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

"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.
Which of the following best summarizes the text?
选项 A、Lots of animals learn, but smarter isn’t better.
B、Humans pay hidden costs for learning.
C、Learning has dangerous side effects to animals.
D、Animals learn to adapt to changing environment.
答案A
解析 属主旨思想题。文章前一部分讲到学习这种行为在动物界非常普及，专家认为具有神经系统的生物都有学习能力，而后一部分讲到学习对动物来说具有危险的副作用，专家甚至开始思考人类的学习行为是否具有隐藏的风险。因此可判断选项A符合文章整体大意，故正确。选项B的内容只是专家们开始思考的内容，并非本文所讲的内容，故错误。选项C则是文章内容的一部分，不能概括全篇，故错误。选项D是与原文相反的观点，故错误。
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