the body cavity of mammoths 252 00:14:28,249 --> 00:14:29,629 in the lung and heart area. 253 00:14:29,767 --> 00:14:33,974 This is state of the art technology 13,000 years ago. 254 00:14:34,111 --> 00:14:36,629 [Narrator] With no prehistoric beasts available today 255 00:14:36,767 --> 00:14:38,146 to test the weapons on, 256 00:14:38,284 --> 00:14:41,180 Andy has a novel way of demonstrating their power. 257 00:14:41,870 --> 00:14:43,249 [tense music] 258 00:14:55,180 --> 00:14:56,870 [glass shattering] 259 00:14:57,008 --> 00:15:00,111 [Narrator] So what would it do to a mammoth? 260 00:15:00,249 --> 00:15:03,387 [Andy] Us sticking that much through into the hay bales 261 00:15:03,525 --> 00:15:04,732 so incredibly lethal 262 00:15:04,870 --> 00:15:07,422 and now the animal somewhere about this far into it 263 00:15:07,560 --> 00:15:10,732 has a projectile wiggling around. 264 00:15:10,870 --> 00:15:13,732 Even minimal movement is incredibly painful 265 00:15:13,870 --> 00:15:18,456 and debilitating so even a non-lethal wound becomes... 266 00:15:18,594 --> 00:15:20,870 debilitating enough that with the rest of our darts 267 00:15:21,008 --> 00:15:23,215 we're going to be able to kill this animal. 268 00:15:30,180 --> 00:15:31,456 [Narrator] So early Americans 269 00:15:31,594 --> 00:15:33,353 were armed with powerful weapons, 270 00:15:33,491 --> 00:15:35,767 and were clearly formidable hunters. 271 00:15:37,008 --> 00:15:40,146 In fact, some think they were so formidable 272 00:15:40,284 --> 00:15:42,939 that they changed the world forever. 273 00:15:45,525 --> 00:15:47,008 [rumbling] 274 00:15:52,836 --> 00:15:54,353 [Narrator] And unexpectedly 275 00:15:54,491 --> 00:15:55,629 the evidence for this 276 00:15:55,767 --> 00:15:58,767 lies right in the heart of Los Angeles. 277 00:15:58,905 --> 00:16:03,870 In a prehistoric treasure trove called, the La Brea Tar Pits. 278 00:16:05,422 --> 00:16:07,560 [tar boiling] 279 00:16:07,698 --> 00:16:08,870 [Narrator] The result of oil 280 00:16:09,008 --> 00:16:11,525 which formed over 5,000,000 years ago, 281 00:16:11,663 --> 00:16:14,387 these pits are the sight of over 3,000,000 282 00:16:14,525 --> 00:16:16,146 archaeological finds. 283 00:16:19,008 --> 00:16:20,905 If anywhere can tell us about the world 284 00:16:21,043 --> 00:16:24,215 of the early Americans, it's this site, 285 00:16:24,353 --> 00:16:27,767 one of the strangest archaeological digs on earth. 286 00:16:29,008 --> 00:16:31,594 Tar pits are difficult to work in. 287 00:16:31,732 --> 00:16:33,594 They're smelly and dirty 288 00:16:33,732 --> 00:16:36,974 and it's impossible not to get stuck in them. 289 00:16:37,111 --> 00:16:41,353 But for Dr. John Harris it doesn't get better than this. 290 00:16:41,491 --> 00:16:44,663 [John] This paleontologist's dream to work here at La Brea 291 00:16:44,801 --> 00:16:46,560 because you've got so many specimens 292 00:16:46,698 --> 00:16:48,249 and they're so well preserved, 293 00:16:48,387 --> 00:16:50,974 it's like a library of the Ice Age, 294 00:16:51,111 --> 00:16:54,456 um, you never know what you might find. 295 00:16:54,594 --> 00:16:56,215 [Narrator] The reason they're so special 296 00:16:56,353 --> 00:16:59,111 is that thousands of years before LA was built, 297 00:16:59,249 --> 00:17:01,905 the stickiness wasn't just an annoyance 298 00:17:02,732 --> 00:17:05,077 it was a death trap. 299 00:17:05,215 --> 00:17:07,939 It will only take two inches of this tar 300 00:17:08,077 --> 00:17:09,905 to immobilize a horse. 301 00:17:10,974 --> 00:17:12,629 [John] The scenario goes like this, 302 00:17:12,767 --> 00:17:16,146 that a bison or a camel or a horse 303 00:17:16,284 --> 00:17:19,698 would inadvertently step into the tar and get stuck 304 00:17:19,836 --> 00:17:21,801 and that would attract saber-tooth cats, 305 00:17:21,939 --> 00:17:23,456 and dire wolves to feed on it 306 00:17:23,594 --> 00:17:25,732 and they in turn would get stuck. 307 00:17:25,870 --> 00:17:28,043 So very quickly you build up the food chain. 308 00:17:29,905 --> 00:17:33,008 [Narrator]Many of the animals which met their death at La Brea 309 00:17:33,146 --> 00:17:34,905 are now extinct. 310 00:17:35,043 --> 00:17:39,456 Strange almost mystical creatures known as megafauna 311 00:17:39,594 --> 00:17:42,629 which lived alongside the early Americans. 312 00:17:43,560 --> 00:17:45,387 Giant ground sloths, 313 00:17:45,525 --> 00:17:47,111 the American lion, 314 00:17:47,249 --> 00:17:51,008 and one of the largest mammals ever to walk the earth, 315 00:17:51,146 --> 00:17:53,870 -the Columbian mammoth. -[mammoth growling] 316 00:18:00,387 --> 00:18:04,801 The mammoth stood between 12 and 13 feet tall 317 00:18:04,939 --> 00:18:07,111 - and weighed about ten tons. -[mammoth roars] 318 00:18:08,594 --> 00:18:10,629 [John] Its thick skin and its size 319 00:18:10,767 --> 00:18:13,146 would have been a deterrent to predators 320 00:18:13,284 --> 00:18:16,836 but it also had a pair of ten-feet long tusks 321 00:18:16,974 --> 00:18:19,732 which helped it to defend itself. 322 00:18:19,870 --> 00:18:22,663 [mammoth growls] 323 00:18:22,801 --> 00:18:24,698 [Narrator]The mammoth wouldn't have been an easy target 324 00:18:24,836 --> 00:18:26,491 for Stone Age hunters, 325 00:18:26,629 --> 00:18:30,249 but we know that they did kill mammoths with stone tools. 326 00:18:30,387 --> 00:18:31,870 [mammoth growls] 327 00:18:32,008 --> 00:18:33,318 [Narrator] In fact, some people think 328 00:18:33,456 --> 00:18:34,767 that they were so good at it, 329 00:18:34,905 --> 00:18:36,215 they hunted both the mammoth 330 00:18:36,353 --> 00:18:39,939 and many other giant animals to extinction. 