剑桥雅思真题阅读解析：Should we try to bring extinct species back to life?

剑桥雅思真题阅读解析：Should we try to bring extinct species back to life?

You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below.

Should we try to bring extinct species back to life?

AThe passenger pigeon was a legendary species. Flying in vast numbers across North America, with potentially many millions within a single flock, their migration was once one of nature's great spectacles. Sadly, the passenger pigeon's existence came to an end on 1 September 1914, when the last living specimen died at Cincinnati Zoo. Geneticist Ben Novak is lead researcher on an ambitious project which now aims to bring the bird back to life through a process known as 'de-extinction'. The basic premise involves using cloning technology to turn the DNA of extinct animals into a fertilised embryo, which is carried by the nearest relative still in existence - in this case, the abundant band-tailed pigeon - before being born as a living, breathing animal. Passenger pigeons are one of the pioneering species in this field, but they are far from the only ones on which this cutting-edge technology is being trialled.

BIn Australia, the thylacine, more commonly known as the Tasmanian tiger, is another extinct creature which genetic scientists are striving to bring back to life. 'There is no carnivore now in Tasmania that fills the niche which thylacines once occupied,' explains Michael Archer of the University of New South Wales. He points out that in the decades since the thylacine went extinct, there has been a spread in a 'dangerously debilitating' facial tumour syndrome which threatens the existence of the Tasmanian devils, the island's other notorious resident. Thylacines would have prevented this spread because they would have killed significant numbers of Tasmanian devils. 'If that contagious cancer had popped up previously, it would have burned out in whatever region it started. The return of thylacines to Tasmania could help to ensure that devils are never again subjected to risks of this kind.'

CIf extinct species can be brought back to life, can humanity begin to correct the damage it has caused to the natural world over the past few millennia? 'The idea of de-extinction is that we can reverse this process, bringing species that no longer exist back to life,' says Beth Shapiro of University of California Santa Cruz's Genomics Institute. 'I don't think that we can do this. There is no way to bring back something that is 100 per cent identical to a species that went extinct a long time ago.' A more practical approach for long-extinct species is to take the DNA of existing species as a template, ready for the insertion of strands of extinct animal DNA to create something new; a hybrid, based on the living species, but which looks and/or acts like the animal which died out.

DThis complicated process and questionable outcome begs the question: what is the actual point of this technology? 'For us, the goal has always been replacing the extinct species with a suitable replacement,' explains Novak. 'When it comes to breeding, band-tailed pigeons scatter and make maybe one or two nests per hectare, whereas passenger pigeons were very social and would make 10,000 or more nests in one hectare.' Since the disappearance of this key species, ecosystems in the eastern US have suffered, as the lack of disturbance caused by thousands of passenger pigeons wrecking trees and branches means there has been minimal need for regrowth. This has left forests stagnant and therefore unwelcoming to the plants and animals which evolved to help regenerate the forest after a disturbance. According to Novak, a hybridised band-tailed pigeon, with the added nesting habits of a passenger pigeon, could, in theory, re-establish that forest disturbance, thereby creating a habitat necessary for a great many other native species to thrive.

EAnother popular candidate for this technology is the woolly mammoth. George Church, professor at Harvard Medical School and leader of the Woolly Mammoth Revival Project, has been focusing on cold resistance, the main way in which the extinct woolly mammoth and its nearest living relative, the Asian elephant, differ. By pinpointing which genetic traits made it possible for mammoths to survive the icy climate of the tundra, the project's goal is to return mammoths, or a mammoth-like species, to the area. 'My highest priority would be preserving the endangered Asian elephant,' says Church, 'expanding their range to the huge ecosystem of the tundra. Necessary adaptations would include smaller ears, thicker hair, and extra insulating fat, all for the purpose of reducing heat loss in the tundra, and all traits found in the now extinct woolly mammoth.' This repopulation of the tundra and boreal forests of Eurasia and North America with large mammals could also be a useful factor in reducing carbon emissions - elephants punch holes through snow and knock down trees, which encourages grass growth. This grass growth would reduce temperatures, and mitigate emissions from melting permafrost.

FWhile the prospect of bringing extinct animals back to life might capture imaginations, it is, of course, far easier to try to save an existing species which is merely threatened with extinction. 'Many of the technologies that people have in mind when they think about de-extinction can be used as a form of "genetic rescue",' explains Shapiro. She prefers to focus the debate on how this emerging technology could be used to fully understand why various species went extinct in the first place, and therefore how we could use it to make genetic modifications which could prevent mass extinctions in the future. 'I would also say there's an incredible moral hazard to not do anything at all; she continues. "We know that what we are doing today is not enough, and we have to be willing to take some calculated and measured risks.'

