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  3. You do not usually get something for nothing. Now, a new study reveals that the evolution of an improved learning ability could

You do not usually get something for nothing. Now, a new study reveals that the evolution of an improved learning ability could

admin2018-05-18  61
问题    You do not usually get something for nothing. Now, a new study reveals that the evolution of an improved learning ability could come at a particularly high price: an earlier death.
   Past experiments have demonstrated that it is relatively easy through selective breeding to make rats, honey bees and—that great favourite of researchers—fruit flies a lot better at learning. Animals that are better learners should be competitive and, thus, over time, come to dominate a population by natural selection. But improved learning ability does not get selected amongst these animals in the wild. No one really understands why.
   Tadeusz Kawecki and his colleagues at the University of Fribourg in Switzerland have measured the effects of improved learning on the lives of fruit flies. The flies were given two different fruits as egg-laying sites. One of these was laced with a bitter additive that could be detected only on contact. The flies were then given the same fruit but without an additive. Flies that avoided the fruit which had been bitter were deemed to have learned from their experience. Their children were reared and the experiment was run again.
   After repeating the experiment for 30 generations, the children of the learned flies were compared with normal flies. The researchers report in a forthcoming edition of Evolution that although learning a-bility could be bred into a population of fruit flies, it shortened their lives by 15%. When the researchers compared their learned flies to colonies selectively bred to live long lives, they found even greater differences. Whereas learned flies had reduced their life spans, the long-lived flies learned less well than even average flies.
   The authors suggest that evolving an improved learning ability may require a greater investment in the nervous system which takes resources away from processes that delay ageing. However, Dr. Kawecki thinks the effect could also be a by-product of greater brain activity increasing the production of Reactive Oxygen Species(ROS), which can increase oxidation in the body and damage health.
   No one knows whether the phenomenon holds true for other animals. So, biologists, at least, still have a lot to learn.
According to Dr. Kawecki, greater brain activity_________.
选项 A、reduces oxygen consumption
B、regulates the nervous system
C、speeds up the ageing process
D、stabilizes the ageing process
答案C
解析 推断题。根据题干中的关键词Dr．Kawecki和greater brain activity可定位至文章第五段最后一句“However，Dr．Kawecki thinks the effect could also be a by-product of greater brain activity increasing the production of Reactive Oxygen Species(ROS)，which can increase oxidation in the body and damage health．”可知，Dr．Kawecki认为这种影响也可能是大脑活动产生活性氧的副作用，活性氧会增强身体的氧化并损害健康。由此可以推断，大量的脑力活动会加速衰老，故C选项符合题意，为正确答案。
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