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
"Migration from Asia" The Asian migration hypothesis is today supported by most of the scientific evidence. The first "hard"
"Migration from Asia" The Asian migration hypothesis is today supported by most of the scientific evidence. The first "hard"
admin
2018-07-24
24
问题
"Migration from Asia"
The Asian migration hypothesis is today supported by most of the scientific evidence. The first "hard" data linking American Indians with Asians appeared in the 1980s with the finding that Indians and northeast Asians share a common and distinctive pattern in the arrangement of the teeth. But perhaps the most compelling support for the hypothesis comes from genetic research. Studies comparing the DNA variation of populations around the world consistently demonstrate the close genetic relationship of the two populations, and recently geneticists studying a virus sequestered in the kidneys of all humans found that the strain of virus carried by Navajos and Japanese is nearly identical, while that carried by Europeans and Africans is quite different.
The migration could have begun over a land bridge connecting the continents. During the last Ice Age 70,000 to 10,000 years ago, huge glaciers locked up massive volumes of water and sea levels were as much as 300 feet lower than today. Asia and North America were joined by a huge subcontinent of ice-free, treeless grassland, 750 miles wide. Geologists have named this area Beringia, from the Bering Straits. Summers there were warm, winters were cold, dry and almost snow-free. This was a perfect environment for large mammals—mammoth and mastodon, bison, horse, reindeer, camel, and saiga (a goatlike antelope). Small bands of Stone Age hunter-gatherers were attracted by these animal populations, which provided them not only with food but with hides for clothing and shelter, dung for fuel, and bones for tools and weapons. Accompanied by a husky-like species of dog, hunting bands gradually moved as far east as the Yukon River basin of northern Canada, where field excavations have uncovered the fossilized jawbones of several dogs and bone tools estimated to be about 27,000 years old.
Other evidence suggests that the migration from Asia began about 30,000 years ago—around the same time that Japan and Scandinavia were being settled. This evidence is based on blood type. The vast majority of modern Native Americans have type O blood and a few have type A, but almost none have type B. Because modern Asian populations include all three blood types, however, the migrations must have begun before the evolution of type B, which geneticists believe occurred about 30,000 years ago.
By 25,000 years ago human communities were established in western Beringia, which is present-day Alaska. A But access to the south was blocked by a huge glacial sheet covering much of what is today Canada. How did the hunters get over those 2,000 miles of deep ice? The argument is that the climate began to warm with the passing of the Ice Age, and about 13,000 b.c.e. glacial melting created an ice-free corridor along the eastern front range of the Rocky Mountains. B Soon hunters of big game had reached the Great Plains.
In the past several years, however, new archaeological finds along the Pacific coast of North and South America have thrown this theory into question. C The most spectacular find, at Monte Verde in southern Chile, produced striking evidence of tool making, house building, rock painting, and human footprints conservatively dated long before the highway had been cleared of ice. D Many archaeologists now believe that migrants moved south in boats along a coastal route rather than overland. These people were probably gatherers and fishers rather than hunters of big game.
There were two later migrations into North America. About 5000 b.c.e. the Athapascan or Na-Dene people began to settle the forests in the northwestern area of the continent. Eventually Athapascan speakers, the ancestors of the Navajos and Apaches, migrated across the Great Plains to the Southwest.
The final migration began about 3000 B.C.E after Beringa had been sub merged, when a maritime hunting people crossed the Bering Straits in small boats. The Inuits (also known as the Eskimos) colonized the polar coasts of the Arctic, the Yupiks the coast of southwestern Alaska, and the Aleuts the Aleutian Islands.
While scientists debate the timing and mapping of these migrations, many Indian people hold to oral traditions that include a long journey from a distant place of origin to a new homeland.
Look at the four squares [ ■ ] that show where the following sentence could be inserted in the passage.
Newly excavated early human sites in Washington State, California, and Peru have been radiocarbon dated to be 11,000 to 12,000 years old.
Where could the sentence best be added?
Click on a square [■] to insert the sentence in the passage.
选项
A、
B、
C、
D、
答案
C
解析
Chronological order and place reference are transitional devices that connect the insert sentence with the previous sentence. The date, 13,000 b.c.e. in the previous paragraph is a date that precedes 11,000 to 12,000 years old in the insert sentence. In addition, Washington State, California, and Peru in the insert sentence refer to the Pacific coast of North and South America in the previous sentence.
转载请注明原文地址:https://kaotiyun.com/show/t3fO777K
0
托福(TOEFL)
相关试题推荐
Completetheflowchartbelow.WriteNOMORETHANTWOWORDSforeachanswer.ExpertiseincreativewritingB
Completetheflowchartbelow.WriteNOMORETHANTWOWORDSforeachanswer.ExpertiseincreativewritingB
Choosethecorrectletter,A,BorC.AdviceonwritingadissertationWhatmotivatedHowardtostartwritinghisdissertation?
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrom
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrompra
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrompra
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.CLIMATEANDARCHITECTURECasesandexamplesarefrompra
WriteONEWORDONLYforeachanswer.Sophiethinksshowingherpassionfor_______mighthelpduringherinterview.
CoursesforinternationalstudentsExampleWritinginfirsttermInsecondterm:【L1】________Throughouttheyear:【L2】_______
PatentsandInventionsWhenaninventionismade,theinventorhasthreepossiblecoursesofactionopentohim:first,hec
随机试题
Theoldcouplewould_________lovetoknowhowthingsaregoingonwiththeirgrandbaby.
A.血红蛋白45g/L,面色苍白伴水肿B.血红蛋白75g/L,黏膜苍白,乏力C.血红蛋白95g/L,乏力,易脱发D.血红蛋白105g/L,易疲倦,乏力E.血红蛋白115g/L,易疲倦妊娠合并轻度贫血的表现是
肠病性肢端皮炎的皮损好发于
绒毛膜促性腺激素(HCG)于妊娠期间分泌量达高峰的时间是
在道路路堤工程施工中,路堤所用填料应优先选用()。【2007年真题】
某公司承担一机电改建工程,工程量主要为新建4台5000m3原油罐及部分管线,更换2台重356t、高45m的反应器,反应器施工方法为分段吊装组焊。针对作业活动,项目部风险管理小组对风险进行了识别和评价,确定了火灾、触电、机械伤害、窒息或中毒、焊接、应急响应等
该省执行最低工资立法,而使有些企业不愿意继续雇佣生产率水平低于最低工资的那些工人,于是这些工人失业了,他们不得不去寻找更低工资的工作,这是最低工资立法对收入分配不平等程度产生的一种()。该省是就业弹性较低的地区,那么该地区()。
_______是指CPU一次可以处理的二进制数的位数,它直接关系到计算机的计算精度、速度等指标;运算速度是指计算机每秒能执行的指令条数,通常以_______为单位来描述。(6)
【26】【37】
ThecitizensofFranceareonceagaintakingapastingontheop-edpages.Theirfailingthistimeisnotthattheyarecheese-e
最新回复
(
0
)