种出个地球（1）

And that allows them to extract oxygen,
不仅在水里 还能从大气中吸收氧气
not just from the water but also from the air.
非常神奇的呼吸器官
It's an amazing breathing apparatus.
该放她走了
Better put her back now.
来 亲爱的 趴稳了
Come on, dear. There you go.
它们只要保持通体湿润
As long as they're kept moist,
这些像肺一般的腮
these lung-like gills enable the crabs
就能让这些蟹长时间待在水体之外
to stay out of water for days at a time.
化石表明 马蹄蟹至少在4亿年前
Fossils show that horseshoe crabs appeared on land
就出现在了陆地上
at least 400 million years ago.
它们属于早期一直在登陆的动物
They are some of the first animals ever to come ashore.
两栖动物和昆虫接踵而至
Amphibians and insects soon followed.
它们靠氧气将其栖息之所转至陆地
Oxygen allowed them to move onto land.
但同时也有些诱惑性因素存在
But something else was also enticing them.
有意思 对植物来说氧气是"废气"
It's funny. Plants create oxygen as a waste product,
可就是这种"废气"在转化着整个大气
and it's that waste product that has transformed our atmosphere.
当然 植物进行光合作用的主要目的
But of course, the main reason that plants photosynthesise
是产生糖类
is to create sugars.
糖类是植物生长的重要因素
Sugars that are vital for plants to live and to grow,
同时为所有动物提供食物源头
and also provide a source of food for all animals.
植物从水中获得糖类
Plants make this sugar from water...
从空气中获得二氧化碳
Carbon dioxide from the air...
从太阳光中获得能量
And energy from the sun.
一如此前
And again,
这一过程再次发生在小小叶绿体中
it all happens in those tiny chloroplasts.
我们已经了解到光把水分
We've seen how light splits water
化为氧和氢的过程
into oxygen and hydrogen.
植物吸收氢原子
The plant takes that hydrogen
并与二氧化碳分子结合
and combines it with carbon dioxide
进而转化为糖类
to make sugar.
将一棵植物贴上放射性标记物
By exposing a plant to carbon dioxide
再将其置于二氧化碳中
tagged with a radioactive marker,
就能清楚看见糖类的产生
you can see the sugar being created.
史上第一次
For the first time,
科学家借助一棵植物
scientists have imaged its creation
想象它的产物及其运作过程
and movement through a plant.
这棵植物就是玉米
In this case - maize.
植物细胞一旦将二氧化碳吸收
As soon as carbon dioxide is sucked into the plant's cells,
它们便开始发光
they begin to glow.
就在这一瞬间
This is the actual moment
光合作用将二氧化碳转化为糖类
that photosynthesis turns the carbon dioxide into sugar.
新生成的糖在十五分钟之内
In just 15 minutes, the newly-formed sugar
运送至根部以便储存
is sent to the roots for storage.
植物利用这些糖迅速地生长
The plant can then use this sugar to grow and thrive.
所以说光合作用是大自然最惊人的成就
That's why photosynthesis is nature' most astonishing achievement.
宇宙中的光线
The ability of plants to
使植物能够产生出能量
be powered by light from beyond our planet
这让植物有别于其他的生命体
sets them apart from all other life.
而植物与太阳之间的联♥系♥
And that connection with that star, our sun,
让它成为所有生命的基石
makes plants a foundation stone for all living things.
真是太神奇了
It's just such a wonderful thought.
四亿年前
400 million years ago,
无叶植物前所未有地茂盛
leafless plants were flourishing like never before.
然而大气中一场巨变
But a dramatic transformation of the atmosphere
将让植物陷入一场全球危机之中
was about to throw plants into a global crisis.
这场巨变不仅会改变植物的形态
Not only would it change their shape
也会改变这个星球上所有的生命
it would change all life on our planet.
这是新西兰的塔拉威拉湖
This is Lake Tarawera in New Zealand.
这片古老的土地在三亿六千万年前
This ancient landscape is home to a plant
首当其冲地面临了地球上的危机
that 360 million years ago confronted that crisis.
这里解决危机的方法给人以启发
It came up with an inspired solution.
时光好像遗忘了这块土地 对吗
Looks like the land that time forgot, doesn't it?
不同形态的植物和树木
Just that strange mixture
奇异地混合在了一起
of different shapes of plants and trees.
非常的新奇陌生
Really unfamiliar and alien.
几乎是原始世界
It's almost primeval.
早期的植物成为自身胜利的受害者
The early plants had become victims of their own success.