331 00:18:42,111 --> 00:18:43,939 [mammoth growling] 332 00:18:45,836 --> 00:18:48,732 [Narrator] And the story told by the megafauna remains 333 00:18:48,870 --> 00:18:51,146 suggests this may well be true. 334 00:18:53,111 --> 00:18:56,663 Because the record of mammoths and many other large beasts 335 00:18:56,801 --> 00:19:00,284 stops around 13,000 years ago, 336 00:19:00,422 --> 00:19:05,077 just a little after the first Clovis tools appear in America. 337 00:19:05,215 --> 00:19:07,491 It's as if the animal's disappearance 338 00:19:07,629 --> 00:19:10,043 is linked to people's arrival. 339 00:19:11,663 --> 00:19:12,974 If this is true, 340 00:19:13,111 --> 00:19:16,077 perhaps the extinction of the megafauna is another clue 341 00:19:16,215 --> 00:19:18,043 to when humans arrived. 342 00:19:20,870 --> 00:19:25,491 So we know these early Americans were tough and ingenious people 343 00:19:25,629 --> 00:19:27,111 with sophisticated weapons 344 00:19:27,249 --> 00:19:31,146 they hunted some of the largest animals on the planet. 345 00:19:31,284 --> 00:19:33,008 And for much of the last century 346 00:19:33,146 --> 00:19:35,698 experts agree that they first entered America 347 00:19:35,836 --> 00:19:38,560 around 13,000 years ago, 348 00:19:38,698 --> 00:19:41,043 down through the gap in the ice sheets. 349 00:19:42,560 --> 00:19:44,732 But now, new discoveries 350 00:19:44,870 --> 00:19:48,249 are threatening to undermine this entire theory. 351 00:19:51,767 --> 00:19:54,318 And just outside the small community of Golt 352 00:19:54,456 --> 00:19:55,870 in Central Texas, 353 00:19:56,008 --> 00:20:00,008 is our first hint that the story might need to be rewritten. 354 00:20:04,629 --> 00:20:06,698 Here in an unassuming field, 355 00:20:06,836 --> 00:20:09,387 Mike Collins is leading the excavation 356 00:20:09,525 --> 00:20:12,939 of one of the largest records of prehistoric human life 357 00:20:13,077 --> 00:20:15,525 in all of the Americas. 358 00:20:15,663 --> 00:20:18,698 [Mike] We have over a million and half artifacts. 359 00:20:19,870 --> 00:20:21,353 An absolutely amazing number, 360 00:20:21,491 --> 00:20:22,732 that's probably more than half 361 00:20:22,870 --> 00:20:24,422 of the excavated Clovis artifacts 362 00:20:24,560 --> 00:20:26,008 from all of North America 363 00:20:26,146 --> 00:20:27,111 and we've only excavated 364 00:20:27,249 --> 00:20:28,767 about three percent of this site. 365 00:20:28,905 --> 00:20:30,939 [Narrator] The site is what is known as a base camp, 366 00:20:31,077 --> 00:20:33,387 a place that people made their home. 367 00:20:33,525 --> 00:20:35,870 [Mike] It was kind of a central operation, 368 00:20:36,008 --> 00:20:38,905 where the whole social group stayed, 369 00:20:39,043 --> 00:20:40,284 men, women, children. 370 00:20:40,422 --> 00:20:43,594 And carried on a whole lot of domestic activities. 371 00:20:43,732 --> 00:20:48,560 We found cooking, food processing, tool making, 372 00:20:48,698 --> 00:20:50,663 they were clearly working leather working wood, 373 00:20:50,801 --> 00:20:53,801 working bone, all of these kind of things. 374 00:20:53,939 --> 00:20:56,043 [Narrator] Most of the finds are from the period of history 375 00:20:56,180 --> 00:20:57,318 known as Clovis. 376 00:20:57,456 --> 00:20:59,801 Around 13,000 years ago. 377 00:21:01,077 --> 00:21:04,974 This has been thought to be when people first arrived. 378 00:21:05,111 --> 00:21:09,249 But Mike's excavations throw a spanner in the works. 379 00:21:09,387 --> 00:21:10,663 You know what's really exciting? 380 00:21:10,801 --> 00:21:12,801 We've got stuff below that. 381 00:21:12,939 --> 00:21:15,111 We have a layer below Clovis. 382 00:21:15,249 --> 00:21:16,629 [Narrator] And to an archaeologist, 383 00:21:16,767 --> 00:21:18,870 below means older. 384 00:21:19,008 --> 00:21:21,353 [Mike] Right through here we get Clovis artifacts, 385 00:21:21,491 --> 00:21:24,629 but as we dug down we continued to get artifacts below that 386 00:21:24,767 --> 00:21:28,491 for about 20, or 25 centimeters more. 387 00:21:29,353 --> 00:21:31,629 And they're absolutely 388 00:21:31,767 --> 00:21:33,870 the product of human workmanship, 389 00:21:34,008 --> 00:21:36,732 a nice flake here for example with a platform 390 00:21:36,870 --> 00:21:41,422 we have one date from down here of 14,400 years. 391 00:21:41,560 --> 00:21:44,491 That's a thousand years before Clovis. 392 00:21:44,629 --> 00:21:47,560 And yes, we have to rethink our period time, 393 00:21:47,698 --> 00:21:49,594 we have to come up with a new accounting 394 00:21:49,732 --> 00:21:51,663 of the peopling of the Americas. 395 00:21:53,939 --> 00:21:56,318 [Narrator] Because if people were living here at Golt 396 00:21:56,456 --> 00:21:58,387 over 14,000 years ago, 397 00:21:58,525 --> 00:22:02,456 this challenges the theory of the corridor through the ice. 398 00:22:02,594 --> 00:22:04,284 It hadn't even appeared by then. 399 00:22:06,008 --> 00:22:09,905 It's only a single date and Mike needs more evidence 400 00:22:10,043 --> 00:22:11,560 but his team aren't the only ones 401 00:22:11,698 --> 00:22:13,215 coming up with challenging theories 402 00:22:13,353 --> 00:22:15,008 about the early Americans. 403 00:22:17,146 --> 00:22:20,043 In 2007, research was published 404 00:22:20,180 --> 00:22:21,560 claiming it wasn't humans 405 00:22:21,698 --> 00:22:23,836 that killed the megafauna after all. 406 00:22:25,905 --> 00:22:28,767 It was something far more dramatic. 407 00:22:29,422 --> 00:22:30,905 [explosion] 408 00:22:36,146 --> 00:22:37,698 [Narrator] Some scientists believe 409 00:22:37,836 --> 00:22:41,180 that not long after humans first arrived in the Americas 410 00:22:41,318 --> 00:22:44,525 a broken comet exploded above North America, 411 00:22:44,663 --> 00:22:46,870 showering the land with debris. 412 00:22:57,663 --> 00:23:00,560 The heat from these blasts were so immense, 413 00:23:00,698 --> 00:23:02,594 it could have set fire to vegetation 414 00:23:02,732 --> 00:23:05,043 throughout the North American continent. 