The oxygen level in our cells is only about a tenth the level found in the atmosphere. 我们细胞里的氧气浓度，只有大气里的大约十分之一。

　　The new oxygen-using organisms had two advantages. 新的会利用氧的细菌有两个优势。

　　Oxygen was a more efficient way to produce energy, and it vanquished competitor organisms. 氧能提高产生能量的效力，它打垮了与之竞争地微生物。

　　Some retreated into the oozy, anaerobic world of bogs and lake bottoms. 有的撤退到厌氧而泥泞的沼泽和湖底世界里；

　　Others did likewise but then later (much later) migrated to the digestive tracts of beings like you and me. 有的也照此办理，但后来（很久以后）又移居到了你和我这样的有消化力地地方。

　　Quite a number of these primeval entities are alive inside your body right now, helping to digest your food, but abhorring even the tiniest hint of O2. 有相当数量的这类原始实体此时此刻就生活在你的体内，帮助消化你的食物，但厌恶哪怕是一丁点儿氧气。

　　Untold numbers of others failed to adapt and died. 还有无数的其他细菌没有适应能力，最后死亡了。

　　The cyanobacteria were a runaway success. 藻青菌逃跑并取得了成功。

　　At first, the extra oxygen they produced didn't accumulate in the atmosphere, 起初，它们所产生的额外的氧没有积聚在大气里，

　　but combined with iron to form ferric oxides, which sank to the bottom of primitive seas. 而是与铁化合，成为氧化铁，沉入了原始的海底。

　　For millions of years, the world literally rusted—a phenomenon vividly recorded in the banded iron deposits that provide so much of the world's iron ore today. 有几百万年的时间，世界真的生锈了——这个现象由条形铁矿生动地记录了下来，今天却为世界提供了那么多的铁矿石。

　　For many tens of millions of years not a great deal more than this happened. 在几千万年时间里，发生的情况比这多不了多少。

　　If you went back to that early Proterozoic world you wouldn't find many signs of promise for Earth's future life. 要是你回到那个元古代初期的世界，你发现不了很多迹象，说明地球上未来的生命是很有前途的。

　　Perhaps here and there in sheltered pools you'd encounter a film of living scum 也许，你在这里和平那里隐蔽的水塘里会遇上薄薄的一层有生命的浮渣，

　　or a coating of glossy greens and browns on shoreline rocks, but otherwise life remained invisible. 或者在海边的岩石上会看到一层亮闪闪的绿色和裼色的东西，但除此之外生命依然毫无踪影。