Questions 14-17

Reading Passage 2 has six paragraphs, A-F.

Which paragraph contains the following information?

Write the correct letter, A-F, in boxes 14-17 on your answer sheet.

NB You may use any letter more than once.

14 a reference to how further disappearance of multiple species could be avoided

15 explanation of a way of reproducing an extinct animal using the DNA of only that species

16 reference to a habitat which has suffered following the extinction of a species

17 mention of the exact point at which a particular species became extinct

Questions 18-22

Complete the summary below.

Choose NO MORE THAN TWO WORDS from the passage for each answer.

Write your answers in boxes 18-22 on your answer sheet.

The woolly mammoth revival project

Professor George Church and his team are trying to identify the

18………….. which enabled mammoths to live in the tundra. The findings could help preserve the mammoth's close relative, the endangered Asian elephant.

According to Church, introducing Asian elephants to the tundra would involve certain physical adaptations to minimise 19………….. .To survive in the tundra, the species would need to have the mammoth-like features of thicker hair, 20………….. of a reduced size and more 21………….. .

Repopulating the tundra with mammoths or Asian elephant/mammoth hybrids would also have an impact on the environment, which could help to reduce temperatures and decrease 22………….. .

Questions 23-26

Look at the following statements (Questions 23-26) and the list of people below.

Match each statement with the correct person, A, B or C.

Write the correct letter, A, B or C, in boxes 23-26 on your answer sheet.

23 Reintroducing an extinct species to its original habitat could improve the health of a particular species living there.

24 It is important to concentrate on the causes of an animal's extinction.

25 A species brought back from extinction could have an important beneficial impact on the vegetation of its habitat.

26 Our current efforts at preserving biodiversity are insufficient.

List of People

A Ben Novak

B Michael Archer

C Beth Shapiro

02

译文

我们应该把那些业已灭绝的物种复活回来吗?

旅鸽是一个传奇般的物种。以众多的数量飞越北美洲的上空，仅仅一群里就可能有着数以百万计只个体，它们的迁徙之旅曾是自然界中最壮观的奇景之一。令人悲伤的是，旅鸽这个物种的存在终止在了1914年的9月1日，那一天最后一只活体在辛辛那提动物园里死去。基因学家Ben Novak是一个宏伟项目的首席研究员，这个项目当前的目标是通过一种被称为“逆转灭绝”的过程令这种鸟类复生。其基本原理是利用克隆技术将已灭绝动物的基因放进一颗受精胚胎中，由其现存于世的血缘最接近的亲缘物种——这一次是数量丰富的斑尾鸽——来孕育一个活生生的、有呼吸的动物。旅鸽是这个领域中率先进行尝试的物种之一，但它们远远不是这项前沿技术正在进行试验的唯一生物。

在澳大利亚，袋狼，或者更广为人知的名字是塔斯马尼亚虎，是基因科学家们正在努力尝试复活的另外一种已经灭绝的生物。“现如今在塔斯马尼亚没有任何肉食动物可以填补袋狼先前所占据的位置。”新南威尔士大学的Michael Archer这样解释道。他指出，自从袋狼灭绝的几十年以来，一种“颇具杀伤力的”面部肿瘤症状四下传播，威胁到了这座岛上另外一种声名远播的住客——袋獾——的生存。袋狼原本是可以阻止这场传播的，因为它们本来会捕杀足够多数量的袋獾。“如果那种传染性的癌症是在先前爆发出来的，其苗头无论始自哪个区域都会就地熄灭。袋狼在塔斯马尼亚的回归将能够确保袋獐永不再受这类风险的影响。”

如果已灭绝物种可以被复活的话，人类能开始改正自己在过去几千年间给自然界造成的种种破 坏么?“逆转灭绝的理念是我们可以扭转这个过程，将那些不再存在于世的物种带回来。”加利福尼亚大学圣克鲁兹分校基因组学研究所的Beth Shapiro这样说道。“我不认为我们能做到这样。不可能将一个很久以前就已灭绝的物种百分之百完全一样地复活回来。”对于灭绝已久的那些物种，一个更现实的办法是提取现有物种的DNA作为底板，插入已灭绝物种的DNA片段来创造一种新的生命；一个杂交品种，基于现存的物种，但看上去和/或在行为上与那种已经灭绝的动物很相像。

