1 00:00:06,205 --> 00:00:08,838 在埃及沙漠的沙丘中， In the sands of the Egyptian Desert, 2 00:00:08,838 --> 00:00:13,938 专家们正在揭开失落历史的线索。 experts are uncovering clues to a lost past. 3 00:00:13,938 --> 00:00:17,171 看这个！就在这里。 Look at this! Right here. 4 00:00:17,171 --> 00:00:21,438 来自比法老时代更久远的时期， From a time long before the pharaohs, 5 00:00:21,438 --> 00:00:24,838 当时这片区域还淹没在海水之下， when this place was underwater 6 00:00:24,838 --> 00:00:27,405 而鲸鱼... and whales... 7 00:00:27,405 --> 00:00:29,471 竟长着腿？ Had legs? 8 00:00:29,471 --> 00:00:31,538 这是这头巨兽的 Here's the hind limb 9 00:00:31,538 --> 00:00:33,105 后肢。 of this beast. 10 00:00:33,105 --> 00:00:35,538 就像霸王龙的前爪一样， It's just like T. rex hand, 11 00:00:35,538 --> 00:00:37,138 毫无用处。 do nothing. 12 00:00:38,705 --> 00:00:41,971 鲸鱼是地球上最大的哺乳动物。 Whales are the world's biggest mammals. 13 00:00:41,971 --> 00:00:45,371 但它们为何会栖身海洋？ But how did they end up in the ocean? 14 00:00:45,371 --> 00:00:46,605 这太不可思议了。 This is so awesome. 15 00:00:48,071 --> 00:00:49,538 它们具备哺乳动物的所有特征， They're doing everything mammals do, 16 00:00:49,538 --> 00:00:50,805 却生活在水中。 but in the water. 17 00:00:54,171 --> 00:00:57,671 如今新发现正在揭示 Now new discoveries are revealing clues 18 00:00:57,671 --> 00:01:00,938 它们进化历程的线索。 about their evolutionary past. 19 00:01:00,938 --> 00:01:02,871 哇！看这个！ Wow! Look at this! 20 00:01:02,871 --> 00:01:05,371 天哪！ Oh, my word! 21 00:01:05,371 --> 00:01:08,471 我初见它时完全不明所以。 When I first saw it, I had no idea what it was. 22 00:01:08,471 --> 00:01:10,505 从史前掠食者 From prehistoric predators 23 00:01:10,505 --> 00:01:15,638 到地球史上最庞大的生命体。 to the largest animal that has ever lived. 24 00:01:15,638 --> 00:01:19,738 鲸类的演化之旅始于何处？ How did the whale's journey begin? 25 00:01:19,738 --> 00:01:24,605 这是最伟大的进化史诗之一。 It's one of the greatest stories of evolution. 26 00:01:24,605 --> 00:01:27,005 "当鲸鱼还行走时" "When Whales Could Walk." 27 00:01:27,005 --> 00:01:30,538 "NOVA"科学探秘，即将呈现。 Right now, on "NOVA." 28 00:01:58,471 --> 00:02:01,705 埃及撒哈拉沙漠的鲸鱼谷。 Wadi Hitan, in Egypt's Sahara Desert. 29 00:02:03,771 --> 00:02:06,871 这些岩层下隐藏着 Hidden beneath these rocks are secrets 30 00:02:06,871 --> 00:02:09,538 人类出现之前的远古秘密。 from a time long before humans. 31 00:02:23,205 --> 00:02:26,638 多数人印象中的埃及 Many people think of Egypt like 32 00:02:26,638 --> 00:02:29,571 只有古埃及文明。 ancient Egyptian civilization. 33 00:02:29,571 --> 00:02:33,138 比如法老、狮身人面像甚至罗马遗迹。 Like pharaohs, Sphinx, and Romans, even. 34 00:02:33,138 --> 00:02:37,838 但我的研究远早于那个时代。 But what I'm studying is way beyond this time. 35 00:02:37,838 --> 00:02:39,671 史前生命。 Prehistoric life. 36 00:02:39,671 --> 00:02:43,538 古生物学家希沙姆·萨拉姆 Paleontologist Hesham Sallam 37 00:02:43,538 --> 00:02:48,305 正致力于揭开祖国的史前之谜。 is on a mission to uncover his country's prehistoric past. 38 00:02:48,305 --> 00:02:51,605 我们前往的地点 The place that we are heading toward 39 00:02:51,605 --> 00:02:54,338 是埃及最重要的 is one of the most important 40 00:02:54,338 --> 00:02:58,971 古生物学遗址之一， place in Egypt, if not in the world, 41 00:02:58,971 --> 00:03:01,705 甚至堪称全球之最。 in term of paleontology. 42 00:03:07,671 --> 00:03:09,738 希沙姆正在寻找 Hesham is searching for clues 43 00:03:09,738 --> 00:03:12,871 一个惊人进化之谜的线索。 to an extraordinary evolutionary mystery. 44 00:03:15,138 --> 00:03:17,105 这里看似荒芜之地， Here, it's the middle of nowhere, 45 00:03:17,105 --> 00:03:19,005 仿佛空无一物， it seems like empty place, 46 00:03:19,005 --> 00:03:23,305 但实际蕴藏着海量证据。 but there is tons of evidence that you can see. 47 00:03:23,305 --> 00:03:25,205 化石俯拾皆是， Fossils are everywhere, 48 00:03:25,205 --> 00:03:27,471 诉说着四千万年前 telling you what life looked like 49 00:03:27,471 --> 00:03:29,771 的生命图景。 40 million years ago. 50 00:03:29,771 --> 00:03:33,671 在这片超过75平方英里的区域， Across more than 75 square miles, 51 00:03:33,671 --> 00:03:37,438 化石遍布沙漠。 fossils litter the desert. 52 00:03:37,438 --> 00:03:40,105 数量如此之多， There are so many, 53 00:03:40,105 --> 00:03:44,205 希沙姆必须脱鞋以免踩碎它们。 Hesham has to remove his shoes to avoid crushing them. 54 00:03:44,205 --> 00:03:47,538 就以这个为例。 Just look at this, for example. 55 00:03:47,538 --> 00:03:51,905 这里有枚精美的贝壳。 There's a really nice shell. 56 00:03:51,905 --> 00:03:55,571 保存极为完好。 Really wonderful, well-preserved. 57 00:03:55,571 --> 00:03:59,005 宛若现代生物， It's look like living one, 58 00:03:59,005 --> 00:04:01,938 但它实际生存于 but it was living 59 00:04:01,938 --> 00:04:03,705 四千万年前。 40 million years ago. 60 00:04:05,738 --> 00:04:10,438 但这片沙漠还埋藏着更巨大的化石。 But this desert also hides much larger fossils. 61 00:04:10,438 --> 00:04:13,105 这是鲸鱼谷的典型景象： This is typically what you see in Wadi Hitan: 62 00:04:13,105 --> 00:04:16,038 峭壁中突起的骨骼， the bone sticking out from the cliff, 63 00:04:16,038 --> 00:04:19,705 仿佛在召唤研究者。 calling you to come and see it. 64 00:04:19,705 --> 00:04:24,671 这确实是种巨型生物。 And indeed, this is a really huge animal. 65 00:04:24,671 --> 00:04:28,071 脊椎骨就有这么大。 The vertebra would be that big. 66 00:04:28,071 --> 00:04:30,705 不仅脊椎骨， And not only the vertebrae, 67 00:04:30,705 --> 00:04:33,805 还能随处找到肋骨。 but also, you can find ribs all over the place. 68 00:04:33,805 --> 00:04:37,305 根据脊椎尺寸推断， Given the size of the vertebrae, 69 00:04:37,305 --> 00:04:41,471 体长可能达20米。 it might be getting up to 20 meter long. 70 00:04:42,671 --> 00:04:46,071 这些岩层中封存的60英尺生物 The size and shape of an animal around 60 feet long 71 00:04:46,071 --> 00:04:48,438 其体型与形态 encased in this rock 72 00:04:48,438 --> 00:04:52,905 让科学家得出惊人结论。 has led scientists to a remarkable conclusion. 73 00:04:52,905 --> 00:04:56,371 我认为我们发现了 I think we have a complete skeleton 74 00:04:56,371 --> 00:04:59,238 远古鲸鱼的完整骨架， of the prehistoric whale that lived here in Egypt, 75 00:04:59,238 --> 00:05:01,771 它们曾生活在埃及的远古时期。 long, long, long time ago. 76 00:05:04,138 --> 00:05:08,538 自1902年首次发现鲸鱼化石以来， Since the first whale fossils were discovered here in 1902, 77 00:05:08,538 --> 00:05:12,505 专家已发现约1000具个体化石。 experts have found around 1,000 individuals. 78 00:05:15,171 --> 00:05:20,171 这是地球已知最大的远古鲸鱼坟场。 This is the biggest ancient whale graveyard known on Earth. 79 00:05:20,171 --> 00:05:24,538 因此古生物学家称其为鲸鱼谷—— That's why paleontologists named it Wadi Hitan-- 80 00:05:24,538 --> 00:05:27,805 鲸之谷。 the Valley of the Whales. 81 00:05:29,405 --> 00:05:31,805 但这些海洋生物为何会出现在 But what are these sea creatures doing here 82 00:05:31,805 --> 00:05:36,771 距离海岸百余英里的沙漠中？ in a desert over 100 miles from the coast? 83 00:05:41,305 --> 00:05:43,671 肖鲁克·阿尔-阿什卡尔是埃及 Shorouq Al-Ashqar is one of Egypt's 84 00:05:43,671 --> 00:05:46,138 首批女性脊椎古生物学家之一。 first female vertebrate paleontologists. 85 00:05:49,438 --> 00:05:52,405 这些是鲨鱼牙齿。 These are shark teeth. 86 00:05:52,405 --> 00:05:56,505 还有这些贝壳。 Also, look at these shells. 87 00:05:56,505 --> 00:06:00,305 这些生物曾生活在海底。 These animals live at the bottom of the sea. 88 00:06:01,805 --> 00:06:06,138 附近，肖鲁克发现了另一线索。 Nearby, Shorouq finds another clue. 89 00:06:06,138 --> 00:06:08,438 看这个构造。 Look at this structure. 90 00:06:08,438 --> 00:06:11,171 许多科学家认为 Many scientists do believe that these 91 00:06:11,171 --> 00:06:13,771 这是红树林根系， are mangrove roots, as they found 92 00:06:13,771 --> 00:06:17,505 因该区域发现大量红树种子。 a lot of mangrove seeds all over the area. 93 00:06:17,505 --> 00:06:19,838 但也有学者认为 But other scientists 94 00:06:19,838 --> 00:06:23,871 可能是甲壳类动物的洞穴。 believe that these might be crustacean burrows. 95 00:06:23,871 --> 00:06:25,805 螃蟹、螺类等生物 Crabs, snails 96 00:06:25,805 --> 00:06:29,671 曾在松软沙地中掘穴而居。 lived there and burrowed in the soft sand. 97 00:06:31,871 --> 00:06:34,571 无论这些是红树林化石根系， Whether these are fossilized mangrove roots 98 00:06:34,571 --> 00:06:37,705 还是史前甲壳类的洞穴， or burrows dug by prehistoric crustaceans, 99 00:06:37,705 --> 00:06:40,505 都明确显示 it's clear 100 00:06:40,505 --> 00:06:44,305 该区域曾为水下世界。 this area was once underwater. 101 00:06:46,605 --> 00:06:49,638 如今的发掘现场在四千万年前 Today's excavation site was at the bottom of the sea 102 00:06:49,638 --> 00:06:52,905 曾是海底世界。 40 million years ago. 103 00:06:52,905 --> 00:06:55,438 当时地中海属于 Back then, the Mediterranean was part 104 00:06:55,438 --> 00:06:59,805 更辽阔的特提斯洋。 of a much larger ocean, the Tethys. 105 00:06:59,805 --> 00:07:02,605 这片海域从欧洲延伸至印度， It stretched from Europe to India, 106 00:07:02,605 --> 00:07:05,605 孕育着丰富海洋生命。 and was full of marine life. 107 00:07:08,005 --> 00:07:10,138 当海平面下降后， But when sea levels dropped, 108 00:07:10,138 --> 00:07:14,238 留下了富含化石的海床。 they left behind a seabed rich in fossils. 109 00:07:15,905 --> 00:07:19,838 如今这片沙漠成为 Today, this desert is the resting place of some 110 00:07:19,838 --> 00:07:23,805 已知最古老鲸鱼的安息之地。 of the earliest whales ever found. 111 00:07:23,805 --> 00:07:28,705 它们或能解开现代海洋巨兽的进化之谜。 They may hold the key to how today's ocean giants evolved. 112 00:07:35,471 --> 00:07:38,938 六千英里外的多米尼加共和国， 6,000 miles away, in the Dominican Republic, 113 00:07:38,938 --> 00:07:42,605 现代鲸群每年初聚集于 living whales gather in these tropical waters 114 00:07:42,605 --> 00:07:44,671 这片热带海域。 early in the year. 115 00:07:51,171 --> 00:07:55,138 正值座头鲸繁殖季。 It's humpback whale breeding season. 116 00:07:55,138 --> 00:07:58,571 比较解剖学家乔伊·雷登伯格 Comparative anatomist Joy Reidenberg 117 00:07:58,571 --> 00:08:01,771 前来进行研究。 has come to study them. 118 00:08:01,771 --> 00:08:03,605 看，有鲸喷。 