1 00:00:03,169 --> 00:00:06,036 The earth does not easily yield its secrets. 2 00:00:07,073 --> 00:00:10,065 Yet around the world scientists are unraveling 3 00:00:10,310 --> 00:00:13,006 the compelling story of human evolution. 4 00:00:13,880 --> 00:00:16,644 It is a saga that blends the rigors of science 5 00:00:16,883 --> 00:00:19,317 with the romance of a detective story. 6 00:00:25,191 --> 00:00:27,591 We have only traces that hint at who our ancestors were 7 00:00:27,827 --> 00:00:31,285 and how they may have lived. 8 00:00:31,898 --> 00:00:36,096 It is like a gigantic puzzle with most of the pieces forever missing. 9 00:00:38,972 --> 00:00:43,136 Today, biological scientists may quibble over the details of evolution, 10 00:00:43,376 --> 00:00:46,140 but they all agree that evolution is a fact. 11 00:00:47,113 --> 00:00:51,573 Animal studies now shed light on why some distant ape like creature 12 00:00:51,818 --> 00:00:53,683 became an upright walker 13 00:00:54,287 --> 00:00:58,553 and how it may have confronted the perils of life on open ground. 14 00:01:08,001 --> 00:01:10,401 Once barely noticeable on the landscape, 15 00:01:10,637 --> 00:01:13,162 humans would come to dominate the earth. 16 00:01:14,307 --> 00:01:16,605 The tool, mother of all inventions, 17 00:01:16,843 --> 00:01:18,834 was a key to our success. 18 00:01:31,357 --> 00:01:35,384 Tools chipped from stone helped bring us to where we are today. 19 00:01:35,762 --> 00:01:38,959 Now new tools help us better understand what paths 20 00:01:39,199 --> 00:01:41,599 we may have traveled along the way. 21 00:01:43,236 --> 00:01:44,669 Much of our current knowledge 22 00:01:44,904 --> 00:01:47,964 our understanding of who we are and where we came from 23 00:01:48,475 --> 00:01:51,876 has come about only in the last 30 years. 24 00:01:56,816 --> 00:01:59,011 Can we reconstruct the past? 25 00:01:59,385 --> 00:02:04,379 Can long silent voices be summoned across the vast reaches of time? 26 00:02:04,791 --> 00:02:09,421 Join us as we probe the MYSTERIES OF MANKIND. 27 00:02:52,906 --> 00:02:56,171 By nature mammals are intensely curious. 28 00:02:56,476 --> 00:02:58,842 We humans are the most curious of all. 29 00:02:59,212 --> 00:03:02,079 And perhaps nothing arouses our curiosity 30 00:03:02,315 --> 00:03:05,148 more than the intriguing question of our origins. 31 00:03:05,718 --> 00:03:07,447 What about the cavemen? 32 00:03:07,687 --> 00:03:09,917 Caveman? Well, what do you think he is? 33 00:03:10,156 --> 00:03:11,248 A caveman. 34 00:03:11,491 --> 00:03:14,585 At the close of the 16th century when William Shakespeare wrote: 35 00:03:14,827 --> 00:03:19,161 All the world's a stage, and all the men and women merely players, 36 00:03:19,399 --> 00:03:24,063 no one had any concept of the vast array of players who preceded us. 37 00:03:24,304 --> 00:03:27,171 Today we yearn to know just who the actors were 38 00:03:27,407 --> 00:03:29,170 in this greatest of dramas. 39 00:03:29,409 --> 00:03:33,470 When did they appear on the stage and when did they finally depart? 40 00:03:41,721 --> 00:03:44,212 The story is elusive at best, 41 00:03:44,457 --> 00:03:51,192 like peering into mists that float above an unfamiliar land. 42 00:03:51,431 --> 00:03:54,161 Here and there through a dusky veil 43 00:03:54,400 --> 00:03:58,598 we think we catch a fleeting echo of some distant call 44 00:03:58,838 --> 00:04:03,866 feel primordial eyes watching us across the ancestral dark. 45 00:04:04,277 --> 00:04:07,144 A thread of kinship surges within us. 46 00:04:07,714 --> 00:04:11,047 Then, just as we grasp at a clue, 47 00:04:11,284 --> 00:04:13,844 the phantom voices melt away. 48 00:04:21,761 --> 00:04:25,288 In the early 1900s the scientific world believed that the cradle 49 00:04:25,531 --> 00:04:27,795 of mankind was in Asia. 50 00:04:29,235 --> 00:04:31,203 Then, in 1924, 51 00:04:31,437 --> 00:04:33,837 South African anatomist Raymond Dart 52 00:04:34,073 --> 00:04:38,271 was brought a skull workmen had found in a limestone quarry. 53 00:04:38,611 --> 00:04:42,809 Dart outraged the scientific community by announcing that this primitive, 54 00:04:43,049 --> 00:04:44,380 apelike child 55 00:04:44,617 --> 00:04:48,246 was a hominid a member of the family of man. 56 00:04:48,488 --> 00:04:52,390 And, he said, it had walked upright just as we do. 57 00:04:53,760 --> 00:04:57,753 Dart named the species Australopithecus Africanus 58 00:04:57,997 --> 00:05:00,158 southern ape of Africa. 59 00:05:02,935 --> 00:05:05,961 For more than a decade Dart's only vocal supporter 60 00:05:06,205 --> 00:05:08,730 was paleontologist Robert Broom. 61 00:05:09,042 --> 00:05:13,308 Dart was finally vindicated when Broom, in the 1930s and 40s, 62 00:05:13,546 --> 00:05:17,880 discovered an assortment of adult australopithecine fossils. 63 00:05:22,722 --> 00:05:24,519 Africa's Great Rift Valley has been 64 00:05:24,757 --> 00:05:27,988 geologically active for millions of years 65 00:05:28,227 --> 00:05:33,221 an ideal setting for the burial of fossils and their later re-exposure 66 00:05:33,466 --> 00:05:38,165 here, Olduvai Gorge would become known as the "Grand Canyon of Evolution" 67 00:05:38,404 --> 00:05:41,305 because of two maverick scientists. 68 00:05:43,309 --> 00:05:47,075 Coming here in the 1930s, Louis Leakey and his wife, Mary, 69 00:05:47,313 --> 00:05:49,406 undertook one of the most persistent efforts 70 00:05:49,649 --> 00:05:51,674 in the history of anthropology. 71 00:05:54,687 --> 00:05:57,747 What particularly excited the Leakeys about Olduvai 72 00:05:57,990 --> 00:06:00,424 was the presence of primitive stone tools 73 00:06:00,660 --> 00:06:03,254 scattered across the eroded landscape 74 00:06:04,263 --> 00:06:07,892 Their passionate dream: to find the remains of the creatures 75 00:06:08,134 --> 00:06:12,764 who fashioned these tools to find the earliest known human. 76 00:06:13,172 --> 00:06:15,197 It would be nearly a quarter of a century 77 00:06:15,441 --> 00:06:19,104 before their single-minded perseverance finally paid off. 78 00:06:19,379 --> 00:06:22,041 The year was 1959. 79 00:06:23,249 --> 00:06:25,740 We appeared to have got what we were looking for. 80 00:06:25,985 --> 00:06:29,386 Here at last was a man or a man-like creature, 81 00:06:29,622 --> 00:06:33,114 apparently the earliest known man in the world. 82 00:06:33,793 --> 00:06:36,353 It would turn out to be a teen-aged male, 83 00:06:36,596 --> 00:06:39,895 and not a true human, but a more primitive hominid 84 00:06:40,133 --> 00:06:42,101 an australopithecine. 85 00:06:43,836 --> 00:06:48,637 And yet surely, like us, he had cried when hungry as a baby, 86 00:06:48,875 --> 00:06:56,077 wobbled his way onto two upright legs, knew pain, love, and joy. 87 00:06:56,315 --> 00:06:59,876 Then in the way of all flesh, he died. 88 00:07:03,322 --> 00:07:06,291 The boy died near the edge of what was then a lake. 89 00:07:06,526 --> 00:07:07,618 The skeleton is missing, 90 00:07:07,860 --> 00:07:11,159 perhaps washed away or destroyed by scavengers. 91 00:07:11,397 --> 00:07:14,855 Fortunately, the skull was buried by sediments. 92 00:07:15,101 --> 00:07:16,363 Over the centuries water 93 00:07:16,602 --> 00:07:19,162 soluble minerals turned bone to stone 94 00:07:19,405 --> 00:07:24,809 as layer upon layer of deposits buried the skull ever deeper into the earth. 95 00:07:25,044 --> 00:07:30,607 Some layers were volcanic ash laid down when a nearby volcano erupted. 96 00:07:30,850 --> 00:07:34,718 Gradual geological uplift typical of the Rift Valley 97 00:07:34,954 --> 00:07:39,982 and subsequent erosion brought the fossil once again to the surface. 98 00:07:40,226 --> 00:07:45,664 The odds of finding a hominid fossil are said to be one in ten million. 