史前星球（2022）

that help them survive in hard times.
这是一头年老的雌毛犀牛
An elderly female.
已经40岁的它视力正在衰退 几乎快失明了
At 40 years old, she's losing her vision and is almost blind.
它待在犀牛群中间 一个相对较安全的位置
She sticks to safer ground in the middle of the herd…
跟它同行的是一个最新加入的成员
alongside its newest arrival.
小犀牛可能还无法独自拨开积雪
He may not be able to plow the snow quite yet…
但它可以向奶奶学习
but he can learn from Grandma.
这正是群居生活的优势之一
Just one of the advantages of living in a herd.
最年长的与最年幼的总会待在一起
The oldest and the youngest stay together.
失明者带领着无助者
The blind leading the defenseless.
在冬日昏暗的光线中
In the low light of winter,
犀牛群察觉不到自己已被盯上了
the herd can't tell they're being watched.
强壮的弯刃齿虎
Powerful, scimitar-toothed cats.
它们协同作战 专挑弱势目标下手
Working as a team to target the weak.
犀牛奔跑起来速度很快
Rhinos are fast.
即便是奶奶 也能以近每小时33公里的速度奔跑
Even Grandma can run at 20 miles an hour.
但这些猫科动物的速度更快
But the cats are faster still.
一组紧密列阵
In a tight formation,
让犀牛们化身为一堵令人畏惧的角墙
the rhinos become a wall of formidable horns.
但犀牛群中少了一头
But one of the herd is missing.
就是奶奶
Grandma.
它在混乱中迷失了方向
She's lost her way in the chaos.
它能听见小犀牛的叫声 但此时孑然一身的它身陷险境
She can hear him, but, alone, she's in trouble.
不过 犀牛群不会丢下同伴
But the herd looks after its own.
年幼与年老的祖孙俩团聚了
Young and old are reunited.
在这严酷的冰河时代
In this harsh Ice Age world,
彼此照应是生死攸关的关键
looking after each other makes the difference.
若必须孤军奋战 一切将更加艰难
It's much harder if you have to go it alone.
一只原产于南美的剑齿虎
A saber-toothed cat, native to South America.
年仅两岁
At just two years old,
这只雌剑齿虎已被迫离开家族
this female has been forced to leave her family.
现在的它必须独自求生
Now, she must fend for herself.
但情况并不顺利
And it's not going well.
它还有两颗乳牙未脱落
Two of her milk teeth are still in place,
这意味着它有两副剑齿
which means she has double sabers.
这对猎捕大型猎物毫无用处
Useless for hunting large prey.
它已经好几周没吃上一顿像样的饭了
She hasn't had a decent meal in weeks.
饥饿迫使它深入山谷
Hunger forces her further down the mountain,
进入不熟悉的领地
into unknown territory.
山谷中隐藏着古老而奇异的森林
The valleys harbor strange and ancient forests.
这里的树木自恐龙时代便已存在
Trees from the time of the dinosaurs
还有比它更危险的猎食者
and hunters more dangerous than her.
像是另一只猫科动物的气味
Smells like another cat.
它本可以将这视为回避警告
She could take it as a warning.
但它反而留下了自己的气味来传达信息
Instead she adds a perfumed message of her own.
嘴里的两副剑齿仍然困扰着它
Her double sabers are still troubling her.
它继续留下气味标记
She continues to leave a trail of calling cards.
是一顿潜在美餐的声音
The sound of a potential meal.
后弓兽
Macrauchenia.
体重达900公斤的草食动物
Two-thousand-pound grazers.
它们巨大的鼻子 能在寒冷中加热吸入的空气
Their huge noses warm the air they breathe in these icy conditions.
同时也赋予它们灵敏的嗅觉
They also give them a keen sense of smell.
对这只尚未成熟的剑齿虎来说 捕猎成功的几率微乎其微
With her double sabers, her chances are slim.
但它已经走投无路了
But she's desperate.
来了另一只剑齿虎
Another sabertooth.
它的致命一口成功猎杀了猎物
He makes the killing bite.
猎杀结束 但问题来了
With the hunt over, the question is…
这猎物到底属于谁
whose kill is this?
面对这只更为强壮的雄性 它毫无胜算
She'll never overpower this larger male.
但它另有策略
But she has another tactic.
就是调情
Flirting.
雄剑齿虎现在可没心思理会其他事
He's got other things on his mind.
但这只雌剑齿虎的气味让它感到熟悉
But her scent is familiar.
之前留下的的气味“情书”起了作用
Her messages have done their job.
这是它数周来的第一顿饱餐
Her first meal in weeks.
这顿后弓兽美餐让它得以活下去 直到它的第二副剑齿脱落
This Macrauchenia will keep her alive until her second sabers fall out
并成为一位致命猎手
and she becomes a deadly hunter.
它挺过了年轻剑齿虎生命中最危险的阶段
She's survived the most dangerous time in a young sabertooth's life.
一同进食让这两只年轻的剑齿虎 产生了感情
Feeding together is forming a bond between the two youngsters.
也许一段新剑齿虎家族故事将从这里开始
Perhaps the beginnings of a new saber-toothed family.
