首页
登录
职称英语
You should spend about 20 minutes on Questions 14-26, which are based on Reading
You should spend about 20 minutes on Questions 14-26, which are based on Reading
游客
2025-02-16
8
管理
问题
You should spend about 20 minutes on Questions 14-26, which are based on Reading Passage 2 below.
Neanderthals and modern humans
A The evolutionary processes that have made modern humans so different from other animals are hard to determine without an ability to examine human species that have not achieved similar things. However, in a scientific masterpiece, Svante Paabo and his colleagues from the Max Planck Institute for Evolutionary Anthropology, in Leipzig, have made such a comparison possible. In 2009, at a meeting of the American Association for the Advancement of Science, they made public an analysis of the genome* of Neanderthal man.
B Homo neanderthalensis, to give its proper name, lived in Europe and parts of Asia from 400,000 years ago to 30,000 years ago. Towards the end of this period it shared its range with interlopers in the form of Homo sapiens**, who were spreading out from Africa. However, the two species did not settle down to a stable cohabitation. For reasons which are as yet unknown, the arrival of Homo sapiens in a region was always quickly followed by the disappearance of Neanderthals.
C Before 2009, Dr Paabo and his team had conducted only a superficial comparison between the DNA of Neanderthals and modern humans. Since then, they have performed a more thorough study and, in doing so, have shed a fascinating light on the intertwined history of the two species. That history turns out to be more intertwined than many had previously believed.
D Dr Paabo and his colleagues compared their Neanderthal genome(painstakingly reconstructed from three bone samples collected from a cave in Croatia)with that of five living humans from various parts of Africa and Eurasia. ’Previous genetic analysis, which had only examined DNA passed from mother to child in cellular structures called mitochondria, had suggested no interbreeding between Neanderthals and modern humans. The new, more extensive examination, which looks at DNA in the cell nucleus rather than in the mitochondria, shows this conclusion is wrong. By comparing the DNA in the cell nucleus of Africans(whose ancestors could not have crossbred with Neanderthals, since they did not overlap with them)and various Eurasians(whose ancestors could have crossbred with Neanderthals), Dr Paabo has shown that Eurasians are between one percent and four percent Neanderthal.
E That is intriguing. It shows that even after several hundred thousand years of separation, the two species were inter-fertile. It is strange, though, that no Neanderthal mitochondrial DNA has turned up in modern humans, since the usual pattern of invasion in historical times was for the invaders’ males to mate with the invaded’s females. One piece of self-knowledge, then—at least for non-Africans—is that they have a dash of Neanderthal in them. But Dr Paabo’s work also illuminates the differences between the species. By comparing modern humans, Neanderthals, and chimpanzees, it is possible to distinguish genetic changes which are shared by several species of human in their evolution away from the great-ape lineage, from those which are unique to Homo sapiens.
F More than 90 percent of the ’human accelerated regions’*** that have been identified in modern people are found in Neanderthals too. However, the rest are not. Dr Paabo has identified 212 parts of the genome that seem to have undergone significant evolution since the species split. The state of genome science is still quite primitive, and it is often unclear what any given bit of DNA is actually doing. But an examination of the 20 largest regions of DNA that have evolved in this way shows that they include several genes which are associated with cognitive ability, and whose malfunction causes serious mental problems. These genes therefore look like good places to start the search for modern humanity’s essence.
G The newly evolved regions of DNA also include a gene called RUNX2, which controls bone growth. That may account for differences in the shape of the skull and the rib cage between the two species. By contrast an earlier phase of the study had already shown that Neanderthals and moderns share the same version of a gene called FOXP2, which is involved in the ability to speak, and which differs in chimpanzees. It is all, then, very promising— and a second coup in quick succession for Dr Paabo. Another of his teams has revealed the existence of a hitherto unsuspected species of human, using mitochondrial DNA found in a little-finger bone. If that species, too, could have its full genome read, humanity’s ability to know itself would be enhanced even further.
* an individual’s complete set of genes
** the scientific name for modern humans
*** parts of the human brain which evolved very rapidly
Questions 14-18
Look at the following characteristics(Questions 14-18)and the list of species below.
Match each feature with the correct species, A, B or C.
Write the correct letter, A, B or C.
NB You may use any letter more than once.
List of species
A Homo neanderthalensis
B Homo sapiens
C both Homo neanderthalensis and Homo sapiens [br] Did not survive long after the arrival of immigrants.
选项
答案
A
解析
PARAGRAPH B ’... the arrival of Homo sapiens in a region was always quickly followed bythe disappearance of Neanderthals.’
转载请注明原文地址:https://tihaiku.com/zcyy/3958942.html
相关试题推荐
Youshouldspendabout20minutesonQuestions27-40,whicharebasedonReading
Youshouldspendabout20minutesonQuestions27-40,whicharebasedonReading
ReadingPassage2hassevenparagraphs,A-G.Whichparagraphcontainsthefollo
ReadingPassage2hassevenparagraphs,A-G.Whichparagraphcontainsthefollo
Youshouldspendabout20minutesonQuestions14-26,whicharebasedonReading
Youshouldspendabout20minutesonQuestions14-26,whicharebasedonReading
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage
DothefollowingstatementsagreewiththeinformationgiveninReadingPassage
Youshouldspendabout20minutesonQuestions1-13,whicharebasedonReading
随机试题
[originaltext]Winterisapainintheanimalkingdom.Birdscanfleeitby
AnexplosionhadthrownradiomanHarleyOlsonoutofbed.Heworkedwildly,
Burnoutcomeswhentherealityoflifeislessthanourexpectations.Andit
下列不属于引火源的是()。A.雷击 B.静电火花 C.煤炭 D.明
市政府为了解居民对其公共服务的满意程度,想从市民中随机抽取若干名居民,调查其居民
根据《城镇职工基本医疗保险用药范围管理暂行办法》在基本医疗保险药品目录中,列出的
有关牙石,不正确的一项是A.牙石对牙周组织的危害主要来自机械刺激 B.牙石增加
财政“汲水政策"的特点有()。A.该政策是一种诱导经济复苏的政策 B.该政
在趋势分析法中,对不同时期的财务指标进行比较采用的定基动态比率是指()。A.分析
中级会计专业技术资格的取得实行考试和评审相结合的制度。( )
最新回复
(
0
)