我们星球上的生命（2023）

以至于今天将近80%的动物
that today, nearly 80% of all animals,
包括昆虫、蜘蛛和螃蟹
including insects, spiders, and crabs,
都与这种古代节肢动物有亲属关系
are related to this ancient arthropod.
但是护甲并不能保护它们 免受一切伤害
But armor couldn't protect them from everything.
（4.68亿年前）
四千万年后 一个新的生命纪♥元♥开始
Forty million years later, and a new era of life has begun,
其多样化程度前所未有
with more diversity than ever before.
在这里 三叶虫仍处于巅峰状态
Here, trilobites are still in their prime,
但它们装甲变得更加坚固
but their armor is even more robust...
因为在这块礁石上 危险来自一种新的捕食者
because on this reef, danger comes from a new type of predator.
这些触须巨兽 是今天章鱼和鱿鱼的祖先
Ancestors of today's octopus and squid, these tentacled giants
它们属于头足动物这个新王朝
are part of a dynasty known as the cephalopods.
最大的 壳长八米
The largest, with a shell eight meters long,
这就是房♥角石
are Cameroceras.
三叶虫在这高耸的猎手面前相信见拙
The trilobite is dwarfed by this towering hunter.
但它们如此危险 并不是因为其大小
But it's not their size that makes them such a threat.
房♥角石进化出了捕捉猎物的新方法
Cameroceras have evolved a new way to catch their prey...
即便看不见猎物 也能得手
even when they can't see it.
因为在这些水域中 它们捕食不仅利用视觉
Because in these waters, they hunt using not just sight,
还利用触觉
but touch.
三叶虫能做的只有设法保持距离
All the trilobite can do is try to stay out of reach.
房♥角石有剪刀般的嘴巴
With a scissor-like beak...
能够切割最硬的护甲
...able to slice through the toughest armor,
它们主宰着这片海洋
Cameroceras dominate these seas.
但是还有另外一个重要的新来者
Although, there is another important new arrival.
外表永远是一副惊讶的样子
Graced with a look of permanent surprise,
这就是阿兰达甲鱼
this is Arandaspis...
一种早期鱼类
an early kind of fish.
它尚未进化出颌
It hasn't yet evolved a jaw,
所以只能吸食残渣
so can only suck up the scraps.
但它进化出的特征将改变历史进程
But what it has evolved will change the course of history.
它有一种新的内部骨骼 令它既快速又灵活
It has a new internal skeleton that makes it both fast and agile.
那就是脊椎
A backbone.
虽然看起来并不起眼
And while it may not look like much,
但像阿兰达甲鱼这样的鱼类
fish like Arandaspis
有朝一日 将导致所有其他脊椎动物的崛起
will one day give rise to all other vertebrates.
两栖动物、爬行动物 哺乳动物以及鸟类
Amphibians, reptiles, mammals, and birds.
但是现在脊椎动物仍处于
But for now, vertebrates are only at the beginning
漫长旅程的起始阶段
of a very, very long journey.
（4.45亿年前）
2000万年后 生命面临又一个巨大的挑战
Twenty million years later, life faced one of its greatest challenges...
气候突然变冷
...as the climate suddenly began to cool...
这将带来可怕的后果
...a development that was to have dire consequences.
海洋逐渐开始冰冻
Little by little, the sea started to freeze.
过去地球上热带水域的“居民们”
For the inhabitants of Earth's once tropical waters,
大难临头
this was a catastrophe.
浅海变成了冰冻的坟墓
The shallow seas became a frozen graveyard.
这是世界上第一次大规模灭绝
The world's first mass extinction.
致命的冰冻 是由二氧化碳减少60%所导致
The fatal freeze was caused by a 60% drop in carbon dioxide.
没有了温室气体保暖
Without this greenhouse gas to warm it,
地球突然陷入冰河期
the planet was plunged into an ice age.
这个时期将持续20万年
One that would last for 200,000 years.
巅峰时期 世界上将近一半区域被冰覆盖
At its peak, almost half the world was covered in ice,
导致85%的生命死亡
causing the demise of 85% of all life,
永远从我们的族谱中消失
lost from our family tree forever.
热带浅海消失了
With the tropical shallows gone,
能够前往更深水域的生物 成为了少数的幸存者
the few survivors were those who could head to deeper waters.
比如鹦鹉螺
Animals like the nautilus,
巨大的房♥角石的小个儿亲戚
a smaller relative of the giant Cameroceras.
最早在数亿年前进化
It first evolved hundreds of millions of years ago,
但如今依然存在
but still exists today.
它的成功要归功于深海的稳定性
It owes its success to the deep ocean's unchanging nature.
在600米以下 温度几乎没有波动
Below 600 meters, the temperature rarely fluctuates,
使其成为稳定的避难所
making it a sanctuary of stability.
