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  3. Every summer, the peacocks that roam free within Whipsnade Wild Animal Park

Every summer, the peacocks that roam free within Whipsnade Wild Animal Park

游客2024-08-05  22
问题     Every summer, the peacocks that roam free within Whipsnade Wild Animal Park in Bedfordshire expose their magnificent trains to the critical and often disdainful gaze of the hens.

    Darwin argues that living creatures came to be the way they are by e-volution: and that the principal mechanism of evolution was natural selection. This is, in a crowded and hence competitive world, the individuals best suited to the circumstances—the "fittest"—are the most likely to survive and have offspring.
    But the implication is that fittest would generally mean toughest, swiftest, cleverest, most alert. The peacock’s tail, by contrast, was at best a waste of space and in practice a severe encumbrance: and Darwin felt obliged to invoke what he felt was a separate mechanism of evolution, which he called "sexual selection", the driving mechanism—in his words—"beauty for beauty’s sake".
    But Darwin’s friend and collaborator, Alfred Russel Wallace, though in many ways more "romantic" than Darwin, was in others even more Darwinian. According to Wallace, then, the train was not an end in itself, but an advertisement for some genuine contribution to survival.
    Now, 100 years later, the wrangle is still unresolved, for the natural behavior of peafowl is much harder to study than might be imagined. In practice, the mature cocks display in groups at a number of sites around Whipsnade, and the hens judge one against the other. Long observation from hides, backed up by photographs, suggests that the cocks with the most eyespots do indeed attract the most mates.
    But whether the males with the best trains are also " better" in other ways remains to be pinned down. Do the children of the attractive cocks grow faster? Are they more healthy? If so, then the females’ choice will be seen to be utilitarian after all, just as Wallace predicted.
    There is a final twist to this continuing story. The great mathematician and biologist R. A. Fisher in the thirties proposed what has become known as "Fisher’s Runaway". Just suppose, for example, that for whatever reason—perhaps for a sound "Wallacian" Reason—a female first picks a male with a slightly better tail than the rest. The sons of that mating will inherit their father’s tail, and the daughters will inherit their mother’s predilection for long tails. This is how the runaway begins. Within each generation, the males with the longest tails will get most mates and leave most offspring: and the females’ predilection for long tails will increase commensurately. Modern computer models show that such a feedback mechanism would alone be enough to produce a peacock’s tail. Oddly, too, this would vindicate Darwin’s apparently fanciful notion—once the process gets going, the females would indeed be selecting "beauty for beauty’s sake".
Question 61 to 65
Answer the following questions with the information given in the passage in a maximum of fifteen words for each question. [br] What does Darwin’s "beauty for beauty’s sake" about peacocks mean ?
选项
答案 Sexual selection is the driving mechanism of the evolution of peacocks’tail．
解析 (文章第三段首先指出最适合生存即意味着最坚强、最迅速、最聪明和最警觉，但是孔雀的尾屏往好了说是浪费空间，实际上是很大的累赘，因此达尔文提出了独立于“自然选择进化论”的进化机制，即sexual selection“雌雄淘汰”，用他的话来说就是“beauty forbeauty’s sake”。)
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