我们星球上的生命（2023）

烟雾散去后
As the smoke cleared,
一种此前只在边缘地带幸存的生物
there rose from the ashes a life-form that had previously only survived
从灰烬中崛起
in the margins.
草
Grass.
草在大干燥时期扎根
Taking root during the great drying...
飞快蔓延
it spread so quickly,
不久将覆盖五分之一的陆地
it would soon cover one-fifth of the land.
但无尽的平原并不是哺乳动物的天堂
But the endless plains were no paradise for the mammals.
许多无法消化草的动物
Many couldn't digest grass
很快灭绝
and soon went extinct.
2000万年之后
Twenty million years later,
今天的食草哺乳动物
and today's grazing mammals
仍在与这绿色入侵者 继续展开军备竞赛
remain locked in an arms race with this green invader.
它们进化出了 一系列极为重要的适应性
They have evolved a whole swathe of game-changing adaptations.
经过特别加强的牙齿
Specialized teeth,
能够防止草中的二氧化硅磨损牙齿
strengthened to prevent silica in the grass from wearing them out...
巨大的腹部 用于将草消化
and huge bellies to process it all.
幼崽一出生就完全成型
Their young are born fully formed...
出生后几小时就能行走
...able to walk within hours of birth...
并跟随兽群寻找新长出的草
and follow their herd in search of fresh growth.
哺乳动物真正征服了草原
Mammals have truly conquered the grassy plains...
它们庞大的数量 就是巨大成功的最明显的标志
their huge numbers the most obvious sign of this exceptional success.
但在一些哺乳动物 进化成以草为食的同时
But just as some mammals evolved to feed on the grass,
另一些哺乳动物 则进化为以食草动物为食
others evolved to feed on the grazers.
猎手
Hunters.
兽群自有 对抗猎豹惊人速度的防御策略
The herd has its own defense against the cheetahs' blistering speed.
许多双眼睛
Many eyes...
很早就发现了危险
...spot the danger early.
兽群奔跑制♥造♥混乱
Running bodies create confusion
使幼崽能够藏身其中
for the young to hide in.
但猎豹早有计划
But the big cat has a plan...
这要归功于它聪明的哺乳动物大脑
forged by its clever mammalian brain.
让兽群陷入恐慌
Panic the herd,
分散兽群
split them up,
盯住一只落单的幼崽
and target a lone calf.
迫切地想要保护自己的幼崽
Desperate to defend her only calf,
母牛铃展开反击
the female wildebeest counters.
追捕远未结束
The chase is far from over.
猎豹节节败退
The cheetah has lost a lot of ground...
但幼崽逐渐疲惫
but the calf is tiring.
随着幼崽转向
As the youngster turns,
现在轮到猎手逃命了
it's the hunter who must now run for its life.
幼崽又安全了
The calf is safe once more...
但猎豹还会回来
...but the cheetah will be back...
草原哺乳动物之间的战争将会继续
and the war between the grassland mammals will continue
几百万年来一直如此
as it has done for millions of years.
（200万年前）
在史前的南美洲
In prehistoric South America,
草原上发生了同样的战斗
the grasslands played host to the same battle...
但参与者则是完全不同的动物
but with very different animals.
巨犰狳
This giant armadillo...
也是哺乳动物
is also a mammal...
尽管体型与汽车相仿
though one the size of a car.
巨犰狳也许不快
Doedicurus may not be fast,
但在速度上的缺失
but what they lack in speed...
它们用护甲和致命的尾巴弥补
...they make up for with armor and a lethal tail...
这些适应性可以保护它们及幼崽
...adaptations that protect them and their young
免受任何潜在捕食者的伤害
from any would-be predators.
一只刃齿虎
A Smilodon...
但尚年少
but a mere youngster.
即便有匕♥首♥一般的牙齿
He's not a serious threat...
但它仍不构成严重威胁
...even with his dagger-like teeth.
它从未如此近距离见过巨犰狳
He's never seen a Doedicurus up close,
它们的防御措施很有趣
and their defenses are intriguing.
它没有控制住好奇心
His curiosity gets the better of him.
从每一个角度进行探索
He explores every angle.