99 00:07:49,068 --> 00:07:52,936 Because the Leakey's fossil was found in a deposit with volcanic ash, 100 00:07:53,172 --> 00:07:55,572 it could be accurately dated. 101 00:07:55,808 --> 00:07:58,902 Volcanic ash contains radioactive potassium that decays 102 00:07:59,145 --> 00:08:03,707 into argon gas at a known rate over time. 103 00:08:03,950 --> 00:08:05,315 Human evolution was then believed 104 00:08:05,551 --> 00:08:08,452 to begin no more than one million years ago. 105 00:08:08,688 --> 00:08:11,816 Yet here was a fossil nearly double that age. 106 00:08:12,058 --> 00:08:14,788 The scientific world was stunned. 107 00:08:17,196 --> 00:08:20,063 Today, the addition of lasers to the dating technique 108 00:08:20,299 --> 00:08:25,498 enables scientists to date minuscule samples even more accurately. 109 00:08:25,838 --> 00:08:27,533 A single grain of ash, 110 00:08:27,773 --> 00:08:30,571 seen magnified here many thousands of times, 111 00:08:30,810 --> 00:08:35,042 can produce a date much more reliable than ever before possible. 112 00:08:41,320 --> 00:08:43,345 The name and age of a fossil tell little 113 00:08:43,589 --> 00:08:45,682 about how the creature actually lived. 114 00:08:45,925 --> 00:08:49,793 But perhaps the behavior of living primates can. 115 00:08:50,029 --> 00:08:54,591 Charles Darwin wrote that we are most closely related to the African apes. 116 00:08:54,834 --> 00:08:59,294 But at that time no one knew how closely or to which species. 117 00:08:59,539 --> 00:09:02,372 The answer would come from a most unlikely source 118 00:09:02,608 --> 00:09:05,907 the test tubes of molecular biologists. 119 00:09:08,481 --> 00:09:10,779 Twenty years ago Dr. Vincent Sarich 120 00:09:11,017 --> 00:09:13,884 and his colleagues at the University of California 121 00:09:14,120 --> 00:09:18,181 were among a small group of scientists dating evolution with molecules 122 00:09:18,424 --> 00:09:21,552 and test tubes instead of fossils. 123 00:09:22,228 --> 00:09:26,995 Sarich's group compared a blood protein in 13 species of primates, 124 00:09:27,233 --> 00:09:30,725 including humans, and charted when each had diverged 125 00:09:30,970 --> 00:09:32,961 from a common ancestor. 126 00:09:36,108 --> 00:09:40,511 The dates differed radically from those obtained from fossils. 127 00:09:41,714 --> 00:09:45,081 Among the great apes, beginning millions of years ago, 128 00:09:45,318 --> 00:09:48,651 the line that led to orangutans was the first to split off 129 00:09:48,888 --> 00:09:50,685 from a common ancestor. 130 00:09:50,923 --> 00:09:53,949 The evidence suggests gorillas were next. 131 00:09:54,193 --> 00:09:57,594 According to Sarich, chimpanzees and man 132 00:09:57,830 --> 00:10:02,699 may have diverged as recently as four to five million years ago. 133 00:10:02,935 --> 00:10:05,563 Such a recent divergence was almost impossible 134 00:10:05,805 --> 00:10:07,636 for many scientists to accept. 135 00:10:07,873 --> 00:10:11,001 Laymen were equally reluctant to listen. 136 00:10:11,243 --> 00:10:16,180 There is still a very strong resistance to looking 137 00:10:16,415 --> 00:10:21,216 at human beings in an evolutionary context, especially behavioral. 138 00:10:21,454 --> 00:10:24,480 Because we want to retain a separateness. 139 00:10:24,724 --> 00:10:27,124 We don't want to see ourselves 140 00:10:27,360 --> 00:10:32,388 as having any non-human in our ancestry. 141 00:10:32,865 --> 00:10:35,333 There are significant differences between us. 142 00:10:35,568 --> 00:10:37,593 We are essentially hairless 143 00:10:37,837 --> 00:10:39,862 Oh, he likes the beard. 144 00:10:40,106 --> 00:10:42,301 We are habitually upright walkers, 145 00:10:42,541 --> 00:10:44,338 we have a much larger brain, 146 00:10:44,577 --> 00:10:47,978 and we have the gift of spoken language. 147 00:10:48,214 --> 00:10:53,584 But genetically humans and chimpanzees are 99% identical. 148 00:10:53,819 --> 00:11:00,019 Chimps may even be more closely related to us than they are to gorillas. 149 00:11:01,560 --> 00:11:05,394 In 1960 Louis Leakey, with uncanny intuition, 150 00:11:05,631 --> 00:11:09,795 sent a young woman into the field to study chimpanzees. 151 00:11:11,203 --> 00:11:15,367 Jane Goodall's 27-year old study has become a classic 152 00:11:15,608 --> 00:11:19,738 and confirms Leakey's conviction that chimps have much to teach us 153 00:11:19,979 --> 00:11:23,745 about the behavior of early humans. 154 00:11:26,185 --> 00:11:28,881 Understanding of chimp behavior today 155 00:11:29,121 --> 00:11:34,821 helps us to understand the way in which our early ancestors may have lived. 156 00:11:35,061 --> 00:11:38,656 Because I think it makes sense to say any behavior shared 157 00:11:38,898 --> 00:11:41,958 by the modern chimpanzee and the modern human 158 00:11:42,201 --> 00:11:45,329 was probably present in the common ancestor. 159 00:11:45,571 --> 00:11:50,406 And if it was present in the common ancestor, therefore in early man. 160 00:11:56,749 --> 00:12:00,082 A mechanical leopard was instrumental in an experiment 161 00:12:00,319 --> 00:12:02,651 with chimpanzees conducted by scientists 162 00:12:02,888 --> 00:12:05,550 from the University of Amsterdam. 163 00:12:05,858 --> 00:12:08,053 Anthropologists have long puzzled over how 164 00:12:08,294 --> 00:12:11,991 our ancestors defended themselves against predators. 165 00:12:12,231 --> 00:12:14,290 How could such small creatures, 166 00:12:14,533 --> 00:12:19,835 not yet intelligent enough to make stone weapons, have possibly survived? 167 00:12:20,072 --> 00:12:23,439 Leopards are natural predators of chimpanzees. 168 00:12:23,676 --> 00:12:25,337 Here, as the chimps attack, 169 00:12:25,578 --> 00:12:27,739 we catch a glimpse of how our ancestors, 170 00:12:27,980 --> 00:12:29,914 having left the safety of the trees, 171 00:12:30,149 --> 00:12:34,108 may have first met the challenges of life on the ground. 172 00:12:55,674 --> 00:12:57,801 Once the leopard is decapitated, 173 00:12:58,043 --> 00:13:00,944 the chimp may not comprehend that it is "dead," 174 00:13:01,180 --> 00:13:05,583 but it clearly knows the enemy is no longer a threat. 175 00:13:10,022 --> 00:13:14,459 If a chimpanzee has the intelligence to defend itself with natural weapons, 176 00:13:14,693 --> 00:13:18,789 it seems likely our early ancestors did the same. 177 00:13:23,135 --> 00:13:27,265 The chimpanzee has never become an habitual upright walker. 178 00:13:27,506 --> 00:13:28,803 Why did we? 179 00:13:29,041 --> 00:13:32,636 Upright walking is so fundamental we seldom think about it, 180 00:13:32,878 --> 00:13:34,368 and yet it is one of the crucial ways 181 00:13:34,613 --> 00:13:37,582 we are set apart from all other mammals on earth. 182 00:13:37,817 --> 00:13:42,311 When did our ancestors take that first tentative step out of the trees 183 00:13:42,555 --> 00:13:46,013 to brave the vast African landscapes? 184 00:13:53,065 --> 00:13:58,230 Important answers would be found in the Afar Triangle region of Ethiopia. 185 00:13:59,405 --> 00:14:01,600 Here, in 1974, 186 00:14:01,841 --> 00:14:04,833 an international expedition of 15 specialists 187 00:14:05,077 --> 00:14:09,036 headed out to the remote badlands known as Hadar. 188 00:14:15,554 --> 00:14:18,614 Co leader of the team, Dr. Donald Johanson 189 00:14:18,858 --> 00:14:21,656 describes himself as superstitious. 190 00:14:21,894 --> 00:14:25,295 After two frustrating months on the sun scorched slopes, 191 00:14:25,531 --> 00:14:30,901 he woke up one morning feeling lucky and so noted in his diary. 192 00:14:31,136 --> 00:14:32,364 Later that very day 193 00:14:32,605 --> 00:14:37,167 the team discovered bones that made headlines around the world 194 00:14:39,245 --> 00:14:45,047 at the time the oldest, most complete hominid ever found. 