生命的奇迹（2013）

They eat cellulose.
主要来源就是我们所见的这些
Primarily the tops of the acacia trees
散布非洲草原的刺槐树的冠层树叶
that you see scattering the African savanna.
它们与白蚁面临同一问题
And they face that same problem,
如何断开那些难分解的碳链
they've got to break those difficult carbon bonds down
它们的解决方法也很相似
and they've come up with a very similar solution
那就是培育细菌和真菌
which is to cultivate bacteria and fungi.
不过这次菌群长在胃里
But they do it inside their stomachs
而长颈鹿这样的反刍动物
and ruminants like giraffes,
培育菌群得靠一个非常复杂的系统
they've had to build a very complex system in order to do that.
瘤胃
长颈鹿长了四个胃
They've got four stomachs,
网胃
重瓣胃
皱胃
其中一个存有这些细菌和真菌
one of them contains their culture of bacteria and fungi,
来消化那些难以分解的纤维素
and they allow them to digest that difficult cellulose.
即便具备了这一硬件
Even with all this hardware,
反刍动物每天仍要花三分之二的时间来进食
ruminants must feed for over two thirds of the day.
不过有某些生物找到了捷径
But there are other creatures here that have found a short cut,
毕竟 如果植物纤维这么难消化
after all, if plant fibres are hard to digest,
何不等其它生物去消化
why not let someone else do the work
再直接偷一餐吃呢
and simply steal a meal?
冲我们来了
It's coming for us.
天哪
Oh, my God...
看我们刚发现了什么
Look what we've just found.
我们今早出来是要找长颈鹿的
We were out looking for giraffe this morning,
刚在那边看到了十只
and we found about ten of them over there,
不过找长颈鹿的途中
but in looking for the giraffe,
我们刚发现了一只豹子
we've just found a leopard.
它是这里的顶级捕食者之一
This is one of the top predators out here.
除了其它豹子
He's got very little to fear
可能还有狮子 没什么能威胁到它了
apart from other leopards and maybe lions.
它正在观察 完全不在意我们
He's having a good look, he certainly doesn't care about us.
这大概两岁左右
He's around two years old
它还没有自己的领地
and at the moment, he doesn't have his own territory,
还太年轻了
he's too young for that.
所以比较低调
And so he's lying low.
它一周得成功猎食两次
He'll have to make about two kills a week,
才能保持体能
to stay in good condition.
所以 大概每隔两三天
So, maybe he'll catch an impala
就得抓一只黑斑羚
every three to four days,
它现在显然就在猎食
and he's obviously doing that.
因为 看看它
Because, look at him!
它要找蛋白质
And he's looking for protein.
我有点担心 因为我也是蛋白质
And I'm a little bit worried, cos I'm protein!
它走的真的很近
He's coming really close to us
因为它要咬录音师的话筒杆
because he's after the sound man's boom pole.
这真是...
Which is...oh!
太不可思议了
That's incredible.
我刚刚...
I just...
始于恒星的灭亡
From its origin in the death of stars...
由植物捕获
its capture by plants...
并流经昆虫和哺乳动物体内
through insects, mammals and on,
这一碳循环才是真正的生命循环
the carbon cycle is the real circle of life.
今夜的草原上 通过食物链
Out there tonight, the relentless recycling of carbon
碳循环不间断地持续着
through the food chain will continue.
当夜幕降临
As night falls,
你甚至能感受到
you can almost sense it -
空气里声音的微妙变化
the change in the sounds in the atmosphere.
随着碳元素在生命之树的
Some will die, so that others can live,
枝桠间流转 一些生物会死去
as carbon leaps from branch to branch
使其他生物得以存活
across the great tree of life.
而引导这一循环的
And guiding it on its way
是一种独特的化学变化
is just one very special form of chemistry.
碳原子的诞生远早于地球上的任何生命
Every living thing is just a temporary home
它的消亡也将远晚于非洲和地球的灭亡
for carbon atoms that existed long before there was life on Earth
而每个生物不过是碳原子的临时宿主
and will exist long after Africa and Earth are gone.