Oh, there's a blow. 119 00:08:03,605 --> 00:08:05,305 哇——另一侧也出现了！ Wow-- oh, and just the other side! 120 00:08:05,305 --> 00:08:06,671 看到了吗？ Did you see that? 121 00:08:06,671 --> 00:08:08,738 那个小鳍——是幼鲸！ There's this tiny little fin-- that's the baby! 122 00:08:08,738 --> 00:08:11,238 母鲸和幼鲸正并肩 We've got a mother and her calf right here together, 123 00:08:11,238 --> 00:08:12,338 同游。 swimming side by side. 124 00:08:14,605 --> 00:08:17,738 座头鲸属于现存约90种鲸类， Humpbacks are one of around 90 different species 125 00:08:17,738 --> 00:08:19,438 包括齿鲸如虎鲸、 of whale living today 126 00:08:19,438 --> 00:08:22,371 海豚和鼠海豚， that include toothed whales, 127 00:08:22,371 --> 00:08:24,938 以及须鲸如这些座头鲸。 like orcas, dolphins, and porpoises, 128 00:08:24,938 --> 00:08:28,238 and baleen whales, like these humpbacks. 129 00:08:28,238 --> 00:08:33,471 鲸类能游弋数千英里， Whales can swim thousands of miles, 130 00:08:33,471 --> 00:08:34,605 深潜数千英尺， dive thousands of feet, 131 00:08:34,605 --> 00:08:38,471 屏息水下超一小时。 and stay underwater for over an hour. 132 00:08:41,105 --> 00:08:43,171 我深爱鲸鱼，真心如此。 I love whales, I really do. 133 00:08:43,171 --> 00:08:46,205 如此壮美而庞大的生物。 Such magnificent, huge creatures. 134 00:08:46,205 --> 00:08:49,705 对水生环境适应得如此完美。 And so well-adapted for being in the water. 135 00:08:52,671 --> 00:08:54,738 但它们却是哺乳动物。 And yet, they're mammals. 136 00:08:54,738 --> 00:08:57,838 用肺呼吸空气， They breathe air using lungs. 137 00:08:57,838 --> 00:09:00,005 和我们一样。 Just like us. 138 00:09:04,805 --> 00:09:06,571 这里有对鲸鱼母子。 We've got a mother and calf over here. 139 00:09:06,571 --> 00:09:08,505 母鲸正在哺育幼崽。 The mother is nursing its baby. 140 00:09:08,505 --> 00:09:11,771 这些动物不仅呼吸空气、分泌乳汁， But these animals not only breathe air and give milk, 141 00:09:11,771 --> 00:09:14,571 还具备哺乳动物的所有特征，却生活在水中。 but they're doing everything mammals do, but in the water. 142 00:09:14,571 --> 00:09:16,305 它们必须在水中交配， They have to mate in the water. 143 00:09:16,305 --> 00:09:18,538 在水中完成妊娠， They have to carry their pregnancy in the water. 144 00:09:18,538 --> 00:09:20,138 在水中觅食， They have to find food in the water. 145 00:09:20,138 --> 00:09:21,771 并在水中分娩。 And then they give birth in the water. 146 00:09:21,771 --> 00:09:22,905 这一切 All of this 147 00:09:22,905 --> 00:09:25,138 都源于它们的进化历程 because these animals have evolved 148 00:09:25,138 --> 00:09:26,905 成为了水生哺乳动物。 to be an aquatic mammal. 149 00:09:28,671 --> 00:09:33,205 用肺呼吸的哺乳动物为何会栖身海洋？ How did air-breathing mammals end up in the ocean? 150 00:09:34,638 --> 00:09:38,905 几个世纪以来，许多人将鲸误认为鱼类， For centuries, many people confused whales with fish, 151 00:09:38,905 --> 00:09:43,105 包括小说《白鲸记》中的角色。 including the characters in the novel "Moby-Dick." 152 00:09:46,205 --> 00:09:48,538 尽管18世纪50年代， Even though, in the 1750s, 153 00:09:48,538 --> 00:09:51,538 瑞典博物学家卡尔·林奈 the Swedish naturalist Carl Linnaeus 154 00:09:51,538 --> 00:09:54,538 早已将鲸归类为哺乳动物， had already classified whales as mammals, 155 00:09:54,538 --> 00:09:57,305 确认它们具有 recognizing that, among other traits, 156 00:09:57,305 --> 00:10:00,671 肺部和泌乳等特征。 they have lungs and produce milk. 157 00:10:00,671 --> 00:10:03,771 但鲸类的起源问题 But where whales came from caused even 158 00:10:03,771 --> 00:10:05,971 连达尔文都百思不解。 Charles Darwin to scratch his beard. 159 00:10:05,971 --> 00:10:08,771 受游泳觅食的熊启发， Inspired by a bear seen feeding while it swam, 160 00:10:08,771 --> 00:10:13,371 他构想了鲸从陆生哺乳动物进化的可能。 he imagined how whales could evolve from land mammals. 161 00:10:13,371 --> 00:10:15,038 但因遭人嘲笑， But faced with ridicule, 162 00:10:15,038 --> 00:10:18,171 他在后期著作中删除了这个观点。 he removed this idea from his later writings. 163 00:10:21,171 --> 00:10:24,838 或许达尔文的直觉确有依据。 Perhaps Darwin's hunch had legs. 164 00:10:24,838 --> 00:10:29,405 有没有可能鲸类并非起源于海洋， Could it be that whales hadn't evolved in the water, 165 00:10:29,405 --> 00:10:31,738 而是由曾经 but were actually descended from mammals 166 00:10:31,738 --> 00:10:34,905 在陆地行走的哺乳动物演化而来？ that once walked on land? 167 00:10:34,905 --> 00:10:41,238 这简直像是进化开了倒车。 It almost seems like evolution had taken a backwards step. 168 00:10:46,305 --> 00:10:49,305 这个问题深深吸引着希沙姆·萨拉姆。 It's a question that fascinates Hesham Sallam. 169 00:10:49,305 --> 00:10:52,171 他认为线索就藏在 He believes clues can be found 170 00:10:52,171 --> 00:10:56,205 这片沙漠散落的巨型化石中。 in the huge fossils that lie scattered in this desert. 171 00:11:00,505 --> 00:11:04,138 这是我们在鲸鱼谷发现的 This is one of the most complete skeleton 172 00:11:04,138 --> 00:11:06,538 最完整的骨架之一。 that we find in Wadi Hitan. 173 00:11:06,538 --> 00:11:08,738 在这荒芜之地， In the middle of nowhere, 174 00:11:08,738 --> 00:11:14,371 竟排列着众多巨型椎骨化石。 you find a lot of really huge vertebrae lined up. 175 00:11:14,371 --> 00:11:18,338 头骨应该在那边的岩层中， The skull would be over there in that rock, 176 00:11:18,338 --> 00:11:21,471 两侧散布着肋骨。 and the ribs on both side. 177 00:11:21,471 --> 00:11:24,638 这是四千万年前 This is really spectacularly huge animal 178 00:11:24,638 --> 00:11:28,738 生活在鲸鱼谷的庞然巨兽—— that lived here in Wadi Hitan 40 million years ago, 179 00:11:28,738 --> 00:11:30,471 龙王鲸。 the Basilosaurus. 180 00:11:32,505 --> 00:11:35,371 龙王鲸化石已在全球多地 Basilosaurus fossils have been discovered 181 00:11:35,371 --> 00:11:37,271 被发现， in many parts of the world, 182 00:11:37,271 --> 00:11:41,671 仅鲸鱼谷就有约600具。 including around 600 here at Wadi Hitan. 183 00:11:42,971 --> 00:11:46,805 这具骨架按发现时的原貌陈列。 This one has been laid out in the place it was found. 184 00:11:48,705 --> 00:11:52,971 1834年首次研究龙王鲸时， When the first Basilosaurus was studied in 1834, 185 00:11:52,971 --> 00:11:55,338 专家们困惑不已。 experts were baffled. 186 00:11:55,338 --> 00:11:57,705 早期科学家发现它时， When the early scientists found this, 187 00:11:57,705 --> 00:11:59,371 认为属于 they thought it's belonged 188 00:11:59,371 --> 00:12:03,205 某种巨型海洋爬行动物。 to a kind of gigantic marine reptile. 189 00:12:03,205 --> 00:12:08,071 因此将其命名为"Basilosaurus"， And the, this is why they give it name "Basilosaurus," 190 00:12:08,071 --> 00:12:10,371 意为"蜥蜴之王"。 which means "king lizard." 191 00:12:12,805 --> 00:12:15,171 但头骨藏有揭示 But the skull contains a clue 192 00:12:15,171 --> 00:12:19,771 龙王鲸真实身份的线索。 to Basilosaurus's true identity. 193 00:12:19,771 --> 00:12:21,971 这是倒置的头骨，可见 This is the skull upside down, and you can see 194 00:12:21,971 --> 00:12:23,638 所有牙齿都朝上突起。 all the teeth are sticking up. 195 00:12:23,638 --> 00:12:25,571 实际上， And this, actually, 196 00:12:25,571 --> 00:12:27,738 它们长有门齿、犬齿、 they have incisors, canine, 197 00:12:27,738 --> 00:12:29,938 前臼齿和臼齿。 premolars, and molar. 198 00:12:29,938 --> 00:12:32,071 就像人类的牙齿， Really, like our teeth, 199 00:12:32,071 --> 00:12:36,271 这明确表明 which is actually a really good indication for, 200 00:12:36,271 --> 00:12:40,838 这并非海洋爬行动物，而是哺乳动物。 this is not a marine reptile, this is actually mammal. 201 00:12:40,838 --> 00:12:43,738 所谓"蜥蜴之王"的龙王鲸， So Basilosaurus, the king lizard, 202 00:12:43,738 --> 00:12:47,805 实为远古鲸类。 it's actually ancient whale. 203 00:12:51,605 --> 00:12:53,271 四千万年前， 40 million years ago, 204 00:12:53,271 --> 00:12:59,138 龙王鲸是当时的顶级掠食者。 Basilosaurus was the apex predator of its day. 205 00:12:59,138 --> 00:13:01,905 体长可达60英尺—— It could grow up to 60 feet long, 206 00:13:01,905 --> 00:13:04,571 相当于保龄球道的长度， the length of a bowling alley, 207 00:13:04,571 --> 00:13:07,438 重量超过七吨。 and weigh more than seven tons. 208 00:13:09,705 --> 00:13:14,005 布满利齿的强健颌骨 Powerful jaws filled with sharp teeth made it 209 00:13:14,005 --> 00:13:15,838 使其成为杀戮机器。 a killing machine. 210 00:13:15,838 --> 00:13:21,371 科学家估计其咬合力近两吨， Scientists estimate its bite had a force of nearly two tons, 211 00:13:21,371 --> 00:13:25,338 足以碾碎其他鲸类的骨骼。 enough to crush the bones of other whales. 212 00:13:25,338 --> 00:13:29,971 龙王鲸是史前兽王。 Basilosaurus was a prehistoric king of beasts. 213 00:13:33,771 --> 00:13:36,871 但其发现最初并未 But its discovery didn't initially shed much light 214 00:13:36,871 --> 00:13:38,971 阐明鲸类进化历程， on whale evolution. 215 00:13:38,971 --> 00:13:42,571 或解释这些哺乳动物如何进入海洋。 Or how these mammals ended up in the ocean. 216 00:13:48,071 --> 00:13:50,971 这个谜题已吸引菲利普·金格里奇 It's a mystery that has intrigued Philip Gingerich 217 00:13:50,971 --> 00:13:53,771 近五十年。 for almost 50 years. 218 00:13:53,771 --> 00:13:57,338 作为鲸类进化研究先驱， A pioneer in the field of whale evolution, 219 00:13:57,338 --> 00:13:59,271 他是最早在鲸鱼谷 he was one of the first paleontologists 220 00:13:59,271 --> 00:14:03,971 开展发掘的古生物学家之一。 to excavate at Wadi Hitan. 221 00:14:03,971 --> 00:14:07,571 这里存放着我研究的化石。 So this is where I keep the fossils I'm working on. 222 00:14:07,571 --> 00:14:11,238 这是龙王鲸的头骨， So here is the skull of Basilosaurus. 223 00:14:11,238 --> 00:14:13,605 嗯，放反了。 Uh, it's upside down. 224 00:14:13,605 --> 00:14:16,738 这是它的模型，复制品。 And this is a model of it, a cast of it. 225 00:14:16,738 --> 00:14:18,971 这些都来自埃及鲸鱼谷， These are all from Egypt, from Wadi Hitan. 226 00:14:18,971 --> 00:14:21,905 2005年采集的。 Collected in 2005. 227 00:14:21,905 --> 00:14:24,105 看，我至今仍在研究它们。 Here we are, I'm still working on them. 228 00:14:24,105 --> 00:14:25,805 需要时间沉淀。 Takes time. 229 00:14:27,005 --> 00:14:31,305 菲利普职业生涯初期研究陆生哺乳动物。 When Philip started his career, he studied land mammals. 230 00:14:31,305 --> 00:14:35,205 当时古生物界对鲸类起源 At the time, paleontologists had very little idea 231 00:14:35,205 --> 00:14:37,871 知之甚少。 