这一复杂过程和可质疑的结果引发了这样一个问题：这种技术的实际意义何在? “对于我们来说，目标一直都是用_个合适的替代者来接替那些已经灭绝的物种。"Novak这样解释道。“当说到品种这个问题时，斑尾鸽是四下分散栖息的，也许每公顷内也就造一或两个窝巢，而旅鸽却是非常社交性的物种，在一公顷的范围内有可能会造上一万个甚至更多的巢。”自从这个关键物种消失以来，美国东部的生态系统已经遭受到了损害，因为不再有成千上万只旅鸽给树木和枝干带来一定破坏，也就意味着基本没有了重新生长的需要。这就使得森林里一片死气沉沉，因此对那些进化出来就是为了帮助森林在遭受破坏之后重焕生机的植物和动物来说也就失去了吸引力。按照Novak的说法，一种杂交之后的斑尾鸽，增添了旅鸽筑巢的习性之后，就能够——在理论上——重建对森林的扰动，并由此创造出一个能令许多其他本土物种在其中兴旺繁衍的栖息地。

这项技术的另一个呼声很高的运用对象是猛犸象。哈佛医学院教授和猛码象复活项目的领头人George Church一直在致力于研究防冻抗冻，这是已灭绝的猛犸象与其血缘最近的现存亲缘物种——亚洲象——之间的主要区别。通过精准定位是哪些基因特质使得猛犯象能够在冰原上寒冷刺骨的天气里存活下来，这个项目的目标是将猛犸象，或者一种类猛犸象的物种，重新带回到这个地区来。“我的最高优先目标会是保护濒危的亚洲象，” Church这样说，“将它们的活动范围拓展到冰原上广大的生态系统中去。有必要作出的调整包括更小的耳朵、更厚的毛，以及额外的保温脂肪层，这一切都是为了减少在冻土上的热量流失，而所有这些特点都能在业已灭绝的猛犸象身上找到。”这个向欧亚大陆和北美洲的冻土和北部森林重新输送大型哺乳动物的做法还可以是这样一个有益的因素，能减少碳排放——大象会在雪上踩出洞来、撞倒树木，这刺激了草皮生长。这种植被生长将会降低温度，并缓解永冻层融化所释放的热量。

虽然能将业已灭绝的各种动物重新带回人间这个前景也许会牢牢吸引人们的想象力，然而更容易得多的做法当然还是去尝试拯救一个目前仅仅是受到了灭绝威胁的物种。‘当人们想到逆转灭绝时出现在他们脑海中的很多技术都可以被用作某种形式的，“基因拯救”。’Shapiro这样解释。 她更倾向于关注这样一场讨论:如何利用这种新兴技术来充分了解各类物种当初为什么会灭绝， 以及因此我们可以如何运用它来进行基因改良，以此来阻止未来的大规模灭绝。“我还要说，如果什么都不做，就会有大到难以置信的道义风险。”她继续说道。“我们知道自己今天正在做的还不够，因此我们必须自愿去承担一些经过测算和衡量之后（确认可以承担）的风险。”

03

答案解析

Question 14

答案：F

关键词：avoided

定位原文：F段前三句，特别是第三句：She prefers to focus the debate on how this emerging technology could be used to fully understand why various species went extinct in the first place, and therefore how we could use it to make genetic modifications which could prevent mass extinctions in the future.

解题思路：如前文中已经多次提到的那样：在“段落匹配信息”这种类型的题目中，大概率会有诸如reference、account、mention这类词汇出现，它们表达的意思都是“提到、说到”，考生切勿将此处的reference理解为此词的其他意义，如“参考”等，徒增理解难度。本题定位不难，无论考生是选择平行阅读、逐句读 懂大意（则会发现F段的前三句话都是围绕这个内容展开的），还是只在文中聚焦寻找“避免更多物种灭绝”这个信息点（则会在第三句原文中找到prevent这个词可以直接对应于题干中的avoid），都不难发现正确答案出处。如果是运用平行阅读法，同时照顾几个题型的解答，则还有意外收获：同样在这个答案句里还提及了人名观点匹配中第24题的对应信息。

Question 15

答案：A

关键词：reproducing, DNA, only

定位原文：A段倒数第二句：The basic premise involves using cloning technology to turn the DNA of extinct animals into a fertilised embryo, which is carried by the nearest relative still in existence - in this case, the abundant band-tailed pigeon - before being born as a living, breathing animal.

