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  3. Half a century before Charles Darwin published On the Origin of Species, the French naturalist Jean-Baptiste Lamarck outlined hi

Half a century before Charles Darwin published On the Origin of Species, the French naturalist Jean-Baptiste Lamarck outlined hi

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问题     Half a century before Charles Darwin published On the Origin of Species, the French naturalist Jean-Baptiste Lamarck outlined his own theory of evolution. A basis of this was the idea that characteristics acquired during an individual’s lifetime can be passed on to their offspring. In its day, Lamarck’s theory was generally ignored or lampooned.
    Now all that is changing. No one is arguing that Lamarck got everything right, but over the past decade it has become increasingly clear that environmental factors, such as diet or stress, can have biological consequences that are transmitted to offspring without a single change to gene sequences taking place. In fact, some biologists are already starting to consider this process as routine. However, fully accepting the idea, provocatively dubbed the "new Lamarckism", would mean a radical rewrite of modern evolutionary theory.
    That’s not all. The implications for public health could also be immense. Some researchers are talking about a paradigm shift in understanding the causes of disease. For example, non-genetic inheritance might help explain the current obesity epidemic, or why there are family patterns for certain cancers and other disorders, but no discernible genetic cause.
    Lamarck’s ideas about exactly how non-genetic inheritance might work were ambiguous at best. He wrote, for example, of the giraffe’s neck becoming elongated over generations because of the animal’s habit of stretching up to feed on leaves in high treetops. The recent research, by contrast, has a firm basis in biological mechanisms—in so-called "epigenetic" change.
    Their studies strongly suggest that a pregnant woman’s diet can affect her child’s epigenetic marks. So perhaps it is not surprising that the effect of certain nutrients is being called into question. And diet is not the only environmental factor that can influence the epigenetic setting of some genes. Michael Meaney at McGill University in Montreal, Canada, and colleagues have found that newborn mice neglected by their mothers are more fearful in adulthood—and that these mice show much higher than normal levels of methylation of certain genes involved in the stress response. In humans, too, there are troubling hints that damaging experiences early in life, while the brain is still developing, can affect epigenetic settings, perhaps with catastrophic consequences.
    In theory, epigenetic marks are wiped clear between generations in mammals. Intriguingly, though, the abnormalities in DNA methylation in scientists’ subjects were not restricted to their frontal cortex: they were also present in their sperm.
The underlined word in Paragraph 4 refers to______.
选项 A、lucid
B、vague
C、reasonable
D、persuasive
答案B
解析 属词义推断题。单词所在句式对L的理论进行了评价，接下来的一句是对这一评价的举例，而通过第四段第三句的一个by contrast可以知道，此句中讲到的内容应该与上文的评价相反。此句中讲到现在的研究有强有力的支撑，因此对L的理论的评价应该为负面的，因此选项B(模糊的)符合题意。其他选项均为正面评价，故不符合题意。
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考研英语一

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