about the origins of whales. 232 00:14:37,871 --> 00:14:43,505 我在中西部长大远离海洋... I grew up in the Midwest and I wasn't near the ocean, and... 233 00:14:43,505 --> 00:14:45,638 对鲸一无所知。 I didn't know anything about whales. 234 00:14:45,638 --> 00:14:48,271 认知的匮乏导致兴趣缺缺。 I knew so little that I wasn't interested. 235 00:14:49,905 --> 00:14:53,171 1978年，菲利普前往巴基斯坦 In 1978, Philip went to Pakistan 236 00:14:53,171 --> 00:14:55,238 寻找史前马类化石。 to search for prehistoric horses. 237 00:14:56,805 --> 00:14:59,838 不料团队却发掘出 Instead, his team unearthed the remains 238 00:14:59,838 --> 00:15:03,338 一种神秘生物的遗骸。 of a mysterious creature. 239 00:15:03,338 --> 00:15:06,571 我们最先发现的是这个头骨。 The first thing we found was this skull. 240 00:15:06,571 --> 00:15:09,405 后脑部分——并不完整。 Back of a skull-- it's not complete. 241 00:15:09,405 --> 00:15:11,871 带有眼睛和牙齿的 The front, the part with the eyes 242 00:15:11,871 --> 00:15:14,005 前半部分已经断裂。 and the teeth and everything, has broken off. 243 00:15:14,005 --> 00:15:17,605 初见时我完全无法辨识。 When I first saw it, I had no idea what it was. 244 00:15:17,605 --> 00:15:19,405 可能有些失望， I was probably disappointed, because 245 00:15:19,405 --> 00:15:22,505 毕竟我寻找的是马类化石，而这显然不是。 I was looking for horses, and it clearly wasn't a horse. 246 00:15:22,505 --> 00:15:26,371 但其真实身份令我百思不解。 But what it was, I couldn't figure out. 247 00:15:27,571 --> 00:15:31,371 团队将这种奇异生物命名为巴基鲸。 The team named the strange animal Pakicetus. 248 00:15:31,371 --> 00:15:34,938 距今约五千万年。 It's about 50 million years old. 249 00:15:34,938 --> 00:15:39,105 当菲利普细致观察时，在它的耳部 When Philip took a closer look, he spotted something 250 00:15:39,105 --> 00:15:42,405 发现了意外特征。 unexpected in the creature's ear. 251 00:15:42,405 --> 00:15:44,605 观察这块覆盖耳部的 So when you look at this covering bone, 252 00:15:44,605 --> 00:15:46,171 骨质结构， covering the ear, 253 00:15:46,171 --> 00:15:50,805 密度极高且增厚， it's very dense, it's thickened, 254 00:15:50,805 --> 00:15:54,138 这一侧呈斜坡状。 it has a sloping surface on this side. 255 00:15:54,138 --> 00:15:57,238 现代哺乳动物中，仅鲸类具有此特征。 And in modern mammals, those are only found in whales. 256 00:15:57,238 --> 00:16:00,905 为何？为了水下听觉定位。 And why? To enable them to hear in water. 257 00:16:02,438 --> 00:16:05,438 这种鲸豚类独有的耳骨， This ear bone, unique to whales and dolphins, 258 00:16:05,438 --> 00:16:09,538 帮助它们判断水下声源方向。 helps them locate the direction of sounds underwater. 259 00:16:09,538 --> 00:16:13,071 这证明了巴基鲸的血统。 It's proof of Pakicetus's pedigree. 260 00:16:13,071 --> 00:16:16,038 这块骨头是理解 This bone was the key to understanding 261 00:16:16,038 --> 00:16:18,405 巴基鲸属于鲸类的关键。 that Pakicetus is a whale. 262 00:16:18,405 --> 00:16:22,171 这使它成为人类发现的最古老鲸类化石。 That made it the oldest fossil whale anybody ever found. 263 00:16:22,171 --> 00:16:25,338 这是突破性发现。 It was groundbreaking. 264 00:16:25,338 --> 00:16:29,538 随着更多巴基鲸化石的出土， And as they discover more Pakicetus fossils, 265 00:16:29,538 --> 00:16:33,438 研究者有了新认知。 they realized something else. 266 00:16:33,438 --> 00:16:38,171 这种鲸类能够行走。 This whale could walk. 267 00:16:38,171 --> 00:16:42,071 巴基鲸体型略大于狼， Pakicetus is an animal a little bigger than a wolf. 268 00:16:42,071 --> 00:16:45,905 骨骼构造近似狼科动物。 Probably built approximately like a wolf. 269 00:16:45,905 --> 00:16:49,438 牙齿结构显示它是肉食性哺乳动物。 It has teeth like a carnivorous mammal. 270 00:16:49,438 --> 00:16:54,471 但与趾端长爪的狼不同， But unlike a wolf, that has claws on the ends of its toes, 271 00:16:54,471 --> 00:16:59,838 巴基鲸趾部长有微型蹄状结构。 Pakicetus had tiny hooves. 272 00:17:02,438 --> 00:17:07,605 巴基鲸是在陆地捕猎的肉食动物， Pakicetus was a carnivore that hunted on land. 273 00:17:07,605 --> 00:17:13,405 但其解剖特征表明已适应水生环境。 But its anatomy suggests it had adapted to living in water. 274 00:17:13,405 --> 00:17:16,871 布满利齿的长吻部 Its long snout, full of sharp teeth, 275 00:17:16,871 --> 00:17:21,371 使其能探入浅水河床搜寻猎物。 also allowed it to probe shallow riverbeds for prey. 276 00:17:23,605 --> 00:17:27,171 双眼位置靠近头顶， Its eyes were squeezed onto the top of its head, 277 00:17:27,171 --> 00:17:30,838 便于游泳时保持警戒。 so it could keep watch while swimming. 278 00:17:32,638 --> 00:17:36,738 部分科学家认为其足骨上的痕迹 And some scientists think markings on its foot bones 279 00:17:36,738 --> 00:17:41,038 证明趾间存在蹼状结构， are evidence it had webbing between its toes, 280 00:17:41,038 --> 00:17:44,738 使其具备水下捕食能力。 allowing it to hunt underwater. 281 00:17:44,738 --> 00:17:47,971 巴基鲸为何长期栖身水域？ Why was Pakicetus spending so much time in the water? 282 00:17:47,971 --> 00:17:52,305 我认为因为水中鱼类资源丰富。 I think it was because the water was full of fish. 283 00:17:52,305 --> 00:17:55,605 从其牙齿判断，显然它们 And judging from its teeth, it's pretty clear that they were 284 00:17:55,605 --> 00:17:57,805 充分利用了这点优势——入水捕鱼， taking advantage of that, going in the water, 285 00:17:57,805 --> 00:18:02,138 且几乎没有竞争者。 feeding on the fish, and didn't have much competition. 286 00:18:02,138 --> 00:18:05,105 自然，它们很快 And of course, it didn't take long until 287 00:18:05,105 --> 00:18:08,705 就永久性迁入水域。 they moved into the water more permanently. 288 00:18:08,705 --> 00:18:11,971 巴基鲸标志着从陆生动物 Pakicetus marks the beginning of an eventful journey 289 00:18:11,971 --> 00:18:17,405 到现代巨鲸的壮阔进化历程的开端。 from land animals to today's gigantic whales. 290 00:18:17,405 --> 00:18:21,471 对菲利普而言，这开启了他毕生的热忱。 For Philip, it was the start of a lifelong passion. 291 00:18:21,471 --> 00:18:24,671 这彻底改变了我的职业生涯， It changed the course of my entire career because 292 00:18:24,671 --> 00:18:28,871 我将此作为进化论的典型案例研究。 I got interested in this as an example of evolution. 293 00:18:28,871 --> 00:18:30,638 其特殊意义在于 And it's especially interesting because 294 00:18:30,638 --> 00:18:32,771 这看似是逆向进化—— it seems like it's backwards-- 295 00:18:32,771 --> 00:18:36,338 是重返海洋而非登陆。 it's back to the sea, not out of the sea. 296 00:18:40,005 --> 00:18:44,471 海洋被认为是生命的起源之地。 The oceans are thought to be where life started. 297 00:18:44,471 --> 00:18:47,071 约四亿年前， Around 400 million years ago, 298 00:18:47,071 --> 00:18:52,005 部分鱼类离开水域登陆生活。 some fish left the water to live on land. 299 00:18:52,005 --> 00:18:54,871 经过漫长演化，它们的后代 Over time, their descendants evolved 300 00:18:54,871 --> 00:18:59,171 逐步进化为两栖类、恐龙和哺乳动物。 into amphibians, dinosaurs, and mammals. 301 00:19:01,105 --> 00:19:03,671 随后在约五千万年前， Then, about 50 million years ago, 302 00:19:03,671 --> 00:19:06,605 惊人的逆转发生了。 something incredible happened. 303 00:19:06,605 --> 00:19:11,838 部分哺乳动物重新回归水域。 Some mammals found their way back into the water. 304 00:19:11,838 --> 00:19:15,171 它们遍布全球海域， They spread to all the world's oceans, 305 00:19:15,171 --> 00:19:18,671 演化成今日所见的鲸类， evolving into the whales we know today, 306 00:19:18,671 --> 00:19:21,705 从庞大的蓝鲸与抹香鲸， from huge blue and sperm whales 307 00:19:21,705 --> 00:19:25,405 到虎鲸与鼠海豚。 to orcas and porpoises. 308 00:19:29,705 --> 00:19:32,738 这种蜕变如何发生？ How did this transformation happen? 309 00:19:32,738 --> 00:19:37,405 为探寻答案，科学家既研究现代鲸类 To find out, scientists examine anatomical clues 310 00:19:37,405 --> 00:19:42,371 也分析远古化石的解剖学特征。 in modern whales, as well as ancient fossils. 311 00:19:42,371 --> 00:19:43,971 通过解剖实验， By doing a dissection, 312 00:19:43,971 --> 00:19:47,838 他们希望揭示更多祖先密码。 they hope to reveal more secrets of their ancestry. 313 00:19:47,838 --> 00:19:50,205 好，开始解封。 Okay, let's unwrap. 314 00:19:50,205 --> 00:19:54,638 比较解剖学家乔伊·雷登伯格正在研究 Comparative anatomist Joy Reidenberg is investigating 315 00:19:54,638 --> 00:19:57,305 一头在美国海岸发现的 a young beaked whale that was found dead 316 00:19:57,305 --> 00:19:59,871 死亡幼年喙鲸。 on the coast of the U.S.A. 317 00:20:01,171 --> 00:20:05,505 进化生物学家迈克尔·麦高恩参与协作。 Joining her is evolutionary biologist Michael McGowen. 318 00:20:05,505 --> 00:20:07,871 每次见到搁浅鲸类都令人痛心。 It's always really sad when you have a stranded whale. 319 00:20:07,871 --> 00:20:10,538 但对我们而言这是珍贵样本。 Yeah. But for us, this is a gold mine. 320 00:20:10,538 --> 00:20:12,571 这是研究稀有生物的 We have an opportunity here to learn something 321 00:20:12,571 --> 00:20:14,071 宝贵机会。 about an animal that's quite rare. 322 00:20:14,071 --> 00:20:17,438 这类物种极少在海面被发现， These particular species are rarely sighted at the surface, 323 00:20:17,438 --> 00:20:18,838 因为它们通常只是 because they just come up, 324 00:20:18,838 --> 00:20:21,371 快速换气后立即下潜。 take a quick breath, and go back down. 325 00:20:21,371 --> 00:20:23,705 最神奇的是喙鲸 What's really cool, I think, is, beaked whales 326 00:20:23,705 --> 00:20:26,338 已完全适应深海生活， are really adapted to stay at depth, 327 00:20:26,338 --> 00:20:27,805 那是它们的常态。 and that's their norm. Yes. 328 00:20:29,038 --> 00:20:31,305 当切开鲸体腹腔时， Cutting into the animal's abdomen, 329 00:20:31,305 --> 00:20:33,738 他们发现了奇特现象： they reveal something curious: 330 00:20:33,738 --> 00:20:38,138 关于鲸类起源的重要线索。 an important clue about the origins of whales. 331 00:20:38,138 --> 00:20:39,871 这是胃部。 That's the stomach. Uh-huh. 332 00:20:39,871 --> 00:20:41,271 看这个奇特结构。 Now, look at, look how weird this is. 333 00:20:42,905 --> 00:20:45,238 作为肉食动物本应像猫狗那样 These animals are carnivores-- you expect them to be like a cat 334 00:20:45,238 --> 00:20:47,171 只有一个胃室， or a dog, and have one stomach chamber, 335 00:20:47,171 --> 00:20:49,471 但事实并非如此。 but in fact, they don't. 336 00:20:49,471 --> 00:20:51,438 它们具有多个胃室， They have multiple stomach chambers, 337 00:20:51,438 --> 00:20:56,638 类似牛、鹿、羊等有蹄类动物。 