在恐龙时代之前数百万年 Millions of years before the age of dinosaurs...
我们的星球被同样神奇的巨兽统治着 our planet was ruled by equally magnificent beasts.
两个伟大的王朝已经崛起 Two great dynasties had emerged
并在争夺统治权 and were vying for domination.
本集将讲述陆地征服之战 This is the story of the battle to conquer land...
以及它如何彻底改变地球上的一切 and how it changed everything for life on our planet.
《我们星球上的生命》
第 3 章：入侵大地
（5亿年前）
在我们星球的大部分历史中 For most of our planet's history,
陆地都不适于生命居住 land has been inhospitable to life.
一片荒芜 A bleak and desolate realm...
更像是月球表面 more like the surface of the moon...
而不像今天的地球 than like Earth today.
很难想象 It's hard to imagine
任何生命 会在如此充满敌意的地方定居 how anything could ever make this hostile place its home.
但是在海浪之下 But from beneath the waves,
生命已在这里繁荣超过10亿年 where life had thrived for more than a billion years,
有一种好奇的生物率先发出挑战 one curious life-form was among the first to rise to the challenge.
地衣看似不起眼 Lichen may not look remarkable,
但它们其实独一无二 but they are in fact completely unique.
这是一种开创性的合作关系 A pioneering partnership.
地衣既不是植物 也不是动物 Neither plant nor animal,
而是真菌和藻类的奇怪组合 lichen are a strange combination of fungi and algae...
只有在一起 that only together
才能克服贫瘠地球的极度险恶 had what it took to overcome the extreme hostility of barren Earth.
但它们不仅具有开创性 But they were more than just pioneering.
还具有开地性 They were groundbreaking.
随着它们的传播 As they spread...
它们的细丝帮助将岩石分解 ...their tiny filaments helped to break down rock
产生了史上第一块土壤 and produce the first ever soil...
为植物的到来铺平道路 paving the way for plants to take over.
苔藓这样的微型植物率先出现 Micro plants, like moss, were first to appear.
叶子只有一层细胞 With leaves only one cell thick,
它们无法向上生长 they couldn't grow upwards,
但可以蔓延开来 but could spread out.
它们的繁殖速度比地衣快 Reproducing faster than lichen,
很快就铺满陆地 they soon carpeted the land,
在之后的4000万年 不受滋扰地统治着陆地 which they ruled undisturbed for the next 40 million years.
但是一场绿色革命即将到来 But a green revolution was coming...
将永远改变陆地的样貌 that would change the landscape forever.
其关键是一种新化合物的进化 Key was the evolution of a new compound,
木质素 lignin.
木质素加强了植物的细胞壁 Lignin strengthened the plants' cell walls...
使植物能够生长得比以往任何时候 都更大、更强壮 allowing them to grow bigger and stronger than ever before.
不再局限于覆盖地面 No longer confined to carpeting the land,
植物开始争夺向上的空间 plants began to battle for the real estate above,
以获取阳光 fighting for access to light.
最终有一些植物长得非常高 Eventually, some plants grew so tall,
从周围的世界中高耸出来 they towered above the world around them.
今天的红杉是大自然的摩天大厦 Today's redwoods are nature's skyscrapers.
高度超过100米 Reaching heights of more than a hundred meters,
是史上最高的生物 they are the tallest living things to have ever existed.
但是红杉只是40万植物物种中的一个 But redwoods are just one of more than 400,000 species of plant,
植物 是我们星球上的生命最鲜明的标志 the most visible signs of life on our planet.
在地球遥远的过去 Back in Earth's distant past,
植物的到来 the arrival of plants
为来自海洋的下一批入侵者 创造了新的栖息地 created new habitats for the next invaders from the sea.
（3.45亿年前）
率先踏上陆地的动物是节肢动物 The first animals to ever set foot on land were the arthropods.
它们是三叶虫的亲戚 Relatives of the trilobites,
坚硬的外骨骼在水下是有用的护甲 their hard exoskeletons had served as useful armor underwater.
