[考博英语]2017考博英语阅读题源经济学人文章每日精析（八十八）_考博_旭晨教育

2017 考博英语 阅读题源经济学人文章每日精析（八十八）

考博英语阅读大部分博士研究生招生院校都使用《经济学人》杂志文章作为题源，旭晨教育考博频道为考博生们将其中的文章进行深度分析，希望能提高大家的考博英语阅读水平，读懂长难句。

导读

猫和小熊猫属于食肉目不同的科：大熊猫属于熊科，而小熊猫属于鼬超科中的小熊猫科，二者分歧已有4000多万年。尽管其系统发育关系较远，它们却演化出相同的食竹食性;更为有趣的是，这两种熊猫的前掌还演化出一个特殊的结构——伪拇指，以帮助抓握竹子，是适应性演化和趋同演化的经典案例。

Panda genetics

熊猫遗传学

Two strange mammals illuminate the process of natural selection

两种不同的哺乳动物阐明自然选择的过程

Hey dude. Give me six!

嘿，伙计。用六指击个掌吧!

Jan 21st 2017

2017年1月21日

CONVERGENT evolution—the arrival, independently, by different species at the same answer to a question posed by nature—is a topic of great interest to biologists. One aspect of the phenomenon which has not yet been much looked at, however, is its underlying genetics. In particular, an issue not previously addressed is how often such changes arise from similar mutations in the two convergent lines, and how often they have different genetic causes that happen to have similar effects on the organisms’ forms and functions. That has now been rectified by an examination of two creatures which, though only distantly related, share an unusual feeding habit, an unusual anatomical feature and an unusual name: panda.

趋同进化是生物学家们有着极大兴趣的话题，它是指在自然作用下，不同物种独立的共同进程。然而该现象在潜在基因方面尚未得到许多的关注。尤其是在两条趋势线中来自相似基因突变引起趋同变化的频率，以及不同基因对生物的形态功能起到相似作用的概率的方面，尚未得到解决。如今通过对两种生物的检验已得到纠正，虽然这两种动物是远亲，但他们都具有与众不同的饮食习性、解剖特性以及一个不寻常的名字：熊猫。

mutation [mjuː'teɪʃ(ə)n] n.突变

anatomical [ænə'tɒmɪk(ə)l] adj.解剖的

注：convergent evolution——趋同进化：不同的物种在进化过程中，由于适应相似的环境而呈现出表型上的相似性。也指不同起源的蛋白质或核酸分子出现相似的结构和功能。

The giant panda is a black and white bear. The red panda is related to weasels, raccoons and skunks. Their habitats—mountainous areas of southern China and its neighbours—overlap, but their last common ancestor lived 43m years ago. They do, though, share a limited kinship, for both are members (along with dogs, cats, hyenas, mongooses, seals and so on) of the mammalian order Carnivora. Which is curious, because both are vegetarian.

大熊猫是一种黑白相间的熊。小熊猫与鼬鼠，浣熊和臭鼬具有亲属关系。他们的栖息地在华南山区且近亲重叠，在4300万年前，他们有着共同祖先。尽管如此，由于它们都是食肉目哺乳动物类(像狗，猫，鬣狗，猫鼬，海豹等)，所以确实有一些相同的血缘关系。令人好奇的是它们都是食草动物。

weasel ['wiːz(ə)l] n.鼬鼠

skunk [skʌŋk] n.臭鼬

hyena [haɪ'iːnə] n.鬣狗

mongoose ['mɒŋguːs] n.猫鼬

carnivora [kɑr'nɪvərə] n.食肉类; 食肉目

More intriguing still, both subsist almost entirely on bamboo (some etymologists think their mutual name is derived from the Nepali phrase nigalyaponya, meaning “bamboo-eater”). And most curiously of all, both have a sixth digit on their forepaws—a kind of ancillary thumb derived from one of the bones of the wrist that helps them hold bamboo stalks for consumption.These common features led Hu Yibo of the Institute of Zoology, in Beijing, and his colleagues, to wonder if the two vegetarian carnivores also shared genetic modifications that might explain those features. And, as Dr Hu observes in a paper just published in the Proceedings of the National Academy of Sciences, they do.

更有趣的是，它们几乎完全以竹子为食(一些词源学家认为它们的共同名字源于尼泊尔语nigalyaponya，指“食竹者”)。最令人惊奇的是，它们的前爪上都长有第六指，是从腕骨长出用来帮助它们在进食时拿住竹茎的辅助拇指。基于这些共同特征，北京动物研究所的胡一波和他的同事们设想，这两种食肉目食草动物是否共有一种能解释这些特征的修饰基因。正如胡博士刚刚在《美国国家科学院院报》发表的论文中所说的，它们确实共有。

Intriguing ['ɪntriːgɪŋ] 有趣的

Ancillary [æn'sɪlərɪ] 辅助的

To search for such genetic commonalities, Dr Hu and his colleagues compared the DNA of the two pandas with that of four other members of the Carnivora: polar bears (close relatives of giant pandas),ferrets (close relatives of red pandas), and tigers and dogs (close relatives of neither). If pandas share features of their DNA with each other, but not with the four comparison species, he reasoned, then it is likely that those features encode recent adaptations common to the two of them.

为了找到这样的遗传共性，胡博士团队将两只熊猫的DNA与另外4种食肉目动物(北极熊(大熊猫的近亲)，白鼬(小熊猫的近亲)，老虎和狗(非两者近亲))的DNA进行比较。如果熊猫们有相同的DNA特征，而四种对照物种没有熊猫所共有的DNA特征，他则推理很有可能这些DNA特征编码了它们两者间近代的共同特性。

Ferret ['ferɪt] 雪貂

Altogether, the team identified 70 genes (out of the 20,000 or so that mammals have) which sport bits of DNA that seemed to be shared. They also found ten genes which have been disabled by crippling mutations in both of the pandas, but not in the other four species. Not all of the shared genetic features obviously tied in with the shared peculiarities of pandas, but some did. These fell into three categories: genes affecting anatomy, genes affecting appetite and genes affecting the digestion and metabolism of nutrients.

研究小组从哺乳动物约20000个基因中，确定了可以共有的70个DNA片段。他们也在两种熊猫中找到了十个因严重突变而丧失功能的基因，而其他四个物种中并未发现。尽管哺乳动物共有遗传特征并不都与熊猫的特性一致，但有些确实具有一定的关系。这分为三类：影响动物体结构的基因，影响食欲的基因和影响营养物质消化和新陈代谢的基因。

peculiarity [pɪ,kjuːlɪ'ærɪtɪ] n.古怪; 怪癖; 特色; 奇形怪状;

metabolism [mɪ'tæbəlɪz(ə)m] n.[生理]新陈代谢