kind of like hoofed animals, like cattle or deer or sheep. 338 00:20:56,638 --> 00:20:58,971 这里有一、二、三、四、 So you got one, two, three, four, 339 00:20:58,971 --> 00:21:03,471 五、六、七、八... five, six, seven, eight... 340 00:21:03,471 --> 00:21:05,138 难以置信。 Wow. 341 00:21:05,138 --> 00:21:06,305 估计有八到九个胃室， I think there's eight or nine chambers, 342 00:21:06,305 --> 00:21:08,171 细想简直不可思议！ which is crazy, when you think about it! 343 00:21:08,171 --> 00:21:09,571 太疯狂了——难以置信。 It's crazy-- it's nuts. 344 00:21:12,505 --> 00:21:15,905 所有鲸豚类都具有这种 All whales and dolphins have this unexpected feature 345 00:21:15,905 --> 00:21:20,205 多室胃的反常特征。 of multiple stomach chambers. 346 00:21:20,205 --> 00:21:22,571 这是它们从陆生祖先 It's a trait they inherited 347 00:21:22,571 --> 00:21:25,971 继承的遗传特征。 from their ancient relatives that walked on land. 348 00:21:25,971 --> 00:21:29,171 正如牛的多室胃 Just like cows have multiple stomachs 349 00:21:29,171 --> 00:21:31,471 用于消化植物纤维， to digest their plant matter, 350 00:21:31,471 --> 00:21:33,138 鲸类的多室胃则用于 whales have multiple stomachs 351 00:21:33,138 --> 00:21:35,805 消化截然不同的鱼类和乌贼—— to digest what they're eating, which is completely different-- 352 00:21:35,805 --> 00:21:37,638 但器官结构仍源自 fishes and squid-- 353 00:21:37,638 --> 00:21:39,438 陆生哺乳动物的 but it's still 354 00:21:39,438 --> 00:21:43,305 相同生理构造。 coming from the same structure as a terrestrial mammal. 355 00:21:43,305 --> 00:21:46,705 这要追溯到它们的陆生祖先—— It's just a throwback to their terrestrial ancestry 356 00:21:46,705 --> 00:21:48,238 因其祖先具备多室胃结构， of having a multi-chambered stomach 357 00:21:48,238 --> 00:21:49,705 后代便保留了这一特征。 because their ancestor did. 358 00:21:52,271 --> 00:21:54,371 这一解剖特征进一步佐证 This anatomy is more evidence 359 00:21:54,371 --> 00:21:58,405 鲸类与有蹄类动物的亲缘关系。 that whales are related to hoofed mammals. 360 00:21:59,871 --> 00:22:03,071 它们的陆生血统甚至能通过 And this terrestrial heritage can even be revealed 361 00:22:03,071 --> 00:22:06,138 基因显现。 in their genes. 362 00:22:08,971 --> 00:22:14,871 迈克尔在实验室通过现代鲸类DNA追溯其进化史。 In his lab, Michael uses modern whales' DNA to map their past. 363 00:22:14,871 --> 00:22:18,638 这为鲸类起源研究开辟了 It's opening up a vast new world of information 364 00:22:18,638 --> 00:22:21,638 广阔的新天地。 about the origins of whales. 365 00:22:21,638 --> 00:22:24,438 对比不同海洋哺乳动物时， So if you think about different marine mammals, 366 00:22:24,438 --> 00:22:28,538 如海牛、海豹或海狮，它们都 such as a manatee or a seal or sea lion, they all swim 367 00:22:28,538 --> 00:22:30,838 具备类似鲸豚的游泳能力 and live in the ocean and have similar adaptations 368 00:22:30,838 --> 00:22:32,905 与海洋适应特征。 to whales and dolphins. 369 00:22:32,905 --> 00:22:36,105 但通过DNA分析可判断鲸豚类 But we can look at the DNA to see whether whales 370 00:22:36,105 --> 00:22:38,071 与这些物种的亲缘关系， and dolphins are closely related to those other groups 371 00:22:38,071 --> 00:22:42,005 或是否另有近亲。 or whether they're related to another species entirely. 372 00:22:42,005 --> 00:22:44,571 科学家希望确认 Scientists wanted to identify 373 00:22:44,571 --> 00:22:46,605 鲸类现存最近的近亲。 the whale's closest living relative. 374 00:22:46,605 --> 00:22:48,671 于是他们将鲸类DNA So they compared 375 00:22:48,671 --> 00:22:53,538 与多种动物进行比对。 whale DNA with a range of other animals. 376 00:22:53,538 --> 00:22:55,971 得出了惊人结论： They came up with a really surprising finding. 377 00:22:55,971 --> 00:22:58,405 DNA分析显示鲸类最近的近亲 And the finding was that the whale's closest relative, 378 00:22:58,405 --> 00:23:00,771 竟然是... using DNA, was... 379 00:23:02,438 --> 00:23:03,505 河马。 ...the hippo. 380 00:23:05,271 --> 00:23:07,605 鲸类与河马共同起源于 Whales and hippos both descended 381 00:23:07,605 --> 00:23:09,771 约比巴基鲸早五百万年的 from a common hoofed ancestor 382 00:23:09,771 --> 00:23:13,771 某种有蹄类祖先。 that lived about five million years before Pakicetus. 383 00:23:14,971 --> 00:23:18,738 两者的家族相似性令人惊叹。 The family resemblance is striking. 384 00:23:18,738 --> 00:23:20,205 巴基鲸等早期鲸类 Some of the earliest whales, like Pakicetus, 385 00:23:20,205 --> 00:23:24,138 可能过着类似河马的生活。 may have lived like hippos. 386 00:23:24,138 --> 00:23:26,605 此外，河马在水中分娩， Also, hippos give birth underwater. 387 00:23:26,605 --> 00:23:28,405 在水中哺育幼崽， They nurse underwater. 388 00:23:28,405 --> 00:23:31,338 皮肤也异常厚实。 Their skin is also very thick. 389 00:23:31,338 --> 00:23:35,838 因此有理由推测鲸豚共同祖先 So it's interesting to think that maybe the common ancestor 390 00:23:35,838 --> 00:23:38,505 可能具备这些特征。 of whales and dolphins had these particular features. 391 00:23:41,271 --> 00:23:43,871 但海洋生存环境与河岸 But life in the ocean is very different 392 00:23:43,871 --> 00:23:46,771 截然不同。 from life on the riverbank. 393 00:23:46,771 --> 00:23:52,471 经过漫长演化，鲸类祖先逐渐适应了新环境。 Over time, whales' ancestors adapted to this new environment. 394 00:23:54,038 --> 00:23:57,505 科学家通过比对河马与鲸类的DNA Scientists compared the DNA of hippos 395 00:23:57,505 --> 00:23:59,971 探寻进化轨迹。 and whales to find out how. 396 00:24:02,638 --> 00:24:04,905 研究鲸类基因组时发现， When we look at the genome of whales, 397 00:24:04,905 --> 00:24:08,905 它们仍保留着大量 we see that whales still have a lot of the genes 398 00:24:08,905 --> 00:24:11,105 陆栖时期的基因。 from when they used to live on land. 399 00:24:11,105 --> 00:24:13,205 包括嗅觉感知、 So they still have genes involved in smelling, 400 00:24:13,205 --> 00:24:17,838 汗腺分泌、色觉分辨和唾液生成等基因。 sweat glands, color vision, producing saliva. 401 00:24:17,838 --> 00:24:21,938 但这些基因已失活，并逐渐退化。 But these genes are inactivated, and they gradually degrade. 402 00:24:21,938 --> 00:24:24,438 这成为鲸类起源于陆生祖先的 But I think this is incredibly powerful evidence that shows 403 00:24:24,438 --> 00:24:27,171 有力证据—— that whales come from land ancestors, 404 00:24:27,171 --> 00:24:29,838 尽管基因失活， that they still have these genes in their genomes, 405 00:24:29,838 --> 00:24:31,838 仍留存于基因组中。 even though they're inactivated. 406 00:24:33,438 --> 00:24:35,505 数百万年间， Over millions of years, 407 00:24:35,505 --> 00:24:38,271 鲸类逐渐舍弃了 whales lost many traits beneficial on land 408 00:24:38,271 --> 00:24:43,105 对水生无益的陆生特征。 that had no use in water. 409 00:24:43,105 --> 00:24:47,738 但陆生动物最关键的肢体—— But what happened to that most vital land animal feature, 410 00:24:47,738 --> 00:24:50,405 腿部去了何方？ legs? 411 00:24:54,938 --> 00:24:58,805 在埃及，希沙姆·萨拉姆正寻找能揭示 In Egypt, Hesham Sallam's mission is to find fossils 412 00:24:58,805 --> 00:25:04,071 鲸类完全水生化的化石证据。 that can tell us more about how whales became fully aquatic. 413 00:25:05,405 --> 00:25:07,838 他离开鲸鱼谷，前往 He's leaving Wadi Hitan to search 414 00:25:07,838 --> 00:25:12,205 附近岩层更古老的未勘探区域。 a nearby unexplored area with older rock deposits. 415 00:25:14,905 --> 00:25:16,905 就是这里。 Here we are. 416 00:25:19,605 --> 00:25:21,205 准备好寻找化石了吗？ Ready to find fossils? 417 00:25:21,205 --> 00:25:22,838 当然。 Sure. 418 00:25:25,971 --> 00:25:28,938 同行还有古生物学家 Joining him are fellow paleontologists 419 00:25:28,938 --> 00:25:34,638 肖鲁克·阿尔-阿什卡尔和阿卜杜拉·戈哈尔。 Shorouq Al-Ashqar and Abdullah Gohar. 420 00:25:34,638 --> 00:25:38,638 地质图显示这片古海床岩层 From geological maps, they know this part of the ancient seabed 421 00:25:38,638 --> 00:25:41,871 比发现龙王鲸的岩层 is about two million years older than the deposits 422 00:25:41,871 --> 00:25:45,571 早约两百万年。 where the giant Basilosaurus was found. 423 00:25:45,571 --> 00:25:47,871 他们寻找的过渡期化石 They're searching for intermediate fossils 424 00:25:47,871 --> 00:25:51,871 可能揭示四足陆生哺乳动物 that might shed light on how four-legged land mammals 425 00:25:51,871 --> 00:25:55,738 如何演化成全水生物种。 evolved into their fully aquatic descendants. 426 00:25:55,738 --> 00:25:57,905 我希望找到 I'm hoping to find maybe 427 00:25:57,905 --> 00:26:02,938 某种远古鲸类的 a full skeleton of, uh, 428 00:26:02,938 --> 00:26:04,371 完整骨架， some ancient whales 429 00:26:04,371 --> 00:26:06,605 目前认知尚少的物种。 that we didn't know much about. 430 00:26:06,605 --> 00:26:08,938 若能幸运发现， If we're lucky to find that, 431 00:26:08,938 --> 00:26:11,038 这只史前生物 this prehistoric animal here 432 00:26:11,038 --> 00:26:13,338 可能具备强健下肢 might have sturdy legs 433 00:26:13,338 --> 00:26:16,438 足以支撑身体离开水面。 that can actually lift the body out of the water. 434 00:26:16,438 --> 00:26:18,638 这正是我的目标—— So this is what I'm trying to do, 435 00:26:18,638 --> 00:26:22,205 寻找更原始的鲸类， is find more primitive whales, 436 00:26:22,205 --> 00:26:28,138 或许几小时、几周 and this is going to happen in, in maybe, 437 00:26:28,138 --> 00:26:32,838 或几个月内会有收获。 in a few hours, few weeks, few months. 438 00:26:32,838 --> 00:26:35,438 取决于我们的运气。 It depends how luck we have. 439 00:26:39,338 --> 00:26:43,171 很快就有化石现身。 And it's not long before fossils start to appear. 440 00:26:43,171 --> 00:26:45,138 哇！看这个！ Wow! Look at this! 441 00:26:45,138 --> 00:26:46,705 发现什么了？ Hey, what have you found? 442 00:26:46,705 --> 00:26:48,605 这里有头巨兽。 We have a monster here. 443 00:26:48,605 --> 00:26:52,305 天啊...巨型... Oh, my word. A giant... 444 00:26:52,305 --> 00:26:54,738 太不可思议了。 This is incredible. 445 00:26:54,738 --> 00:26:56,871 看这巨物。 Yeah. Look at this beast. 446 00:26:56,871 --> 00:26:58,505 没错。 Yes. 447 00:26:58,505 --> 00:27:01,238 这是鲨鱼牙齿。 This is a shark tooth. 448 00:27:01,238 --> 00:27:05,171 来自体型惊人的史前巨鲨。 This is really huge shark. 449 00:27:06,371 --> 00:27:09,871 但仍未见鲸类踪迹。 But there's still no sign of a whale. 