在陆地上 这护甲支撑着它们 On land, that armor supported them
并防止水分流失 and prevented them from drying out.
它们也可以通过这坚硬的外壳呼吸 They could also breathe through this tough exterior.
当时的氧气水平比今天高60% And with oxygen levels 60% higher than they are today,
有一些节肢动物长得异常巨大 some grew to be giants.
节胸蜈蚣 Arthropleura,
地球历史上最大的千足虫 the largest millipede to ever walk the Earth.
长度超过2.5米 宽度超过半米 At over two and a half meters long and a half meter wide,
没有天敌 he has no natural enemies...
所以可以把全部精力放在觅偶上 ...so can focus all his energy on finding a mate.
但是对节胸蜈蚣来说 But for Arthropleura,
寻找一位完美的伴侣并不简单 the pursuit of the perfect partner is not straightforward.
因为它看不见 For he's virtually blind...
它的世界仅限于它能感知的范围 ...and his world extends only as far as he can sense.
蕨类森林广袤无边 The fern forest is vast,
雌性节胸蜈蚣不知在何处 and a female could be anywhere.
但它的搜寻并不是那么毫无希望 But his search isn't as hopeless as it might seem.
准备交配的雌性会留下气味痕迹 Females ready to mate leave scent trails
供雄性追踪 for males to follow.
这是黑暗中的一线生机 A lifeline in the darkness.
然而感知雌性曾去过哪里 And yet, sensing where she once was
不同于感知雌性现在在哪里 is not the same as sensing where she is.
它施展魅力的机会终于到来 Finally, his chance to charm can begin.
通过自身甲壳间的摩擦 它唱出了独一无二的情歌 By rubbing together parts of his shell, he creates his own unique love song.
在陆地上交配有时是一件尴尬的事 Mating on land can be an awkward affair.
交配成功需要完美的配合 Success requires the perfect alignment.
所以在这关键的时刻 So it's important at this critical stage
不容踏错半步 not to put a foot wrong.
3.45亿年之后 345 million years later,
在今天的森林中 and in today's forests,
节肢动物的求爱艺术有了长足发展 the arthropod art of seduction has come a long way.
对于一些护甲较少的节肢动物 尤其如此 Especially for some of the less armored members of the group.
与古代节胸蜈蚣不同 Unlike the ancient Arthropleura,
雄性跳蛛视力超常 male jumping spiders have superb vision
而且只有一粒米那么大 and are no larger than a grain of rice.
体型上的不足 But what they lack in stature...
它们在风格上弥补 they make up for in style.
每个物种都有自己独特的舞蹈动作 Each species has its own signature dance move
来吸引雌性的注意 to attract female attention.
孔雀开屏 The peacock.
侧身摇摆 The side shuffle.
迪斯科舞步 The disco dancer.
还有摇动羽毛 And the feather shake.
雄性进化出了 多彩的服装和精美的舞步 While the males evolved colorful costumes and intricate dance moves...
雌性则进化出了挑剔的品味 females developed impeccable taste.
它的侧身摇摆吸引了雌性的注意 His side shuffle has caught her attention.
但它是否有对方所钟情的舞姿呢？ But has he got the moves she's looking for?
只有最好的才行 Only the very best will do.
雌性摇动腹部 表示自己并不满意 Waving her abdomen signals she's not impressed.
它需要小心 He needs to be careful,
因为挑剔的雌性有时会吃掉求爱者 for fussy females sometimes eat their suitors.
尽管如此 Still...
再努力一把也是值得的 ...it's worth one more try.
它显然还在自作多情 Clearly, he's not getting the message.
它在爱情方面也许不太幸运 He may be unlucky in love,
但它的节肢动物王朝却运气不错 but his arthropod dynasty has had better luck.
节肢动物 如今已占据所有动物物种的80%以上 They now make up over 80% of all animal species.
节肢动物成功的秘诀 The secret to arthropod success
在于其简单的分节结构 lies in their simple segmented body plan...
