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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 lifestyle 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. |
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shuì mián shì gǔ lǎo de. cóng nǎo diàn tú shàng kàn, wǒ men rén lèi hé suǒ yǒu líng zhǎng mù dòng wù yǐ jí jī hū suǒ yǒu de bǔ rǔ dòng wù hé niǎo lèi dōu yí yàng xū yào shuì mián shèn zhì pá xíng lèi dòng wù yě yǒu shuì mián. yǒu zhèng jù xiǎn shì, yǒu mèng shuì mián hé wú mèng shuì mián zhè liǎng zhǒng lèi xíng de shuì mián qǔ jué yú gāi dòng wù de shēng huó fāng shì. cóng tǒng jì shàng kàn, shí ròu dòng wù bǐ bèi bǔ shí dòng wù yǒu gèng duō de yǒu mèng shuì mián, ér bèi bǔ shí dòng wù gèng duō dì wú mèng shuì mián. dòng wù zài yǒu mèng shuì mián shí, bèi yǒu xiào dì jiě chú dòng zuò néng lì, bìng qiě duì wài jiè cì jī quē fá fǎn yìng. wú mèng shuì mián zé yào qiǎn dé duō. wǒ men dōu kàn dào guò māo hé gǒu zài xiǎn rán de hān shuì zhōng, yǒu yì diǎn xiǎng dòng ěr duǒ jiù huì shù qǐ lái. bèi bǔ shí dòng wù hěn shǎo yǒu shēn dù de yǒu mèng shuì mián, zhè kàn lái xiǎn rán shì zì rán xuǎn zé de jié guǒ. ér qiě zhè yì diǎn shì yǒu dào li de: dāng shuì mián gāo dù jìn huà yǐ hòu, yú bèn de dòng wù bǐ cōng míng de dòng wù gèng shǎo zài shēn dù shuì mián zhuàng tài xià sàng shī dòng zuò néng lì. dàn shì dòng wù wèi shí me yào jìn rù shēn dù shuì mián ne? wèi shí me zhè yàng de wú dòng zuò zhuàng tài yě huì jìn huà chū lái ne? hǎi tún jīng yú yǐ jí shuǐ shēng bǔ rǔ dòng wù shuì mián dōu jí shǎo, zhè yī shì shí kě yǐ gěi shuì mián de gēn běn gōng néng tí gōng yǒu yòng de xiàn suǒ. hǎi yáng zhōng shì méi yǒu cáng shēn zhī chù de. huì bú huì shì zhè yàng, shuì mián bù dàn bù zēng jiā dòng wù shòu shāng hài de kě néng xìng, fǎn ér shì jiǎn shǎo le zhè zhǒng kě néng xìng ne? fó luó lǐ dá dà xué de Wilse Webb hé lún dūn dà xué de Ray Meddis rèn wéi qíng kuàng jiù shì rú cǐ. kě yǐ xiǎng xiàng dé chū, zài wēi xiǎn de shí kè, nèi xiē yóu yú tài yú bèn ér bù néng zì dòng bǎo chí ān jìng de dòng wù, huì bù yóu zì zhǔ dì biàn de dòng tan bù dé. zhè yì diǎn zài shí ròu dòng wù de yòu shòu shēn shàng biǎo xiàn dé tè bié míng xiǎn. zhè shì yí gè hěn yǒu yì sī de kàn fǎ, tā zhì shǎo bù fèn shì zhèng què de. |