450 00:27:13,738 --> 00:27:16,038 就在这时... And then... 451 00:27:16,038 --> 00:27:17,638 嘿！ Hey! 452 00:27:17,638 --> 00:27:19,038 他们有所发现。 They've found something. 453 00:27:19,038 --> 00:27:20,771 看这里。 Look at this. 454 00:27:22,471 --> 00:27:24,371 就在此处。 Right here. 455 00:27:24,371 --> 00:27:26,538 小型椎骨化石。 A small vertebra. 456 00:27:26,538 --> 00:27:27,671 哇。 Oh. AL-ASHQAR: Wow. 457 00:27:27,671 --> 00:27:28,871 这里还有一块。 Right there, another one here. 458 00:27:28,871 --> 00:27:30,738 太棒了。 Amazing. SALLAM: Another one there. 459 00:27:30,738 --> 00:27:32,671 看起来像是... So it seems like a... 460 00:27:32,671 --> 00:27:35,471 完整的骨架。 Um, a complete skeleton here. Yeah. 461 00:27:35,471 --> 00:27:37,538 看这排列走向。 Look at this line up. 462 00:27:37,538 --> 00:27:42,138 可能是朝那个方向延伸的脊椎。 Could be the vertebral column going that way. 463 00:27:42,138 --> 00:27:44,971 这绝非龙王鲸。 But this is definitely not Basilosaurus. 464 00:27:44,971 --> 00:27:49,538 椎骨尺寸明显偏小。 The size of the vertebra is quite small. 465 00:27:54,671 --> 00:27:56,271 凭借专业眼光， With his expert eye, 466 00:27:56,271 --> 00:27:59,638 希沙姆立即辨识出骨骼形态。 Hesham can recognize the shape of the bones immediately. 467 00:27:59,638 --> 00:28:02,405 我认为这是具完整骨架， I think this is a, a skeleton, 468 00:28:02,405 --> 00:28:05,738 头骨可能在那方位。 and I do believe might be the skull over there. 469 00:28:05,738 --> 00:28:07,638 令人振奋。 Really exciting. 470 00:28:09,571 --> 00:28:10,871 它能揭示鲸类 Could it provide clues 471 00:28:10,871 --> 00:28:13,971 腿部退化的奥秘吗？ to how whales lost their legs? 472 00:28:13,971 --> 00:28:16,971 这绝对早于龙王鲸时代， So this is definitely older than Basilosaurus, 473 00:28:16,971 --> 00:28:18,638 因为龙王鲸化石 because the Basilosaurus 474 00:28:18,638 --> 00:28:21,871 出自更年轻的地层。 come later, in the younger deposits. 475 00:28:21,871 --> 00:28:25,438 可能是两栖生活的鲸类， So this might be a kind of amphibious lifestyle whale, 476 00:28:25,438 --> 00:28:29,638 后肢应相当强健。 but with really sturdy hind limb. 477 00:28:29,638 --> 00:28:30,838 若足够幸运， If we are lucky enough, 478 00:28:30,838 --> 00:28:33,105 或许能找到骨盆 we might find the pelvis somewhere 479 00:28:33,105 --> 00:28:34,471 和后肢骨骼。 and the hind limbs right here. 480 00:28:40,138 --> 00:28:42,071 就在深入探索前， Before they can find out more, 481 00:28:42,071 --> 00:28:43,771 突发状况降临。 they hit a problem. 482 00:28:46,538 --> 00:28:51,305 风势越来越猛， If it's actually getting too windy, 483 00:28:51,305 --> 00:28:53,705 我们只能暂时撤离 we just have to leave the site and come 484 00:28:53,705 --> 00:28:56,371 待天气转好再返回。 when the nature calm down. 485 00:28:56,371 --> 00:28:58,038 建议暂停作业。 I think we should stop. 486 00:28:59,571 --> 00:29:02,838 他们做好标记便于后续重返。 They mark the spot so they can return to it later. 487 00:29:04,271 --> 00:29:08,005 在此之前，这头鲸类 Until then, this whale's place in the family tree 488 00:29:08,005 --> 00:29:10,438 在进化树上的位置仍是谜团。 will remain unknown. 489 00:29:19,805 --> 00:29:22,771 与此同时，在曼苏拉大学的实验室， Meanwhile, in their lab at Mansoura University, 490 00:29:22,771 --> 00:29:25,471 希沙姆与阿卜杜拉正在研究 Hesham and Abdullah are investigating 491 00:29:25,471 --> 00:29:28,005 另一块关键拼图。 another new piece of the puzzle. 492 00:29:33,305 --> 00:29:36,805 这是最重要的发现之一。 This is one of the most important discovery. 493 00:29:36,805 --> 00:29:40,638 我们拥有近乎完整的头骨、 Here we have nearly complete skull, 494 00:29:40,638 --> 00:29:42,171 下颌骨、 a lower jaw, 495 00:29:42,171 --> 00:29:43,571 部分椎骨 some of the vertebrae, 496 00:29:43,571 --> 00:29:46,705 以及断裂的肋骨。 and some of the broken ribs. 497 00:29:48,505 --> 00:29:52,638 这是此前未知的远古鲸类新物种。 This is a previously unknown species of ancient whale. 498 00:29:54,171 --> 00:29:57,838 阿卜杜拉将其命名为阿努比斯原鲸， Abdullah has named it Phiomicetus anubis, 499 00:29:57,838 --> 00:29:59,438 取自埃及死神 after Anubis, 500 00:29:59,438 --> 00:30:03,171 阿努比斯之名。 the ancient Egyptian god of death. 501 00:30:03,171 --> 00:30:05,171 有明确证据表明 We have a clear indication 502 00:30:05,171 --> 00:30:07,205 这是凶悍的顶级掠食者， of very powerful predator 503 00:30:07,205 --> 00:30:10,305 猎杀周围一切生物。 that hunt everything around him. 504 00:30:10,305 --> 00:30:13,205 堪称四千三百万年前 So we clearly can consider him 505 00:30:13,205 --> 00:30:16,138 所有同期生物的 the god of death for all living animal 506 00:30:16,138 --> 00:30:19,205 死亡主宰。 that lived by him 43 million years ago. 507 00:30:19,205 --> 00:30:21,571 这是非洲出土的 It's one of the oldest whale fossils 508 00:30:21,571 --> 00:30:24,371 最古老鲸类化石之一。 ever unearthed in Africa. 509 00:30:24,371 --> 00:30:29,671 但它能否像祖先巴基鲸那样在陆地行走？ But could it walk on land, like its ancestor Pakicetus? 510 00:30:29,671 --> 00:30:31,538 团队尚未发现腿骨， The team hasn't found leg bones, 511 00:30:31,538 --> 00:30:35,571 需从其他证据寻找答案。 so they must look for other evidence. 512 00:30:35,571 --> 00:30:37,838 阿卜杜拉在椎骨 Abdullah has found a clue 513 00:30:37,838 --> 00:30:40,738 的骨突结构中发现线索。 in a bony projection on one of the vertebrae. 514 00:30:40,738 --> 00:30:44,171 这是胸廓区域的胸椎， This is a thoracic vertebra from the rib cage region, 515 00:30:44,171 --> 00:30:46,905 这个凸起结构 and you can see, this sticking-out bone here 516 00:30:46,905 --> 00:30:48,538 称为神经棘。 is called neural spine. 517 00:30:48,538 --> 00:30:51,705 人类的神经棘很短， It's very short in human, here, 518 00:30:51,705 --> 00:30:56,205 而这明显是陆栖特征的证据—— but this is very clear evidence of walking lifestyle, 519 00:30:56,205 --> 00:30:59,871 因为凸起部分越长， because the longer this sticking-out bone, 520 00:30:59,871 --> 00:31:03,105 越能附着强健肌肉 the more ability to hold massive muscles 521 00:31:03,105 --> 00:31:06,571 支撑四足行走。 that support the walking on four legs. 522 00:31:06,571 --> 00:31:09,505 因此陆生哺乳动物的 So, land mammals have this 523 00:31:09,505 --> 00:31:13,305 神经棘特别长。 very long neural spine here. 524 00:31:13,305 --> 00:31:16,905 以牛为例。 This is a cow. 525 00:31:16,905 --> 00:31:20,438 而现代海豚的 But if you look at the modern dolphin, 526 00:31:20,438 --> 00:31:25,671 神经棘明显 you can see clearly this sticking neural spine 527 00:31:25,671 --> 00:31:27,971 比陆生动物 is much, much shorter 528 00:31:27,971 --> 00:31:32,505 短得多。 comparing to the walking terrestrial animal. 529 00:31:32,505 --> 00:31:34,338 这是完全水生的， So this is fully aquatic, 530 00:31:34,338 --> 00:31:35,938 这是完全陆生的， this is fully terrestrial, 531 00:31:35,938 --> 00:31:37,571 原鲸介于两者之间。 and anubis in between. 532 00:31:39,138 --> 00:31:43,771 团队认为若阿努比斯原鲸背部肌肉发达， The team believes that if anubis had strong back muscles, 533 00:31:43,771 --> 00:31:46,471 很可能用于行走。 it probably used them for walking. 534 00:31:50,471 --> 00:31:52,505 "死亡之神"阿努比斯原鲸 Anubis, the god of death, 535 00:31:52,505 --> 00:31:55,738 是凶悍的海洋掠食者。 was a formidable marine predator. 536 00:31:55,738 --> 00:31:59,038 体长约三米， It measured around ten feet long 537 00:31:59,038 --> 00:32:03,305 重逾半吨。 and weighed over half a ton. 538 00:32:03,305 --> 00:32:06,271 长期栖息海洋， It spent extended periods in the sea, 539 00:32:06,271 --> 00:32:09,171 捕食鱼类和海龟。 where it hunted fish and turtles. 540 00:32:13,405 --> 00:32:16,338 根据发现的骨骼判断， But from the bones the team has found, 541 00:32:16,338 --> 00:32:18,971 它能返回陆地， they think it was able to come back to land, 542 00:32:18,971 --> 00:32:22,071 可能用于繁殖。 perhaps to breed. 543 00:32:22,071 --> 00:32:25,838 它不像海豹那样扭动上岸， And it didn't wriggle out of the water like a seal. 544 00:32:25,838 --> 00:32:29,938 而是能行走的鲸类。 Anubis was probably a walking whale. 545 00:32:34,071 --> 00:32:35,371 放哪里好呢？ Where can I put it? 546 00:32:35,371 --> 00:32:37,938 谢谢。 Thank you. 547 00:32:37,938 --> 00:32:39,438 为确认阿努比斯原鲸 To find out more about 548 00:32:39,438 --> 00:32:41,838 在鲸类进化树上的位置， anubis's place in the whale family tree, 549 00:32:41,838 --> 00:32:44,105 希沙姆与阿卜杜拉带着头骨 Hesham and Abdullah take the skull 550 00:32:44,105 --> 00:32:47,105 前往附近医院进行CT扫描。 to a nearby hospital for a CT scan. 551 00:32:49,171 --> 00:32:50,538 我们现在出去？ Shall we get outside now? 552 00:32:50,538 --> 00:32:51,738 对，出去。 Yes, yes, yes, outside. 553 00:32:57,438 --> 00:33:00,371 能进去看看吗？ Can you go inside? 554 00:33:00,371 --> 00:33:02,605 希沙姆重点观察 Hesham wants to take a closer look 555 00:33:02,605 --> 00:33:05,171 阿努比斯原鲸的鼻孔位置... at the position of anubis's nostrils... 556 00:33:05,171 --> 00:33:06,638 好， Okay, 557 00:33:06,638 --> 00:33:09,071 请拉远镜头？ can you zoom out, please? 558 00:33:09,071 --> 00:33:12,038 ...发现了惊人特征。 ...and spots something striking. 559 00:33:12,038 --> 00:33:13,705 阿努比斯原鲸的 So here in anubis, 560 00:33:13,705 --> 00:33:16,638 吻部前端断裂， the tip of the snout is broken off, 561 00:33:16,638 --> 00:33:19,038 原本应延伸至此， and it could be up to here, 562 00:33:19,038 --> 00:33:22,638 但鼻孔开口位于吻部 but the nasal opening would be right here, 563 00:33:22,638 --> 00:33:26,205 后三分之一处。 one-third the way back in the snout. 564 00:33:26,205 --> 00:33:28,705 现代鲸类的 Comparing to the modern whale, 565 00:33:28,705 --> 00:33:31,338 呼吸孔位于头骨顶端。 the blowhole would be on the top of the skull. 566 00:33:32,838 --> 00:33:37,638 陆生哺乳动物鼻孔在鼻尖， Land mammals' nostrils are at the tip of the nose. 567 00:33:37,638 --> 00:33:39,538 现代鲸类鼻孔上移至头顶 Modern whales' nostrils have moved to 568 00:33:39,538 --> 00:33:42,671 形成呼吸孔。 the top of their heads to become blowholes. 569 00:33:46,805 --> 00:33:48,805 而阿努比斯原鲸的鼻孔 But anubis's nostrils are 570 00:33:48,805 --> 00:33:52,505 位于吻部后方三分之一处。 a third of the way back on its snout. 