415 00:23:09,111 --> 00:23:10,560 [fire crackling] 416 00:23:18,870 --> 00:23:22,525 Even today, the scientists find evidence of fires 417 00:23:22,663 --> 00:23:24,663 in a mysterious black layer 418 00:23:24,801 --> 00:23:28,456 embedded in the rock in sites across America. 419 00:23:28,594 --> 00:23:31,249 Inside the layers are tiny spheres 420 00:23:31,387 --> 00:23:33,698 like beads made of carbon 421 00:23:33,836 --> 00:23:36,870 which only form in extreme temperatures. 422 00:23:39,491 --> 00:23:42,387 If it was the comet explosion that created them, 423 00:23:42,525 --> 00:23:47,422 it would have had a catastrophic effect on life in the continent. 424 00:23:47,560 --> 00:23:49,180 With the vegetation gone, 425 00:23:49,318 --> 00:23:51,801 mammoths would have struggled to find food, 426 00:23:51,939 --> 00:23:53,836 so even if they survived the blast 427 00:23:53,974 --> 00:23:56,146 they would have been faced with starvation. 428 00:23:57,387 --> 00:23:58,594 If this is true, 429 00:23:58,732 --> 00:24:00,525 the disappearance of the megafauna 430 00:24:00,663 --> 00:24:01,905 may have nothing to do 431 00:24:02,043 --> 00:24:04,663 with the arrival of humans after all. 432 00:24:05,663 --> 00:24:06,905 And what's more, 433 00:24:07,043 --> 00:24:09,008 some scientists are starting to doubt 434 00:24:09,146 --> 00:24:11,560 that a migration through the ice sheets 435 00:24:11,698 --> 00:24:14,008 would even have been possible. 436 00:24:16,491 --> 00:24:18,525 [dramatic music] 437 00:24:24,111 --> 00:24:28,146 This Canadian landscape may look beautiful on a summer's day 438 00:24:28,284 --> 00:24:30,801 but in winter it's a very different picture 439 00:24:30,939 --> 00:24:34,491 as trucker, Burt van Durvetting knows all too well. 440 00:24:37,732 --> 00:24:40,491 [Burt] It can get very crazy here. 441 00:24:42,215 --> 00:24:44,698 We see a lot of snow. 442 00:24:44,836 --> 00:24:48,422 The area we're going to get into here in a little bit 443 00:24:48,560 --> 00:24:50,525 has all these shoots coming down, 444 00:24:50,663 --> 00:24:52,939 so they're slides and the highway is closed 445 00:24:53,077 --> 00:24:55,870 a lot of the time because of these avalanches. 446 00:24:58,525 --> 00:25:00,732 [Narrator] Even in the comfort of a modern truck, 447 00:25:00,870 --> 00:25:02,698 traveling through this landscape 448 00:25:02,836 --> 00:25:04,698 is a phenomenal challenge. 449 00:25:07,284 --> 00:25:08,560 You can get freezing rain, 450 00:25:08,698 --> 00:25:10,249 you can get real cold temperatures 451 00:25:10,387 --> 00:25:12,491 around minus 20 and minus 25. 452 00:25:14,629 --> 00:25:16,008 [Narrator] And we now know 453 00:25:16,146 --> 00:25:18,698 that when the corridor through the ice first opened 454 00:25:18,836 --> 00:25:20,594 it would have been far worse, 455 00:25:20,732 --> 00:25:23,905 full of icy lakes, marshes and bogs, 456 00:25:24,043 --> 00:25:27,077 constantly blown by a bitterly cold wind. 457 00:25:29,008 --> 00:25:33,491 And with so little food people couldn't have survived. 458 00:25:33,629 --> 00:25:36,318 So the theory that the first people entered the Americas 459 00:25:36,456 --> 00:25:40,767 through this corridor is looking decidedly shaky. 460 00:25:40,905 --> 00:25:43,008 And to find a new explanation 461 00:25:43,146 --> 00:25:45,801 we need to look for the earliest evidence 462 00:25:45,939 --> 00:25:47,180 of our arrival. 463 00:25:50,560 --> 00:25:52,387 The site with the greatest claim to this 464 00:25:52,525 --> 00:25:53,939 is in South America 465 00:25:54,077 --> 00:25:57,008 in a part of Chile known as Los Lagos, 466 00:25:57,146 --> 00:25:58,560 or the lake district 467 00:25:58,698 --> 00:26:01,629 famous for its stunning volcanic landscape. 468 00:26:05,008 --> 00:26:07,663 Some years back a stream in the area 469 00:26:07,801 --> 00:26:09,974 became the site of one of the most important 470 00:26:10,111 --> 00:26:13,870 archaeological finds in all of the Americas. 471 00:26:15,905 --> 00:26:18,353 Local laborers working in the stream 472 00:26:18,491 --> 00:26:21,043 accidentally stumbled upon an object, 473 00:26:21,180 --> 00:26:23,249 sticking out of the bank. 474 00:26:23,387 --> 00:26:24,801 On closer inspection, 475 00:26:24,939 --> 00:26:28,870 it turned out to be one of a number of bones. 476 00:26:29,008 --> 00:26:30,698 And when experts began to examine 477 00:26:30,836 --> 00:26:32,353 the place in more detail, 478 00:26:32,491 --> 00:26:35,698 it soon became clear that what the workers had found 479 00:26:35,836 --> 00:26:39,560 was something more than mere animals remains. 480 00:26:39,698 --> 00:26:42,525 Mario Pino was the geologist on the team 481 00:26:42,663 --> 00:26:46,801 which excavated the remains of an entire human settlement. 482 00:26:49,146 --> 00:26:50,663 [Mario speaking Spanish] 483 00:26:51,870 --> 00:26:53,387 [interpreter] Among others, 484 00:26:53,525 --> 00:26:57,008 the remains of a huge awning from a tent of rare dimensions 485 00:26:57,146 --> 00:26:59,629 where around 20 people could sleep. 486 00:27:02,249 --> 00:27:05,180 [Mario speaking Spanish] 487 00:27:05,318 --> 00:27:07,318 [interpreter] The tent was heated with braciers, 488 00:27:07,456 --> 00:27:10,249 small holes in the sand filled with clay 489 00:27:10,387 --> 00:27:11,836 where they put hot coal. 490 00:27:11,974 --> 00:27:14,456 Very different to the bigger bonfires outside 491 00:27:14,594 --> 00:27:16,836 that were probably made for cooking. 492 00:27:19,698 --> 00:27:21,249 [speaking Spanish] 493 00:27:21,387 --> 00:27:22,801 [interpreter] The construction of the tent 494 00:27:22,939 --> 00:27:25,491 required a lot of energy, a lot of work, 495 00:27:25,629 --> 00:27:28,594 so it probably wasn't made for a short stay. 496 00:27:31,732 --> 00:27:35,525 [Narrator]And 30 meters away they found another smaller tent, 497 00:27:35,663 --> 00:27:38,629 so small only a couple of people could fit inside. 