195 00:14:50,322 --> 00:14:52,950 To anthropologists who usually consider themselves 196 00:14:53,192 --> 00:14:56,889 lucky to recover a tooth or a broken fragment of bone, 197 00:14:57,129 --> 00:15:00,963 this 40% complete skeleton was a bonanza. 198 00:15:01,200 --> 00:15:02,292 Nicknamed Lucy, 199 00:15:02,534 --> 00:15:06,834 she quickly became the object of intense study. 200 00:15:07,907 --> 00:15:10,933 What is most exceptional about a skeleton 201 00:15:11,176 --> 00:15:13,940 as complete as Lucy is all the information that 202 00:15:14,179 --> 00:15:17,046 we as anthropologists can glean from a skeleton like this. 203 00:15:17,283 --> 00:15:20,184 For example, looking at her femur or her thigh bone, 204 00:15:20,419 --> 00:15:22,717 which is only about 12 inches in length, 205 00:15:22,955 --> 00:15:26,083 we know that she was no taller than three and a half or four feet. 206 00:15:26,325 --> 00:15:30,352 Now that brings up the question or was it perhaps a child? 207 00:15:30,596 --> 00:15:34,088 If we look at the state of development 208 00:15:34,333 --> 00:15:36,995 for example, of the third molar or the wisdom tooth, 209 00:15:37,236 --> 00:15:39,204 it is fully erupted and is already beginning to wear. 210 00:15:39,438 --> 00:15:41,429 So that relative to modern humans, 211 00:15:41,674 --> 00:15:43,767 she was an adult when she died. 212 00:15:44,009 --> 00:15:47,410 We're able to tell from the weight bearing area 213 00:15:47,646 --> 00:15:49,546 of the hip socket, for example, 214 00:15:49,782 --> 00:15:53,479 that she probably only weighed about 50 or 55 pounds. 215 00:15:53,719 --> 00:15:56,620 From the size of the brain case, 216 00:15:56,855 --> 00:15:59,221 there is enough of the brain case preserved 217 00:15:59,458 --> 00:16:01,824 to suggest to us that the brain was very small 218 00:16:02,061 --> 00:16:06,327 about one fourth the size of a modern human brain. 219 00:16:08,734 --> 00:16:13,296 Historically, large brains have been considered the fundamental human trait. 220 00:16:13,539 --> 00:16:18,067 In the 20s when Raymond Dart suggested a small brained creature walked upright 221 00:16:18,310 --> 00:16:20,676 he had only a skull to work with. 222 00:16:20,913 --> 00:16:23,438 Here was a significant portion of a skeleton a creature 223 00:16:23,682 --> 00:16:28,346 with some very ape like features that walked upright. 224 00:16:29,922 --> 00:16:33,915 Lucy had an ape like brain, a human like skeleton, 225 00:16:34,159 --> 00:16:38,994 and teeth both ape and human like a startling mixture of traits. 226 00:16:39,231 --> 00:16:44,635 Yet clearly she was a hominid, a member of the family of man. 227 00:16:47,206 --> 00:16:49,174 Returning to Hadar the following year, 228 00:16:49,408 --> 00:16:54,436 the team combed the slopes hoping to discover newly exposed fossils. 229 00:16:54,680 --> 00:16:58,582 They never dreamed they would find anything as exciting as Lucy. 230 00:16:58,817 --> 00:17:04,449 But the Johanson luck proved even better than the year before. 231 00:17:04,556 --> 00:17:10,324 We have the femur and the foot and the knee! 232 00:17:11,063 --> 00:17:14,658 They had come across the first fragments of 13 individuals, 233 00:17:14,900 --> 00:17:17,232 possibly members of the same band. 234 00:17:17,469 --> 00:17:22,463 They may have all perished together perhaps in a flash flood. 235 00:17:23,308 --> 00:17:26,675 The fossils from Hadar and similar ones from Tanzania 236 00:17:26,912 --> 00:17:30,507 represent from 35 to 65 individuals. 237 00:17:30,749 --> 00:17:32,341 Based on the abundant evidence, 238 00:17:32,584 --> 00:17:35,246 Johanson and his colleagues felt confident 239 00:17:35,487 --> 00:17:39,218 in announcing an entirely new species. 240 00:17:40,592 --> 00:17:43,993 They called it Australopithecus Afarensis 241 00:17:44,229 --> 00:17:46,993 and put forth the still controversial idea 242 00:17:47,232 --> 00:17:50,724 that it is the common ancestor to other Australopithecines 243 00:17:50,969 --> 00:17:52,493 who eventually died out, 244 00:17:52,738 --> 00:17:57,107 as well as the line that led to true humans. 245 00:18:01,947 --> 00:18:04,677 In the laboratory fragments of skulls and jaws 246 00:18:04,917 --> 00:18:09,013 from several males were combined into a composite plaster skull 247 00:18:09,254 --> 00:18:12,621 by Johanson's colleague, Dr. Tim White. 248 00:18:13,492 --> 00:18:15,687 After initial discovery and analysis 249 00:18:15,928 --> 00:18:19,830 scientists rarely work with an original, fragile fossil. 250 00:18:20,065 --> 00:18:20,292 In fact, 251 00:18:20,599 --> 00:18:23,796 the fossils are usually returned to the country where they were found. 252 00:18:24,036 --> 00:18:25,503 But these durable casts 253 00:18:25,737 --> 00:18:30,140 are exact replicas down to the most minute details. 254 00:18:35,414 --> 00:18:37,382 In Alexandria, Virginia, 255 00:18:37,616 --> 00:18:40,779 the composite skull begins a magical transformation 256 00:18:41,019 --> 00:18:45,547 in the hands of anthropologist turned artist, John Gurche. 257 00:18:49,561 --> 00:18:53,588 Gurche has been fascinated with human evolution since childhood. 258 00:18:53,832 --> 00:18:56,733 Today he combines the talents of an anatomist 259 00:18:56,969 --> 00:18:59,233 with those of a master sculptor. 260 00:18:59,471 --> 00:19:02,565 His workroom is a cross between an artist's studio 261 00:19:02,808 --> 00:19:05,675 and a scientific laboratory. 262 00:19:11,783 --> 00:19:14,718 Placing the eyes is often a special moment. 263 00:19:14,953 --> 00:19:18,116 I base the position of the eyes on scientific data, 264 00:19:18,357 --> 00:19:21,190 but there's also often a mystical side of it as well. 265 00:19:21,426 --> 00:19:25,226 That is often the moment when I begin to feel that I'm being watched 266 00:19:25,464 --> 00:19:29,161 by the thing I'm working on that it is not so much a thing 267 00:19:29,401 --> 00:19:32,302 of clay and plaster, but is actually a living being. 268 00:19:34,706 --> 00:19:37,573 What I really want to do is get at the human past, 269 00:19:37,809 --> 00:19:40,801 and having the scientific data behind me 270 00:19:41,046 --> 00:19:42,775 makes it much more rewarding for me 271 00:19:43,015 --> 00:19:44,778 because I can believe in what I'm doing. 272 00:19:45,017 --> 00:19:46,575 I can believe that the face that's developing 273 00:19:46,818 --> 00:19:48,718 in front of me is very much like the face 274 00:19:48,954 --> 00:19:51,252 of the individual that it actually belonged to. 275 00:19:57,629 --> 00:19:59,062 The really fascinating thing about working 276 00:19:59,298 --> 00:20:01,858 with Australopithecines is that you have something that's right 277 00:20:02,100 --> 00:20:04,933 on the line between being human and not human. 278 00:20:05,170 --> 00:20:06,933 You have a lot of features that are ape like 279 00:20:07,172 --> 00:20:09,936 and yet it's in the process of becoming human. 280 00:20:15,280 --> 00:20:19,239 The reconstruction will take Gurche more than two months. 281 00:20:19,484 --> 00:20:20,451 It is painstaking, 282 00:20:20,686 --> 00:20:25,851 arduous work that often continues well into the night. 283 00:20:30,329 --> 00:20:31,796 I'd really like to be able to make the claim 284 00:20:32,030 --> 00:20:34,692 for this kind of work that it's a hard science. 285 00:20:34,933 --> 00:20:36,924 Unfortunately, it's not. 286 00:20:37,169 --> 00:20:39,330 It's as good as it can be without actually going back 287 00:20:39,571 --> 00:20:42,836 in time and coming face to face with our ancestors. 288 00:21:00,425 --> 00:21:03,656 The end result is often a surprise even to me. 289 00:21:03,895 --> 00:21:07,387 I'm basing the restoration on clues one by one 290 00:21:07,633 --> 00:21:09,464 that I'm getting from the bony anatomy 291 00:21:09,701 --> 00:21:14,968 and the cumulative effect of those clues is often a surprise. 