571 00:33:52,505 --> 00:33:56,938 这离完全水生化更近一步。 It's one step closer to becoming fully aquatic. 572 00:34:00,371 --> 00:34:03,071 那么，行走的鲸类 So, how did walking whales 573 00:34:03,071 --> 00:34:06,571 如何退去四肢演化为现代鲸类？ lose their legs to become modern whales? 574 00:34:06,571 --> 00:34:08,905 回到鲸鱼谷， Back at Wadi Hitan, 575 00:34:08,905 --> 00:34:13,838 希沙姆仔细观察龙王鲸化石。 Hesham takes a closer look at Basilosaurus. 576 00:34:14,971 --> 00:34:17,138 这种巨型海洋掠食者 This huge marine predator 577 00:34:17,138 --> 00:34:21,605 比阿努比斯原鲸晚三百万年出现。 evolved about three million years after anubis. 578 00:34:21,605 --> 00:34:25,205 但它能在陆地支撑身体吗？ But could it support itself on land? 579 00:34:25,205 --> 00:34:27,205 这是它的前肢， Here is the arm of this beast. 580 00:34:27,205 --> 00:34:33,038 不同于典型哺乳动物的前肢， It's actually wasn't like a regular arm of a mammal's, 581 00:34:33,038 --> 00:34:37,171 已特化为鳍肢用于游泳。 but flippers, to allow it to swim in the sea. 582 00:34:37,171 --> 00:34:42,738 龙王鲸的前肢进化成鳍状肢， Basilosaurus's front legs have turned into flippers. 583 00:34:42,738 --> 00:34:44,671 而身体后部 And at the back of the animal 584 00:34:44,671 --> 00:34:47,038 结构更为奇妙。 is something even more intriguing. 585 00:34:48,038 --> 00:34:49,371 这是鲸类进化中 This is really something 586 00:34:49,371 --> 00:34:52,605 非常特别的特征。 very cool in the whale evolution. 587 00:34:52,605 --> 00:34:56,371 这是巨兽的后肢， This is the hind limb of this monster, 588 00:34:56,371 --> 00:34:58,671 这是完整的骨盆。 and this is a complete pelvis. 589 00:34:58,671 --> 00:35:01,371 位于这些椎骨 Would be underneath 590 00:35:01,371 --> 00:35:03,738 下方，像这样。 one of these vertebrae, like that. 591 00:35:03,738 --> 00:35:06,505 这是这头巨兽 And this is the whole legs 592 00:35:06,505 --> 00:35:10,605 完整的后肢。 of this really huge animal. 593 00:35:10,605 --> 00:35:12,805 右后肢—— This is the right leg-- 594 00:35:12,805 --> 00:35:15,271 股骨、 the thigh bone, 595 00:35:15,271 --> 00:35:18,505 胫骨、 the shinbone, 596 00:35:18,505 --> 00:35:21,371 以及足部。 and the foot. 597 00:35:25,938 --> 00:35:29,371 模型显示龙王鲸的后肢 These casts show that Basilosaurus's legs 598 00:35:29,371 --> 00:35:34,371 比人类手臂还细小。 were smaller than the arms of a human. 599 00:35:34,371 --> 00:35:37,038 以20米体长对比后肢尺寸， Definitely Basilosaurus cannot walk, 600 00:35:37,038 --> 00:35:40,838 龙王鲸绝对 given the size of these hind limbs 601 00:35:40,838 --> 00:35:45,205 无法陆地行走。 comparing to the whole body, 20 meter long. 602 00:35:45,205 --> 00:35:50,405 完全无法支撑陆地活动。 Just totally cannot support walking on land. 603 00:35:50,405 --> 00:35:54,771 就像霸王龙的前肢，毫无功能。 Just like T. rex hand, do nothing. 604 00:35:58,905 --> 00:36:01,671 与能行走的祖先不同， Unlike its walking whale ancestors, 605 00:36:01,671 --> 00:36:05,071 龙王鲸已完全水生。 Basilosaurus was fully aquatic. 606 00:36:09,505 --> 00:36:11,638 但在现代鲸类体内， But in modern whales, 607 00:36:11,638 --> 00:36:16,805 是否留存着行走时代的痕迹？ are there any remnants of their walking past? 608 00:36:16,805 --> 00:36:18,805 实验室内， Back in the lab, 609 00:36:18,805 --> 00:36:21,271 乔伊·雷登伯格与迈克尔·麦高恩 Joy Reidenberg and Michael McGowen 610 00:36:21,271 --> 00:36:24,271 继续解剖喙鲸寻找线索。 are looking for more clues inside the beaked whale. 611 00:36:24,271 --> 00:36:26,438 现在观察侧腹区域， We're now looking at the flank area, 612 00:36:26,438 --> 00:36:27,605 我要展示 and I'm going to show you 613 00:36:27,605 --> 00:36:29,238 这里的神奇结构。 something really cool in this area. 614 00:36:29,238 --> 00:36:31,805 此处有块小骨头。 Right in here is a small bone. 615 00:36:31,805 --> 00:36:34,471 这是祖先具有后肢的 Something that is really a throwback 616 00:36:34,471 --> 00:36:37,938 进化残留。 to the ancestral condition of having hind legs. 617 00:36:37,938 --> 00:36:42,938 仅存骨盆的微小残迹。 All that's left is a little remnant of a pelvis. 618 00:36:42,938 --> 00:36:44,838 这块微型骨盆 This tiny pelvic bone 619 00:36:44,838 --> 00:36:47,071 隐藏在鲸的后腹部， is hidden in the whale's hind quarters, 620 00:36:47,071 --> 00:36:51,338 原本应是臀部的位置。 where hips would once have been. 621 00:36:51,338 --> 00:36:52,971 唯一缺失的是 The only thing it doesn't have is 622 00:36:52,971 --> 00:36:55,571 与脊柱的连接部分。 the connection back to the spine. 623 00:36:55,571 --> 00:36:57,238 人类的骨盆连接脊柱， So ours is connected in the back to the spine. 624 00:36:57,238 --> 00:36:58,605 而这是游离的。 This one is just free-floating. 625 00:36:58,605 --> 00:37:00,705 比预期小得多—— It's tiny-- it's actually 626 00:37:00,705 --> 00:37:02,471 尺寸惊人地小。 a lot smaller than I thought it was gonna be. 627 00:37:02,471 --> 00:37:04,238 这块骨盆意义重大， This pelvis is so interesting, 628 00:37:04,238 --> 00:37:05,738 因为它是陆生祖先 because it's a throwback 629 00:37:05,738 --> 00:37:06,971 用骨盆行走的 to the land animals 630 00:37:06,971 --> 00:37:08,605 进化遗迹。 that were using a pelvis for walking. 631 00:37:08,605 --> 00:37:09,771 但鲸类不再行走， But whales aren't walking. 632 00:37:09,771 --> 00:37:11,505 也没有后肢。 They don't have hind legs. 633 00:37:13,738 --> 00:37:16,305 所有现代鲸类仍保留骨盆， All modern whales still have a pelvis, 634 00:37:16,305 --> 00:37:21,138 部分还隐藏着微小的腿部残骨。 and some have tiny hidden leg bones, too. 635 00:37:21,138 --> 00:37:24,905 但鲸类为何需要骨盆？ But why would a whale need a pelvis? 636 00:37:24,905 --> 00:37:26,605 它仍有功能。 It still has function. 637 00:37:26,605 --> 00:37:28,171 部分功能是 Part of that function 638 00:37:28,171 --> 00:37:30,938 固定腹部肌肉辅助游泳， is to anchor the muscles of the belly for swimming, 639 00:37:30,938 --> 00:37:32,805 仍参与运动系统， so it's still being used in locomotion, 640 00:37:32,805 --> 00:37:34,038 只是不用于行走。 just not with legs. 641 00:37:34,038 --> 00:37:35,771 就像人类腹部的 So think about, in the front, you know, 642 00:37:35,771 --> 00:37:37,505 六块腹肌？对。 we have the six-pack muscles? Yeah. 643 00:37:37,505 --> 00:37:39,238 这些肌肉帮助身体 These help to bend the body 644 00:37:39,238 --> 00:37:41,305 向下弯曲。 in this downward motion like that. 645 00:37:41,305 --> 00:37:43,371 这是游泳动作的一部分。 So that's part of the swimming action. 646 00:37:43,371 --> 00:37:44,905 原来如此。 Oh, wow, okay. 647 00:37:44,905 --> 00:37:46,371 肌肉附着于这块骨头， They anchor on this bone. 648 00:37:46,371 --> 00:37:47,505 也附着在其他部位， They anchor in other places, too, 649 00:37:47,505 --> 00:37:48,671 但这里也是锚定点。 but they also anchor on this bone. 650 00:37:49,671 --> 00:37:52,238 这是哺乳动物祖先的另一遗迹—— And that's another remnant of its mammal past, 651 00:37:52,238 --> 00:37:55,105 通过脊柱上下摆动游动。 is that they move their spine up and down. 652 00:37:55,105 --> 00:37:56,671 而鱼类和爬行类 And with fish 653 00:37:56,671 --> 00:37:58,971 则是左右摆动脊柱 and even reptiles, they move side to side. 654 00:37:58,971 --> 00:38:00,171 观察蛇类爬行 You watch a snake move, 655 00:38:00,171 --> 00:38:01,471 或是鳄鱼行走 you watch a crocodile walking, 656 00:38:01,471 --> 00:38:03,038 它们的运动方式类似鱼类游泳 they're swimming like fish, 657 00:38:03,038 --> 00:38:04,538 只不过是在陆地上用腿移动 but on the land, with legs. Yeah. 658 00:38:04,538 --> 00:38:06,238 哺乳动物的进化 When you get to mammals, 659 00:38:06,238 --> 00:38:07,638 使四肢移至躯干下方 the legs come underneath, 660 00:38:07,638 --> 00:38:09,738 脊柱和身体抬离地面 the spine and the body come off the ground, 661 00:38:09,738 --> 00:38:12,738 从而能够快速奔跑 and now they're free to gallop. 662 00:38:17,238 --> 00:38:18,971 当鲸类重返海洋时 And when whales went 663 00:38:18,971 --> 00:38:20,605 保留了这种 back into the water, 664 00:38:20,605 --> 00:38:22,238 上下摆动的脊柱运动方式 they kept the up and down spinal movement, 665 00:38:22,238 --> 00:38:24,105 相当于在水中 so they're still galloping. 666 00:38:24,105 --> 00:38:25,938 "奔跑"！ In the water! 667 00:38:37,938 --> 00:38:39,871 后肢退化 Losing their legs 668 00:38:39,871 --> 00:38:41,871 只是鲸类适应海洋生活 was just one change whales underwent 669 00:38:41,871 --> 00:38:45,505 众多改变中的一环 as they adapted to life in the ocean. 670 00:38:48,505 --> 00:38:51,005 为在水下环境中生存 To survive in this underwater environment, 671 00:38:51,005 --> 00:38:56,138 鲸类的四肢变得更加强壮 游泳更加高效 whales' limbs grew stronger, making swimming easier. 672 00:38:56,138 --> 00:38:59,671 尾部进化出水平尾鳍 They grew horizontal flukes on the ends of their tails, 673 00:38:59,671 --> 00:39:02,705 前肢逐渐演变成鳍状肢 and front limbs began to turn into flippers 674 00:39:02,705 --> 00:39:05,505 用于保持平衡和转向 for stability and steering. 675 00:39:05,505 --> 00:39:08,771 当游泳方式转变为尾部驱动后 As they moved to tail-powered swimming, 676 00:39:08,771 --> 00:39:11,438 它们的身体更加流线型 their bodies became more streamlined, 677 00:39:11,438 --> 00:39:13,871 后肢萎缩 hind limbs shrank, 678 00:39:13,871 --> 00:39:17,471 脊柱延长 and their spines grew longer. 679 00:39:17,471 --> 00:39:20,538 它们已经完全适应水生生活 They had become fully aquatic 680 00:39:20,538 --> 00:39:23,405 无法再返回陆地 and were unable to return to the land. 681 00:39:35,238 --> 00:39:38,671 鲸鱼谷的沙漠中散布着 The desert at Wadi Hitan is dotted with the skeletons 682 00:39:38,671 --> 00:39:41,638 最早一批远古鲸类的骨骼化石 of some of the first ancient whales. 683 00:39:41,638 --> 00:39:44,605 但约3400万年前 But around 34 million years ago, 684 00:39:44,605 --> 00:39:49,405 它们从这里的地质记录中神秘消失 they mysteriously vanish from the fossil record here. 685 00:39:49,405 --> 00:39:54,538 在距离鲸鱼谷约80公里的区域 In an area about 50 miles from Wadi Hitan, 686 00:39:54,538 --> 00:39:56,938 肖鲁克·阿尔-阿什卡尔正在调查 Shorouq Al-Ashqar investigates 687 00:39:56,938 --> 00:40:01,605 鲸类从此地消失的原因 why the whales disappeared from this region. 688 00:40:02,938 --> 00:40:06,871 这些奇特物体给出了答案 These strange objects provide an answer. 