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SSS 2010-01-21

时间:2010-05-20 01:53来源:互联网 提供网友:mark@li   字体: [ ]
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    (单词翻译:双击或拖选)

At one time or another, you’ve probably said, “It’s a small world.” Well, it used to be much, much smaller. Because according to scientists from the University of Utah, about a million years ago our ancestors numbered fewer than 20,000. The estimate appears in the Proceedings1 of the National Academy of Sciences.

The scientists based this ancestral census2 on a reading of modern human genomes. In particular, they tracked the positions of transposable elements. These small pieces of DNA3 are basically genomic parasites4. Over time, they’ve spread through our genomes and though they’re still capable of hopping5 from one place to another, they do so quite rarely. One particular transposon first appeared about a million years ago. And by seeing where these sequences now sit, scientists can get a sense of the size of the breeding population back then.

Their estimate of 18,500 individuals is pretty sparse6 considering that these early humans were spread across the Old World. By comparison, some 25,000 gorillas7 and 21,000 chimps8 were concentrated in Africa alone. So a million years ago, we were essentially9 an endangered species. Here’s hoping our recovery is permanent.

 


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1 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
2 census arnz5     
n.(官方的)人口调查,人口普查
参考例句:
  • A census of population is taken every ten years.人口普查每10年进行一次。
  • The census is taken one time every four years in our country.我国每四年一次人口普查。
3 DNA 4u3z1l     
(缩)deoxyribonucleic acid 脱氧核糖核酸
参考例句:
  • DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
  • Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
4 parasites a8076647ef34cfbbf9d3cb418df78a08     
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫
参考例句:
  • These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的,而与寄生虫无关。
  • Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。
5 hopping hopping     
n. 跳跃 动词hop的现在分词形式
参考例句:
  • The clubs in town are really hopping. 城里的俱乐部真够热闹的。
  • I'm hopping over to Paris for the weekend. 我要去巴黎度周末。
6 sparse SFjzG     
adj.稀疏的,稀稀落落的,薄的
参考例句:
  • The teacher's house is in the suburb where the houses are sparse.老师的家在郊区,那里稀稀拉拉有几处房子。
  • The sparse vegetation will only feed a small population of animals.稀疏的植物只够喂养少量的动物。
7 gorillas a04bd21e2b9b42b0d71bbb65c0c6d365     
n.大猩猩( gorilla的名词复数 );暴徒,打手
参考例句:
  • the similitude between humans and gorillas 人类和大猩猩的相像
  • Each family of gorillas is led by a great silverbacked patriarch. 每个大星星家族都由一个魁梧的、长着银色被毛的族长带领着。 来自《简明英汉词典》
8 chimps 2a09048610e52de775e2fe426c063f06     
(非洲)黑猩猩( chimp的名词复数 )
参考例句:
  • Chimps are too scarce, and too nearly human, to be routinely slaughtered for spare parts. 黑猩猩又太少,也太接近于人类,不可以作为人器官备用件说杀就杀。 来自英汉非文学 - 生命科学 - 医学的第四次革命
  • And as nonprimates, they provoke fewer ethical and safety-related concerns than chimps or baboons. 而且作为非灵长类,就不会产生像用黑猩猩或狒狒那样的伦理和安全方面的顾虑。 来自英汉非文学 - 生命科学 - 医学的第四次革命
9 essentially nntxw     
adv.本质上,实质上,基本上
参考例句:
  • Really great men are essentially modest.真正的伟人大都很谦虚。
  • She is an essentially selfish person.她本质上是个自私自利的人。
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