对巨犰狳幼崽来说 唯一的选择是保持原地不动
For the young Doedicurus, the only option is to stay put.
巨犰狳的盔甲坚不可摧
The giant armadillos' armor is completely impregnable...
而且它们自己很清楚
...and they know it.
但有一个明显的机会
But there is one obvious opportunity.
巨犰狳幼崽小得多
The young Doedicurus is so much smaller.
如果它能抓住幼崽
If he can get a hold on it...
也许可以将它翻过来
...he might be able to turn it over.
但有成年巨犰狳在就没戏
But not with the adults around.
又陷入了僵局
Another stalemate.
哺乳动物之间的战斗 始终推动着它们的进化
Battles between the mammals have always driven their evolution,
这不仅仅发生在草原上
and they don't just happen in the grasslands.
5000万年前
Fifty million years ago,
如今的印度和亚洲 以极大的规模碰撞在一起
what are now India and Asia collided on an epic scale.
将陆地推向天空
The crash forced the land into the sky,
形成了高耸的喜马拉雅山脉
creating the towering Himalayas.
如今该山脉长2500公里
Today, they are 2,500 kilometers long,
高度接近9000米
almost nine kilometers high,
而且仍在继续增长
and still growing.
由于寒冷的气温和稀薄的空气
With their freezing temperatures and thin air,
这些山脉 对于大多数动物来说无法居住
these mountains are uninhabitable for most animals.
但也有例外
But not all.
在没有阳光的山谷深处
Deep in a sunless valley...
一头雄性雪豹
a male snow leopard...
和一头摔死的羱羊
and an ibex that has fallen to its death.
雪豹年纪很大了
The leopard is very old,
受尽了严酷山区生活的折磨
worn and tattered by his harsh mountain life.
海拔如此之高 哺乳动物必须定时进食以保持体温
At these altitudes, mammals must feed regularly to keep warm.
但喜马拉雅山脉给出了终极捕猎挑战
But the Himalayas present the ultimate hunting challenge.
在山谷上方 一只母豹
High above the valley, a female...
和它的两只幼崽
and her cubs,
它们是那只公豹的孩子
fathered by the male.
三头豹都有着出色的伪装
Three of them in total, all amazingly camouflaged.
雪豹有着厚厚的毛皮
Snow leopards have thick fur,
巨大的爪子
large paws,
和长长的尾巴
and long tails...
完美地适应了
perfect adaptations
地球上最寒冷、最陡峭的养育场所
for the coldest, most precipitous nursery on Earth.
离开危险的悬崖之后
Away from the dangerous cliffs...
母豹开始教授狩猎课程
...the mother initiates a hunting lesson.
教育和照护幼崽
Teaching and caring for one's young
是哺乳动物的一项重要特征
is a key mammalian trait.
小豹会与母亲待在一起将近两年
These cubs will stay with their mother for nearly two years...
学习在生命边缘生存所需的技能
learning the skills needed to survive on the very edge of life.
在这样的海拔高度
At these altitudes,
必须抓住每一次机会
every opportunity must be taken.
年老的公豹在追踪一群山羊
The old male is tracking a herd.
在这个垂直的世界中 它必须到猎物上方
In this vertical world, he must get above his prey...
并且足够靠近
...and close enough...
以发动伏击
for an ambush.
这一次
This time
二者同归于尽
death has claimed them both.
但这只雪豹的遗志会传承下去
But the leopard's legacy lives on.
几个月之后
In a few months' time,
它的幼崽将离开母亲 开始独自捕猎
his cubs will leave their mother and start to hunt alone,
到时它们将学会一切所需技能
having learned all the skills they need
可以在世界之巅生存下去
to survive at the top of the world.
虽然哺乳动物征服了陆地
Although they had conquered the land,
但它们并未止步于此
the mammals didn't stop there.
有一个分支 朝一个完全不同的方向发展
One branched out and went in an entirely different direction.
5000万年前
Fifty million years ago,
蝙蝠通过飞行
bats opened up a whole new realm...
开辟了一个全新的领域
through flight.
飞行使动物能够到更远的地方觅食
Flying allows animals to search much further for food...
并且可以成千上万只聚在一起
and gather in their millions.
如今