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
14
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] Which of following is mentioned by Ben Potter as the "exciting new puzzles"?
选项
A、Whether Xach’itee’aanenh T’eede Gaay belonged to Native American groups.
B、How Xach’itee’aanenh T’eede Gaay’s population separated from major groups.
C、Why the two major Native American groups diverged from the common ancestor.
D、When the populations crossed over the land bridge and arrived in the Americas.
答案
B
解析
转载请注明原文地址:https://tihaiku.com/zcyy/2901891.html
相关试题推荐
[originaltext]M:Shakinganinfantoutofangerorfrustrationcanleadtoasev
[originaltext]M:Shakinganinfantoutofangerorfrustrationcanleadtoasev
中国中央电视台(ChinaCentralTelevision),简称为CCTV,1958年正式投入使用,是中国的官方电视媒体之一。它所有的节目都通过
[originaltext]M:Shakinganinfantoutofangerorfrustrationcanleadto
Asix-week-oldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-week-oldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
Asix-weekoldinfantwhodiedsome11,500yearsagoincentralAlaskaisno
随机试题
对……上瘾tobe/getaddictedto…
VideodischoldsgreatpromiseofhelpingtomeettheneedsofAmericanschoo
初中信息技术《分类存储-利用收藏夹分类管理网址》 一、考题回顾
A.①② B.③④ C.②③ D.②④
A.棕黑色溢液 B.黄褐色溢液 C.棕褐色溢液 D.血性溢液 E.黄绿色
阴道自净作用中,能将糖原分解为乳酸的细菌是以下哪项A.加德纳菌 B.乳酸杆菌
Thechangeinthatvillagewasmiraculou
档案室内部分隔墙上开设的门也要采取防火措施,耐火极限要求为1.2h。
入境人员每人仅限携带2只伴侣动物进境。()
(2016年真题)某具有出口经营权的电器生产企业(增值税一般纳税人)自营出口资产
最新回复
(
0
)