689 00:40:06,871 --> 00:40:09,138 这是硅化木化石 This is fossilized wood. 690 00:40:09,138 --> 00:40:12,638 看似木头实为岩石 It seems like wood, but it's rock. 691 00:40:12,638 --> 00:40:15,371 木质被二氧化硅和矿物质取代 The wood replaced by silica and minerals, 692 00:40:15,371 --> 00:40:19,305 虽然沉重却明确指示着 so it's so heavy, but it's a good indication 693 00:40:19,305 --> 00:40:22,805 这里曾经是茂密森林 that this area one day was a forest. 694 00:40:22,805 --> 00:40:27,238 树木高达40-50米 The trees were very tall, 40 to 50 meters long, 695 00:40:27,238 --> 00:40:30,638 彩色飞鸟盘旋天际 colorful birds flying in the area. 696 00:40:30,638 --> 00:40:33,838 龟蛇成群 生机勃勃 Turtles, snakes-- full of life. 697 00:40:35,438 --> 00:40:40,371 这些硅化木距今约3400万年 The fossilized wood is around 34 million years old. 698 00:40:40,371 --> 00:40:44,138 标志着这片曾经的繁荣海域 It's a sign that this area, once a thriving ocean, 699 00:40:44,138 --> 00:40:47,205 经历了翻天覆地的变化 underwent a dramatic change. 700 00:40:51,038 --> 00:40:56,505 当时地球气候开始变冷 At that time, Earth's climate began to cool. 701 00:40:56,505 --> 00:40:58,571 南极冰盖形成 The Antarctic ice sheet formed 702 00:40:58,571 --> 00:41:01,605 海平面下降 and sea levels dropped. 703 00:41:01,605 --> 00:41:06,338 特提斯洋退缩形成地中海 The Tethys Ocean receded, forming the Mediterranean. 704 00:41:06,338 --> 00:41:10,071 鲸类曾经畅游的温暖浅海 And where whales once swam in warm, shallow waters, 705 00:41:10,071 --> 00:41:14,138 变成了茂密森林 a forest grew. 706 00:41:14,138 --> 00:41:17,105 生活在鲸鱼谷的原始鲸类 The primitive whales that lived in Wadi Hitan, 707 00:41:17,105 --> 00:41:20,371 全部走向灭绝 all of them are, died out. 708 00:41:20,371 --> 00:41:25,505 幸运的是部分鲸类适应了气候变化 Fortunately, some of whales adapt with the climatic change. 709 00:41:25,505 --> 00:41:27,171 鲸作为哺乳动物 Whales are mammals, 710 00:41:27,171 --> 00:41:29,638 具有恒温特性 and mammals are warm-blooded bodies, 711 00:41:29,638 --> 00:41:32,105 能够适应寒冷水域 so they can adapt with the cold water 712 00:41:32,105 --> 00:41:34,238 寻找新的栖息地 and find new places to live in. 713 00:41:36,205 --> 00:41:37,771 恒温特性使它们 Being warm-blooded, 714 00:41:37,771 --> 00:41:40,605 能够自主产生热量 they were able to generate their own heat 715 00:41:40,605 --> 00:41:43,671 并发展出鲸脂层抵御寒冷 and grow blubber to insulate their bodies from the cold, 716 00:41:43,671 --> 00:41:49,505 得以迁徙至全球海域繁衍生息 allowing them to migrate and thrive all over the world. 717 00:41:49,505 --> 00:41:53,705 但鲸类的进化传奇并未就此终结 But the whale's story doesn't end there. 718 00:42:00,838 --> 00:42:03,071 在史密森尼国家自然历史博物馆 In a warehouse at the 719 00:42:03,071 --> 00:42:05,671 的仓库中收藏着 Smithsonian National Museum of Natural History 720 00:42:05,671 --> 00:42:10,538 世界上最大的鲸骨标本库 is the world's largest whale bone collection. 721 00:42:10,538 --> 00:42:14,938 保存着近万头鲸类的遗骸 It holds remains from nearly 10,000 whales. 722 00:42:17,038 --> 00:42:20,971 进化生物学家艾伦·库姆斯通过扫描头骨 Evolutionary biologist Ellen Coombs scans their skulls 723 00:42:20,971 --> 00:42:24,371 研究它们的演化历程 to investigate how they changed over time. 724 00:42:27,138 --> 00:42:29,405 头骨研究至关重要 Studying the skull is really important, 725 00:42:29,405 --> 00:42:30,838 因为在鲸类进化中 because in whales, 726 00:42:30,838 --> 00:42:32,038 许多关键变化都发生在 it's where a lot of changes have happened 727 00:42:32,038 --> 00:42:34,171 这个部位 over their evolutionary history, 728 00:42:34,171 --> 00:42:36,105 它容纳着众多感觉器官 because it houses a lot of sensory organs-- 729 00:42:36,105 --> 00:42:38,838 眼睛、鼻腔、大脑 the eyes, the nose, the brain-- 730 00:42:38,838 --> 00:42:40,438 能告诉我们许多关于 and this can tell us lots of things 731 00:42:40,438 --> 00:42:41,938 它们的进食方式 about how the animal has evolved to eat 732 00:42:41,938 --> 00:42:43,338 和生存策略的演化 and live its life. 733 00:42:45,571 --> 00:42:49,038 3D扫描技术让艾伦能够详细研究 The 3D scans allow Ellen to look in detail 734 00:42:49,038 --> 00:42:50,871 鲸类进化史上 at the more recent chapters 735 00:42:50,871 --> 00:42:54,938 较晚近的演化篇章 in the whale's evolutionary tale. 736 00:42:57,871 --> 00:43:00,971 当最后一批远古鲸类灭绝后 When the last of the ancient whales died out, 737 00:43:00,971 --> 00:43:05,138 现代鲸类的演化征程才真正开始 the modern whale's journey began. 738 00:43:05,138 --> 00:43:08,405 随着进化树不断延伸 And as the family tree continued to grow, 739 00:43:08,405 --> 00:43:11,738 惊人的分化出现了 something surprising happened. 740 00:43:11,738 --> 00:43:13,638 部分鲸类保留牙齿 Some kept their teeth, 741 00:43:13,638 --> 00:43:18,238 如虎鲸、抹香鲸和海豚 like orcas, sperm whales, and dolphins. 742 00:43:18,238 --> 00:43:21,971 部分如蓝鲸、座头鲸和露脊鲸 And some, like the blue, humpback, and right whales, 743 00:43:21,971 --> 00:43:23,738 则失去牙齿 lost their teeth 744 00:43:23,738 --> 00:43:26,205 进化出全新的滤食器官 and developed a new filter-feeding tool 745 00:43:26,205 --> 00:43:29,838 鲸须板 called baleen. 746 00:43:33,371 --> 00:43:35,738 这是座头鲸的下颌部位 This is the underside of the mouth of a humpback whale, 747 00:43:35,738 --> 00:43:37,471 属于须鲸的一种 which is one of the baleen whales. 748 00:43:37,471 --> 00:43:39,171 其须鲸特征体现在 And what makes it a baleen whale 749 00:43:39,171 --> 00:43:40,705 这个特殊结构 is what's going on here. 750 00:43:40,705 --> 00:43:41,938 这就是鲸须 So this is baleen. 751 00:43:41,938 --> 00:43:44,071 在虎鲸或海豚 This sits where teeth would normally sit 752 00:43:44,071 --> 00:43:46,171 长牙齿的位置 in something like a killer whale or a dolphin. 753 00:43:46,171 --> 00:43:49,071 须鲸则进化出 But instead, they have these amazing plates of baleen, 754 00:43:49,071 --> 00:43:51,805 由角蛋白构成的鲸须板 which are made of keratin, just like our hair or nails. 755 00:43:51,805 --> 00:43:52,971 可以看到末端 And you can see that it has 756 00:43:52,971 --> 00:43:54,438 密布着细密绒毛 these kind of hairs on the end here, 757 00:43:54,438 --> 00:43:55,938 用于过滤猎物 which are used to filter out prey. 758 00:43:55,938 --> 00:43:57,405 它们先吸入 And what they do is, they suck in 759 00:43:57,405 --> 00:44:00,138 充满鱼类或磷虾的海水 a big mouthful of water full of fish or krill, 760 00:44:00,138 --> 00:44:01,405 这些是它们的主要食物 which is what they eat, 761 00:44:01,405 --> 00:44:02,905 然后用舌头 and then they use their tongue 762 00:44:02,905 --> 00:44:05,838 将海水挤出 将猎物困在 to force out that water and capture all of their prey 763 00:44:05,838 --> 00:44:07,205 鲸须板之间 in these plates of baleen. 764 00:44:07,205 --> 00:44:09,238 单次滤食可获取 And that is sometimes up to 765 00:44:09,238 --> 00:44:11,805 高达50万卡路里的能量 half a million calories in one mouthful. 766 00:44:27,205 --> 00:44:29,805 为何这些鲸类会走上 Why did these whales take such a different path 767 00:44:29,805 --> 00:44:31,971 与齿鲸截然不同的进化道路？ from their toothed cousins? 768 00:44:31,971 --> 00:44:34,471 这是蓝鲸的头骨标本 Here we can see a blue whale skull. 769 00:44:34,471 --> 00:44:36,171 最显著的特征是 The main thing that we see here 770 00:44:36,171 --> 00:44:39,005 平坦的面部结构 is how flat the face is, 771 00:44:39,005 --> 00:44:41,671 以及异常宽阔的口腔 how wide the mouth is, 772 00:44:41,671 --> 00:44:43,671 这些都是 and these are perfect adaptations 773 00:44:43,671 --> 00:44:45,605 大规模滤食的完美适应特征 for mass filter feeding with baleen. 774 00:44:45,605 --> 00:44:48,838 与此同时 齿鲸则进化出 Meanwhile, the toothed whale has evolved 775 00:44:48,838 --> 00:44:51,105 完全不同的头骨形态 a very different skull shape. 776 00:44:51,105 --> 00:44:52,671 观察这具虎鲸头骨 So, if we take a look 777 00:44:52,671 --> 00:44:54,305 侧面可见 at the skull of this killer whale from the side, 778 00:44:54,305 --> 00:44:55,705 其前额呈现 you can see that 779 00:44:55,705 --> 00:44:57,171 明显的凹陷结构 the forehead is concave. 780 00:44:57,171 --> 00:44:58,838 这里容纳着 This is because it houses a load of organs 781 00:44:58,838 --> 00:45:01,405 用于回声定位的器官组织 that are used for echolocation. 782 00:45:06,605 --> 00:45:10,005 回声定位这种高度特化的技能 The highly specialized skill of echolocation 783 00:45:10,005 --> 00:45:13,938 已在蝙蝠和鲸类等动物中演化形成 has evolved in some animals, like bats and whales. 784 00:45:16,838 --> 00:45:20,338 鲸类通过发射高频声波来"视物" Whales "see" by emitting high-frequency sounds 785 00:45:20,338 --> 00:45:22,038 然后聆听 and then listening for 786 00:45:22,038 --> 00:45:24,138 声波如何从物体表面反射 how they bounce back off objects 787 00:45:24,138 --> 00:45:27,138 从而在深海寻找猎物 to find prey in the depths of the ocean. 788 00:45:34,938 --> 00:45:36,371 齿鲸通过 Toothed whales do this 789 00:45:36,371 --> 00:45:39,005 额部高度特化的器官实现这一功能 in a very specialized apparatus in their forehead, 790 00:45:39,005 --> 00:45:41,005 关键结构是声唇 the key ones being the phonic lips, 791 00:45:41,005 --> 00:45:43,271 能发出高频咔嗒声 which make a high-frequency clicking sound, 792 00:45:43,271 --> 00:45:46,271 以及额隆这个脂肪器官 and the melon, which is a fatty organ, 793 00:45:46,271 --> 00:45:48,338 帮助聚焦这些高频声波 which helps to focus these high-frequency sounds 794 00:45:48,338 --> 00:45:49,771 当声波离开动物体时 as they leave the animal. 795 00:45:51,338 --> 00:45:54,671 但这项技能的演化过程仍是未解之谜 But how this skill evolved is still a mystery. 796 00:45:56,738 --> 00:45:58,771 我们已知灭绝的远古鲸类 So we have ancient whales dying out 797 00:45:58,771 --> 00:46:00,405 不具备回声定位能力 that we know they could not echolocate. 798 00:46:00,405 --> 00:46:02,438 而后出现了 And then we have the appearance 799 00:46:02,438 --> 00:46:04,471 具备回声定位能力的早期齿鲸 of the early toothed whales that could echolocate. 