这种结构向无数不同方向进化 ...which has evolved in countless different directions.
有的在腿上有眼睛 Some have ears in their legs.
有的眼睛长在杆子上 Others, eyes on stalks.
还有后备护甲板 And armor plating for battle.
不断变异 Variation after variation,
节肢动物的进化 arthropods are evolution
放纵不羁 run wild.
包括其中最出色的奔跑者 Including the greatest runner of them all,
虎甲 the tiger beetle.
它的设计经过了数百万年的精心调整 Its design has been fine-tuned over millions of years.
最新版本为速度而生 The latest model is built for speed.
就其体积而言 它是地球上最快的短跑运动员之一 For its size, it is one of the fastest sprinters on Earth.
如果按照人类的比例放大 If scaled up to human proportions,
它的奔跑速度 it would run
超过每小时1000公里 at over 1,000 kilometers per hour.
但是快车道上的生活也有一个缺点 But there is one drawback to life in the fast lane.
它的大脑跟不上 His brain can't keep up.
在追逐猎物的过程中 He must frequently stop to get his bearings
它必须经常停下来确认方向 while hunting down his next victim.
但它对食物的疯狂搜寻 也可能让它陷入危险境地 But his frantic search for food can lead him into dangerous territory...
因为有时候猎手也会成为猎物 because sometimes the hunter can also be the hunted.
速度与激情不是这种活板门蛛的风格 Fast and furious is not this trapdoor spider's style.
它更喜欢等待猎物靠近 She prefers to wait for prey to come to her.
在节肢动物的争斗中 In the battle of the arthropods,
飞行往往能决定生死 flight would often make the difference between life and death.
3亿多年前 More than 300 million years ago,
一群节肢动物 one group of arthropods
成为率先上天的生物 were the first creatures to take to the skies.
翅膀的进化 And the evolution of wings
最终将使它们在全球范围内取得成功 would eventually launch them to global success.
昆虫 The insects.
今天地球上的昆虫 Today, for every human on the planet,
超过人类数量的10亿倍 there are more than a billion insects.
它们是地球上数量最多的动物 They are the most abundant group of animals on Earth.
（3.1亿年前）
尽管它们如今非常成功 Despite their current success,
最终能够飞行的昆虫 最早出现在古代沼泽中 the ultimate flying insects first appeared back in the ancient swamps.
蜻蜓 Dragonflies.
它们的飞行几乎堪称完美 Their flight is as close to perfect as it gets.
四片灵活的翅膀 Four flexible wings,
可以独立控制 independently controlled,
使它们拥有无与伦比的机动性 give them unparalleled mobility.
它们可以朝任何方向飞行 They can fly in any direction,
完成最急的转弯 pull off the tightest turns...
加速比战斗机更快 and accelerate faster than a fighter jet.
如此成功的设计 A winning design
已经保持了数亿年 几乎不变 that has remained almost the same for hundreds of millions of years.
然而在同一片史前沼泽之中 And yet, living in the same prehistoric swamps,
另一群动物正在经历巨变 another group of animals were undergoing their own radical change.
在水面下方 Beneath the surface,
脊椎动物继续进化 vertebrates had continued to evolve...
一种新型鱼类蓬勃发展 and a new type of fish was thriving,
叶鳍鱼 the lobe-finned fish.
有一些长成了巨大而可怕的捕食者 Some grew to be monstrous predators.
在这个鱼吃鱼的世界 In this fish-eat-fish world,
大就是好 it pays to be big.
较小的鱼 可以在浅海寻求庇护 For the smaller ones, there's refuge in the shallows...
在那里 它们独特的叶鳍是一种明显的优势 where their unique lobed fins are a distinct advantage.
它们肌肉发达且随机应变 Muscular and highly versatile,
叶鳍与其他鱼的鳍不同 they are different to those of other fish.
不仅有助于游泳 Not only do they help them swim...
而且足够强壮 能够支撑它们的体重 but they're strong enough to support their body weight...
帮助它们从水中爬出 and help them crawl out of the water.
