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  3. Humans are unique among primates for our near-total bodily hairlessness. In fact, only a handful of the 5,000 or so mammals—most

Humans are unique among primates for our near-total bodily hairlessness. In fact, only a handful of the 5,000 or so mammals—most

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问题     Humans are unique among primates for our near-total bodily hairlessness. In fact, only a handful of the 5,000 or so mammals—mostly semi-aquatic species such as whales, walruses, and hippopotamuses—are not covered in dense fur.
    Now, a controversial new theory suggests that human hairlessness evolved as a strategy to shed lice, fleas, and other parasites that nestle deep in fur. The scientists propose that pressure imposed by parasites, in combination with man’s unique intelligence, allowed humans to shed fur along with its resident fleas, and lice. Though parasites also infect clothing, clothes can more easily be cleaned, or changed, to remove the problem.
    The new theory might also explain the trait in the only other virtually hairless terrestrial mammal, says the study. Buck-toothed, pink, naked mole rats live in underground colonies. This not only means that the chance of parasite transmission is very high, but also means that the temperature remains relatively constant. This sheltered environment may have also allowed them to lose their fur.
    "One of the most unusual things about humans is that we don’t have fur," said study co-author Mark Pagel, evolutionary biologist at Reading University in England. Though humans are not literally hairless, much of our hair has become so small and fine as to render it virtually invisible.
    The new theory may also explain the difference in hairiness between men and women. If having less hair leads to a reduction in parasites, then it would offer a big advantage in the race of life and might become a sexually attractive feature, said Pagel. Hair might have been retained on the head, and on the face in men, as a feature of sexual display, he said, like peacocks’ tails or stags’ antlers.
    Though the researchers have not yet produced data to back up their idea, they suggest it can be tested. Research should focus on comparing amount of body hair in people living in regions of the world with low and high levels of external parasites, said Pagel, and confirming existing anecdotal evidence that parasite loads are higher on hairy parts of the body.
According to the text, most hairless mammals______.
选项 A、are walruses
B、are semi-aquatic
C、are covered in dense fur
D、have but a handful of fur
答案B
解析 属事实细节题。第一段告诉我们，没有体毛的哺乳动物中大部分是半水栖动物。
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