498 00:27:38,767 --> 00:27:40,215 [speaking in Spanish] 499 00:27:40,353 --> 00:27:42,767 [interpreter] The foundation is made of gravel and sand 500 00:27:42,905 --> 00:27:44,939 and was glued with animal fat. 501 00:27:47,560 --> 00:27:48,939 [Narrator] Inside the tent 502 00:27:49,077 --> 00:27:52,215 they found the remains of several medicinal plants. 503 00:27:52,353 --> 00:27:55,629 [speaking Spanish] 504 00:27:55,767 --> 00:27:57,525 [interpreter] Very useful for many things, 505 00:27:57,663 --> 00:28:00,974 analgesic, antibiotic and anti-epliectic, 506 00:28:01,111 --> 00:28:04,560 incidentally they are still used by the Mapuche Indians 507 00:28:04,698 --> 00:28:06,905 to cure these types of illness today. 508 00:28:10,008 --> 00:28:11,077 [Narrator] And the team also found 509 00:28:11,215 --> 00:28:14,111 some more familiar plant remains. 510 00:28:14,249 --> 00:28:15,560 -[Mario speaking Spanish] -[interpreter] The leftovers 511 00:28:15,698 --> 00:28:17,008 of the white potato 512 00:28:17,146 --> 00:28:19,801 which apparently is the oldest potato in America. 513 00:28:22,387 --> 00:28:26,180 [Narrator] The 50,000 or so items retrieved from Monte Verde 514 00:28:26,318 --> 00:28:30,353 are now stored at the University of Southern Chile. 515 00:28:30,491 --> 00:28:34,043 Many of the objects show signs of human workmanship. 516 00:28:37,180 --> 00:28:38,422 There's a piece of wood 517 00:28:38,560 --> 00:28:41,974 with what looks like a hole drilled in it. 518 00:28:42,111 --> 00:28:45,801 a wooden stake and a piece of the hide of a mastodon, 519 00:28:45,939 --> 00:28:48,077 an extinct elephant-like creature, 520 00:28:48,215 --> 00:28:50,663 perhaps used to cover the huts. 521 00:28:52,318 --> 00:28:55,284 Wood and hide normally decay very quickly 522 00:28:55,422 --> 00:28:56,663 so you'd be forgiven for thinking 523 00:28:56,801 --> 00:28:58,836 the finds weren't that ancient. 524 00:29:00,560 --> 00:29:03,043 But in fact, they are so ancient 525 00:29:03,180 --> 00:29:06,111 they've caused major controversy. 526 00:29:06,249 --> 00:29:08,077 When their age was first announced 527 00:29:08,215 --> 00:29:11,939 other archaeologists refused to believe it. 528 00:29:12,077 --> 00:29:15,594 And it was not until ten years after the excavation began 529 00:29:15,732 --> 00:29:17,663 that the implications of these finds 530 00:29:17,801 --> 00:29:20,008 started to be accepted. 531 00:29:20,146 --> 00:29:22,180 People were living in Monte Verde 532 00:29:22,318 --> 00:29:25,353 fourteen and a half thousand years ago. 533 00:29:25,491 --> 00:29:26,974 More than a thousand years 534 00:29:27,111 --> 00:29:29,629 before the Clovis people of North America. 535 00:29:31,043 --> 00:29:36,043 This shatters our theory of how humans reached America. 536 00:29:36,180 --> 00:29:39,318 There's no way these people could have entered the continent 537 00:29:39,456 --> 00:29:40,870 through the ice sheets, 538 00:29:41,008 --> 00:29:44,422 the corridor through them just didn't exist. 539 00:29:44,560 --> 00:29:47,249 There must have been another way in. 540 00:29:48,215 --> 00:29:49,491 But how? 541 00:29:53,870 --> 00:29:56,077 Maybe the finds of Monte Verde 542 00:29:56,215 --> 00:29:59,387 can lead us to a different solution. 543 00:29:59,525 --> 00:30:01,629 The site was littered with seaweed, 544 00:30:01,767 --> 00:30:05,249 pebbles and salt, that all point to one place. 545 00:30:08,491 --> 00:30:09,629 The sea. 546 00:30:13,111 --> 00:30:14,387 Up till now, 547 00:30:14,525 --> 00:30:18,008 we've assumed the people entered America from the north, 548 00:30:18,146 --> 00:30:19,353 but is it possible 549 00:30:19,491 --> 00:30:21,939 that instead of coming over land from the north, 550 00:30:22,077 --> 00:30:25,767 they came from the south over the water. 551 00:30:27,387 --> 00:30:28,939 [upbeat music] 552 00:30:38,870 --> 00:30:41,111 Extraordinary as a 12,000 kilometer 553 00:30:41,249 --> 00:30:42,836 sea crossing might sound, 554 00:30:42,974 --> 00:30:45,284 in a museum in Rio de Janeiro 555 00:30:45,422 --> 00:30:47,111 of a skeletal remains of a lady 556 00:30:47,249 --> 00:30:50,077 which could convince us this was possible. 557 00:30:52,043 --> 00:30:55,456 [Walter] What I have here is the skull of Luzia, 558 00:30:55,594 --> 00:30:58,525 one of the oldest if not the oldest 559 00:30:58,663 --> 00:31:02,698 human skeleton ever found in the Americas. 560 00:31:03,456 --> 00:31:06,836 She died like, 13,000 years ago 561 00:31:06,974 --> 00:31:13,353 and she was aged between 20 and 25 years. 562 00:31:13,491 --> 00:31:18,422 [Narrator] Luzia was found in central Brazil in the 1970's. 563 00:31:18,560 --> 00:31:20,663 Whilst she may not look unusual 564 00:31:20,801 --> 00:31:23,249 her skull actually poses a puzzle. 565 00:31:24,353 --> 00:31:26,111 Whilst today's Native Americans 566 00:31:26,249 --> 00:31:28,629 share the wide high cheek bone face shape 567 00:31:28,767 --> 00:31:31,732 of people from Siberia and East Asia. 568 00:31:31,870 --> 00:31:37,043 Walter's detailed measurements show Luzia's skull is different. 569 00:31:37,180 --> 00:31:39,629 [Walter] When one of the greatest differences 570 00:31:39,767 --> 00:31:41,594 happens in the cheek bones. 571 00:31:41,732 --> 00:31:43,905 You see that here 572 00:31:44,043 --> 00:31:49,249 you have a very high cheek bone and flatten cheek bone. 573 00:31:50,939 --> 00:31:55,905 When you look at Luzia you have very low cheek bones 574 00:31:56,043 --> 00:32:01,215 and they are not flat as you saw in this Asian's skull. 575 00:32:06,594 --> 00:32:10,077 [Narrator] And when experts reconstructed Luzia's head 576 00:32:10,215 --> 00:32:12,939 in clay, the results confirmed their suspicions. 