考研英语阅读理解中的文章，很多来自一些外刊杂志方面的题材。接下来，北京文都考研网为扩宽2020考研学子的知识面，整理了考研英语经济学人外刊:动物的魔法(上)，供考生参考。
2020考研英语经济学人外刊:动物的魔法(上)
The Cambrian explosion was caused by a lack of oxygen,not an abundance
造成寒武纪物种大爆发的，是缺氧而非富氧
During the Cambrian period, which began 541m years ago, animal life took a remarkable leap forward.
在始于5.41亿年前的寒武纪时期，动物生命有了向前的巨大飞跃。
The first creatures believed by most (though not all) palaeontologists to be multicellular animals appear in the previous geological period, the Ediacaran.
被多大数(尽管不是全部)古生物学家承认最早的多细胞动物在更早的地质时期——埃迪卡拉纪就已经出现了。
But though they are abundant and reasonably diverse,Ediacaran creatures do not look ancestral to modern animals.
但是，尽管这些生物数量丰富且种类相当繁多，埃迪卡拉动物群似乎并不是现代动物的祖先。
That is in contradistinction to Cambrian fossils, among which are found representatives of all the main animal groups (annelids, arthropods, brachiopods, chordates, cnidarians, echinoderms, molluscs and soon) that are around today.
在这一点上，寒武纪化石则截然不同——今天广泛分布的所有主要动物类群(环节动物、节肢动物、腕足类动物、脊索动物、刺胞动物、棘皮动物、软体动物等)的代表生物都能在寒武纪化石中找到。
And these groups appear in what is, in geological terms,an eyeblink.
而且，从地质学角度来说，这些类群几乎都是在一眨眼的功夫里出现的。
Several explanations have been put forward to explain the Cambrian explosion of animal life.
为了解释动物生命的寒武纪大爆发，人们提出了许多种解释。
One of the most popular is that it was fuelled by a dramatic rise in oxygen levels, permitting large and active creatures to thrive.
其中最流行的一种认为，氧气水平的显著上升使得活跃的大型生物得以繁盛，从而推动了生物大爆发的进程。
However, a study just published in Geology by Wei Guangyi of Nanjing University suggests this tale is not true.
然而，来自南京大学的魏广祎在《地质学》上刚发表的一项研究表明，这个故事并不属实。
Though oxygen levels certainly did rise in the late Ediacaran and early Cambrian, he and his colleagues suggest that what propelled animal evolution was actually two occasions when they crashed.
虽然氧气水平在埃迪卡拉纪晚期和寒武纪早期确实有所上升，但魏广祎和他的同事们认为，实际上是氧含量骤降的两个时机驱动了动物进化。
Dr Wei's evidence comes from rocks in the Chinese provinces of Hubei and Yunnan.
魏博士的证据来自于中国湖北省和云南省的岩石。
Specifically, he and his colleagues looked at uranium in limestone that had formed in shallow Ediacaran and Cambrian seas.
具体来说，他和他的同事们研究了在埃迪卡拉纪、寒武纪浅水域形成的石灰岩中的铀。
Uranium has two isotopes, 235U and 238U, that differ by three in the number of neutrons in their nuclei.
铀元素有两种同位素，即235U和238U，两者原子核的中子数相差3。
This small mass difference is enough to affect the speed of chemical reactions involving them, particularly if those reactions are biologically mediated by, say, bacteria, and thus involve interactions with enzymes.
这种微小的质量差异足以影响相关的化学反应速率，尤其是在由细菌等生物介导、涉及到与酶相互作用的反应中。
The upshot is that uranium compounds precipitated in well-oxygenated water have more 238U in them than those from anoxic water.
这带来的结果是，相比起氧气缺乏的水中，在含氧充足的水中沉淀的铀化合物含有更多的238U。
[重难点词汇]
abundance [ə'bʌndəns] n. 充裕，丰富
contradistinction [,kɑntrədɪ'stɪŋkʃən] n. 对比;对比的区别
representative ['rɛprɪ'zɛntətɪv] adj. 典型的，有代表性的;代议制的 n. 代表;典型;众议员
以上是北京文都考研网给出的“2020考研英语经济学人外刊:动物的魔法(上)”，希望对备考2020考研英语的考生有所帮助!祝2020考研顺利!
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