800 00:46:04,471 --> 00:46:06,305 这中间存在断层 So there's a gap in there, 801 00:46:06,305 --> 00:46:08,105 可能有些化石标本 where there'll be several fossils 802 00:46:08,105 --> 00:46:10,371 具备原始回声定位特征 that have maybe very basic echolocation, 803 00:46:10,371 --> 00:46:12,638 这些正是我们需要寻找的关键化石 and they're the fossils that we really need to find. 804 00:46:15,205 --> 00:46:18,071 科学家认为这些早期鲸类存活下来 Scientists think these early whales survived 805 00:46:18,071 --> 00:46:20,505 将基因传递给后代 to pass on their genes to their offspring, 806 00:46:20,505 --> 00:46:23,271 相关能力因此逐步完善 and so their abilities gradually improved. 807 00:46:26,405 --> 00:46:30,305 如今某些齿鲸已成为高效掠食者 Today, some toothed whales are such efficient predators, 808 00:46:30,305 --> 00:46:32,305 甚至捕食须鲸近亲 they even hunt their baleen cousins. 809 00:46:34,938 --> 00:46:39,271 为此座头鲸演化出新的生存策略 So these humpbacks have evolved new survival strategies. 810 00:46:48,038 --> 00:46:50,505 回到多米尼加共和国 Back in the Dominican Republic, 811 00:46:50,505 --> 00:46:54,171 乔伊·雷登伯格与海洋生物学家米思里尔·麦凯 Joy Reidenberg and marine biologist Mithriel MacKay 812 00:46:54,171 --> 00:46:56,671 正在进行鲸类观测任务 are on a whale-watching mission. 813 00:46:56,671 --> 00:46:58,271 有喷气 There's a blow, 814 00:46:58,271 --> 00:47:00,538 大约1点钟方向 around 1:00. 815 00:47:00,538 --> 00:47:01,871 第三头 没错 And the third. Yeah. 816 00:47:01,871 --> 00:47:03,671 第四头 And four. 817 00:47:03,671 --> 00:47:07,071 那里共有四头 There's four there. 818 00:47:07,071 --> 00:47:10,471 多数鲸类以家族群居 Most whales live in family groups 819 00:47:10,471 --> 00:47:13,938 拥有复杂的社会生活 and have complex social lives. 820 00:47:13,938 --> 00:47:16,405 米思里尔和乔伊希望探究 Mithriel and Joy want to understand 821 00:47:16,405 --> 00:47:18,605 某些行为如何 how certain behaviors 822 00:47:18,605 --> 00:47:21,638 赋予它们演化优势 give them an evolutionary advantage. 823 00:47:21,638 --> 00:47:23,005 我们观察行为 We look at the behaviors 824 00:47:23,005 --> 00:47:25,438 进而提出问题 and then we start asking questions. 825 00:47:25,438 --> 00:47:26,805 它们为何这样做？ Why are they doing those things? 826 00:47:26,805 --> 00:47:30,071 因为行为动机的答案 Because the answer to the why 827 00:47:30,071 --> 00:47:32,705 揭示了演化的原因 gives us the reason they evolved this way. Mm-hmm. 828 00:47:41,271 --> 00:47:43,038 太震撼了 Oh, that's awesome. 829 00:47:43,038 --> 00:47:44,571 美极了—— That's beautiful-- beautiful. 830 00:47:44,571 --> 00:47:45,838 看它如何将幼鲸 Look at how she's putting 831 00:47:45,838 --> 00:47:47,038 托在自己... the baby on her, on her... MACKAY: Yep. 832 00:47:47,038 --> 00:47:48,571 它会下潜托起幼鲸 She'll scoop under and pick it up. 833 00:47:48,571 --> 00:47:49,905 它正利用 And she's using that, 834 00:47:49,905 --> 00:47:51,771 头部平坦的表面 that flat surface of the top of her head 835 00:47:51,771 --> 00:47:53,038 固定幼鲸 to hold the calf there, 836 00:47:53,038 --> 00:47:54,938 如同天然摇篮 almost like it's got a cradle surface. 837 00:47:54,938 --> 00:47:56,971 这样能让幼鲸休息 So she can give the calf a rest this way. 838 00:47:56,971 --> 00:47:59,138 若感知幼鲸遇险 Or if she feels like the calf's in danger, 839 00:47:59,138 --> 00:48:01,405 可直接将其顶出水面 she could pull this calf right up out of the water. 840 00:48:01,405 --> 00:48:04,405 雄性出现了 And there's the male. 841 00:48:04,405 --> 00:48:06,938 这头母鲸正被雄性追逐 This mom is being pursued by a male. 842 00:48:10,071 --> 00:48:12,971 它将幼鲸置于头顶 She's putting the calf on her head 843 00:48:12,971 --> 00:48:17,071 以保护其免受求偶冲撞 to protect it from his aggressive advances. 844 00:48:17,071 --> 00:48:19,505 米思里尔认为这种保护行为 Mithriel thinks this protective behavior 845 00:48:19,505 --> 00:48:24,438 关乎须鲸的生存延续 plays a role in baleen whale survival. 846 00:48:24,438 --> 00:48:26,771 想象它们遭遇虎鲸时 Picture them out, and killer whales coming up 847 00:48:26,771 --> 00:48:28,538 幼鲸成为绝佳猎物 and seeing this baby as a good meal. 848 00:48:28,538 --> 00:48:32,671 能用扁平头部托起幼鲸 The moms that are able to use their flat head 849 00:48:32,671 --> 00:48:35,871 迅速撤离的母鲸 to scoop the baby up out of the water and get away 850 00:48:35,871 --> 00:48:39,438 其后代才更可能延续血脉 are the ones whose babies are going to have babies. 851 00:48:39,438 --> 00:48:42,905 传统认知认为演化改变物种 We're always taught evolution changes things, 852 00:48:42,905 --> 00:48:44,538 实则不然 but it doesn't. 853 00:48:44,538 --> 00:48:46,638 实质是淘汰 What it really does is, it eliminates 854 00:48:46,638 --> 00:48:48,438 适应性欠佳的个体 the stuff that doesn't work as well, 855 00:48:48,438 --> 00:48:50,805 留存最优特质 so what's left is what works. 856 00:48:50,805 --> 00:48:52,971 属于被动筛选 确实如此 It's reactive, it's not proactive. Exactly. 857 00:48:54,338 --> 00:48:58,338 这些鲸类还有另一项终极防御机制： And these whales have one other vital defense mechanism: 858 00:48:58,338 --> 00:49:01,005 庞大体型 their huge size. 859 00:49:01,005 --> 00:49:04,671 它们如何变得如此巨大？ How did they get so big? 860 00:49:04,671 --> 00:49:06,971 这些鲸类的祖先 The ancestors of these whales 861 00:49:06,971 --> 00:49:08,571 体型比如今小得多 were actually smaller than our current whales. 862 00:49:08,571 --> 00:49:10,505 这使得它们更灵活 That made them more nimble. 863 00:49:10,505 --> 00:49:11,805 能敏捷地穿梭水中 They could swim through the water 864 00:49:11,805 --> 00:49:13,105 捕食鱼类 more agilely, picking out fish. 865 00:49:13,105 --> 00:49:15,838 但现代大型须鲸 But when we look at these large baleen whales, 866 00:49:15,838 --> 00:49:18,605 采用完全不同的摄食方式 they are feeding in a completely different way, 867 00:49:18,605 --> 00:49:21,138 这正是巨型化的原因之一 and that is partly what's allowed them to get so big. 868 00:49:21,138 --> 00:49:24,338 庞大身躯意味着巨口 So, having large bodies means they have large mouths, 869 00:49:24,338 --> 00:49:27,038 巨口能获取更多猎物 and the large mouths allowed them to get a lot of prey. 870 00:49:27,038 --> 00:49:29,405 庞大身躯还可储存 And having a large body also allows them 871 00:49:29,405 --> 00:49:30,638 大量脂肪储备 to carry a lot of fat reserves, 872 00:49:30,638 --> 00:49:33,071 用于支撑长途洄游 which they are using for swimming 873 00:49:33,071 --> 00:49:34,605 前往猎物丰富海域 to the regions where the prey are. 874 00:49:36,305 --> 00:49:38,371 但实现绝对巨型化 But having that absolute big size 875 00:49:38,371 --> 00:49:42,538 完全得益于水生环境 is something that really evolves because they're in water. 876 00:49:42,538 --> 00:49:44,405 如此生物量 You know, that biomass 877 00:49:44,405 --> 00:49:46,238 在陆地上难以维系 would be very hard to support on the land. 878 00:49:46,238 --> 00:49:47,705 会被自重压垮 They would just be crushed. 879 00:49:51,038 --> 00:49:52,505 鲸类从四足陆地动物 The whale's transition 880 00:49:52,505 --> 00:49:56,005 演化为海洋巨兽的历程 from four-legged land mammal to the giant of the oceans 881 00:49:56,005 --> 00:49:58,971 是进化史上 is one of the most extraordinary stories 882 00:49:58,971 --> 00:50:01,238 最非凡的篇章 in the history of evolution. 883 00:50:03,605 --> 00:50:07,338 鲸类演化之谜是否已经破解？ Has the mystery of whale evolution been solved? 884 00:50:07,338 --> 00:50:09,705 某种程度上是的 To some degree. 885 00:50:09,705 --> 00:50:13,371 但每填补一个空白 就会产生两个新问题 But when we fill a gap, we make two more, and so, 886 00:50:13,371 --> 00:50:16,171 探索永无止境 we're always going to want to know more. 887 00:50:17,605 --> 00:50:19,905 从最初狼大小的生物 From the first wolf-sized creatures 888 00:50:19,905 --> 00:50:21,938 涉足淡水河流 that ventured into freshwater rivers, 889 00:50:21,938 --> 00:50:26,571 到擅长游泳的行走鲸 to the walking whales that were champion swimmers, 890 00:50:26,571 --> 00:50:29,105 再到凶猛的海洋掠食者 to fearsome marine predators, 891 00:50:29,105 --> 00:50:34,571 最终成为地球史上最大动物 to the largest animal that has ever lived. 892 00:50:36,838 --> 00:50:39,571 如今科学家仍在追寻 Today, scientists continue to search 893 00:50:39,571 --> 00:50:44,105 鲸类故事缺失的章节 for the missing chapters in the whale's story. 894 00:50:44,105 --> 00:50:46,705 鲸鱼谷仍蕴藏更多秘密 There is more to find in Wadi Hitan. 895 00:50:46,705 --> 00:50:51,771 岩层中埋藏着无数化石 There are so many fossils still hidden inside the rocks, 896 00:50:51,771 --> 00:50:55,171 我们期待有朝一日 and we hoping someday to find 897 00:50:55,171 --> 00:50:57,338 在更古老的地层中发现 very primitive whale 898 00:50:57,338 --> 00:51:00,238 原始鲸类化石 in very ancient deposits 899 00:51:00,238 --> 00:51:03,971 补全鲸类 that can actually complete the story 900 00:51:03,971 --> 00:51:05,705 进化拼图 in whale evolution. 901 00:51:05,705 --> 00:51:08,005 那将是重大突破 That will be a really huge discovery. 902 00:51:10,771 --> 00:51:14,438 鲸类的进化之旅仍在继续 The whale's evolutionary journey is not over. 903 00:51:14,438 --> 00:51:17,538 如今它们必须应对新威胁 Today, they must survive new threats 904 00:51:17,538 --> 00:51:21,405 某些物种已濒临灭绝 that are driving some species close to extinction. 905 00:51:23,571 --> 00:51:24,938 鲸类正面临 There are a lot of new challenges 906 00:51:24,938 --> 00:51:26,371 诸多新挑战 that the whales are facing today, 907 00:51:26,371 --> 00:51:29,338 渔业活动 船只交通 噪音污染 whether it's fishing, ship traffic, noise, 908 00:51:29,338 --> 00:51:32,205 气候变化——都可能成为影响因素 climate change-- anything could be a factor, 909 00:51:32,205 --> 00:51:33,871 只要威胁栖息地 because if it affects their habitat, 910 00:51:33,871 --> 00:51:35,371 就会影响进化轨迹 it affects their evolution. 911 00:51:35,371 --> 00:51:36,505 正是如此 Exactly. 912 00:51:36,505 --> 00:51:38,471 关键在于 And the challenge is, 913 00:51:38,471 --> 00:51:40,238 进化非朝夕之功 evolution doesn't happen overnight, 914 00:51:40,238 --> 00:51:42,071 我们无法预知 so we don't really know 915 00:51:42,071 --> 00:51:44,538 最终影响 what the consequences of that will be. 916 00:51:46,071 --> 00:51:49,438 鲸类前途未卜 Whales face a precarious future. 917 00:51:49,438 --> 00:51:52,605 希望它们能像过去五千万年那样 The hope is that they will adapt and survive 918 00:51:52,605 --> 00:51:56,371 不断适应 延续种族 as they have done for 50 million years.