577 00:32:14,974 --> 00:32:17,249 She didn't look Asian at all. 578 00:32:18,905 --> 00:32:21,456 So who does she look like? 579 00:32:24,767 --> 00:32:27,387 I show you what we discover, 580 00:32:27,525 --> 00:32:30,698 we discovered that amazingly... 581 00:32:30,836 --> 00:32:35,836 she looks much more like Australasians 582 00:32:35,974 --> 00:32:39,870 than with East Asians or Native Americans. 583 00:32:42,698 --> 00:32:43,870 [Narrator] Comparing Luzia 584 00:32:44,008 --> 00:32:46,249 with skulls from the Australian region 585 00:32:46,387 --> 00:32:47,974 Walter was able to identify 586 00:32:48,111 --> 00:32:50,629 a number of striking similarities. 587 00:32:51,836 --> 00:32:53,870 Given these similarities could 588 00:32:54,008 --> 00:32:56,663 Luzia's ancestors originally have come 589 00:32:56,801 --> 00:32:59,146 not from Siberia over the land 590 00:32:59,284 --> 00:33:02,111 but from Australia by sea? 591 00:33:05,180 --> 00:33:07,008 [Walter] Well, lots of people think 592 00:33:07,146 --> 00:33:12,422 that because Luzia looking like Australian Aborigines 593 00:33:12,560 --> 00:33:16,008 that we are proposing a trans-pacific mitigation 594 00:33:16,146 --> 00:33:20,525 from Australia to South America to explain this. 595 00:33:20,663 --> 00:33:22,491 If you take into account 596 00:33:22,629 --> 00:33:26,974 the technology available to about 13,000 years ago, 597 00:33:27,111 --> 00:33:28,663 that would be impossible. 598 00:33:28,801 --> 00:33:32,974 We know these people did not have enough sailing technology 599 00:33:33,111 --> 00:33:35,525 to cross such a long... 600 00:33:35,663 --> 00:33:39,767 a longer way from Australia to South America. 601 00:33:39,905 --> 00:33:43,353 [Narrator] In which case the ocean crossing route is out! 602 00:33:43,491 --> 00:33:45,077 And despite her appearance, 603 00:33:45,215 --> 00:33:46,801 it seems even Luzia's people 604 00:33:46,939 --> 00:33:50,043 must have somehow come here by land. 605 00:33:50,180 --> 00:33:53,801 So once again we're faced with our conundrum. 606 00:33:55,698 --> 00:33:58,008 Archaeology suggests people were living 607 00:33:58,146 --> 00:34:00,491 in South and North America 608 00:34:00,629 --> 00:34:04,077 at a time when the land route into the continent was blocked 609 00:34:04,215 --> 00:34:06,767 by an impassable barrier of ice. 610 00:34:08,008 --> 00:34:09,008 But so far, 611 00:34:09,146 --> 00:34:10,318 these archaeological clues 612 00:34:10,456 --> 00:34:12,905 have not told us how they got there. 613 00:34:14,594 --> 00:34:16,698 This seemingly impossible riddle 614 00:34:16,836 --> 00:34:19,732 has stimulated scientists in many different fields 615 00:34:19,870 --> 00:34:22,180 using many different methods, 616 00:34:22,318 --> 00:34:25,077 they're all looking for an answer to the question, 617 00:34:25,215 --> 00:34:28,767 "How did these people get past the ice?" 618 00:34:33,870 --> 00:34:36,698 One reason archaeology can't tell us everything 619 00:34:36,836 --> 00:34:38,836 is that some of possibly the best clues 620 00:34:38,974 --> 00:34:41,043 are very difficult to dig for. 621 00:34:42,318 --> 00:34:43,629 During the Ice Age, 622 00:34:43,767 --> 00:34:46,249 so much water was locked in the ice sheets 623 00:34:46,387 --> 00:34:48,146 that sea levels were much lower 624 00:34:48,284 --> 00:34:51,767 and some of what is sea today would then have been land. 625 00:34:53,284 --> 00:34:56,387 So maybe the land the early Americans crossed 626 00:34:56,525 --> 00:35:01,111 and any clues they left behind are now underwater. 627 00:35:02,629 --> 00:35:04,732 But there is one science we can turn to 628 00:35:04,870 --> 00:35:08,111 which could help us uncover this underwater evidence. 629 00:35:08,249 --> 00:35:11,525 It's a science that's more usually associated with crime, 630 00:35:12,422 --> 00:35:13,732 forensics. 631 00:35:14,456 --> 00:35:15,560 [reporter] On Sunday. 632 00:35:15,698 --> 00:35:17,111 the partially clothed body of a... 633 00:35:17,249 --> 00:35:18,629 [Narrator] When a young girl's body was found in a lake 634 00:35:18,767 --> 00:35:20,870 near Vancouver in Canada, 635 00:35:21,008 --> 00:35:24,111 it was identification of tiny particles in her hair 636 00:35:24,249 --> 00:35:26,043 that helped convict her killer. 637 00:35:28,111 --> 00:35:31,663 The man that did that identification is Rolf Matthews 638 00:35:31,801 --> 00:35:33,525 a forensic botanist. 639 00:35:36,284 --> 00:35:38,801 And when he's not helping solve murders, 640 00:35:38,939 --> 00:35:41,801 Rolf uses his knowledge of minuscule particles 641 00:35:41,939 --> 00:35:44,698 to recreate landscapes of the past. 642 00:35:47,249 --> 00:35:48,870 So maybe his forensics 643 00:35:49,008 --> 00:35:53,525 can help us uncover the path taken by our American ancestors. 644 00:35:54,767 --> 00:35:56,180 The evidence Rolf uses 645 00:35:56,318 --> 00:35:58,318 is something we wouldn't normally think of 646 00:35:58,456 --> 00:35:59,905 as being very useful. 647 00:36:01,525 --> 00:36:03,491 Pollen. 648 00:36:03,629 --> 00:36:06,043 [Rolf] Pollen, even though it's microscopic, 649 00:36:06,180 --> 00:36:07,249 is produced in huge quantities 650 00:36:07,387 --> 00:36:09,560 as any hay fever sufferer would know. 651 00:36:09,698 --> 00:36:13,698 Um, It also preserves extremely well in wet environments, 652 00:36:13,836 --> 00:36:16,249 in fact, it can preserve essentially forever. 