292 00:21:18,443 --> 00:21:21,241 A face long lost to the tides of time 293 00:21:21,480 --> 00:21:24,847 emerges out of plaster and clay. 294 00:21:25,384 --> 00:21:29,912 We come face to face with one of out earliest known relatives 295 00:21:30,155 --> 00:21:34,114 across a chasm of three million years. 296 00:21:45,537 --> 00:21:48,005 More than half a million years before Lucy 297 00:21:48,240 --> 00:21:51,937 and more than a thousand miles away, a volcano erupted 298 00:21:52,177 --> 00:21:56,409 spewing ash across Tanzania's Serengeti Plain. 299 00:21:56,648 --> 00:22:00,709 Then a moment was frozen in time. 300 00:22:01,353 --> 00:22:05,619 An amazing sequence of chance events created a record unique 301 00:22:05,857 --> 00:22:08,417 in the pageant of prehistory. 302 00:22:08,660 --> 00:22:13,063 Soon after the eruption the rain clouds that had been threatening parted. 303 00:22:13,298 --> 00:22:14,560 Then three hominids, 304 00:22:14,800 --> 00:22:18,668 perhaps of the same species as Lucy, walked by. 305 00:22:18,904 --> 00:22:22,670 Their footprints left an impression in the dampened ash fall. 306 00:22:22,908 --> 00:22:26,935 Only because the sun then came out did the footprints harden. 307 00:22:27,179 --> 00:22:32,082 And only because continued eruptions laid down yet other layers of ash 308 00:22:32,317 --> 00:22:38,278 were the traces entombed more than three and a half million years. 309 00:22:39,758 --> 00:22:40,622 Today this area, 310 00:22:40,859 --> 00:22:47,321 not far from Olduvai Gorge in northern Tanzania, is called Laetoli. 311 00:22:47,599 --> 00:22:51,831 Here, in 1978, a team led by Dr. Mary Leakey 312 00:22:52,070 --> 00:22:55,506 finds what is one of the most astounding archeological discoveries 313 00:22:55,741 --> 00:22:59,973 of all time the very footprints not seen on this earth 314 00:23:00,212 --> 00:23:04,774 since the eruption of one volcano millions of years ago. 315 00:23:05,016 --> 00:23:07,814 Dr. Leakey and her team begin the delicate process 316 00:23:08,053 --> 00:23:10,988 of removing the cement hard rock. 317 00:23:17,496 --> 00:23:21,762 To Dr. Leakey the prints are more evocative than any fossil. 318 00:23:22,000 --> 00:23:26,596 They tell a vivid story of one fleeting moment in time. 319 00:23:26,838 --> 00:23:30,569 The track of footprints that you see here on my left 320 00:23:30,809 --> 00:23:34,609 was a truly remarkable find that we made this season. 321 00:23:34,846 --> 00:23:37,076 It's a trail left by three people 322 00:23:37,315 --> 00:23:40,682 who walked across a flat expanse of volcanic ash 323 00:23:40,919 --> 00:23:43,683 three and a half million years ago. 324 00:23:43,922 --> 00:23:46,789 We can say they were relatively short. 325 00:23:47,025 --> 00:23:52,964 We can estimate that their height was probably between four and five feet. 326 00:23:53,198 --> 00:23:57,760 We can say they had this free striding walk. 327 00:23:58,003 --> 00:24:01,439 One assumes they were perhaps holding hands or 328 00:24:01,673 --> 00:24:06,440 They are so evenly spaced, the tracks, and they're keeping step, 329 00:24:06,678 --> 00:24:10,114 always left foot for left foot and right foot for right foot, 330 00:24:10,348 --> 00:24:15,513 that it may, for all we know, have been a family party. 331 00:24:15,754 --> 00:24:19,349 The emotional impact of the footprints is universal, 332 00:24:19,591 --> 00:24:22,992 but scientifically they arouse debate: 333 00:24:23,228 --> 00:24:26,322 Were these creatures related to Lucy, 334 00:24:26,565 --> 00:24:32,435 and could their upright walk so long ago have been the same as ours today? 335 00:24:34,840 --> 00:24:38,571 Tim White helped excavate the Laetoli footprints. 336 00:24:38,810 --> 00:24:41,438 Now, to answer some of the questions raised, 337 00:24:41,680 --> 00:24:43,910 he has devised an experiment. 338 00:24:44,149 --> 00:24:46,242 With our closest living relative, 339 00:24:46,485 --> 00:24:49,716 he walks across an expanse of wet sand. 340 00:24:49,955 --> 00:24:54,551 Its consistency is roughly the same as damp volcanic ash. 341 00:24:59,865 --> 00:25:02,493 Here we have my footprint with a strong heel strike 342 00:25:02,734 --> 00:25:05,760 and the big toe in line with the other toes. 343 00:25:06,004 --> 00:25:09,531 The chimpanzee's footprint is here and the knuckle print is right behind it. 344 00:25:09,774 --> 00:25:13,232 We see the chimpanzee's toe is divergent, 345 00:25:13,478 --> 00:25:16,538 whereas the human toe is in line with the other toes. 346 00:25:16,781 --> 00:25:19,875 The human foot also has a dramatic arch to it. 347 00:25:20,118 --> 00:25:23,576 The chimpanzee foot and its print lacks this arch. 348 00:25:23,822 --> 00:25:27,280 And at Laetoli we have evidence from three and a half million years ago 349 00:25:27,526 --> 00:25:31,326 of a large toe in line with the rest of the toes and a longitudinal arch 350 00:25:31,563 --> 00:25:33,053 and a strong heel strike. 351 00:25:33,298 --> 00:25:34,196 In other words, 352 00:25:34,432 --> 00:25:37,697 the human pattern has been established three and a half million years ago 353 00:25:37,936 --> 00:25:40,427 in Tanzania with these early hominids. 354 00:25:44,309 --> 00:25:48,575 Some scientists feel that only by studying the locomotion of apes 355 00:25:48,813 --> 00:25:55,218 can we know how Lucy and our other early ancestors actually walked. 356 00:25:55,487 --> 00:25:58,047 At the state University of New York at Stony Brook, 357 00:25:58,290 --> 00:26:02,056 a team led by anatomists Randall Susman and Jack Stern 358 00:26:02,294 --> 00:26:05,058 videotapes the movements of an orangutan. 359 00:26:05,297 --> 00:26:08,232 They have also extensively studied chimpanzees. 360 00:26:08,466 --> 00:26:09,433 Come on. 361 00:26:11,570 --> 00:26:14,437 Electrodes implanted in the arm and leg muscles 362 00:26:14,673 --> 00:26:17,733 send signals to monitoring equipment. 363 00:26:17,976 --> 00:26:21,776 Clothing holds the transmitter in place on the animal's back. 364 00:26:22,514 --> 00:26:24,846 That's good bipedalism. Keep him going. 365 00:26:25,750 --> 00:26:29,846 On their screen Susman and Stern receive a superimposed image 366 00:26:30,088 --> 00:26:34,149 of the electrical output of the muscles as the animal moves. 367 00:26:34,392 --> 00:26:35,916 One intriguing finding: 368 00:26:36,161 --> 00:26:39,619 The hip muscles used by apes in climbing are used in many 369 00:26:39,864 --> 00:26:43,595 of the same ways as human hip muscles are in walking. 370 00:26:43,902 --> 00:26:47,030 So the transition from tree dweller to ground walker 371 00:26:47,272 --> 00:26:49,740 may have been relatively simple. 372 00:26:49,975 --> 00:26:53,502 The pattern of muscle usage was already in place. 373 00:26:54,646 --> 00:26:55,704 Good boy. 374 00:26:59,551 --> 00:27:02,987 But Susman and Stern, unlike Johanson, White, and others, 375 00:27:03,221 --> 00:27:07,123 believe that these ancestors did not walk exactly as we do, 376 00:27:07,359 --> 00:27:10,817 but more like an ape when it walks on two legs. 377 00:27:11,096 --> 00:27:13,496 They maintain that those creatures, like apes, 378 00:27:13,732 --> 00:27:16,064 still spent much time in the trees 379 00:27:16,301 --> 00:27:19,395 and had not yet fully adapted to life on the ground. 380 00:27:22,073 --> 00:27:23,199 In earlier days, 381 00:27:23,441 --> 00:27:27,104 anthropologists compared and contrasted stones and bones, 382 00:27:27,345 --> 00:27:30,803 but could only ponder questions about behavior. 383 00:27:31,983 --> 00:27:33,507 Today they can directly address 384 00:27:33,752 --> 00:27:37,051 some of the fundamental issues of our ancestry. 385 00:27:37,288 --> 00:27:39,415 How did Lucy and the others live? 386 00:27:39,958 --> 00:27:41,391 Where did they sleep? 