解题思路：本题所对应的原文句中包含了较多比较生僻的词汇，例如fertilised和embryo（尽管这两个单词在“动物类”题材的雅思阅读文章中其实出镜率也都不低），但是这些较为陌生的词汇其实并不会影响到考生对于整个句子的大体理解，因此也就不影响考生看出本句说的就是“利用克隆技术把已灭绝鸽子的DNA放在另一种近亲鸽子身上孕育、进而复活前者”，从而对应得出正确答案。一个句子中出现若干个生僻词汇、从而可能会给考生充分理解句子的意思造成一定障碍的现象，其实在雅思阅读文章中非常常见。在考场上不允许查单词的情况下，考生需要拥有冷静的心态和平时积累的分析长句结构的能力，就可以在不一定认识所有单词的情况下，仍然能看懂句子大意从而解题。

Question 16

答案：D

关键词：habitat, suffered

定位原文：D段特别是第四句：Since the disappearance of this key species, ecosystems in the eastern US have suffered, as the lack of disturbance caused by thousands of passenger pigeons wrecking trees and branches means there has been minimal need for regrowth.

解题思路：如果是运用平行阅读的方法，本题的定位和理解就都不困难，因为在有了D段前三句对于旅鸽和斑尾鸽筑巢习性的对比描述这个背景下，考生可以在读到第四句时轻松得出正确答案;如果单纯去寻找habitat或suffer这些题干词在原文中的对应，最终也是能找到答案的，但可能会耗费更多时间，因为定位了单词以后还是需要通读整个句子来进一步确认，反而不如依次阅读每句的速度更快、理解更顺畅。

Question 17

答案：A

关键词：exact point

定位原文：A段第三句：Sadly, the passenger pigeon's existence came to an end on 1 September 1914, when the last living specimen died at Cincinnati Zoo.

解题思路：本题在文章中的出处比较靠前，理解难度也比较低，是这部分题型中比较友好的一道题目。即使考生在阅读题干时并没有直接理解到exact point在此处暗含着“时间点”这个信息，其实也能在读到文章中相应描述的时候，将原句内容与本题题干进行匹配，从而得出正确答案。

Question 18

答案：genetic traits

关键词：Professor George Church

定位原文：E段第三句：By pinpointing which genetic traits made it possible for mammoths to survive the icy climate of the tundra, the project's goal is to return mammoths, or a mammoth-like species, to the area.

解题思路：本题的定位难度极低，无论是人名大写信息George Church，还是一模一样出现在原文中的tundra这个词，都能帮考生轻松找到答案句出处附近;同时，题干表述enabled与原文made it possible之间的同义替换也非常明显，由此可知答案应为：genetic traits。

Question 19

答案：heat loss

关键词：physical adaptations, minimise

定位原文：E段第五句：Necessary adaptations would include smaller ears, thicker hair, and extra insulating fat, all for the purpose of reducing heat loss in the tundra, and all traits found in the now extinct woolly mammoth.

解题思路：本题的定位与上一道题距离并不远，且题干中的adaptations在原文中一模一样地出现了，另一个帮助定位答案的题干词minimise与原文中reduce的同义替换表述关系也十分明显，且这两个词都是雅思阅读文章中的常客，考生要顺利得出答案为heat loss并不困难。

Question 20

答案：ears

关键词：thicker hair, reduced size

定位原文：E段第五句：Necessary adaptations would include smaller ears, thicker hair, and extra insulating fat, all for the purpose of reducing heat loss in the tundra, and all traits found in the now extinct woolly mammoth.

解题思路：本题与下一题出自同一个答案句，题干中和两个空格形成并列关系的thicker hair是一模一样地出现在原文中的，考生完全可以凭借这个词组定位到大致句中位置，再利用题干中reduced size与原文更为直白的表述smaller之间的对应关系，轻松得出答案为：ears。 如果一定要说有什么困难之处，大约就是本题和下一题的岀题位置跟第19题的出处略有乱序，但是由于三者都处在同一个长难句的范围之内，所以虽然乱序，但答案也相隔不远，并不会对考生阅读和答题造成实质性的干扰。

Question 21

答案：(insulating) fat

关键词：more

定位原文：E段第五句：Necessary adaptations would include smaller ears, thicker hair, and extra insulating fat, all for the purpose of reducing heat loss in the tundra, and all traits found in the now extinct woolly mammoth.

解题思路：本题与上一题是并列关系，定位后对比分析题干，即可轻松得出答案为：insulating fat。

Question 22

答案：(carbon) emissions

关键词：reduce temperatures, decrease

定位原文：E段第六句：This repopulation of the tundra and boreal forests of Eurasia and North America with large mammals could also be a useful factor in reducing carbon emissions - elephants punch holes through snow and knock down trees, which encourages grass growth.

