IV. 閱讀測驗: (5%)
A widely held theory today is that the ancestors of today’s Native American peoples traveled
to the Western Hemisphere from Asia between 25,000 and 30,000 years ago, which was around
the same time that Japan was being settled by Stone Age inhabitants. There is dental evidence and
blood-type evidence to support this theory. A dental pattern that is found among most ancient
human fossils in the Americas is consistent with the dental pattern of ancient human fossils in
northeastern Asia. In blood type, the fact that blood type B is almost nonexistent among Native
American populations but exists in Asian populations leads to the conclusion that migrations to the
Americas from Asia took place before the evolution of blood type B, which is believed to have
occurred around 30,000 years ago. In addition to the dental and blood-type evidence, more
general evolutionary evidence suggests that it took more than 20,000 years for the variety of
physical traits common to Native American populations to evolve, and linguists broadly concur
that the development of the approximately 500 distinct languages of the Native American would
require approximately 25,000 years.
The proposed migration from Asia to the Americans took place during the Ice Age that
characterized the Pleistocene epoch. During that period of time, there were huge glaciers holding
enormous volumes of water, and, because of the huge glaciers, sea levels were as much as 100
meters lower than they are today. The reduced sea levels meant that Asia and North America were
linked with a 750-mile-wide landmass, named Beringia after the Bering Straits that now cover it,
and consisted of treeless grassland with warm summers and cold dry winters. Because of the
geographical features of Beringia during the Pleistocene epoch, it was an environment well-suited
to the large mammals of the time, such as mammoth, mastodon, bison, horse, and reindeer, as
well as to the Stone Age hunters who depended on these animals for their existence. The Stone
Age inhabitants of the area used these animals not only for food but also for shelter, clothing, and
weapons; they were able to spread out and expand their hunting areas as their populations grew,
and their populations most likely grew at a very high rate because of the huge amount of territory
available for expansion.
In spite of the evidence, not all anthropologists are convinced that the migrations from Asia to
the Americas took place as early as 25,000 to 30,000 years ago. There is general agreement that
the migrations took place, but some believe that the migrations took place much later. No
fossilized human bones have been found in what used to be Beringia; finding human bones dating
from 25,000 to 30,000 years ago would be strong proof of the dates when the migration took place.
However, because what was once Beringia is submerged beneath ocean waters, it may be a
formidable task to uncover fossil evidence of migration from Asia to the Americas through
Beringia.
【題組】47.Which of the following statements is NOT provided as evidence to support the hypothesis that
the migration discussed in the passage occurred 25,000 and 30,000 years ago?
(A) The dental patterns of the human fossils found in the Americas and Asia are common.
(B) It took the Native Americas roughly 25,000 years to decide on the universal language.
(C) There are variations in blood types between Asians and Native Americans.
(D) The variety of the physical features of Native Americans requires time to develop.
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