387 00:27:41,626 --> 00:27:43,355 What did they eat? 388 00:27:48,633 --> 00:27:53,036 In the line of other Australopithecines to which Lucy may have given rise, 389 00:27:53,271 --> 00:27:56,570 there were smaller creatures known as graciles 390 00:27:56,808 --> 00:28:01,177 and robust ones with puzzlingly massive jaws and teeth 391 00:28:02,347 --> 00:28:07,307 The fossil teeth themselves hold clues to what these hominids were eating. 392 00:28:08,086 --> 00:28:13,285 Thousands or millions of years later, the wear on the teeth remains. 393 00:28:15,360 --> 00:28:17,157 Let's see if we can't acquire that image. 394 00:28:17,395 --> 00:28:19,693 Dr. Fred Grine, also at Stony Brook, 395 00:28:19,931 --> 00:28:25,062 studies diet, using a scanning electron microscope and computer graphics. 396 00:28:25,303 --> 00:28:29,171 Different foods leave distinctively different marks on teeth. 397 00:28:29,407 --> 00:28:31,967 Comparing the two patterns of a gracile 398 00:28:32,210 --> 00:28:34,644 and robust australopithecine side by side, 399 00:28:34,879 --> 00:28:36,039 it becomes quite evident 400 00:28:36,281 --> 00:28:38,545 that the wear patterns are very dissimilar, 401 00:28:38,783 --> 00:28:40,182 and that, therefore, 402 00:28:40,418 --> 00:28:42,409 the foods they would have eaten would have been dissimilar. 403 00:28:42,654 --> 00:28:45,521 The scratches and the polished surfaces found 404 00:28:45,757 --> 00:28:49,090 on a gracile Australopithecine molar would have been produced 405 00:28:49,327 --> 00:28:52,660 by soft foods such as soft fruits and leaves, 406 00:28:52,897 --> 00:28:55,127 whereas the pitting which characterizes 407 00:28:55,366 --> 00:28:57,891 a robust Australopithecine molar would have been produced 408 00:28:58,136 --> 00:29:00,798 by hard food objects such as seeds and nuts. 409 00:29:04,909 --> 00:29:07,207 Shrouded in myth since their discovery 410 00:29:07,445 --> 00:29:10,141 Australopithecines were long characterized 411 00:29:10,381 --> 00:29:13,145 as blood thirsty killer apes. 412 00:29:14,119 --> 00:29:17,316 It now seems far more likely they were vegetarians 413 00:29:17,555 --> 00:29:19,853 who should be seen in their more rightful place 414 00:29:20,091 --> 00:29:22,753 in the human evolutionary drama. 415 00:29:23,328 --> 00:29:27,924 Robust Australopithecines flourished for well over a million years, 416 00:29:28,166 --> 00:29:32,830 then disappeared an apparent evolutionary dead end. 417 00:29:35,507 --> 00:29:38,499 It is possible they lost out in competition with another, 418 00:29:38,743 --> 00:29:42,975 more intelligent species a hominid tool user 419 00:29:43,214 --> 00:29:47,014 a line that would eventually lead to modern human beings. 420 00:29:52,457 --> 00:29:54,391 Like the remains of their predecessors 421 00:29:54,626 --> 00:29:58,528 the fossil bones of the tool users are almost always discovered 422 00:29:58,763 --> 00:30:02,392 in deposits formed along lake shores or streams. 423 00:30:04,068 --> 00:30:05,831 The areas around Lake Turkana 424 00:30:06,070 --> 00:30:08,561 in northern Kenya have a record of both human 425 00:30:08,807 --> 00:30:12,470 and animal life that is perhaps unmatched in the world. 426 00:30:21,219 --> 00:30:23,346 Every week during the field season, 427 00:30:23,588 --> 00:30:27,684 a light plane from Nairobi brings expedition leader Richard Leakey, 428 00:30:27,926 --> 00:30:30,895 son of Louis and Mark Leakey. 429 00:30:32,864 --> 00:30:36,425 Despite an early decision not to follow in his parents' footsteps, 430 00:30:36,668 --> 00:30:39,694 Richard's passion for paleontology won out. 431 00:30:39,938 --> 00:30:44,875 For two decades he has been digging here with remarkable success. 432 00:30:45,243 --> 00:30:50,078 Over the years since 1968 the Turkana region has yielded ten 433 00:30:50,315 --> 00:30:53,716 to fifteen thousand fossil remains. 434 00:30:53,952 --> 00:30:59,390 Most are animal, but amazingly more than 300 are early human. 435 00:30:59,858 --> 00:31:04,693 Leakey has been called the "organizing genius of modern paleontology". 436 00:31:04,929 --> 00:31:07,625 He heads a team that scours the exposures daily 437 00:31:07,866 --> 00:31:09,493 for several months at a time. 438 00:31:09,734 --> 00:31:14,603 They cover every foot of the 600 square mile area each year. 439 00:31:15,607 --> 00:31:18,474 Looking for new evidence in any scientific discipline is exciting. 440 00:31:18,710 --> 00:31:20,507 In our field it's particularly rewarding 441 00:31:20,745 --> 00:31:22,440 because every year there is a new opportunity. 442 00:31:22,680 --> 00:31:26,207 These vast areas of desert are periodically washed by rain. 443 00:31:26,451 --> 00:31:28,112 and every time it rains, 444 00:31:28,353 --> 00:31:29,320 there's a chance that something new 445 00:31:29,554 --> 00:31:32,079 will be exposed something new that's going 446 00:31:32,323 --> 00:31:33,347 to tell us something that we never knew before. 447 00:31:33,591 --> 00:31:35,559 It's going to expose a completely new chapter 448 00:31:35,793 --> 00:31:37,761 in our understanding of human origins. 449 00:31:37,996 --> 00:31:39,361 And it's really great fun to be out there 450 00:31:39,597 --> 00:31:42,532 on the desert realizing that although you were there the year before, 451 00:31:42,767 --> 00:31:45,600 this year it will be different because it rained a few months ago 452 00:31:45,837 --> 00:31:48,635 and something new must have washed up somewhere. 453 00:31:48,873 --> 00:31:51,205 It's simply a question of finding it. 454 00:31:52,010 --> 00:31:55,446 In 1984 a small piece of skull was found. 455 00:31:55,680 --> 00:32:01,710 It was immediately recognized as human by Leakey's colleague Kamoya Kimeu. 456 00:32:02,220 --> 00:32:05,087 With anatomist Alan Walker and the rest of the team, 457 00:32:05,323 --> 00:32:09,817 he went on to unearth a seemingly endless array of bones. 458 00:32:10,495 --> 00:32:13,123 The rest of the skull and face were found 459 00:32:13,364 --> 00:32:18,392 and painstakingly glued together from 70 separate pieces. 460 00:32:20,939 --> 00:32:24,636 The bones were clearly those of a Homo erectus, 461 00:32:24,876 --> 00:32:29,973 a species on the path that eventually led to modern humans. 462 00:32:30,214 --> 00:32:32,808 The skeleton, a boy of about 12, 463 00:32:33,051 --> 00:32:36,748 was dated at more than a million and a half years old. 464 00:32:36,988 --> 00:32:39,183 Far more complete than even Lucy, 465 00:32:39,424 --> 00:32:43,827 it is one of the most remarkable finds in the study of human evolution. 466 00:32:44,062 --> 00:32:46,189 The boy differs little from a modern human 467 00:32:46,431 --> 00:32:50,333 in stature and body proportions. 468 00:32:50,802 --> 00:32:54,499 An artist imagines what he might have looked like; 469 00:32:54,739 --> 00:32:59,438 Richard Leakey reconstructs what his life may have been like. 470 00:32:59,677 --> 00:33:02,669 The area that he was living in was probably lake margin, 471 00:33:02,914 --> 00:33:05,212 swampy ground near the lake edge. 472 00:33:05,450 --> 00:33:07,680 There was grassland; there were forests; 473 00:33:07,919 --> 00:33:10,114 there were permanent rivers running into the lake. 474 00:33:10,355 --> 00:33:13,324 Probably an enormous amount of animals plains animals, 475 00:33:13,558 --> 00:33:14,991 carnivores, scavengers. 476 00:33:15,226 --> 00:33:18,354 I suppose one could visualize an area like one of the better national parks 477 00:33:18,596 --> 00:33:19,392 in East Africa today, 478 00:33:19,630 --> 00:33:23,566 teeming with wildlife ideal conditions for an early human. 479 00:33:23,801 --> 00:33:26,235 I think it's remarkable because it's so complete. 