但这些鱼 还有另一种极为重要的适应性 But these fish also have another game-changing adaptation...
呼吸空气的能力 the ability to breathe air.
不是通过腮 而是通过原始的肺呼吸 Not through gills but through primitive lungs.
这些进化一起作用 Together, these evolutionary advances
使脊椎动物能够离开水体并探索陆地 allowed vertebrates to leave the water and explore the land.
争夺新世界的竞赛已经开始 The race was on to colonize this new world.
但对于这些叶鳍鱼来说 But it was already too late
已经太晚了 for these lobe-finned fish.
其他动物先它们一步完成了这种转变 Others had made this transition before them.
比如三米长的石炭鲵 Like the three-meter-long Anthracosaurus...
已经长出腿来 ...that had already found its feet.
从鳍到肢的进化用了数百万年 The evolution from fin to limb took millions of years.
但一旦完成 But once completed,
陆地上的生活将永远改变 life on land would never be the same again.
两栖动物的时代 The age of amphibians
已经开始 had begun.
今天有超过8000个两栖动物物种 Today, there are more than 8,000 species of amphibian.
这是一个奇怪却多样的种群 A peculiar but diverse group...
有蝾螈 ...of newts,
青蛙 frogs,
火蝾螈 salamanders,
还有蟾蜍 and toads.
虽不再是曾经的巨兽 Not quite the giants they once were,
但仍然是成功的猎手 but still successful hunters...
拥有独特的杀手风格 ...with their own killer style.
石炭鲵出现之后几亿年 Hundreds of millions of years after Anthracosaurus,
沼泽仍然是两栖动物的根据地 swamplands remain a stronghold for amphibians.
在欧洲的多瑙河三角洲 Here in Europe's Danube delta,
湖侧褶蛙成千上万 marsh frogs live in their thousands
已经成为专业的昆虫猎手 and have become expert insect hunters...
尤其喜欢捕食蜻蜓 with a particular taste for dragonflies.
蜻蜓有全方位视觉 Thanks to their wraparound vision,
要抓住它可不容易 catching one isn't easy.
但是湖侧褶蛙也进化出了 一些奇特的适应性 But marsh frogs have evolved some quirky adaptations of their own.
蹼有助于腾空 Webbed feet help them get airborne.
弹射式的舌头 使它们拥有了超长的射程 And a projectile tongue gives them extraordinary reach.
即便如此 Even so,
飞行中的蜻蜓仍然很难捕获 dragonflies in flight can be just too hard to catch.
等待这些空中杂技演员降落 可能会降低抓捕难度 Waiting for the aerial acrobats to land might make things easier.
是时候换一种方法了 Time to take a different approach.
一只雌性蜻蜓在水上产卵 A female laying eggs in the water.
半浸在水中 Half-submerged,
它应该是一个比较容易对付的目标 she should be an easier target.
但蜻蜓实在太快了 The dragonflies are just too fast.
还会翻滚动作 And they can barrel-roll.
又没抓住 Missed again.
但青蛙生性坚持不懈 But frogs are nothing if not persistent.
虽然命中率低 Despite the low hit rate,
但两栖动物已在地球上生存 超过3.5亿年 amphibians have survived for over 350 million years.
然而它们并未征服 地球上的每一种环境 And yet, they never conquered every environment the planet had to offer...
因为所有两栖动物养育后代 都需要一样东西 because there's something all amphibians need to raise their young.
水 Water.
这是哥斯达黎加的草莓箭毒蛙 This is the strawberry dart frog of Costa Rica.
它的蝌蚪危在旦夕 Her tadpoles are in mortal danger.
小水洼几乎快要干涸 Their tiny puddle, almost dry.
唯一的逃生方法 Their only means of escape
就是爬到母亲的背上 is on their mother's back.
难点在于找到水 The hard part is finding water.
幸运的是 Luckily...
它知道该去哪里 ...she knows exactly where to go.
