手机APP下载

您现在的位置: 首页 > 英语听力 > 英语美文欣赏 > 跟可可背精美短文 > 正文

跟可可背精美短文 第21篇:Evolution of Sleep睡眠的进化

来源:可可英语 编辑:alex   可可英语APP下载 |  可可官方微信:ikekenet
  下载MP3到电脑  [F8键暂停/播放]   批量下载MP3到手机
加载中..

Evolution of Sleep

Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles.

There is some evidence that the two types of sleep, dreaming and dreamless, depend on the life-style of the animal, and that predators are statistically much more likely to dream than prey, which are in turn much more likely to experience dreamless sleep. In dream sleep, the animal is powerfully immobilized and remarkably unresponsive to external stimuli. Dreamless sleep is much shallower, and we have all witnessed cats or dogs cocking their ears to a sound when apparently fast asleep. The fact that deep dream sleep is rare among prey today seems clearly to be a product of natural selection, and it makes sense that today, when sleep is highly evolved, the stupid animals are less frequently immobilized by deep sleep than the smart ones. But why should they sleep deeply at all? Why should a state of such deep immobilization ever have evolved? Perhaps one useful hint about the original function of sleep is to be found in the fact that dolphins and whales and aquatic mammals in general seem to sleep very little. There is, by and large, no place to hide in the ocean. Could it be that, rather than increasing an animal's vulnerability, the function of sleep is to decrease it? Wilse Webb of the University of Florida and Ray Meddis of London University have suggested this to be the case. It is conceivable that animals who are too stupid to be quiet on their own initiative are, during periods of high risk, immobilized by the implacable arm of sleep. The point seems particularly clear for the young of predatory animals. This is an interesting notion and probably at least partly true.

重点单词   查看全部解释    
evidence ['evidəns]

想一想再看

n. 根据,证据
v. 证实,证明

联想记忆
evolution [.i:və'lu:ʃən]

想一想再看

n. 进化,发展,演变

联想记忆
implacable [im'plækəbl]

想一想再看

adj. 难宽恕的,难和解的,执拗的

联想记忆
vulnerability [.vʌlnərə'biliti]

想一想再看

n. 易受攻击,弱点,[计]漏洞

 
original [ə'ridʒənl]

想一想再看

adj. 最初的,原始的,有独创性的,原版的

联想记忆
function ['fʌŋkʃən]

想一想再看

n. 功能,函数,职务,重大聚会
vi. 运行

 
prey [prei]

想一想再看

n. 被掠食者,牺牲者
vi. 捕食,掠夺,使

 
conceivable [kən'si:vəbl]

想一想再看

adj. 想得到的,可想像的,可能的

联想记忆
smart [smɑ:t]

想一想再看

adj. 聪明的,时髦的,漂亮的,敏捷的,轻快的,整洁的

 
initiative [i'niʃətiv]

想一想再看

adj. 创始的,初步的,自发的
n. 第一步

联想记忆

发布评论我来说2句

    最新文章

    可可英语官方微信(微信号:ikekenet)

    每天向大家推送短小精悍的英语学习资料.

    添加方式1.扫描上方可可官方微信二维码。
    添加方式2.搜索微信号ikekenet添加即可。