万物简史 第356期:孤独的行星(21)

 　　We have evolved to utilize¹ or tolerate these things—we could hardly be here otherwise— but even then we live within narrow ranges of acceptance. 我们已经逐步学会利用或忍受这些东西——要不然我们几乎不可能在这里——但即使那样，我们所能忍受的范围也很窄。

　　Selenium is vital to all of us, but take in just a little too much and it will be the last thing you ever do. 硒对我们大家都是至关重要的，但只要摄入一丁点儿，你就会呜呼哀哉。

　　The degree to which organisms require or tolerate certain elements is a relic² of their evolution. 生物对某些元素的要求或耐受性是它们进化的结果。

　　Sheep and cattle now graze side by side, but actually have very different mineral requirements. 现在羊和牛在一起吃草，实际上它们所要求的矿物质非常不同。

　　Modern cattle need quite a lot of copper³ because they evolved in parts of Europe and Africa where copper was abundant. 现代的牛需要大量的铜，因为它们是在铜很丰富的欧洲和非洲地区进化的。

　　Sheep, on the other hand, evolved in copper-poor areas of Asia Minor⁴. 而羊是在铜很缺乏的小亚细亚进化的。

　　As a rule, and not surprisingly, our tolerance⁵ for elements is directly proportionate to their abundance in the Earth's crust. 一般来说，我们对元素的耐受力与那些元素在地壳里德丰度成正比，这是不足为怪的。

　　We have evolved to expect, and in some cases actually need, the tiny amounts of rare elements that accumulate in the flesh or fiber⁶ that we eat. 我们已经进化到这种程度，希望——在有些情况下其实需要——在我们所吃的肉类或纤维里积累着少量的稀有元素。

　　But step up the doses, in some cases by only a tiny amount, and we can soon cross a threshold. 但是，要是加大剂量，在有的情况下就加大一丁点儿，我们可能会很快去另一个世界。

　　Much of this is only imperfectly understood. 这类知识在很大程度上我们还是一知半解。

　　No one knows, for example, whether a tiny amount of arsenic⁷ is necessary for our well-being⁸ or not. 比如，谁也说不清，摄入一丁点儿砷对我们的健康到底是有益的还是有害的。

　　Some authorities say it is; some not. 有的权威说有益，有的权威说有害。

　　All that is certain is that too much of it will kill you. 只有一点是肯定的，摄入太多，你就会送命。

　　The properties of the elements can become more curious still when they are combined. 元素一旦化合，它们的性质会变得更加奇特。

　　Oxygen and hydrogen, for instance, are two of the most combustion-friendly elements around, but put them together and they make incombustible water. 比如，氧和氢是两种最易燃的元素，但要是结合在一起，就变成了不易燃的水。

1 utilize   

vt.使用，利用

参考例句：

• The cook will utilize the leftover ham bone to make soup.厨师要用吃剩的猪腿骨做汤。
• You must utilize all available resources.你必须利用一切可以得到的资源。

2 relic   

n.神圣的遗物，遗迹，纪念物

参考例句：

• This stone axe is a relic of ancient times.这石斧是古代的遗物。
• He found himself thinking of the man as a relic from the past.他把这个男人看成是过去时代的人物。

3 copper   

n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的

参考例句：

• The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
• Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。

4 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

5 tolerance   

n.宽容；容忍，忍受；耐药力；公差

参考例句：

• Tolerance is one of his strengths.宽容是他的一个优点。
• Human beings have limited tolerance of noise.人类对噪音的忍耐力有限。

6 fiber   

n.纤维，纤维质

参考例句：

• The basic structural unit of yarn is the fiber.纤维是纱的基本结构单元。
• The material must be free of fiber clumps.这种材料必须无纤维块。

7 arsenic   

n.砒霜，砷；adj.砷的

参考例句：

• His wife poisoned him with arsenic.他的妻子用砒霜把他毒死了。
• Arsenic is a poison.砒霜是毒药。

8 well-being   

n.安康，安乐，幸福

参考例句：

• He always has the well-being of the masses at heart.他总是把群众的疾苦挂在心上。
• My concern for their well-being was misunderstood as interference.我关心他们的幸福，却被误解为多管闲事。