在它上方20米处 Twenty meters above her,
一株凤梨科植物蓄集雨水 a bromeliad collects rainwater.
对它珍贵的蝌蚪来说 是完美的池塘 The perfect pool for her precious tadpole.
但是它首先必须上去 But first, she must get there...
一次跳一步 one hop at a time.
它仅有人类指甲般大小 Barely the size of a human thumbnail,
这对它来说是珠穆朗玛峰 this is her own personal Everest.
终于安全了 Safe at last.
不论两栖动物 在征服陆地的过程中达到如何的高度 No matter what great heights amphibians reached in their conquest of land...
它们永远无法摆脱与水的联系 they never escaped their tie to water...
当地球上的环境剧变时 a tie that would be their undoing when conditions on Earth...
这种联系将使它们毁灭 radically changed.
（3亿年前）
在石炭纪 During the period known as the Carboniferous,
地球各大陆合为一体 Earth's great land masses merged,
超级大陆“盘古大陆”诞生 and the supercontinent of Pangaea was born.
随着陆地变干 As the land dried,
广阔的沼泽开始消失 the vast swamps began to disappear.
由于缺水 多数两栖动物苦苦挣扎 Lacking water, most amphibians struggled.
但并非全部如此 But not all.
有一种两栖动物 进化出了一种革命性的适应性 One evolved a revolutionary adaptation
使其繁荣发展 that enabled it to thrive.
它的卵进化出了一层保护性外壳 Its egg developed a protective shell
将胚胎保护在“私家泳池”之中 that held the embryo in its own private pool of fluid.
幼崽在其中能够安全地发育 而不会干涸 Inside, the young could develop safely without drying out.
由于蛋的进化 The tie to water
与水的联系终于被断开 was finally broken by the evolution of this amniotic egg.
这些羊膜动物 Known as the amniotes,
能够以两栖动物无法做到的方式 these creatures could colonize the drier land
在干旱的土地上繁衍 in a way that amphibians could not.
从这一共同祖先开始 And from this one common ancestor,
所有哺乳动物、爬行动物、鸟类 all mammals, reptiles, birds,
以及恐龙都将发展而来 and dinosaurs would descend.
（2.52亿年前）
进化出蛋之后6000万年 Sixty million years after the evolution of the amniotic egg,
羊膜动物已遍布盘古大陆 amniotes have spread across Pangaea...
形成两个新的王朝 ...producing two new dynasties
无尽的竞争也由此开始 and the start of an endless rivalry.
这些沉睡着的身穿护甲的野兽 是一种原始的爬行动物 These sleeping armored beasts are a primitive type of reptile.
盾甲龙是陆地上最大的动物之一 Scutosaurus, among the largest animals on land.
重量超过一吨 Weighing over a ton,
它们地球上最早的巨型食草动物 they are the first giant plant-eaters to roam the planet.
蛋能使它们在干旱的环境下兴旺发展 Amniotic eggs allowed them to flourish in the drier conditions
并前往其他动物去不了的地方 and go where others could not.
但是盘古大陆并不只属于它们 But Pangaea didn't just belong to them.
另一条血脉出现了 Another new bloodline had emerged.
它们是哺乳动物的祖先 The ancestors of the mammals.
水龙兽虽然无法与盾甲龙相匹敌 While a Lystrosaurus is no match for a Scutosaur...
但它的亲戚可以 ...he has cousins here who are.
丽齿兽 A gorgonopsid.
它是哺乳动物更为显赫的前身 A more impressive forerunner to the mammals.
身长超过三米 体重超过300千克 At over three meters long and 300 kilos,
它能与如今的任何大型猫科动物 一较高下 she rivals any big cat alive today.
它有强大的嗅觉 With her powerful sense of smell,
追踪猎物对它来说易如反掌 tracking her prey is easy.
但是击穿对方的重甲 Getting past their heavy armor
就没那么容易了 will be her greatest challenge.
但它有一样秘密武器 But she has a secret weapon.
刀刃一般的牙齿 Saber-like teeth.
