"Why are humans so smart?" is a question that fascinates scientists. Tadeusz Kawecki, an evolutionary biologist at the Universit

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问题     "Why are humans so smart?" is a question that fascinates scientists. Tadeusz Kawecki, an evolutionary biologist at the University of Fribourg, likes to turn around the question. "If it’s so great to be smart," Dr. Kawecki asks, "why have most animals remained dumb?"
    Dr. Kawecki and like-minded scientists are trying to figure out why animals learn and why some have evolved to be better at learning than others. One reason for the difference, their research finds, is that being smart can be bad for an animal’s health. Learning is remarkably widespread in the animal kingdom. The worms are not born with an innate aversion to the dangerous bacteria. They need time to learn to tell the difference and avoid becoming sick.
    Dr. Dukas hypothesizes that any animal with a nervous system can learn. Even in cases where scientists have failed to document learning in a species, he thinks they should not be too quick to rule it out. "Is it because I’m not a good teacher or because the animal doesn’t learn?" Dr. Dukas asked.
    Although learning may be widespread among animals, Dr. Dukas wonders why they bothered to evolve it in the first place. "You cannot just say that learning is an adaptation to a changing environment," he said. It is possible to adapt to a changing environment without using a nervous system to learn. Bacteria can alter behavior to help their survival. If a microbe senses a toxin, it can swim away. If it senses a new food, it can switch genes on and off to alter its metabolism.
    Learning also turns out to have dangerous side effects that make its evolution even more puzzling. Dr. Kawecki and his colleagues have produced striking evidence for these side effects by studying flies as they evolve into better learners in the lab.
    Dr. Kawecki suspects that each species evolves until it reaches an equilibrium between the costs and benefits of learning. His experiments demonstrate that flies have the genetic potential to become significantly smarter in the wild. But only under his lab conditions does evolution actually move in that direction. In nature, any improvement in learning would cost too much.
    Dr. Kawecki also says it is worth investigating whether humans also pay hidden costs for extreme learning. "We could speculate that some diseases are a byproduct of intelligence," he said. The benefits of learning must have been enormous for evolution to have overcome those costs, Dr. Kawecki argues.
By mentioning microbe, the author intends to______.

选项 A、advocate that animals with a nervous system can all learn
B、argue that learning is an adaptation to a changing environment
C、claim that learning has some kind of side effects
D、prove that the adaptation may not include learning with a nervous system

答案D

解析 属信息推断题。“microbe”出现在第四段第五句。第四段第三句中说到,动物是可以不用神经系统去学习就可以适应环境的,故选项D符合题意。选项A犯了答非所问的错误,尽管此观点在第三段中提到,但不是作者提到“microbe”的意图,故错误。选项B犯了曲解文意的错误,第四段第二句中提到,不能简单地认为学习就是适应不断改变的环境,故错误。选项C犯了答非所问的错误,学习的副作用出现在第五段,与题目无关,故错误。
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