首页
登录
职称英语
A six-week-old infant who died some 11,500 years ago in central Alaska is no
A six-week-old infant who died some 11,500 years ago in central Alaska is no
游客
2023-08-06
41
管理
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." [br] 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://tihaiku.com/zcyy/2901890.html
相关试题推荐
[originaltext]M:Shakinganinfantoutofangerorfrustrationcanleadto
[originaltext]M:Shakinganinfantoutofangerorfrustrationcanleadto
Asix-week-oldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-week-oldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-week-oldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Thecentralheatingsystemseemstohavegonewrong.______(为什么不叫修理工检查一下呢)?Whyno
随机试题
A—BearmarketJ—EarningspershareB—BullmarketK—PricepershareC—Closingpri
InonlytwodecadesAsianAmericanshavebecomethefastest-growingU.S.min
ItappearsillogicaltosomepeoplethatWestGermany,whichbanssuchseemingl
AnewtropicalstormhasformedintheCaribbean,matchinga72-year-oldrec
在发明专利的审查授权程序中,()属于实质审查的内容A.该发明是否具备新颖性、创造
图形推理。请从所给的四个选项中,选择最合适的一个填在问号处,使之呈现一定的规律性
患者,男性,35岁,服用别嘌醇3周后全身出现皮疹,瘙痒伴低热.查尿常规示白细胞(
女性,65岁,主因头痛,右半肢体麻木,乏力2个月,入院查体,神清,血压正常,眼底
下列各项不符合20世纪30年代国际形势特点的是()A.大危机、大动荡和正义与非正
胰头癌最主要的临床表现是A:左上腹痛、夜痛尤剧 B:进行性黄疸 C:消瘦、贫
最新回复
(
0
)