即便如此 Even so,
它仍需要悄无声息地靠近 she'll need stealth to get close.
它必须非常谨慎 She must choose her moment...
选好时机 and her target
选好目标 carefully.
慢慢地 Slowly
悄无声息地 and silently...
展开行动 does it.
哺乳动物与爬行动物的竞争 The rivalry between mammals and reptiles
数亿年来 一直是地球生命的特点 has been a feature of life on Earth for hundreds of millions of years.
但它们的早期崛起并不会持续太久 But their early rise was not to last,
因为在盘古大陆遥远的北方 because in the far north of Pangaea,
灾难正在发生 something catastrophic was happening.
埋在地球表面之下多年的巨大力量 Lying dormant for years on end, the colossal forces at work beneath Earth's surface
很容易被遗忘 are easily forgotten.
但这地下熔岩世界 But the molten underworld
总在不停搅动 is always stirring,
寻找弱点 always probing for weakness.
在盘古大陆的地壳之下 Beneath Pangaea's crust,
一股极热的岩浆 a plume of superheated magma
正朝着地表前进 was working its way to the surface.
二叠纪的喷发一旦开始 Once these Permian eruptions started...
就无法停止 there was no stopping them.
其特点是规模极大 What made them unique was their monumental scale.
是生命见证过的 They were among the largest,
最大、最猛烈的喷发之一 most violent eruptions that life has ever witnessed.
持续肆虐了10万年 And they raged for 100,000 years.
造成的破坏前所未见 The devastation was unprecedented.
一个面积相当于半个美国的区域 An area half the size of the United States
被熔岩吞噬 lost to lava.
数百万平方公里 Millions of square kilometers,
曾经充满生命 once so full of life,
却被地球自身所毁灭 obliterated by the Earth itself.
而这还只是刚刚开始 And that was just the beginning.
喷发释放出比熔岩更危险的东西 The eruptions released something far more dangerous than lava.
一种有毒的混合气体 A toxic concoction of noxious gases.
当这些气体与水结合时 When these gases combined with water...
威力强大的酸雨倾泻而下 a potent cocktail of acid rain poured down.
水 Water, the giver of life,
生命的赐予者 the giver of life,
如今却成了生命的毁灭者 was now its destroyer.
毒雨毒害大地 The toxic rain poisoned the ground...
灭绝植物 killing off the plants.
没有了根来固定土壤 Without their roots to bind the soil together...
整个生态系统被冲走 entire ecosystems were washed away.
然而空气中 还有一种更具破坏性的东西 And yet, there was something even more destructive in the air.
一位隐形杀手 A silent killer.
二氧化碳 Carbon dioxide.
火山释放出的二氧化碳 The volcanoes released
比我们今天大气中的二氧化碳多六倍 six times more CO2 than is in our atmosphere today...
导致全球气温升高十度 triggering ten degrees of global warming...
各种气候灾难 ...and all the climate devastation
随之而来 that comes with it.
温室效应在大自然的力量下肆虐 Hothouse Earth raged as the forces of nature ran wild.
一片混乱 无处可藏 There was nowhere to hide from the chaos.
海洋受到的影响最为严重 And the oceans were worst affected.
随着海洋变暖和酸化 As they warmed and acidified,
氧含量锐减 oxygen levels plummeted...
最早孕育生命的海洋 turning the seas, where life first took hold,
变成了荒芜的坟场 into a desolate graveyard.
这是地球上第三次 This was the planet's third,
也是最具毁灭性的大规模灭绝事件 and most devastating, mass extinction.
90%的物种 Ninety percent of all species
永远消失 lost forever.
进化树的许多分支完全断裂 Entire branches torn off the evolutionary tree.
许多物种灭绝了 But in the loss of many,
但是少数物种幸存下来 endured the few.
它们是一个过去时代的仅存硕果 All that remained of a bygone age.
其生存从未如此重要 Never had their survival been so important.
一切生命的未来 The future of all life
如今都悬于一线 now hung by a thread.
字幕翻译：朱音