480 00:33:26,471 --> 00:33:29,804 But perhaps another aspect that is often overlooked 481 00:33:30,041 --> 00:33:31,872 is that many people who don't like the idea 482 00:33:32,110 --> 00:33:35,443 of human evolution have been able to discount much of the work we've done. 483 00:33:35,680 --> 00:33:38,945 On the basis that it was built on fragmentary evidence 484 00:33:39,183 --> 00:33:40,616 just little bits and pieces. 485 00:33:40,852 --> 00:33:41,784 And who knows. 486 00:33:42,020 --> 00:33:43,920 Those little bits of bone could belong to anything. 487 00:33:44,155 --> 00:33:45,520 To confront some of these people 488 00:33:45,757 --> 00:33:48,157 with a complete skeleton that is so manifestly human 489 00:33:48,393 --> 00:33:50,953 and is so obviously related to us. 490 00:33:51,195 --> 00:33:52,560 In a context where it's definitely one 491 00:33:52,797 --> 00:33:57,461 and a half million years or a little more is fairly convincing evidence. 492 00:33:57,702 --> 00:34:01,103 And I think many of the people who are fence sitters on this discussion 493 00:34:01,339 --> 00:34:04,570 about creationism versus evolution are going to have to get off the fence 494 00:34:04,809 --> 00:34:06,401 in the light of this discovery. 495 00:34:11,182 --> 00:34:15,346 A Homo erectus head would have looked very different from our own. 496 00:34:15,586 --> 00:34:21,024 It had a heavy brow ridge, jutting face, and a smaller braincase. 497 00:34:21,259 --> 00:34:23,819 It is very likely their skin was dark 498 00:34:24,062 --> 00:34:27,998 nature's protection against the tropical sun. 499 00:34:28,633 --> 00:34:33,593 Some scientists believe Homo erectus was the first hominid to hunt. 500 00:34:33,838 --> 00:34:37,569 In earlier times our ancestors, themselves prey, 501 00:34:37,809 --> 00:34:41,438 were probably accepted without fear at Africa's water holes. 502 00:34:41,679 --> 00:34:43,203 But when they began to hunt, 503 00:34:43,448 --> 00:34:47,145 the other animals would sense them as a threat. 504 00:34:50,822 --> 00:34:54,121 Exactly when hunting began may never be known. 505 00:34:54,358 --> 00:34:56,121 But it is clear that the tools made 506 00:34:56,360 --> 00:35:01,662 by erectus were far more sophisticated than any that had been made before. 507 00:35:06,037 --> 00:35:08,835 Even the earliest and most primitive tools marked 508 00:35:09,073 --> 00:35:11,701 a momentous advance for humankind 509 00:35:11,943 --> 00:35:14,707 the first evidence of culture. 510 00:35:15,179 --> 00:35:17,579 And, as intelligence grew over time, 511 00:35:17,815 --> 00:35:22,047 tools became ever more refined and specialized. 512 00:35:38,202 --> 00:35:40,796 Learning how tools may have been made and used 513 00:35:41,038 --> 00:35:44,633 provides a window into the behavior of our ancestors. 514 00:35:44,876 --> 00:35:50,815 Dr. Nicholas Toth of Indiana University has become a master of the technique. 515 00:35:52,383 --> 00:35:54,613 Many scientists had believed that the objective 516 00:35:54,852 --> 00:35:58,982 of the earliest toolmakers was to create these large cobbles 517 00:35:59,223 --> 00:36:02,590 and that the chipped off flakes were merely the debris. 518 00:36:02,827 --> 00:36:06,786 Toth's experimentation led him to conclude it was quite the reverse. 519 00:36:07,031 --> 00:36:09,329 The razor sharp flakes, he believes, 520 00:36:09,567 --> 00:36:13,936 were often the tools our ancestors made and used. 521 00:36:17,375 --> 00:36:19,673 If you take a hard look at your average human being, 522 00:36:19,911 --> 00:36:20,809 we're very poor carnivores. 523 00:36:21,045 --> 00:36:24,412 We have small canines; we don't have slashing claws; 524 00:36:24,649 --> 00:36:25,946 we're not very strong; 525 00:36:26,184 --> 00:36:28,516 we don't look anything like a hyena or a lion. 526 00:36:28,753 --> 00:36:31,688 And I think with the simplest flake stone technology, 527 00:36:31,923 --> 00:36:34,517 you can butcher an animal from the size of a gazelle 528 00:36:34,759 --> 00:36:38,525 to the size of an elephant with absolutely no problem. 529 00:36:52,476 --> 00:36:56,037 Even hyenas will not tackle the biggest bones on a carcass. 530 00:36:56,280 --> 00:36:59,841 But with the simplest tools used like a hammer and anvil, 531 00:37:00,084 --> 00:37:04,020 an early hominid could get at the marrow inside. 532 00:37:06,324 --> 00:37:10,385 Almost completely fat, marrow is high in calories, 533 00:37:10,628 --> 00:37:15,964 essential to a hominid roaming the African landscape. 534 00:37:17,034 --> 00:37:18,592 When an animal bone is butchered, 535 00:37:18,836 --> 00:37:22,067 the edge of the tool leaves cutmarks. 536 00:37:23,241 --> 00:37:25,004 Often ignored in the past, 537 00:37:25,243 --> 00:37:31,239 cutmarks are now recognized as vital clues to the behavior of early humans. 538 00:37:31,482 --> 00:37:36,112 They can tell us, for instance, which animals our ancestors ate, 539 00:37:36,354 --> 00:37:39,118 which parts of these animals they may have favored, 540 00:37:39,357 --> 00:37:44,556 and ultimately they may reveal when hominids became successful hunters. 541 00:37:46,831 --> 00:37:50,892 In the past scientists often suspected cutmarks were man made 542 00:37:51,135 --> 00:37:53,831 if tools were found nearby. 543 00:37:54,071 --> 00:38:00,670 Today they know many factors from the natural world can plant false clues. 544 00:38:03,514 --> 00:38:08,213 One factor not often considered came to light in unusual experiment conducted 545 00:38:08,452 --> 00:38:11,012 by Dr. Kay Behrensmeyer. 546 00:38:11,255 --> 00:38:14,019 In Asia she had been puzzled by grooves and scratches 547 00:38:14,258 --> 00:38:16,852 on bones eight to nine million years old, 548 00:38:17,094 --> 00:38:19,426 long before hominids existed. 549 00:38:19,664 --> 00:38:21,154 Later, in Africa, 550 00:38:21,399 --> 00:38:26,234 she saw how bones frequently are trampled by migrating game herds. 551 00:38:26,470 --> 00:38:28,529 Could random trampling, she wondered, 552 00:38:28,773 --> 00:38:33,710 leave marks that could be confused with those made purposefully by a tool. 553 00:38:35,313 --> 00:38:37,781 Dr. Pat Shipman of Johns Hopkins University 554 00:38:38,015 --> 00:38:42,008 has been experimenting with cutmarks since 1978. 555 00:38:42,253 --> 00:38:44,778 She believes that by creating them herself 556 00:38:45,022 --> 00:38:47,286 and examining them microscopically, 557 00:38:47,525 --> 00:38:54,021 she and other can better define what is a true cutmark and what is not. 558 00:38:56,634 --> 00:39:00,661 Into a scanning electron microscope, or SEM, 559 00:39:00,905 --> 00:39:05,808 she inserts a gold coated cast of the marks she has made. 560 00:39:07,078 --> 00:39:08,602 Compared with regular microscopes, 561 00:39:08,846 --> 00:39:11,337 the SEM offers greater depth of field to look 562 00:39:11,582 --> 00:39:14,107 at three-dimensional structures. 563 00:39:15,286 --> 00:39:17,584 It seems likely that marks on bones found 564 00:39:17,822 --> 00:39:22,020 in sandy soil may remain open to interpretation. 565 00:39:22,259 --> 00:39:23,021 But for others, 566 00:39:23,260 --> 00:39:26,354 Shipman has found that what distinguish a true cutmark 567 00:39:26,597 --> 00:39:32,331 are the fine lines within a groove. Experimenting, she says, 568 00:39:32,570 --> 00:39:34,367 is the best way to suggest what happened 569 00:39:34,605 --> 00:39:38,837 to a bone thousands or millions of years ago. 570 00:39:39,210 --> 00:39:41,405 The problem for us today 571 00:39:41,645 --> 00:39:46,344 is to tease out of the past, to coax out of the evidence 572 00:39:46,584 --> 00:39:49,849 the specialness of early hominids. 573 00:39:50,087 --> 00:39:52,681 And once we know where we started and how we started 574 00:39:52,923 --> 00:39:54,083 and what was important then, 575 00:39:54,325 --> 00:39:57,294 we may have a very different idea of what it is to be human. 