首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
A six-week-old infant who died some 11,500 years ago in central Alaska is now providing clues about how the Americas first came
A six-week-old infant who died some 11,500 years ago in central Alaska is now providing clues about how the Americas first came
admin
2021-08-20
42
问题
A six-week-old infant who died some 11,500 years ago in central Alaska is now providing clues about how the Americas first came to be populated.
Genomic data from remains of the girl—named "Xach’itee’aanenh T’eede Gaay" (Sunrise Girl-Child) by the local indigenous community—broadly support a migration model that scientists have long argued for, while also revealing the existence of an ancient population previously unknown to science. The girl was a member of an ancient population that the report authors have named "Ancient Beringians". Beringia is the name given to Alaska, Eastern Siberia, and the land bridge that periodically connected the two during the last ice age.
The findings suggest a revised family tree: a single ancestral Native American group split from East Asians about 35,000 years ago, before later splitting, some 20,000 years ago, into two distinct groups. One was the Ancient Beringians. and the other constituted the ancestors of modern-day Native Americans, who later split into northern and southern populations about 15,700 years ago.
"Trying to integrate these findings with what we know fromhaeology (考古学) and paleoecology (古生态学) presents exciting new puzzles," says Ben Potter, an anthropologist (人类学家) at the University of Alaska. "The peopling has been shown now to be more complex than we thought previously. " Scientists have sought ancient human remains from Beringia at the end of the last ice age, but Xach’itee’aanenh T’eede Gaay’s genome held a surprise: it was clearly Native American, but not from either of the two major modern Native American groups. It represented a population that diverged from that common ancestor.
All of this helps narrow down and strengthen the theories of just how those populations arrived in the Americas. But mysteries remain, including definitive answers about where and when some of these population splits occurred and which migration routes were used.
Researchers outline two possible models. In one scenario, which Dr. Potter favors since it matches well with haeological data and paleoecological data, the split occurred in Northeast Asia, and the two separate populations later crossed over the land bridge prior to 15,700 years ago, when the Native American ancestors split again. In the other theory, the ancestral population had already arrived in Alaska or eastern Beringia by 20,000 years ago, and the split occurred there, with the second split into North and South American populations occurring south of the ice sheets. What happened to the Ancient Beringians? They might have died out, says Potter, or they could have been absorbed by Northern Native Americans who migrated back to the far North.
Researchers liken the puzzle to a murder mystery. "You read the book, and the author reveals new clues over the course of the book. Every time a new genome is analyzed and reported, it provides a new clue that’s making the pathway to uncover the real story that much clearer."
What can we learn about the girl called "Xach’itee’aanenh T’eede Gaay"?
选项
A、She was found dead about six years old some 11,500 years ago.
B、She provided new clues for the study on the first American population.
C、She belonged to an ancient population that used to dwell in Beringia.
D、She migrated to central Alaska sometime during the last ice age.
答案
C
解析
转载请注明原文地址:https://kaotiyun.com/show/dgD7777K
0
大学英语六级
相关试题推荐
A、Coffeedrinkerslivelongerthannon-drinkers.B、Drinkingcoffeecanhelpcurecertaindiseases.C、Drinkingcoffeedailygives
PatientsStruckoffbyGPsA)ThousandsofpatientsarebeingarbitrarilystruckoffbyGPs(普通开业医生)whosaytheycannolongercop
PatientsStruckoffbyGPsA)ThousandsofpatientsarebeingarbitrarilystruckoffbyGPs(普通开业医生)whosaytheycannolongercop
PatientsStruckoffbyGPsA)ThousandsofpatientsarebeingarbitrarilystruckoffbyGPs(普通开业医生)whosaytheycannolongercop
PatientsStruckoffbyGPsA)ThousandsofpatientsarebeingarbitrarilystruckoffbyGPs(普通开业医生)whosaytheycannolongercop
A、Havingarestfrequentlyduringtheday.B、Thelackofsleeponweekends.C、Thelackofexerciseintheevening.D、Eatingchee
A、Aproductdesignedfornewbornbabies.B、Acompanyprovidingbabysitterservices.C、Atelevisionprogramregardingbabies.D、A
A、Topreserveitlonger.B、Togiveitaparticulartaste.C、Tomakeitsmoother.D、Toincreasethefermentation.B①四个选项都是动词不定式结构
随机试题
某市工商局发现,某中外合资游戏软件开发公司生产的一种软件带有暴力和色情内容,决定没收该软件,并对该公司处以3万元罚款。中方投资者接受处罚,但外方投资者认为处罚决定既损害了公司的利益,也侵害了自己的权益,向法院提起行政诉讼。下列选项中正确的是(
早在夏朝时期,_______、在夏、商、周和春秋战国时期,_______、秦朝的________、唐朝的对外经济交往空前兴旺发达。
治疗水湿困脾鼓胀的主方是
行政领导活动的一个主要内容是:
围堰可以按()进行分类。
根据企业会计准则的规定,企业销售商品发生的现金折扣应在实际发生时()。
银行一般不能向借款人提供与抵押物等价的贷款,其原因包括()。
招聘的内容不同,评估报告的内容也会有不同的侧重。外部招聘报告一般侧重于()。
强攻战是在谈判中以绝不退让或高压的态度,迫使对方让步的策略。强攻战可以随时随地发生,却又可随时随地死而复生。强攻战的具体策略有:针锋相对、最后通牒、扮疯相、最大预算、说绝话等。根据上述定义,下列各项不能达到强攻战效果的是:
A、Shehadtoborrowbooks.B、Shehadtothinkofwords.C、ShehadtoseeadentistD、Shehadtofinishanassignment.C选项均是Sheh
最新回复
(
0
)