解题思路：由于答案出处位置比较集中，所以考生在解答完前面的题目、顺序向下阅读的过程中，很快就能在原文中定位到reduce这个与题干中的decrease同义替换、且在雅思听说读写各科目中都高频出现的单词，进而顺利得出答案为：carbon emissions。

Question 23

答案：B

关键词：Michael Archer

定位原文：B段第三句到本段结束：He points out that in the decades since the thylacine went extinct, there has been a spread in a 'dangerously debilitating' facial tumour syndrome which threatens the existence of the Tasmanian devils, the island's other notorious resident. Thylacines would have prevented this spread because they would have killed significant numbers of Tasmanian devils. 'If that contagious cancer had popped up previously, it would have burned out in whatever region it started. The return of thylacines to Tasmania could help to ensure that devils are never again subjected to risks of this kind.'

解题思路：考生解答此题的速度，在一定程度上取决于自身的单词量高低。如果在利用大写人名Michael Archer定位到B段后，在阅读第三句话时认识syndrome“疾病症状”、threaten“威胁”、resident“居住者”这些单词的意思，其实已经能得出“袋狼灭绝以后，另一种本地生物袋獐受到了疾病威胁”这个理解，进而在下一句中从would have prevented这个虚拟语气的表达中得出结论：如果袋狼能在本地复活，其实袋獴就不会受到这么大的威胁，由此可以顺利得出正确答案为本句人名对应的选项B。但是如果并不认识上面说到的词汇，对虚拟语气的意思表达也不够敏感，则可能需要拿出耐心来、多往下再看两句话，也能根据难度更低的词汇和句子大意的表达，得出同样的结论。

Question 24

答案：C

关键词：Beth Shapiro

定位原文：F段第三句：She prefers to focus the debate on how this emerging technology could be used to fully understand why various species went extinct in the first place, and therefore how we could use it to make genetic modifications which could prevent mass extinctions in the future.

解题思路：本题的难度比较高，其中最主要的原因是：Beth Shapiro这个人名第一次出现的位置是在文章的C段中;然而这一段重点表达的意思是“用已灭绝动物的DNA片段和这种动物的近亲物种可以杂交出一种类似但并非完全一样的生物”，完全没有提及“聚焦物种灭绝原因”这个信息。这无疑对考生提升阅读速度、准确理解句子大意、甚至是保持稳定的心态都提出了一定挑战。在此提示考生：做题的本质一方面在于准确对应到正确的答案出处，但另一方面在于当发现所读之处并不对应问题信息的时候，需及时果断做出判定，继续向后文中寻找还未看过的文章部分，而不是轻易产生自我怀疑和动摇，盲目回读之前的内容。当然，这种果断需建立在平时进行语句篇章分析练习、对自己准确读懂句意这一点有自信的基础之上。 而一旦具备了这个自信、判定C段Shapiro所表达的内容与解题无关之后，考生即可迅速去定位这个人名的下一个出处，从而在F段的第三句里找到正确的对应。

Question 25

答案：A

关键词：Ben Novak

定位原文：D段第四句到本段结束：Since the disappearance of this key species, ecosystems in the eastern US have suffered, as the lack of disturbance caused by thousands of passenger pigeons wrecking trees and branches means there has been minimal need for regrowth. This has left forests stagnant and therefore unwelcoming to the plants and animals which evolved to help regenerate the forest after a disturbance. According to Novak, a hybridised band-tailed pigeon, with the added nesting habits of a passenger pigeon, could, in theory, re-establish that forest disturbance, thereby creating a habitat necessary for a great many other native species to thrive.

解题思路：本题的难点与上一道题类似，同样是因为人名Ben Novak第一次出现的位置是在A段，然而A段中却并没有任何表述了题干对应信息的语句，所以考生需及时判定并转而寻找下一次的人名出处，从而定位到D段。同时，在定位之后，虽然通过第四句话中trees and branches这个信息与题干中vegetation这个上义下义之间的同义替换，确实能获得强烈的暗示，但要百分之百确定此处为正确答案对应处的话，考生最好还是耐心向下文再多看几句，从而最终敲定正确答案为人名对应的选项A。

Question 26

答案：C

关键词：Beth Shapiro

定位原文：F段最后一句：We know that what we are doing today is not enough, and we have to be willing to take some calculated and measured risks.

解题思路：本题的定位距离同样对应于Shapiro这个人名的另外一个观点表述，也就是第24题的答案出处，并不算很远;考生在定位到本段人名Shapiro和找到24题答案后，只需再耐心确认一下后文的几句话，发现还是同一个人在继续表达观点，原本就应该再向后阅读几句，查对是否还有其他对应题目的表述。本题的难度来自于答案的对应点在全文最后一段的最后一句话里，考生需一直读到此处，才能轻松看出原文中的not enough这个表述正是直接对应于题干里的insufficient，且本段也确实是在说“保护各种各样的物种”这个话题，从而准确匹配到正确答案为C。