中国精品色片,嫩草影院日韩无码,美女裸身免费91

当前位置: 网校排名> 新东方在线> 托福IBT必背经典文章:睡眠的进化
新东方在线 托福(Toefl)培训

托福好课

  • 精品课程
  • 公开讲座
  • 真题练习
  • 备考指导
  • 答疑解惑

【托福VIP小班】8-10人直播班

新东方实力师资精讲;全新托福教研升级;官方授权TPO;一站式学习

录播:128

赠录播课

25800

  • 李冰洁
  • 张仪
  • 吴奇
  • 徐欣

【知心托福】60-80分录播课

新东方实力师资录播精讲;循环直播互动课堂;电子版全科讲义;口语写作批改

课时:278

推荐:★★★★★

8879

  • 张仪
  • 费扬
  • 吴奇
  • 徐欣

【知心托福】76-95分录播课

备考冲分不走弯路;精华干货;优质课程服务;学习事半功倍

课时:278

推荐:★★★★★

7880

  • 张仪
  • 吴奇
  • 葛姝含
  • 李盛

托福(Toefl)

发布时间: 2016年04月21日

托福IBT必背经典文章:睡眠的进化

托福网课试听

托福IBT必背经典文章:睡眠的进化

【新东方托福IBT必背50篇经典文章:睡眠的进化这份资料可以帮助考生在托福网考备考过程中,提高托福口语水平,同时对提高托福写作水平和托福阅读都有很大帮助。托福IBT必背50篇经典文章,助你托福考试成功!

新东方托福IBT必背50篇经典文章:睡眠的进化

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 pray 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 genera 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 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 quite 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.

编辑推荐》

新东方托福培训

托福培训冲刺班

托福辅导视频



备考资料历年真题
×