Open the window and let some fresh air down.Ok!
打开窗户让新鲜空气进来。好的。
Take a deep breath of oxygen.
啊！深吸一口氧气。
It might not always been there,you know.
你知道的，它不是一直都有的。
What do you mean?
什么意思？
According to climate researcher James Kasting, when the earth first formed there might not have beenany oxygen around.
气候研究员的 James Kasting指出当地球初始形成时，周围并没有氧气。
Before the begining of the life？
在生命开始之前吗？
No,there would have been life, just no oxygen.
不，有生命，只是没有氧气。
For example, take methanogens, the microbes that make methane.
比如产烷生物，一种制造甲烷的微生物。
They only thrive when there's no oxygen around.
它们只在周围没有氧气的时候才能生存。
Is that why they live in airless places like the stomachs of cows?
这就是它们为什么生活在像牛胃那样不通风的地方的原因吗？
Correct!And according to the theory, back when the earth was young and there was no oxygen around, methanogens ruled and the atmosphere was filled with methane.
正确。根据理论，当地球年轻并且没有氧气的时候，产烷生物统治着地球，空气里面充满了甲烷。
So when did Oxygen come on the scene?
那么氧气是什么时候出现的呢？
Not untill about a billion years later.
直到大约十亿年后。
But without methane, oxygen-producing microbes might not haveevolved as quickly as they did.
但是如果没有甲烷，制氧微生物就不会进化的如此之快。
See, methane is a powerful greenhouse gas, meaning that it could havehelped keep the sun's rays trapped near the earth's surface.
甲烷是一种强有力的温室气体，它可以维持地球表面的太阳光线。
This was important, since billions of yearsago the sun was weaker than it is today.
这是非常重要的。因为几十亿年前太阳的光线比现在弱。
So without the methane-induced greenhouse effect, the earth might have frozen solid until the sun got hotter.
因此如果没有甲烷制造的温室效应，地球可能会被冻成一个坚硬的固体，直到阳光变强为止。
But when the earth would have become way too hot?
但是地球变得太热了怎么办呢？
Yes. If not for the fact that the methane rich atmosphere also could have helped to reflect enough incoming sunlight to maintain a delicate temperature balance.
是的。甲烷丰富的大气同样有助于折射足够多的射入阳光，使温度保持一种微妙的平衡。
So maybe the earth stayed warm, but not too warm, until oxygen-producing microbes evolved andfilled the atmosphere with oxygen, which drove away most of the methane.
所以地球保持着温暖，但不至于太温暖。直到制氧生物进化完成，赶走了绝大多数的甲烷，让大气充满氧气。
Right.
是的。
Well!You've just made my breath of fresh air more interesting.
嗯，你让我呼吸新鲜空气变得更有趣了。