过多地吞食大气中的二氧化碳
They were gorging on so much carbon dioxide in the atmosphere
耗尽了所有的二氧化碳
that they were using it up.
二氧化碳水平线暴跌了90%
Levels plummeted by 90%.
缺少足够救命的气体 植物岌岌可危
Without enough of this vital gas, plants began struggling.
如果找不到吸入更多二氧化碳的办法
If they couldn't find a way to breathe in more carbon dioxide,
植物会窒息而死
they'd suffocate.
早期植物 比如这些美丽的蕨类植物
The early plants, plants like these gorgeous ferns here,
生成了一种了不起的新结构
came up with a remarkable new structure.
在这些巨大平整的表面之中
Large, flat surfaces that house within them
有一个复杂的呼吸装置
a complex breathing apparatus.
这就是叶子
We call them leaves.
叶子就是解决所有植物呼吸问题的办法
Leaves were the answer to all plants' breathing problems.
植物千百倍地扩展了
They massively increased their surface area
覆盖面♥积♥
by over a hundredfold,
从而能吸收更多的二氧化碳
allowing them to absorb far more carbon dioxide.
这是第一次
Now, for the first time,
美丽精致的树冠生成了树荫
shade was cast by a beautiful and delicate canopy,
就像是这些蚌壳蕨属树木
like these Dicksonia.
这些蕨类植物真是不可思议
These ferns are incredible.
就像是巨大的伞
They're like giant umbrellas.
这种高级呼吸装置的关键之处
The key to this advanced breathing apparatus
就在每片蕨叶的背面
is on the underside of each fern leaf.
也就是称之为气孔的微孔
They're microscopic holes called stomata.
在电子显微镜的拍摄下
Filmed and actioned with an electron microscope,
可以看到它们的闭合
this is them opening and closing.
画面加速了140倍
Speeded up 140 times.
地球上的每一片叶子上都有千万个气孔
There are thousands of stomata on every leaf on Earth.
使得每棵蕨
They allow a single fern
每天能吸入五升的二氧化碳
to breathe in five litres of carbon dioxide a day.
叶子的进化 大量的气孔
The evolution of leaves, rich in stomata,
将植物从窒息中解救出来
saved plants from suffocation.
叶子也能让植物捕获更多光线
But leaves also allow plants to capture more light.
就相应的加剧了激烈的竞争
This in turn fuelled fierce competition,
每棵植物都迫切地渴望阳光
each plant desperate for the sun's rays.
植物大家庭的争斗孕育了一个新型植物
This family squabble would lead to a new type of plant.
它会对植物造成意想不到的影响
One that would have surprising repercussions for the planet.
我们是如何得知的
How do we know?
多亏在加拿大新斯科舍省
Well, it's all thanks to some rare evidence here
找到了一些罕见的证据
in Nova Scotia in Canada.
要看到证据 先从30米高的悬崖爬下
To reach it, you have to abseil to the bottom of this 30m cliff.
科学家在这里发现了神秘世界的遗存
Here, scientists discovered the remains of a mysterious world.
这是观察岩石最好的方法
You know, this is just the best way to see rocks.
感觉自己就像是一个时光旅行者
You really feel as if you're a time traveller,
在降落时一层一层地掀开覆盖着的历史
peeling back the layers of history one by one as you go down.
这些岩石有超过三亿年的历史
These rocks are over 300 million years old.
但深锁在悬崖底部岩石中的东西
But it's what's locked inside the rocks at the base of this cliff
才真正让科学家屏息期待
that took scientists' breath away.
这些化石残骸真壮观
These fossilised remains are just spectacular!
看看这纹理
I mean, look at the texture.
看得出来这是一颗植物
You can tell it's a plant
但这不是什么大灌木 或过度生长的蕨
but this isn't some big shrub or overgrown fern.
看这里 有树皮的痕迹
You can see here, look, you can get traces of bark.
这下面有一些伸出来的树根
And down here, you can see there are some roots coming off.
它彻底灭绝了 别的地方都没有
This is completely extinct, you don't get this any more,
可我现在正蹲在
but what I'm actually crouching beside
地球上非常早期的一棵树干旁边
is one of the planet's very early tree trunks.
不止一棵 看这
And not just one tree, cos look here.
这还有一棵
There's another one here.
那也有一棵
There's another there.
这是一片化石森林
This is a fossil forest.
这些鳞木有奇怪的钻石状树皮
These Lepidodendron trees had strange diamond-shaped bark.
每块钻石树皮长出了针状叶子
Each diamond sprouting a needle-like leaf.
在三亿年前
Over 300 million years ago,
它们形成了地球上第一片热带雨林