653 00:36:17,249 --> 00:36:18,560 In a place like a lake bottom 654 00:36:18,698 --> 00:36:21,905 where mud accumulates year by year in small increments 655 00:36:22,043 --> 00:36:23,939 the pollen is trapped in that mud 656 00:36:24,077 --> 00:36:25,491 and... 657 00:36:25,629 --> 00:36:27,353 is buried at the bottom of the lake 658 00:36:27,491 --> 00:36:29,663 and over time it builds up. 659 00:36:29,801 --> 00:36:32,284 [Narrator] Because the pollen preserves so well, 660 00:36:32,422 --> 00:36:35,077 Rolf and his colleagues are able to study samples 661 00:36:35,215 --> 00:36:37,043 from thousands of years ago. 662 00:36:38,836 --> 00:36:40,594 [Rolf] Now to get our history of the vegetation area, 663 00:36:40,732 --> 00:36:43,422 we can use coring devices of various kinds 664 00:36:43,560 --> 00:36:45,146 that are pushed down into sediments 665 00:36:45,284 --> 00:36:47,043 like lake bottoms or bogs, 666 00:36:47,180 --> 00:36:50,422 and we can recover cores much like this one 667 00:36:50,560 --> 00:36:53,698 and this material contains a record of plants 668 00:36:53,836 --> 00:36:56,422 from the Ice Age right to the present day. 669 00:36:56,560 --> 00:36:57,974 That gives you like a book 670 00:36:58,111 --> 00:37:00,836 a story of how the climate has changed. 671 00:37:02,491 --> 00:37:03,629 [Narrator] Rolf and his team 672 00:37:03,767 --> 00:37:05,836 studied samples from under the water 673 00:37:05,974 --> 00:37:07,905 off the west coast of Canada. 674 00:37:09,560 --> 00:37:10,939 When they analyzed them 675 00:37:11,077 --> 00:37:14,318 they found a particularly distinctive type of pollen. 676 00:37:14,456 --> 00:37:17,456 [Rolf] These pollen types here are sedges 677 00:37:17,594 --> 00:37:19,663 and here's a typical example of a sedge pollen grain 678 00:37:19,801 --> 00:37:22,939 that this characteristic triangular shape, 679 00:37:23,077 --> 00:37:25,353 and they also all have these light areas 680 00:37:25,491 --> 00:37:26,801 with the dark spots on them. 681 00:37:26,939 --> 00:37:29,180 These are magnified 600 times. 682 00:37:29,318 --> 00:37:30,525 [Narrator] As well as sedge 683 00:37:30,663 --> 00:37:32,767 they found grasses and other plants 684 00:37:32,905 --> 00:37:35,801 typical of wet swampy environments. 685 00:37:37,284 --> 00:37:38,560 But the major discovery 686 00:37:38,698 --> 00:37:42,146 was when they found out how old their samples were. 687 00:37:42,284 --> 00:37:47,215 The pollen they were looking at dated back to 17,000 years ago 688 00:37:47,353 --> 00:37:49,594 the last Ice Age. 689 00:37:53,456 --> 00:37:55,422 Well, the interpretation of all the pollen 690 00:37:55,560 --> 00:37:57,215 and the radio carbon dates 691 00:37:57,353 --> 00:37:58,698 makes it very clear that 692 00:37:58,836 --> 00:38:02,387 the coast had a growing thriving vegetation cover on it 693 00:38:02,525 --> 00:38:05,974 when the mainland was still locked in the huge ice cap. 694 00:38:06,111 --> 00:38:07,974 [Narrator] It seems that even whilst the mainland 695 00:38:08,111 --> 00:38:09,732 was buried under ice, 696 00:38:09,870 --> 00:38:11,732 there were places along the coast 697 00:38:11,870 --> 00:38:15,008 where it had begun to melt enough for plants to grow. 698 00:38:17,974 --> 00:38:20,801 This means, it's theoretically possible 699 00:38:20,939 --> 00:38:24,594 that humans could have edged their way around the ice. 700 00:38:28,422 --> 00:38:31,284 But the landscape Rolf's pollen grains tell us about 701 00:38:31,422 --> 00:38:33,870 wasn't always warm or inviting. 702 00:38:34,008 --> 00:38:35,215 Would there have been enough food 703 00:38:35,353 --> 00:38:37,111 to sustain whole families? 704 00:38:39,043 --> 00:38:40,387 To find out 705 00:38:40,525 --> 00:38:43,698 scientists are turning to some unlikely helpers. 706 00:38:48,043 --> 00:38:49,008 Bears. 707 00:38:49,146 --> 00:38:50,215 [bear growls] 708 00:38:52,836 --> 00:38:54,318 Strange as it sounds 709 00:38:54,456 --> 00:38:58,836 their history may hold crucial clues about our past. 710 00:39:03,318 --> 00:39:07,008 Over the last few years anthropologist Quentin Mackie 711 00:39:07,146 --> 00:39:08,698 has been delving into the history 712 00:39:08,836 --> 00:39:11,043 of these iconic creatures. 713 00:39:13,801 --> 00:39:15,974 [Quentin] We've been looking at cave sites 714 00:39:16,111 --> 00:39:17,732 on the Northwest coast of North America 715 00:39:17,870 --> 00:39:19,836 that date to the end of the last Ice Age, 716 00:39:19,974 --> 00:39:22,525 and in them we've been finding an awful lot of bear bones, 717 00:39:22,663 --> 00:39:26,180 we've found over 6,000 bear bones 718 00:39:26,318 --> 00:39:29,318 and most of them are little chewed up bits and pieces 719 00:39:29,456 --> 00:39:32,525 but some of them are fairly nice bear bones. 720 00:39:32,663 --> 00:39:36,560 This is for example, the skull of a brown bear 721 00:39:36,698 --> 00:39:41,629 that died about fourteen and a half thousand years ago. 722 00:39:41,767 --> 00:39:44,077 There's no sign of injury, 723 00:39:44,215 --> 00:39:47,318 we think that the bear fell down a little pit inside the cave 724 00:39:47,456 --> 00:39:49,008 and was trapped and couldn't get out 725 00:39:49,146 --> 00:39:51,767 and died a lonely death. 726 00:39:51,905 --> 00:39:53,732 This is a more typical little piece, 727 00:39:53,870 --> 00:39:57,939 this is part of the leg bone of a juvenile brown bear 728 00:39:58,077 --> 00:40:01,629 and this is actually the oldest specimen that we have, 729 00:40:01,767 --> 00:40:06,905 and this dates to over 17,000 years old. 730 00:40:07,043 --> 00:40:09,043 [Narrator] This is a surprising find 731 00:40:09,180 --> 00:40:10,594 because it tells Quentin 732 00:40:10,732 --> 00:40:13,698 that bears were able to live on the coast of America 733 00:40:13,836 --> 00:40:16,905 before the Ice Age ended. 734 00:40:17,043 --> 00:40:20,318 And this piece of information is curiously significant 735 00:40:20,456 --> 00:40:22,043 for the human story. 736 00:40:23,732 --> 00:40:26,077 [Quentin] You know bears by their nature are large 737 00:40:26,215 --> 00:40:29,594 terrestrial omnivores they eat both plants, 738 00:40:29,732 --> 00:40:34,008 they eat terrestrial animals and they eat marine resources. 