生命的奇迹（2013）

that are most interesting
是最为有趣的
from a perspective of life in the universe.
因为头部是由另一个星系形成的
Because the head is formed by another galaxy,
一个拥有上亿颗恒星的第三个星系
a third galaxy, an island of billions and billions of stars,
以每秒250公里的速度 撞向
colliding with two galaxies that form the wings and the body
形成翅膀和躯干的另外两个星系
at a speed of around 250 miles a second.
其造成的动荡
The turbulence, the disturbance,
导致许多新恒星的诞生
that that creates is causing many new stars to be formed.
这些恒星在初期消耗氢元素
These stars begin their lives by burning hydrogen,
产生更多的氦元素
to produce ever more helium.
但是随着恒星老化 氢元素消耗殆尽
But as they age, as the hydrogen runs out,
它们变成这种氦元素
they turn to this helium.
核内的温度开始升高
The temperature at their core rises
增加了三个氦原子核
increasing the chances of three helium nuclei
聚合形成新的碳元素的机会
fusing together to form a new element - carbon.
宇宙存在至今 几乎130亿年
That process has been going on for almost
这个过程一直在进行
the entire history of the universe, back 13 billion years,
而正是恒星的形成
and it's the formation of stars
成为生命诞生至关重要的第一步
that is the vital first step in the formation of life,
因为恒星负责制♥造♥宇宙中的重元素
because stars produce the heavy elements in the universe
其中就包括碳
including carbon.
自宇宙初期起
From the universe's earliest times,
暮年的恒星就在不停地♥产♥生碳
carbon has been created inside ageing stars.
久而久之 碳越积越多
And over time, this carbon has built up,
如尘埃一般漂浮在宇宙中
drifting through the cosmos as dust...
直到一个叫地球的行星
Until some of it was caught up
在形成过程中将一些碳固定了下来
in the formation of a planet called Earth.
在这颗行星上
And it's here
我们将目睹这些古老的碳元素
that we can see this ancient carbon
激起鲜活的生命
brought vividly to life.
宇宙至今走过的千年万载
Today, the universe is old enough
足以见证无数恒星的生死
that countless stars have lived and died.
宇宙成型时期产生的氢和氧
So, there's been plenty of time to synthesise
有足够的时间来合成重元素
the primordial hydrogen and helium into the heavy elements.
现在的问题是
The question now is,
这些碳是怎样进入生命中的呢
how does that carbon get into the web of life?
现在 我要用这只气球
Well, today, it enters via one ingredient
测量当今碳进入生命中所依赖的原料
and I'm going to measure it using this balloon.
这个原料即为二氧化碳
The ingredient is carbon dioxide,
它在光合作用中起重要作用
which plays a key role in photosynthesis.
每晚二氧化碳浓度都会增加
Each night the carbon dioxide concentration increases,
溢满在树冠枝叶的周边
filling the air around the leaves at the top of the trees.
这只气球中装有二氧化碳监测仪
This balloon has a carbon dioxide monitor in it
我将用它来监测昼夜交替时
which is going to measure the change in the levels of CO2
森林冠层顶部二氧化碳浓度的变化
at the top of the forest canopy as night turns to day.
太阳升起后
As the sun rises,
树木就开始进行光合作用
the trees begin to photosynthesise.
昨晚6点 刚日落的时候
At 6pm last night, just after sunset,
二氧化碳浓度约为百万分之三百五十单位
the concentration was around 350 parts per million.
10点时 即日落后约4小时
Around 10pm, four hours after sunset,
浓度上升到约百万分之四百单位
the concentration had risen to about 400 parts per million.
现在 大概是正午 浓度降到了
Now, at about midday, the concentration's back down
约百万分之三百四十五单位
to about 345 parts per million.
我们可以看到在18小时中
So that's a variation over a period of about 18 hours
二氧化碳浓度有上下10%的波动
of 10% in the concentration of carbon dioxide,
就在森林冠层上方的这层空气中
just in that piece of atmosphere at the top of the forest canopy.
这些数字所体现的 就是光合作用
What you are seeing there is photosynthesis in action.
每时每刻 全球各个角落的植物
Every day, across the planet,
都在利用阳光进行着光合作用
photosynthesis uses sunlight
将二氧化碳和水转化为糖
to turn carbon dioxide and water into simple sugars.
自然界中绝大多数的碳
The overwhelming majority of the carbon
都被锁在了两类糖分子长链之中
is locked up inside long chains of sugar molecules
分别叫做纤维素和木质素
called cellulose and lignin.