576 00:39:59,263 --> 00:40:04,223 Homo erectus was the first human species to leave Africa. 577 00:40:04,468 --> 00:40:07,665 Sometime after a million years ago, their fossil remains, 578 00:40:07,905 --> 00:40:09,964 and those of a number of African mammals, 579 00:40:10,207 --> 00:40:14,075 first appear in other tropical regions of the world. 580 00:40:14,512 --> 00:40:15,945 Some scientists believe that 581 00:40:16,180 --> 00:40:20,344 by then meat had become an appreciable part of the diet. 582 00:40:20,584 --> 00:40:22,449 With the addition of this important protein, 583 00:40:22,686 --> 00:40:26,019 this intelligent and curious creature would have been well equipped 584 00:40:26,257 --> 00:40:29,226 to expand out to unknown lands. 585 00:40:31,395 --> 00:40:36,628 We know from preserved remains and tools that erectus reached China, 586 00:40:36,867 --> 00:40:39,995 Java and southern Europe. 587 00:40:43,674 --> 00:40:45,471 On the Sussex coast of England, 588 00:40:45,709 --> 00:40:50,408 quarry workers were the first to unearth a site called Boxgrove. 589 00:40:50,648 --> 00:40:53,708 It may hold answers to the life style of the species that came 590 00:40:53,951 --> 00:40:56,920 after Homo erectus. 591 00:40:58,255 --> 00:41:00,519 About 350,000 years old, 592 00:41:00,758 --> 00:41:03,921 Boxgrove is an unusually important site. 593 00:41:04,161 --> 00:41:05,628 It covers a hundred acres, 594 00:41:05,863 --> 00:41:08,093 and it contains vast numbers of tools 595 00:41:08,332 --> 00:41:13,269 and animal bones that are extraordinarily well preserved. 596 00:41:14,438 --> 00:41:17,839 Erectus probably never reached this far north in Europe, 597 00:41:18,075 --> 00:41:20,043 but his descendants did. 598 00:41:20,277 --> 00:41:24,976 They were the earliest form of our own species, Homo sapiens. 599 00:41:25,216 --> 00:41:27,844 Here flags mark the locations where their tools 600 00:41:28,085 --> 00:41:30,815 or fragments have been found. 601 00:41:32,056 --> 00:41:34,354 Animal bones abound. 602 00:41:34,692 --> 00:41:36,091 Deer teeth. 603 00:41:39,196 --> 00:41:42,563 Part of the lower jaw of an extinct bear. 604 00:41:45,503 --> 00:41:50,372 A large pelvic bone with cutmarks that hint at a tool user's presence. 605 00:41:50,608 --> 00:41:55,375 Yet strangely, no human remains have been found. 606 00:41:57,715 --> 00:42:02,277 So untouched is the site that if one could peer back through the centuries, 607 00:42:02,520 --> 00:42:06,854 here would sit an ancestor chipping stone to make a tool. 608 00:42:10,961 --> 00:42:15,762 Nearby, what may have been that very tool is held again in a human hand 609 00:42:16,000 --> 00:42:20,232 for the first time in 350,000 years. 610 00:42:20,471 --> 00:42:22,439 Perhaps it was used to scrape wood, 611 00:42:22,673 --> 00:42:26,268 prepare a hide, or dig for roots in the ground. 612 00:42:26,510 --> 00:42:30,640 It may have helped kill the deer or bring down the bear. 613 00:42:30,881 --> 00:42:34,146 But where is the maker of the tool? 614 00:42:41,158 --> 00:42:45,959 Once Boxgrove was a beach front, ideal for the preservation of fossils. 615 00:42:46,196 --> 00:42:50,394 Why no people have been found remains just another missing piece 616 00:42:50,634 --> 00:42:52,625 in the human puzzle. 617 00:42:56,740 --> 00:43:01,734 These pre modern Homo sapiens seemingly evolved from Homo erectus, 618 00:43:01,979 --> 00:43:04,311 but their exact relationship to erectus, 619 00:43:04,548 --> 00:43:10,384 as well as to the more modern humans who followed, is still unclear. 620 00:43:12,222 --> 00:43:17,159 One of the most puzzling of these pre modern Homo sapiens was Neanderthal. 621 00:43:17,394 --> 00:43:23,060 Some scientists think they were a short lived side branch on the family tree. 622 00:43:23,567 --> 00:43:26,001 Indeed, the longest ongoing controversy 623 00:43:26,236 --> 00:43:31,299 in paleoanthropology has been who were the Neanderthals? 624 00:43:31,542 --> 00:43:33,908 But there are more questions than answers. 625 00:43:34,144 --> 00:43:37,113 We do know the Neanderthals were not the dimwitted brutes 626 00:43:37,348 --> 00:43:40,010 so often portrayed by cartoonists. 627 00:43:40,250 --> 00:43:43,879 But one characteristic attributed to them is true. 628 00:43:44,121 --> 00:43:46,419 They were cave people. 629 00:43:51,328 --> 00:43:53,057 At Kebara Cave in Israel, 630 00:43:53,297 --> 00:43:59,497 a Neanderthal excavation in run jointly by Israeli and French teams. 631 00:44:01,438 --> 00:44:02,462 When carefully studied, 632 00:44:02,706 --> 00:44:06,142 layers in a cave can tell a rich story. 633 00:44:06,377 --> 00:44:10,336 Too often in the past they were dug with reckless abandon. 634 00:44:10,581 --> 00:44:14,517 Thirty years ago Kebara was attacked with pickaxe and shovel. 635 00:44:14,752 --> 00:44:21,021 Today, dental probes and fine brushes move methodically, inch by inch. 636 00:44:23,494 --> 00:44:28,830 Each pail of dirt is screened for even the tiniest fragment of bone or stone. 637 00:44:29,066 --> 00:44:34,265 Each piece will then be washed, identified, labeled, and cataloged. 638 00:44:36,040 --> 00:44:38,531 By far the greatest number of finds at Kebara 639 00:44:38,776 --> 00:44:41,768 have been these well fashioned tools. 640 00:44:42,346 --> 00:44:46,612 Literally hundreds of thousands have been unearthed. 641 00:44:49,687 --> 00:44:54,147 The leader of the Israeli team is Professor Ofer Bar Yosef. 642 00:44:54,391 --> 00:44:57,622 He has clear evidence that over many thousands of years 643 00:44:57,861 --> 00:45:02,093 Neanderthals repeatedly occupied Kebara Cave. 644 00:45:02,332 --> 00:45:05,597 What we can see here are the fireplaces as built 645 00:45:05,836 --> 00:45:11,206 by the people around 45-46,000 years ago. 646 00:45:11,442 --> 00:45:14,343 And this is one of the special features of Kebara Cave 647 00:45:14,578 --> 00:45:16,409 that we can see these fireplaces 648 00:45:16,647 --> 00:45:18,672 which are built one on top of the other 649 00:45:18,916 --> 00:45:22,977 and always at the same place in the central area of the cave. 650 00:45:23,220 --> 00:45:24,414 They were either heating the area 651 00:45:24,655 --> 00:45:29,024 of the cave during wintertime or also using them for cooking. 652 00:45:29,259 --> 00:45:31,454 And then when you still have the hot ashes, 653 00:45:31,695 --> 00:45:34,459 spreading them so they can sleep on them. 654 00:45:34,698 --> 00:45:37,895 One problem that we should always keep in mind is that we cannot 655 00:45:38,135 --> 00:45:42,799 and we should not perhaps excavate the entire cave area 656 00:45:43,040 --> 00:45:46,601 because we have to preserve part of it for future archeologists 657 00:45:46,844 --> 00:45:51,008 who will probably use better techniques of excavation or better approaches. 658 00:45:51,248 --> 00:45:53,910 And, therefore, we'll never know the entire picture 659 00:45:54,151 --> 00:45:56,517 of what really happened everywhere. 660 00:45:58,722 --> 00:46:02,089 We do know Neanderthals camped in this natural shelter, 661 00:46:02,326 --> 00:46:04,157 or at least came here with food, 662 00:46:04,394 --> 00:46:08,262 perhaps huddling in groups around the warmth of a fire. 663 00:46:08,499 --> 00:46:12,128 We also know some of them died here. 664 00:46:15,205 --> 00:46:18,834 Neanderthals were the first people to bury their dead. 665 00:46:19,076 --> 00:46:20,134 This skeleton, 666 00:46:20,377 --> 00:46:23,869 except for the missing skull which may have been used in some ritual, 667 00:46:24,114 --> 00:46:28,551 is among the most complete Neanderthals ever found. 668 00:46:31,755 --> 00:46:36,385 What the meaning of burials was in the life of these long vanished ancestors 669 00:46:36,627 --> 00:46:38,857 cannot be known for certain. 