Mountains rise and melt away, ocean basins come and go, ice sheets advance and withdraw. 大山隆起又复平，海洋出现又消失，冰原前进又后退。

　　And throughout the whole, about three times every minute, 在整个这段时间里，每分钟大约三次，

　　somewhere on the planet there is a flashbulb pop of light marking the impact of a Manson-sized meteor or one even larger. 在这颗行星的某个地方亮起一道闪光，显示曼森尺度的或更大的陨石撞击了地球。

　　It's a wonder that anything at all can survive in such a pummeled and unsettled environment. 在陨石轰击、很不稳定的环境里，竟然还有东西能存活下来，这是令人惊叹的。

　　In fact, not many things do for long. 实际上。没有很多东西能挺过很长时间。

　　Perhaps an even more effective way of grasping our extreme recentness as a part of this 4.5-billion-year-old picture 要了解我们在这部45亿年长的电影里登场是极其微末的事，也许还有一种更有效的方法。

　　is to stretch your arms to their fullest extent and imagine that width as the entire history of the Earth. 你把两条手臂伸展到极限，然后想像那个宽度是整个地球史。

　　On this scale, according to John McPhee in Basin and Range, the distance from the fingertips of one hand to the wrist of the other is Precambrian. 按照这个比例，据约翰·麦克菲在《海洋和山脉》一书中说，一只手的指尖到另一只手的手腕之间的距离代表寒武纪以前的年代。

　　All of complex life is in one hand, "and in a single stroke with a medium-grained nail file you could eradicate human history." 全部复杂生命都在一只手里，“你只要拿起一把中度粒面的指甲锉，一下子就可以锉掉人类历史”。

　　Fortunately, that moment hasn't happened, but the chances are good that it will. 幸亏那种事情没有发生，但将来很可能会发生。

　　I don't wish to interject a note of gloom just at this point, 我不想在这个时刻散布悲观论调，

　　but the fact is that there is one other extremely pertinent quality about life on Earth: it goes extinct. Quite regularly. 但地球上的生命有着另一个极其相似的特点：生命会灭绝。而且相当经常。