So thank goodness for atoms. 所以，谢天谢地，有了原子。

But the fact that you have atoms and that they assemble in such a willing manner is only part of what got you here. 不过，有了原子，它们心甘情愿地聚集在一起，这只是你来到这个世界的部分条件。

"To be here now, alive in the 21st century and smart enough to know it, 你现在在这个地方，生活在21世纪，聪明地知道有这回事，

you also had to be the beneficiary of an extraordinary string of biological good fortune. 你还必须是生物方面一连串极不寻常的好运气的受益者。

Survival on Earth is a surprisingly tricky¹ business. 在地球上幸存下来，这是一件非常微妙的事。

Of the billions and billions of species of living thing that have existed since the dawn of time, most-99.99%-are no longer around. 自开天辟地以来，存在过上百上千亿物种，其中大多数--据认为是99.9％--已经不复存在。

Life on Earth, you see, is not only brief but dismayingly tenuous². 你看，地球上的生命不仅是短暂的，而且是令人沮丧的脆弱的。

It is a curious feature of our existence that we come from a planet that is very good at promoting life but even better at extinguishing it. 我们产生于一颗行星，这颗行星善于创造生命，但又更善于毁灭生命，这是我们的存在的一个很有意思的特点。

The average species on Earth lasts for only about 4 million years, 地球上的普通物种只能延续大约400万年，

so if you wish to be around for billions of years, you must be as fickle³ as the atoms that made you. 因此，若要在这里待上几十亿年，你不得不像制造你的原子那样变个不停。

You must be prepared to change everything about yourself-shape, size, color, species affiliation⁴, everything-and to do so repeatedly. 你要准备自己身上的一切都发生变化--形状、大小、颜色、物种属性等等--反复地发生变化。

That's much easier said than done, because the process of change is random⁵. 这说起来容易做起来难，因为变化的过程是无定规的。

"protoplasmal primordial⁶ atomic globule", as the Gilbert and Sullivan song put it, 从\"细胞质的原始原子颗粒\"，到有知觉、

to sentient⁷ upright modern human has required you to mutate new traits over and over in a precisely⁸ timely manner for an exceedingly long while.", 能直立的现代人，要求你在特别长的时间里，以特别精确的方式，不断产生新的特点。

So at various periods over the last 3.8 billion years you have abhorred⁹ oxygen and then doted on it, 因此，在过去38亿年的不同时期里，你先是讨厌氧气，后又酷爱氧气，

grown fins¹⁰ and limbs and jaunty¹¹ sails, laid eggs, flicked¹² the air with a forked tongue, been sleek¹³, been furry¹⁴, 长过鳍、肢和漂亮的翅膀，生过蛋，用叉子般的舌头舔过空气，曾经长得油光光、毛茸茸，

lived underground, lived in trees, been as big as a deer and as small as a mouse, and a million things more. 住过地下，住过树上，曾经大得像麋鹿，小得像老鼠，以及超过100万种别的东西。

The tiniest deviation¹⁵ from any of these evolutionary¹⁶ shifts, 这些都是必不可少的演变步骤，

and you might now be licking algae¹⁷ from cave walls or lolling walrus-like on some stony¹⁸ shore 只要发生哪怕最细微的一点偏差，你现在也许就会在舔食长在洞壁上的藻类，或者像海象那样懒洋洋地躺在哪个卵石海滩上，

or disgorging air through a blowhole in the top of your head before diving 60 feet for a mouthful of delicious sandworms.", 或者用你头顶的鼻孔吐出空气，然后钻到18米的深处去吃一口美味的蚯蚓。