时间:2018-12-24 作者:英语课 分类:Scientific American(一)月


英语课

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 Proceedings 1 of the National Academy of Sciences.


The scientists based this ancestral census 2 on a reading of modern human genomes. In particular, they tracked the positions of transposable elements. These small pieces of DNA 3 are basically genomic parasites 4. Over time, they’ve spread through our genomes and though they’re still capable of hopping 5 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 sparse 6 considering that these early humans were spread across the Old World. By comparison, some 25,000 gorillas 7 and 21,000 chimps 8 were concentrated in Africa alone. So a million years ago, we were essentially 9 an endangered species. Here’s hoping our recovery is permanent.


 



1 proceedings
n.进程,过程,议程;诉讼(程序);公报
  • 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
n.(官方的)人口调查,人口普查
  • 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
(缩)deoxyribonucleic acid 脱氧核糖核酸
  • 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
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫
  • 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
adj.稀疏的,稀稀落落的,薄的
  • 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。
6 gorillas
n.大猩猩( gorilla的名词复数 );暴徒,打手
  • 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》
7 chimps
(非洲)黑猩猩( chimp的名词复数 )
  • 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
8 essentially
adv.本质上,实质上,基本上
  • 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。
标签: SSS census
学英语单词
ADIH
alphabetic telegram
alpine strawberry
ankersmit
anomal-
anterior pituitary gonadotrophin
arabidopsis lyratas
arms backward lift
arsenous acid anhydride
bad lot
barium enemator
blendent
blood-activating drug
breunig
Bruins
Calciobiotite
cape winter
caradons
clean up your act
cobbling
conditional independence graph
contactor density
craker
crystallosicope
cuparenone
curtains
cytometopus
decimal coefficient of absorption
decreasingly
demess
diazides
Dick Tracy
dimension size
dodecaedron
domestic population
Donovans Corner
eletronic oxytocic apparatus
enamcl bud
ethionamides
exhaust gas nozzle
free evaluation of the evidence
Galfan
gasket
girardelli
gulped down
gynecology of TCM
hadars
Harrower-Erickson tests
holy bark
hydroxyamino-norleucine
incision of scalp
indirectly heated thermister
indium arsenide
keiun
lactoproteinotherapy
latirus polygonus
lazyback
lithopedian
lowest tone
magastromancy
middlefield
Mlicrococcus acidi lactis
molded epoxy insulated coil
monophthongise
mpa (modulated pulse amplifier)
N-bromoacetamide
new-mercantilism
non-constant cost
not long
oeillet
of unsound mind
officered
Okawe
optically tracked
oscillator supply
oxalyl-urea
Palmarola, I.
Pechi
perfervid
phylic
podsolisation
programmed amplifier
pulsimeters
punier
queue arrangement
radial chromatic displacement
raghu
reduced cycle matrix
rounded bottom
senior certificate
single ingot pit
space detector
sthreal
Stovall-Black stain
tax on gifts
through and through
trimodular
twillies
undisclose
uninerviate
wrapping post
yoichis