其中木质素决定木材的强度
Lignin is the stuff that gives wood its strength.
虽然大多数碳以这种形式存在
So, in this form, remember, that is most of it,
却很难被动物所利用
it is very difficult indeed for animals to access.
锁在这些长碳链中的
For the energy and nutrients locked away
能量和营养成分
inside these long carbon chains
经分解后才能在食物网中流通
to move through the food web, they must be broken down.
而这一分解过程的最佳实例
And the best place to see that process in action
就发生在广袤的原野上
is out on the open plain.
这一巨型粮仓养活了各种有机体
It's one vast larder for all manner of organisms.
但至今固碳效率最高的
But by far the most effective harvester of carbon
却是大草原上最小的生物的之一
is actually one of the smallest creatures on the savanna.
白蚁
等翅目
白蚁是一种社会性昆虫
Termites are social insects,
它们协作造出具有代表性的一景
working together to form a characteristic sight,
并在灌木丛中随处可见
seen all over the bush.
那是个白蚁丘
That's a termite mound.
不过这只是冰山一角
Actually, it's the tip of the iceberg.
底下的白蚁城可比这小丘大多了
The termite city extends way beyond that underground.
白蚁丘的功能非常奇妙
And its function is fascinating.
这其实是个空调系统
It's essentially an air-conditioning system.
它能为蚁冢内部维持特定的气候
What it does is maintain very specific conditions
营造出热带雨林环境
inside the mound - the conditions of the rainforest.
约三千万年前 当第一批白蚁
When the termites first colonised the savanna
在热带草原上安家时
some 30 million years ago,
它们把热带雨林一起搬了过去
they brought the rainforest with them
来维持以枯木为食
to support a form of life that was already
这一它们已完全适应的生活方式
wonderfully adapted to living off dead wood.
这就是白蚁丘的精髓
This is what these termite mounds are all about.
看到那些构造了吗
Can you see those structures,
那些蜂巢状的构造
those white honeycomb-like structures?
它们叫做菌圃
Those are called fungal combs.
这里含有木浆 可能还有些枯草残骸
Their're wood pulp and possibly bits of dead grass
白蚁运回这些原料来建造菌圃
that the termites bring in and build into that structure.
而之所以蚁冢内部
And the reason the conditions
必须维持热带雨林的气候
have to be the same as the rainforest
是因为白蚁要在这些蜂巢结构周围
is because they grow a particular genus of fungus
培育一种叫小白蚁伞的真菌
called termitomyces around those honeycombs.
小白蚁伞
白蚁伞属
白蚁利用这些真菌来分解木材中的
The job of that fungus is to break down the lignin
木质素和纤维素
and cellulose inside the wood
并将其转化为可食用的东西
and convert it into a form that the termites can eat,
你可以看到 就是蜂巢状结构上
which actually you can see there, the little white nodules,
结出的那些白色小球
just present on the honeycomb structure.
白蚁体内的酶
The termites lack the enzymes
无法高效地分解木头
to break down the wood efficiently,
所以它们就转做农场主
so they've become farmers,
共同经营一个巨大的公用消化系统
tending to one giant social stomach.
白蚁与这种真菌
There's a very intense relationship
关系非常紧密
between the termites and the fungus.
其实据我们所知
You don't find that fungus anywhere else
还未在白蚁冢外的任何地方
actually in the world as far as we know,
发现过这种菌类
other than inside termite mounds.
人们认为 非洲这部分地区
It's thought that up to 90% of the carbon
有90%被锁在木质素中的碳
locked up in lignin in this part of Africa
都被白蚁和这种真菌分解
is released back into the food chain again,
并重新释放到了食物链中
solely by those termites and that fungus.
尽管白蚁搞定了大部分的木质素
So the termites deal with most of the lignin,
但仍有大量的碳
but that still leaves a vast store of carbon
被贮存在纤维素里
in the form of cellulose.
非洲有成群的哺乳动物以草和叶为食
Across Africa, herds of mammals graze on grasses and leaves,
将纤维素转化为肉
turning the cellulose into meat.
其中许多为反刍动物
Many are a type of mammal known as a ruminant.
而体型最大的一种
The largest of which
也是在草原上最容易发现的
is one of the easiest animals to spot on safari.
南非长颈鹿
长颈鹿属
那里也有一只长颈鹿
There's a giraffe there as well.
长颈鹿的饮食结构与白蚁相似
Giraffes live off a diet similar to termites.
它们以纤维素为食