-
(单词翻译:双击或拖选)
睡眠革命
Evolution of sleep
Sleep is very ancient. In the electroencephalographicsense we share it with all the primates1 and almost allthe other mammals and birds: it may extend back asfar as the reptiles2.
There is some evidence that the two types of sleep,dreaming and dreamless, depend on the life-style ofthe animal, and that predators3 are statistically4 muchmore likely to dream than prey5, which are in turnmuch more likely to experience dreamless sleep. Indream sleep, the animal is powerfully immobilized and remarkably6 unresponsive to externalstimuli. Dreamless sleep is much shallower, and we have all witness target=_blank class=infotextkey>witnessed cats or dogs cocking theirears to a sound when apparently7 fast asleep. The fact that deep dream sleep is rare amongpray 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 sleepthan the smart ones. But why should they sleep deeply at all? Why should a state of such deepimmobilization ever have evolved?
Perhaps one useful hint about the original function of sleep is to be found in the fact thatdolphins and whales and aquatic8 mammals in genera seem to sleep very little. There is, by andlarge, no place to hide in the ocean. Could it be that, rather than increasing an animal’svulnerability, the University of Florida and Ray Meddis of London University have suggestedthis to be the case. It is conceivable that animals who are too stupid to be quite on their owninitiative are, during periods of high risk, immobilized by the implacable arm of sleep. Thepoint seems particularly clear for the young of predatory animals. This is an interesting notionand probably at least partly true.
点击收听单词发音
1 primates | |
primate的复数 | |
参考例句: |
|
|
2 reptiles | |
n.爬行动物,爬虫( reptile的名词复数 ) | |
参考例句: |
|
|
3 predators | |
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面) | |
参考例句: |
|
|
4 statistically | |
ad.根据统计数据来看,从统计学的观点来看 | |
参考例句: |
|
|
5 prey | |
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨 | |
参考例句: |
|
|
6 remarkably | |
ad.不同寻常地,相当地 | |
参考例句: |
|
|
7 apparently | |
adv.显然地;表面上,似乎 | |
参考例句: |
|
|
8 aquatic | |
adj.水生的,水栖的 | |
参考例句: |
|
|