但生命的形态却得以延续
But, the pattern of life,
斑马 树 人类或狮子
the information needed to build a zebra,
生命所必须的生物讯息
or a tree, or a human being
却能得以保存
or a lion persists.
通过一个分子 世代流传
It's passed on from generation to generation, in a molecule.
一个以碳为基础的螺旋型分子 DNA
A helical molecule with a backbone of carbon called DNA.
曾经的地球看似毫无生气
There was a time when Earth appeared empty.
但抛开表象 38亿年前
Yet despite appearances, 3.8 billion years ago,
生命就在悄然酝酿了
life was already under way,
这些微小的生命
in the form of tiny living specks
也许都具有相同的生化特性
that probably all shared the same biochemistry.
我们知道 如今地球上的所有生物
We know that every living thing on the planet today -
就是说所有你吃过的食物 见过的动物
so every piece of food you eat, every animal you've seen,
认识或将要遇见的人
everyone you've ever known or will know,
事实上 日后这个星球上的所有生物
in fact every living thing that will ever exist on this planet -
都是那个微生物的后代
was descended from that one speck.
我们叫它最后的共同祖先 简称露卡
We call it the last universal common ancestor, or LUCA.
就像宇宙的起源是宇宙大爆♥炸♥
So, just as the universe had its origin at the Big Bang,
地球所有生命的起源正是那一个瞬间
all life on this planet had its origin in that one moment.
35亿年前
形成后不到一亿年
Less than a billion years after its formation,
地球上就已经有生命存在了
there was already life on Earth.
可能其中有些生物的生化特性
It's possible that some of it used biochemistry
与如今的生物截然不同
utterly different from the life we see today.
若是如此 这种生物早已灭绝
If so, it has long been extinct.
也有可能
It's also possible
生命的开端并非细胞生物
that the first life may not have been cellular -
只是某个远古海中多孔岩石上的
just living chemistry in the porous rocks
化学物质
of some ancient ocean.
我们并不确定
We're not sure,
但能确定的是
but what's certain is that one day,
某一天 一种生物诞生了
a population of organisms showed up
它拥有我们能够识别的生化特性
with biochemistry that we would recognise.
这就是露卡了
This was LUCA.
这一生命的最初形式
The first expression of a form of life
将在日后进化出一群人
that would in time throw up a group of humans
在非洲 在这里留下足迹
who left their mark in this part of Africa.
我们不知道露卡长什么样子
Now, we don't know what LUCA looked like,
也不明确它曾在哪里 如何存活
we don't know precisely where it lived or how it lived.
但我们知道
But we do know this.
如果追溯我的祖先 从我的父母
If you start to trace my ancestral line back to my parents,
到父母的父母 父母的父母的父母
to their parents, to their parents, to their parents,
在地质年代表上
all the way back through geological timescales
一直回溯到成千上万亿年前
over hundreds of thousands of millions and billions of years,
肯定有一条线从头到尾
there will be an unbroken line from me
把我连向了露卡
all the way back to LUCA.
这点毋庸置疑
We know that,
因为目前地球上所有的生物
because every living thing on the planet today
都有同样的生化特性
shares the same biochemistry.
我们都有DNA
We all have DNA.
腺嘌呤(A)
胸腺嘧啶(T)
鸟嘌呤(G)
胞嘧啶(C)
都由A C T G四种碱基组成
It's made of the same bases, A, C, T and G.
为同一组氨基酸编码
They code for the same amino acids.
这些氨基酸继而组成各种蛋白质
Those amino acids build the same proteins,
在无论植物 细菌
which do very similar jobs,
或是我这样的两足动物体内
whether you're a plant, a bacterium,
发挥着大同小异的作用
or a bipedal hominid, like me.
这就是说所有生命的本源都是一致的
So all life uses the same fundamental biology...
A C T G这四种碱基
Those four bases, A, C, T and G,
只编码20种氨基酸
which code for just 20 amino acids,
却能构建出
which in turn build each
生命所需的每一种蛋白质
and every one of life's proteins.
无论是细菌 植物 虫或兽
Be you bacteria, plant, bug or beast,
所有构造都来自DNA
your design comes from your DNA.