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The primary purpose of the passage is to
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The author of the passage suggests that Mary McCarthy`s writing is characterized by
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Some archaeologists speculate that the Americas might have been initially colonized between 40,000 and 25,000 years ago. However, to support this theory it is necessary to explain the absence of generally accepted habitation sites for that time interval in what is now the United States. Australia, which has a smaller land area than the United States, has many such sites, supporting the generally accepted claim that the continent was colonized by humans at least 40,000 years ago. Australia is less densely populated (resulting in lower chances of discovering sites) and with its overall greater aridity would have presented conditions less favorable for hunter-gatherer occupation. Proportionally, at least as much land area has been lost from the coastal regions of Australia because of postglacial sea-level rise as in the United States, so any coastal archaeological record in Australia should have been depleted about as much as a coastal record in the United States. Since there are so many resource-rich rivers leading inland from the United States coastlines, it seems implausible that a growing population of humans would have confined itself to coasts for thousands of years. If inhabitants were present 25,000 years ago, the chances of their appearing in the archaeological record would seem to be greater than for Australia.
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The passage is primarily concerned with doing which of the following?
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The author of the passage implies which of the following about 25,000 years ago?
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The author of the passage implies that, in what is now the United States, archaeological evidence of inhabitation in the period from 40,000 to 25,000 years ago is lacking because that region is
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Animals live longer when their calorie intake is restricted to two-thirds of what is considered normal for their species. Animals so restricted are also generally healthier: most disease, including cancer, diabetes, and neurodegenerative illness, are forestalled. This phenomenon was long attributed to a simple slowing of metabolism (cells` production of energy from fuel molecules) and consequent reproduction of its toxic by-products in response to less food. In fact, however, calorie restriction does not slow mammalian metabolism, and in yeast and worms, metabolism is both sped up and altered. Some scientists now theorize that calorie restriction is a biological stressor that, like natural food scarcity, induces a more complex defensive response, which in mammals includes changes in cellular defenses and repair.
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In the passage, the function of the highlighted portion( in yeast and worms, metabolism is both sped up and altered) is to
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The passage implies which of the following about the explanation mentioned in the highlighted text(This phenomenon was long attributed to a simple slowing of metabolism)?
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An influential early view held that ecosystems contain niches for a limited number of species and that competition for resources among species—whether native or nonnative invading ones—determines ecosystems' species composition. However, factors other than competition often help explain invading species' success. For example, the American grey squirrel, often cited as a classic example of competitively superior invading species, was introduced in England in 1876 and now thrives, while the native red squirrel population has declined. Although scientists have found gray squirrels to be more efficient foragers than red ones, they also indicate that even before the gray squirrel's arrival, Britain's red squirrel populations had a periodic tendency to die out, only to be subsequently reintroduced. Furthermore, many gray squirrels are silent carriers of a disease fatal to red squirrels.
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It can be inferred that the author of the passage mentions the efficiency with which gray squirrels forage primarily in order to
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