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  3. A period of climate change about 130,000 years ago would have made water travel easier by lowering sea levels and creating navig

A period of climate change about 130,000 years ago would have made water travel easier by lowering sea levels and creating navig

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问题     A period of climate change about 130,000 years ago would have made water travel easier by lowering sea levels and creating navigable lakes and rivers in the Arabian Peninsula, the study says. Such a shift would have offered early modern humans—which arose in Africa about 200,000 years ago—a new route through the formerly scorching northern deserts into the Middle East. The new paper was spurred by the discovery of several 120,000-year-old tools at a desert archaeological site in the United Arab Emirates. The presence of the tools—whose design is uniquely African, experts say—so early in the region suggests early humans marched out of Africa into the Arabian Peninsula directly from the Horn of Africa, roughly present-day Somalia Previously, scientists had thought humans first left via the Nile Valley or the Far East.
    "Up till now we thought of cultural developments leading to the opportunity of people to move out of Africa," said study co-author Hans-Peter Uerpmann, a retired archaeobiologist at the University of Tubingen in Germany. "Now we see, I think, that it was the environment that was the key to this," Uerpmann said during a press briefing Wednesday.
    The discovery "leaves a lot of possibilities for human migrations, and keeping this in mind, might change our view completely." During the past few years, a series of tools were discovered at the Jebel Faya site in the U.AE., some of which—such as hand axes—had a two-sided appearance previously seen only in early Africa.
    Scientists used luminescence dating to determine the age of sand grains buried with the stone tools. This technique measures naturally occurring radiation stored in the sand. For the climatic data, scientists studied the climate records of ancient lakes and rivers in cave stalagmites, as well as changes in the level of the Red Sea. This warmer period 130,000 years or so ago caused more rainfall on the Arabian Peninsula, turning it into a series of lush rivers that humans might have boated or rafted.
    During this period the southern Red Sea’s levels dropped, offering a "brief window of time" for humans to easily cross the sea—which was then as little as 2.5 miles wide, according to Adrian Parker, a physical geographer from Oxford Brookes University in the United Kingdom.
    Once humans entered the peninsula, they dispersed and likely reached the Jebel Faya site by about 125,000 years ago, according to the study, published in the journal Science.
    Geneticist Spencer Wells called the discovery a "very interesting find," especially because the Arabian Peninsula is becoming a hot spot for archaeological finds—particularly underwater, since the Persian Gulf was a fertile river delta during early human migrations. But he noted that the study doesn’t "rewrite the book on what we know about human migratory history." That’s because tools dating to the same period have already been found in Israel, so it’s "consistent with what we suspected" about an earlier wave of migration into the Middle East, said Wells, director of the National Geographic Society’s Genographic Project. Wells also noted there’s no evidence yet that the migrants in the new paper were our ancestors—the group, and their genes, may have died out long ago.
    Bence Viola, of the Max-Planck-Institute for Evolutionary Anthropology in Leipzig, Germany, agreed the finding was interesting but not that surprising, also citing the evidence of humans in Israel about 120,000 years ago. Viola, who wasn’t involved in the study, added that the migration route proposed in the paper makes sense on another level—the Arabian Peninsula would have been something early humans were used to. "If you look even today, the environment in the Horn of Africa, in Somalia or northern Ethiopia, is similar to what you see in Oman or Yemen—not like the big desert," Viola noted. "It’s not like they needed to adapt to a completely different environment—it’s an environment that they knew."
    Why they made the trek is another question, since they wouldn’t have been hurting for food or resources in their African homeland, Viola noted. "Curiosity," he said, "is a pretty human desire."
The phrase "offering a ’brief window of time’ for humans to easily cross the sea"(5th paragraph) is closest in meaning to
选项 A、providing a panoramic view of the sea and an easier way to cross it.
B、Only a small window zone of the sea as little as 2.5 miles wide could be crossed.
C、The descending supplied a temporary opportunity to cross the sea easily.
D、The sea was as narrow as a window so that people could cross it without effort.
答案C
解析 根据第5段第1句话可知，由于红海南部的水平面下降，而且海面不宽，这就为人类轻易穿过海峡提供了一个“短暂的时机”。所以正确答案为C。
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