739 00:40:34,146 --> 00:40:37,422 They're quite territorial, they're slow to reproduce 740 00:40:37,560 --> 00:40:38,836 they need a large territory, 741 00:40:38,974 --> 00:40:41,663 in other words they're quite similar to humans. 742 00:40:41,801 --> 00:40:45,111 [Narrator] So maybe if bears could find food in the ice age, 743 00:40:45,249 --> 00:40:46,939 humans could too. 744 00:40:48,387 --> 00:40:49,698 [Quentin] Humans are omnivores 745 00:40:49,836 --> 00:40:53,146 and they would have been able to eat pretty well anything 746 00:40:53,284 --> 00:40:54,594 that a bear would eat 747 00:40:54,732 --> 00:40:58,008 as well as a whole variety of foods especially marine foods 748 00:40:58,146 --> 00:41:00,801 that wouldn't have been accessible to bears. 749 00:41:00,939 --> 00:41:03,663 So i think if it was a good environment for bears 750 00:41:03,801 --> 00:41:05,698 which it clearly was, then it was a great environment 751 00:41:05,836 --> 00:41:07,077 for humans. 752 00:41:08,594 --> 00:41:10,767 [dramatic music] 753 00:41:12,387 --> 00:41:15,698 [Narrator] And new research suggests there something else, 754 00:41:15,836 --> 00:41:17,387 lurking under the water 755 00:41:17,525 --> 00:41:20,111 which may have helped people survive right down the length 756 00:41:20,249 --> 00:41:21,870 of the American coast. 757 00:41:26,043 --> 00:41:29,732 Forests of kelp a tough buoyant seaweed 758 00:41:29,870 --> 00:41:31,456 which can grow at the phenomenal rate 759 00:41:31,594 --> 00:41:33,905 of up to half a meter a day. 760 00:41:35,491 --> 00:41:36,663 Kelp forests make up 761 00:41:36,801 --> 00:41:39,801 some of the world's richest ecosystems 762 00:41:39,939 --> 00:41:42,663 and are teaming with life. 763 00:41:42,801 --> 00:41:46,008 They provide nutrients for fish, crustaceans, 764 00:41:46,146 --> 00:41:48,077 sea mammals and birds. 765 00:41:49,732 --> 00:41:52,560 In fact, with so much living in the sea 766 00:41:52,698 --> 00:41:53,939 these forests may have made 767 00:41:54,077 --> 00:41:56,215 excellent hunting and fishing grounds 768 00:41:56,353 --> 00:42:00,698 for people battling to survive on the newly ice-free coast. 769 00:42:02,974 --> 00:42:06,698 And as varieties of kelp are found in Siberia, Alaska 770 00:42:06,836 --> 00:42:08,594 and along virtually the entire length 771 00:42:08,732 --> 00:42:11,801 of both North and South America, 772 00:42:11,939 --> 00:42:15,836 some have gone as far as to call it the kelp highway. 773 00:42:21,353 --> 00:42:24,974 So the idea of people moving into America along the coast 774 00:42:25,111 --> 00:42:28,111 is starting to sound more likely. 775 00:42:28,249 --> 00:42:30,456 The first migrants could have found refuge 776 00:42:30,594 --> 00:42:33,387 in the ice-free sections of the western coast 777 00:42:33,525 --> 00:42:36,870 and it seems that there would have been plenty of food. 778 00:42:37,008 --> 00:42:40,974 But are there any clues that they actually lived this way? 779 00:42:41,111 --> 00:42:43,974 An intriguing piece of archaeological evidence 780 00:42:44,111 --> 00:42:45,698 may tell us more. 781 00:42:46,905 --> 00:42:49,629 [engine revving] 782 00:42:58,353 --> 00:43:00,732 [Narrator] Off the coast of southern California 783 00:43:00,870 --> 00:43:04,698 is a craggy island called Santa Rosa. 784 00:43:04,836 --> 00:43:07,043 Even today there's no daily ferry 785 00:43:07,180 --> 00:43:09,180 and visitor numbers are limited. 786 00:43:09,318 --> 00:43:12,215 The best way to get there is by air taxi. 787 00:43:17,801 --> 00:43:20,594 But it's here in this isolated spot 788 00:43:20,732 --> 00:43:23,456 that we find the key to how people may have lived 789 00:43:23,594 --> 00:43:26,215 and travelled along the coast. 790 00:43:26,353 --> 00:43:28,043 [birds squawking] 791 00:43:35,629 --> 00:43:38,077 [Narrator] For museum curator John Johnson, 792 00:43:38,215 --> 00:43:40,870 this island has a special significance. 793 00:43:41,801 --> 00:43:43,939 Some years ago his predecessor 794 00:43:44,077 --> 00:43:46,698 of the Santa Barbara Museum of Natural History 795 00:43:46,836 --> 00:43:49,318 was on the island looking for mammoth bones 796 00:43:49,456 --> 00:43:52,146 when he made an accidental discovery. 797 00:43:52,284 --> 00:43:57,663 Back in 1959, Phil Ore got his vehicle stuck in the mud 798 00:43:57,801 --> 00:44:00,249 right here below where we are right now. 799 00:44:01,594 --> 00:44:02,939 And when he was looking around 800 00:44:03,077 --> 00:44:05,836 trying to figure out how he was going to get his vehicle unstuck 801 00:44:05,974 --> 00:44:11,077 he found two bones sticking out of the side of Arlington Cannon. 802 00:44:16,111 --> 00:44:20,215 And these are casts of the original bones 803 00:44:20,353 --> 00:44:22,870 just like the ones that he found. 804 00:44:23,008 --> 00:44:26,146 There was this one femur that was pretty much complete... 805 00:44:26,974 --> 00:44:29,284 you can see right here. 806 00:44:29,422 --> 00:44:32,836 Uh, and then there's a second one here you can see, 807 00:44:34,111 --> 00:44:36,215 these two bones were all that were left 808 00:44:36,353 --> 00:44:37,836 of Arlington man. 809 00:44:39,043 --> 00:44:40,284 [Narrator] For 30 years, 810 00:44:40,422 --> 00:44:43,353 Arlington man's bones were kept in the museum. 811 00:44:43,491 --> 00:44:45,215 And little was done with them. 812 00:44:46,215 --> 00:44:49,905 Then in 1994 something happened. 813 00:44:52,043 --> 00:44:54,353 I had a visit from a colleague of mine, 814 00:44:54,491 --> 00:44:56,594 a specialist doing radio carbon dating, 815 00:44:56,732 --> 00:44:58,008 and he told me he says 816 00:44:58,146 --> 00:45:01,180 You know, John, you have the oldest dated human skeleton 817 00:45:01,318 --> 00:45:02,663 in North America. 818 00:45:05,077 --> 00:45:06,732 And i about fell out of my chair. 