670 00:46:39,096 --> 00:46:41,564 But the fact that they buried their dead links them 671 00:46:41,799 --> 00:46:45,599 to us in deep and meaningful ways. 672 00:46:47,638 --> 00:46:51,165 From Neanderthal excavations throughout Europe and the Middle East, 673 00:46:51,408 --> 00:46:54,639 a picture of how they lived has gradually emerged. 674 00:46:54,878 --> 00:46:57,472 Theirs was a non-settled existence. 675 00:46:57,714 --> 00:47:00,410 A socially organized people, they traveled in groups 676 00:47:00,651 --> 00:47:04,052 as they moved from place to place in search of food. 677 00:47:04,288 --> 00:47:09,817 Hardy and robust, they were probably much stronger than most modern people. 678 00:47:10,060 --> 00:47:14,121 They survived even in harsh Ice Age conditions. 679 00:47:14,364 --> 00:47:17,356 Whether they had language as we know it is unclear. 680 00:47:17,601 --> 00:47:20,570 But surely, in some sophisticated way, 681 00:47:20,804 --> 00:47:23,602 they communicated with their own. 682 00:47:26,643 --> 00:47:30,875 Then about 30 to 40,000 years ago these intelligent, 683 00:47:31,114 --> 00:47:34,675 well-adapted people mysteriously disappeared. 684 00:47:34,918 --> 00:47:39,287 They may or may not have evolved into modern Homo sapiens. 685 00:47:39,523 --> 00:47:43,186 If modern Homo sapiens evolved elsewhere and then migrated, 686 00:47:43,427 --> 00:47:47,193 Neanderthals may have simply lost out to them. 687 00:47:48,298 --> 00:47:50,323 Anatomically much like us, 688 00:47:50,567 --> 00:47:53,502 these early modern humans stood at the threshold of 689 00:47:53,737 --> 00:47:56,035 everything we usually define as human. 690 00:47:57,241 --> 00:48:01,644 Farming and the rise of great cities would await a later time. 691 00:48:01,879 --> 00:48:07,112 But these early modern humans were the very first to create fine art. 692 00:48:07,351 --> 00:48:08,750 This rich record of the past 693 00:48:08,986 --> 00:48:13,980 ranks among the greatest artistic achievements of humankind. 694 00:48:39,983 --> 00:48:43,783 We know these people spread to every habitable part of the globe, 695 00:48:44,021 --> 00:48:46,649 but where had they come from? 696 00:48:50,227 --> 00:48:54,186 One scientist at the British Museum of Natural History in London 697 00:48:54,431 --> 00:48:57,423 thinks the answer has been found. 698 00:48:57,668 --> 00:49:01,729 Physical anthropologist Dr. Chris Stringer. 699 00:49:01,972 --> 00:49:06,341 The research on the origin of modern people is interesting obviously 700 00:49:06,576 --> 00:49:09,875 because it deals with the origins of all living people alive today. 701 00:49:10,113 --> 00:49:14,049 And my idea of an African origin is based partly on the fossil evidence. 702 00:49:14,284 --> 00:49:16,980 I feel that modern people appeared earliest in Africa 703 00:49:17,220 --> 00:49:19,950 and then later on in other parts of the world. 704 00:49:20,190 --> 00:49:21,885 But there is also genetic data, 705 00:49:22,125 --> 00:49:26,186 and the genetic data also support the idea 706 00:49:26,430 --> 00:49:28,398 of an African origin of modern people. 707 00:49:29,599 --> 00:49:33,729 At the University of Hawaii one of the primary genetic researchers 708 00:49:33,971 --> 00:49:38,067 in this field investigates the migration patterns of modern races 709 00:49:39,176 --> 00:49:43,442 Dr. Becky Cann believes her research adds rather startling information 710 00:49:43,680 --> 00:49:46,945 to the theory of an African origin. 711 00:49:48,418 --> 00:49:52,479 All humans who are alive today can trace their ancestry 712 00:49:52,723 --> 00:49:55,624 in their genes back to a single female 713 00:49:55,859 --> 00:49:58,555 who, we think, lived in Africa 714 00:49:58,795 --> 00:50:02,322 sometime perhaps two hundred thousand years ago 715 00:50:03,567 --> 00:50:09,005 Dr. Cann bases her theory on studies of DNA extracted from women. 716 00:50:09,239 --> 00:50:11,571 She traces backward in time one part 717 00:50:11,808 --> 00:50:16,370 of the DNA molecule that only females can pass on. 718 00:50:17,647 --> 00:50:20,377 The genetic work is supplemented 719 00:50:20,617 --> 00:50:24,610 with interviews about the women's maternal ancestry. 720 00:50:24,855 --> 00:50:28,256 Could I ask you about your maternal grandmother, your mother's mother? 721 00:50:28,492 --> 00:50:33,486 My grandmother was born on August 10, 1903 in Macau, 722 00:50:33,730 --> 00:50:36,665 Macau is the coast of China. 723 00:50:36,900 --> 00:50:39,630 Dr. Cann has studied Americans of European, 724 00:50:39,870 --> 00:50:41,861 African, and Asian descent, 725 00:50:42,105 --> 00:50:44,801 as well as Australian Aborigines. 726 00:50:46,376 --> 00:50:49,903 By comparing small segments of DNA from these women, 727 00:50:50,147 --> 00:50:54,083 Dr. Cann assesses the similarities and the differences. 728 00:50:54,317 --> 00:50:56,046 The more alike the DNA, 729 00:50:56,286 --> 00:50:59,517 the more closely related two individuals are. 730 00:50:59,756 --> 00:51:00,552 With a computer, 731 00:51:00,791 --> 00:51:05,319 Cann suggests different migration patterns over the centuries. 732 00:51:05,562 --> 00:51:07,553 If she is right, modern humans, 733 00:51:07,798 --> 00:51:12,326 like earlier hominids, evolved in Africa. 734 00:51:13,804 --> 00:51:16,932 In Africa it seems that the evolution of modern people first began 735 00:51:17,174 --> 00:51:20,666 and from there we all trace our ancestry. 736 00:51:20,911 --> 00:51:22,936 So we're all very closely related. 737 00:51:23,180 --> 00:51:26,343 And that goes for all people American Indians, 738 00:51:26,583 --> 00:51:28,483 Australian Aborigines, Eskimos, 739 00:51:28,718 --> 00:51:30,310 Europeans we all trace our origin to Africa, 740 00:51:30,554 --> 00:51:33,318 and under the skin we are all Africans. 741 00:51:33,590 --> 00:51:37,185 Old concepts of human diversity die hard. 742 00:51:37,427 --> 00:51:41,022 But certainly we must consider the possibility that human equality 743 00:51:41,264 --> 00:51:46,463 is a fact of our evolution that it's in our very genes. 744 00:51:46,703 --> 00:51:49,433 We are all time travelers together, 745 00:51:49,673 --> 00:51:52,141 the most recent players in a drama that began 746 00:51:52,375 --> 00:51:55,742 at least four million years ago. 747 00:52:00,083 --> 00:52:02,244 In the detective story of human evolution 748 00:52:02,486 --> 00:52:05,751 we know in a broad sense how the plot turned out. 749 00:52:05,989 --> 00:52:09,686 But we know very little about the chapters along the way. 750 00:52:09,926 --> 00:52:13,327 There are too many fossils that are merely fragments 751 00:52:13,563 --> 00:52:18,330 and too many gaps in time for which we have no fossils at all. 752 00:52:18,568 --> 00:52:22,561 The science of anthropology is little more than a hundred years old. 753 00:52:22,806 --> 00:52:26,173 But as it moves forward, it opens new mysteries, 754 00:52:26,409 --> 00:52:29,173 poses greater riddles. 755 00:52:29,412 --> 00:52:31,539 To begin filling in the numerous blanks, 756 00:52:31,781 --> 00:52:35,080 the discovery of new fossils is essential. 757 00:52:35,318 --> 00:52:39,846 New technologies will add other pieces to the expanding puzzle. 758 00:52:40,090 --> 00:52:44,527 But that is all we can expect random puzzle pieces. 759 00:52:44,761 --> 00:52:49,528 Never can the entire picture be known. 760 00:52:50,934 --> 00:52:56,429 For scientists the excitement of the quest never diminishes. 761 00:52:59,109 --> 00:53:02,704 And as the rains come again next year and the next, 762 00:53:02,946 --> 00:53:06,643 they know that somewhere in thousands of square miles, 763 00:53:06,883 --> 00:53:08,316 with a bit of luck, 764 00:53:08,552 --> 00:53:12,249 they will find new and even more provocative clues 765 00:53:12,489 --> 00:53:16,391 to the ongoing drama of our human past.