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2.1.6. 鸟类声音系统的进化(2010-8-12, updated 2010-8-13)
文章结构和内容
P1 开始讲三种鸟是已知鸟类中仅有的三种后天学习发声而不是基因里就会发声的。(vocalization learning instead of genetically programmed)而其他学习发声的都是哺乳动物,如人,蝙蝠等等。然后详细说这三种鸟学习唱歌(sing)就和小孩子学说话一样的,生下来后逐渐和父母学习才会唱歌,所以如果主人变了,它会纠正之前"wrong"的发音;如果把这三种鸟的幼鸟交给别的鸟养大,他们发声就会很奇怪(odd);如果把他们单独开养(isolate),就哑巴了。
P2 EJ是个这方面的研究者,他发现这三种鸟在发声时,脑中七个部分的活动是非常相似的,而这是很奇怪的,因为这三种鸟的生物种属离得很远。所以有两个假说:一是他们有共同的祖先。“但是这不太可能,因为这意味着……存在大批的灭绝”(记不清了,反正引号内高亮,意思很晦涩)(有题说前面高亮推断出什么,我想的是假设这个祖先的后代都是学习发声,那么现在应该有很多学习发声的鸟,为什么只有三种,因为其他的都灭绝了,而这是不太可能的)那么只剩下一种假说,就是凡是学习发声的脑部活动都一样,就像鸟与蝙蝠明明相距甚远,却发展出如此相近的翅膀。
P3. 有谈到关于人类发声时,脑部七个部位的活动和上文三种鸟也一致。这就更加说明第二个假说才是对的,但是所有Vertebrate动物可能继承同一祖先的什么大脑功能系统之类的。最后一句谈到学习发声也是movement learning,结果有一道细节题就考这最后两个单词。
原文
Cardinals, along with other songbirds, are among the few kinds of animals that learn the vocalizations they make. Among the others, two groups are also birds—hummingbirds and parrots—and the rest are mammals: bats, cetaceans, elephants and humans. All other creatures, from dogs and tigers to swans, owls and pigeons, produce sounds that, according to current research, are programmed by the species’ genes. According to Jarvis and other scientists, baby songbirds learn to sing much like human infants learn to speak. Both begin by listening to their parents or other adults and memorizing the sounds. The next step is to mimic the mentors, slowly perfecting their “language” over time through practice. A young songbird raised by a different species of adult, or with recordings of a different species, will end up learning the “wrong” song—and will produce only an odd, improvised tune if it is raised in isolation. A vocal nonlearner such as a phoebe or a dove, on the other hand, will sing its species’ correct song even if it’s brought up by another kind of bird, or by none at all.
A few years ago, Jarvis and his colleagues made the surprising discovery that when a songbird, parrot or hummingbird is producing its learned vocalization, a set of seven similar structures in the birds’ brains become active. The finding was unexpected because the three avian groups are only distantly related to one another. At the same time, they are closely related to other birds that are not vocal learners. Flycatchers, for example, belong to the same order as songbirds—Passeriformes—yet no flycatcher species tested so far displays the trait. One possible explanation, says Jarvis, is that the three groups of vocal learning birds had a common ancestor that possessed the skill. “But this means there would have been multiple losses of the ability over time, a sort of mass extinction of vocal learning,” he says. Another hypothesis is that vocal learners evolved similar brain structures independently over the last 65 million years, much the same way that birds and bats separately evolved wings that turned out to be so much alike.
Discoveries about the human brain support this latter hypothesis. Scientists conducting imaging studies have found that when people speak, parts of their brains’ cerebrums that are similar to those of vocalizing songbirds, parrots and hummingbirds become active. They’ve also found that the same neural pathways are damaged in people who have lost the ability to speak due to injury or stroke. Jarvis now believes that vocal learning most likely developed independently in humans and the three bird groups (as well as in other learners whose brains have not been studied)—yet it arose from a preexisting brain system, probably shared by all vertebrates, that controls learning to move.
题目
Q1作者对这个实验的结果感到unexpected是因为什么?
我选的哺乳动物和鸟类很少有共同的啥啥啥
Q2 ……所以有两个假说:一是他们有共同的祖先。“但是这不太可能,因为这意味着……存在大批的灭绝” 问高亮部分表明实验者认为什么/前面高亮推断出什么?
选E,不太可能有XXX。。我想的是假设这个祖先的后代都是学习发声,那么现在应该有很多学习发声的鸟,为什么只有三种,因为其他的都灭绝了,而这是不太可能的
Q3这些动物虽然有similar brain structure, 但是都是单独进化的;就像“蝙蝠啊,鸟啊,单独进化完,翅膀都差不多”一样 问高亮部分有什么作用?
to illustrate the brain structure … ; analogy to ...vocal...... 两个里面有一个是对的
Q4最后一句谈到学习发声也是movement learning,结果有一道细节题就考这最后两个单词。
Q5 问最后一段在文中的作用是什么,也就是问相关的更多研究的结论跟上面的学术论述有什么作用。
Q6 which one is J(是个人名)questioned?
我选的是鸟类和baby学习发声什么一致,因为文章最后一段有讲到finally J believed鸟类和baby学习发声什么是一致的,不确定对不对 |
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