Evolution and Wheels

In the past, evolutionary biologists contemplating the absence of wheels in

nature agreed that the explanation was      not undesirability: wheels would be

good for animals, just as they are for us. Animals were prevented from

evolving wheels, the biologists reasoned, by the following dilemma: living

cells in an animal's body are connected to the    heart by blood vessels, and

to the brain by nerves. Because a rotating joint is essential to a wheel, a

wheel made         of living cells would twist

its artery vein and nerve connections at the first revolution, making

living          impracticable. However, there is a flaw in the argument that the

evolution of wheeled animals was thwarted

by the insoluble joint    problem. The theory fails to explain why animals

have not evolved wheels of  dead  tissue  with  no  need  for  arteries   

and  nerves.  Countless  animals,  including  us,  bear external structures

without blood supply or nerves - for        example, our hair and fingernails, or

the scales, claws, and ho rns of other animals. Why have rats not evolved     

bony wheels, similar to roller skates?Paws  might be more useful than

wheels in some situations, but  cats' claws are retractable: why not

retractable wheels?We thus arrive at the serious biological paradox

flippantly termed the RRR     dilemma: nature's failure to produce rats with

retractable roller skates.

進(jìn)化與輪子 

從前，研究自然界沒(méi)有輪子的進(jìn)化論生物學(xué)家都同意不能用無(wú)此需要來(lái)解釋 這種現(xiàn)象：輪子對(duì)于動(dòng)物會(huì)像對(duì)于我們?nèi)祟愐粯佑泻锰帯?/p>

生物學(xué)家們推論，動(dòng)物沒(méi)有進(jìn)化 出輪子是由下述困難所致：動(dòng)物身上的活細(xì)胞通過(guò)血管與心臟相連，通過(guò)神經(jīng)與大腦相連。

因?yàn)橐粋�(gè)旋轉(zhuǎn)的接頭對(duì)輪子來(lái)說(shuō)是至關(guān)重要的，由活的細(xì)胞構(gòu)成的輪子在第一次轉(zhuǎn)動(dòng)時(shí)便會(huì) 扭傷其上的動(dòng)脈和神經(jīng)的連結(jié)，因而不現(xiàn)實(shí)。

不過(guò)，動(dòng)物未能進(jìn)化出輪子是受阻于無(wú)法解決接頭問(wèn)題的說(shuō)法有一個(gè)缺陷。  這種理論 無(wú)法解釋為何動(dòng)物沒(méi)有進(jìn)化出由死組織構(gòu)成的而無(wú)需動(dòng)脈和神經(jīng)的輪子。

包括人在內(nèi)的無(wú) 數(shù)動(dòng)物都有一些沒(méi)有血液供應(yīng)和神經(jīng)的體外構(gòu)造，例如，我們的頭發(fā)和指甲，或者鱗片、爪 子和其它一些動(dòng)物的角。

為什么老鼠沒(méi)有進(jìn)化出類似于滑輪溜冰鞋的骨質(zhì)的輪子呢?在某些 情況下，爪子可能比輪子更有用，但貓的爪子是可以伸縮的：  為什么不能有可以伸縮的輪

子呢?這樣，我們便得出了一個(gè)被戲稱為 RRR 的嚴(yán)肅的生物學(xué)悖論：大自然未能產(chǎn)生出有可 伸縮的滑輪溜冰鞋的老鼠。

譯路通武漢江漢區(qū)翻譯公司整理

2012.6.19