819 00:45:06,870 --> 00:45:10,663 I couldn't believe that it was as old as he said it was. 820 00:45:10,801 --> 00:45:14,525 [Narrator] Arlington man was alive 13,000 years ago. 821 00:45:15,767 --> 00:45:17,594 What's so surprising about this date 822 00:45:17,732 --> 00:45:19,491 is not so much its age, 823 00:45:19,629 --> 00:45:21,008 but what it tells us about the life 824 00:45:21,146 --> 00:45:24,318 that people were leading on the island. 825 00:45:24,456 --> 00:45:26,560 [Johnson] The significance of Arlington man 826 00:45:26,698 --> 00:45:28,939 being here 13,000 years ago 827 00:45:29,077 --> 00:45:33,491 is that this island was ten kilometers from the mainland, 828 00:45:33,629 --> 00:45:36,180 so the only way he could get here is by boat, 829 00:45:36,318 --> 00:45:38,905 and that means that people are using watercraft 830 00:45:39,043 --> 00:45:42,560 along the Pacific coast of North America 831 00:45:43,111 --> 00:45:44,560 13,000 years ago 832 00:45:44,698 --> 00:45:47,905 and probably exploiting coastal resources, 833 00:45:48,043 --> 00:45:51,008 hunting sea mammals, fishing in the kelp beds 834 00:45:51,146 --> 00:45:53,318 and gathering shellfish. 835 00:45:53,456 --> 00:45:55,698 [Narrator]And some people think that the coastal waterway 836 00:45:55,836 --> 00:45:59,870 was crucial to the journey of our American ancestors. 837 00:46:03,180 --> 00:46:05,215 If they could cross ten kilometers 838 00:46:05,353 --> 00:46:07,353 to reach an offshore island, 839 00:46:07,491 --> 00:46:10,491 they could no doubt make short journeys down the coast 840 00:46:10,629 --> 00:46:14,146 fishing and hunting in the water on their doorstep. 841 00:46:16,215 --> 00:46:19,008 Perhaps this was how the early Americans 842 00:46:19,146 --> 00:46:21,732 made the journey into the continent. 843 00:46:23,560 --> 00:46:24,870 It's frustrating that pretty much 844 00:46:25,008 --> 00:46:28,525 the only archaeological evidence is two leg bones, 845 00:46:28,663 --> 00:46:30,974 but John has some evidence of another kind 846 00:46:31,111 --> 00:46:33,491 which might make the picture clearer. 847 00:46:38,525 --> 00:46:40,180 For the last 15 years 848 00:46:40,318 --> 00:46:43,146 he's been involved in a project looking at the prehistory 849 00:46:43,284 --> 00:46:45,629 of some of today's Native Americans, 850 00:46:45,767 --> 00:46:48,249 using a database of DNA. 851 00:46:50,146 --> 00:46:52,387 What he and the rest of his team have discovered 852 00:46:52,525 --> 00:46:56,629 is nothing less than an ancient genetic route map. 853 00:47:00,146 --> 00:47:02,801 [Johnson] A few years ago, a colleague of mine called me 854 00:47:02,939 --> 00:47:04,594 and told me that a very rare type 855 00:47:04,732 --> 00:47:06,215 of DNA had been found 856 00:47:06,353 --> 00:47:09,353 in an ancient jaw bone from Southern Alaska, 857 00:47:09,491 --> 00:47:11,732 that was found in a cave in Southern Alaska. 858 00:47:13,249 --> 00:47:17,111 The remarkable thing is that this rare type of DNA 859 00:47:17,249 --> 00:47:18,836 matched a rare type 860 00:47:18,974 --> 00:47:22,422 that I also found here among the Chumash Indians 861 00:47:22,560 --> 00:47:24,560 who live in this part of California. 862 00:47:25,456 --> 00:47:26,870 [Narrator]And more excitingly, 863 00:47:27,008 --> 00:47:30,111 when checked against a wider database of DNA samples 864 00:47:30,249 --> 00:47:31,491 from Native Americans, 865 00:47:31,629 --> 00:47:33,939 there were several other matches too. 866 00:47:36,353 --> 00:47:38,215 In Northwest Mexico, 867 00:47:38,353 --> 00:47:41,594 in the Kauppa Indians in coastal Ecuador, 868 00:47:41,732 --> 00:47:44,387 the Mapuche Indians in southern Chile, 869 00:47:44,525 --> 00:47:46,870 the Yargon in southern Patagonia 870 00:47:47,008 --> 00:47:50,491 and in prehistoric burials in Tierra del Fuego . 871 00:47:51,146 --> 00:47:52,318 Plotted on a map, 872 00:47:52,456 --> 00:47:54,629 this DNA signature forms a pattern 873 00:47:54,767 --> 00:47:58,043 all the way down the Pacific coast. 874 00:47:58,180 --> 00:48:00,284 [Johnson] What's interesting about this distribution 875 00:48:00,422 --> 00:48:02,767 is it's all Pacific coastal, 876 00:48:02,905 --> 00:48:05,043 or almost entirely Pacific coastal. 877 00:48:07,043 --> 00:48:09,215 This is the best evidence to date 878 00:48:09,353 --> 00:48:10,836 that there was a coastal migration, 879 00:48:10,974 --> 00:48:13,939 leaving behind these pockets of people 880 00:48:14,077 --> 00:48:17,732 all along the western margin of the two continents. 881 00:48:17,870 --> 00:48:21,180 And their descendants still live in this area today. 882 00:48:23,077 --> 00:48:24,387 [Narrator] At last, 883 00:48:24,525 --> 00:48:26,870 it feels like we could have found the key to this, 884 00:48:27,008 --> 00:48:31,180 our final great human journey. 885 00:48:31,318 --> 00:48:34,974 In this series we've seen how a small group of our ancestors 886 00:48:35,111 --> 00:48:39,629 emerged out of Africa around 70,000 years ago. 887 00:48:40,525 --> 00:48:42,974 Over the next 50,000 odd years, 888 00:48:43,111 --> 00:48:46,525 their descendants traveled to the ends of the earth. 889 00:48:51,905 --> 00:48:54,353 Eventually some of our ancestors began 890 00:48:54,491 --> 00:48:56,663 to explore the Americas. 891 00:48:58,870 --> 00:49:02,629 These people were skilled craftsmen and fantastic hunters, 892 00:49:02,767 --> 00:49:05,732 at home on land and sea. 893 00:49:05,870 --> 00:49:07,594 And the descendants of America's 894 00:49:07,732 --> 00:49:11,560 Stone Age pioneers still live here today. 895 00:49:11,698 --> 00:49:15,974 They like all of us are members of a young species, 896 00:49:16,111 --> 00:49:19,974 and the study of bones, stones and genes shows 897 00:49:20,111 --> 00:49:21,594 wherever we've ended up 898 00:49:21,732 --> 00:49:24,560 we're all part of one family. 899 00:49:26,008 --> 00:49:28,008 [closing theme music]