在遥远的北方
In the far north,
猛犸象家族正踏上漫长而危险的跋涉旅程
the mammoth family is facing a long and dangerous march
前往春季的觅食地
to the spring feeding grounds.
它们每年都必须迁徙数千公里
They must migrate thousands of miles every year.
刚出生的小象必须跟上队伍
The newborn calf needs to keep up.
尽管个头小 这头幼崽却拥有惊人的毅力
Although tiny, this one is strong.
对这个象群以及地球上的所有生命来说
For this herd, and the rest of life on Earth,
大冰期的生存挑战才刚刚开始
the challenge of surviving the Big Freeze has only just begun.
（下集预告）
冰河时代的延续 正在悄然改写整个地球的面貌
As the Ice Age continues, it brings changes to the whole world.
海平面的下降使大♥陆♥彼此相连
Falling sea levels join continents together,
让从未谋面的动物们首次正面交锋
bringing animals face to face for the first time.
冲突随之而来
Creating conflict
也孕育出新的伙伴关系
and forming new partnerships.
这是一个充满惊奇的世界
This is a world full of surprises,
在这里 鸟能吞象
where birds can eat elephants
同时 庞然巨兽入侵陌生的新领地
and monstrous creatures invade new lands.
远在冰河时代来临之前 地球的气候温暖 湿润
Long before the Ice Age, planet Earth was a much warmer, wetter place.
南极洲覆盖着温带森林
Antarctica was covered with temperate forests,
而北极则栖息着像短吻鳄这样的热带动物
and the Arctic was home to heat-loving creatures like alligators.
但后来 一切发生了变化
But then, everything changed.
全球气温骤降
Global temperatures plunged.
冰河时代对整个地球的影响 实在令人难以置信
It's just incredible, the impact that the Ice Age has had on the entire planet.
但为何会发生这样的变化
But why did it change?
（冰河时代的成因究竟是什么 ）
原来 冰河时代的形成原因 就埋藏在冰层之中
It turns out, the secret to what caused the Ice Age is in the ice itself.
冰芯机构实在令人惊叹
The Ice Core Facility is absolutely amazing.
这里收藏了来自全球的冰芯样本
It's an archive of ice from around the world
（地质学家 纳塔莉克瓦尔德博士）
包括来自南北两极和高山地区的冰
from the poles and from high mountain locations.
（冰芯机构 科罗拉多州 丹佛）
每一根管子里都保存着1米长的冰芯
Inside each of these tubes is one meter of ice
是从冰川表层一路钻探到三千米深
that has been drilled from the surface of the glacier
直达岩床的冰芯样本
3,000 meters down to the bedrock.
冰盖是由一层层积雪压实而成的
Ice sheets are built up in layers.
它们如此厚重 每一根冰芯都像一部时光机器
They are so thick that these cores contain clues that can take us back in time
能把我们带回到八十万年前的地球
800,000 years.
这些冰层就像是地球历史中 精确标记的时间刻度
These layers are kind of like precise time periods in the history of the planet.
（冰川学家 希迪塞维斯特博士）
当我们切开一段冰芯
When you take a slice of a core,
可以看到无数被困在冰里的小气泡
you'll see a multitude of bubbles that are trapped in the ice.
这些气泡是
These bubbles directly sample
上个冰河时代大气的原始样本
what the atmosphere was like during the last ice age.
大气中的二氧化碳越多
The more carbon dioxide you have in the atmosphere,
气温就越高
the warmer the temperature.
分♥析♥这些气泡揭示了一个惊人的发现
Analyzing the bubbles shows something surprising.
冰河时代并非一个漫长不变的寒冷时期
The Ice Age wasn't one long cold spell.
我们发现
We're able to see that temperatures go up
温度在像现在这样的温暖时期会上升
during a nice warm period like we're in now,
然后又像过山车一样急剧下降 进入冰河时代的严寒
and then they dive down deeply like a roller coaster into the Ice Age.
所收集的冰芯 显示了在过去的八十万年里
The ice cores show that across the last 800,000 years,
地球经历的冰河时代不止一次 而是八次
there wasn't one single ice age but eight.
我们常常把冰河时代当作一个整体来谈论
We talk about the Ice Age as though it's one thing,
但其实那段时期里 曾有过无数次的冰河时代
but actually there were many ice ages within that period.
（进化生物学家 维多利亚赫里奇博士）
这些迷你冰河时代
These mini ice ages happen regularly,
每隔十万年就会出现一次
every 100,000 years.
是什么引发了这种规律性的变化
What could cause such regular changes?
答案来自太空
The answer lies in space.
地球并不是一个完美的球体
The Earth isn't a perfect sphere.
它更像一个椭圆型状 这让它在自转轴上产生摆动
It's a little more egg-shaped and because of that it wobbles on its axis.
此外 地球绕太阳公转的轨道 也会发生变化
Also the Earth orbits the sun, but the shape of that orbit can change.
有时接近圆形 有时则拉伸成椭圆形
So it goes from being pretty circular, to being more of a stretched-out oval.
这些地球轨道的变化