It was a considerable leap in human history. 这是人类历史上质的飞跃
And thanks to a more clement climate, humans settled down. 多亏更加温和的气候 人类定居了下来
Every species has a role to play, 每个物种都有其所扮演的角色
A 10th of them? A hundredth perhaps? 十分之一 百分之一
They are a world of incessant activity... 这是一个不断运行的世界
Which then decompose into a mixture of water, 之后这些再分解成为 水