当冰河时期袭来时
When the Ice Age struck,
各种动物都朝深渊前进
all kinds of animals headed into the abyss.
但头足动物却蓬勃发展
But it's the cephalopods who have thrived.
今天许多头足动物仍在深海中出没
Today, many still haunt the deep sea...
包括章鱼和鱿鱼
including octopus and squid.
它们的胶状身体 不受深海巨大压力的影响
Their gelatinous bodies are unaffected by the deep's immense pressure.
而超强的感官 使它们能在黑暗中找到前进的方向
And super senses let them find their way in the dark.
它们不再受到壳的限制
No longer constrained by shells,
进化出了各种大小和形状
they've evolved into almost every size and shape.
但这个漆黑的世界并不只属于它们
But this pitch-black world isn't theirs alone.
这里还有节肢动物 比如这只蜘蛛蟹
Arthropods, like this spider crab, live here too...
它们在海底摸索着前进
feeling their way across the ocean floor.
它们周围还有脊椎动物
Alongside them, the vertebrates.
在这里 食物很少 因此它们的数量也很稀少
With little food on offer, down here, they're rare.
今天只有大约10%的鱼类生活在深海
Only around 10% of all fish today live in the deep.
这里并不是它们擅长的场地
This is not a place they excel...
而头足动物 则成为了深海中近乎完美的掠食者
unlike the cephalopods, who have become the deep's near-perfect predators.
这只虾也许很快就会发现这一点
Something this shrimp may soon discover.
它的周围的水闪烁着蓝♥光♥ 因为布满了能够生物发光的浮游生物
All around it, the water twinkles with bioluminescent plankton.
任何扰动 都会在瞬间点亮这些浮游生物
Any disturbance, and for the briefest of moments, they light up.
但这里并非只有这只虾
But the shrimp has company.
一只半藏着的鱿鱼
A half-concealed squid
正在观看这场表演
is watching the show.
它的大眼睛 使它能够在黑暗中看得非常清晰
Its large eyes allow it to see exceptionally well in the dark.
它能看到光点
Picking out the dots of light,
追踪这只虾的每一个动作
it can follow every move the shrimp makes.
它需要的只是一个合适的时机
All it needs is the right moment.
虾毫无防备
The shrimp never saw it coming.
凭借如此非凡的感官
With such extraordinary senses,
鱿鱼称霸这个寒冷而黑暗的世界 也许就不令人意外了
perhaps it's no surprise that squid have mastered this cold, dark world.
但是对于生活在冰河时期的生物来说
But for those who lived back in the Ice Age,
局势开始升温
things were beginning to heat up.
（4.44亿年前）
大冰冻的20年之后
200,000 years after the big freeze,
冰中出现了一条蓝色血管
there appeared in the ice a vein of blue.
水
Water.
二氧化碳水平回升
Carbon dioxide levels had bounced back,
导致全球温度上升
causing global temperatures to rise.
大融化开始
The great melt had begun.
起初较慢 但很快就加快了速度
Slow at first, the thaw rapidly gathered pace.
不久之后
Before long,
高达数百米的冰川 倾泻进入正在变暖的海洋
glaciers hundreds of meters tall cascaded into the warming seas.
在几千年内
Within a few millennia,
地球上几乎一半的冰已经融化
almost half the planet's ice had melted.
又过了几千年 冰完全消失
Within a few more, it had entirely gone.
对于那些在深海寻求庇护的生物来说
For those who had sought refuge in the deep,
现在有机会回到浅海
now was a chance to head back up.
在今天的澳大利亚海岸边
Off the coast of modern-day Australia,
这是一只年轻的巨型墨鱼
this is a young giant cuttlefish.
与冰河时代的祖先一样
Like his Ice Age ancestors,
它来到浅海求偶
he's come to the shallows in search of a mate.
但是别人已先一步来到这里
But others have got here first...
包括一位雄性领袖
...including an alpha male...
小心翼翼地保护着自己选择的伴侣
jealously protecting his chosen partner.
而且它不打算与它人分享
And he does not intend to share.
但较小的这只雄性并没有被吓倒
But the smaller male isn't deterred.
相反 它等待时机
Instead, he bides his time
并观察着
and watches
又有一只雄性进入竞技场
as a new male enters the arena...
发出信♥号♥♥
and signals his intention...
挑战雄性领袖
to challenge the alpha.
双方都不退让 争斗无可避免
With neither backing down, a fight is inevitable...
年轻的雄性渔翁得利
...allowing the young male to make his move.
它慢慢靠近 收起触角
As he approaches, he tucks in his tentacles
并改变颜色
and changes color...
完美地模仿一只雌性
to perfectly mimic a female.
它利用智慧而非力量
Using brain, not brawn,
无声无息地潜入