達(dá)爾文不知道：闌尾并非可有可無(wú)

發(fā)布日期：2009-11-07

核心提示：A study in the Journal of Evolutionary Biology finds that many more animals have appendixes than was thought, and that the appendix is not merely a remnant of a digestive organ called the cecum. All of which means that the appendix might not be so u

A study in the Journal of Evolutionary Biology finds that many more animals have appendixes than was thought, and that the appendix is not merely a remnant of a digestive organ called the cecum. All of which means that the appendix might not be so useless.

發(fā)表在《進(jìn)化生物學(xué)雜志》（Journal of Evolutionary Biology ）上的一項(xiàng)研究發(fā)現(xiàn)，和我們?cè)瓉?lái)認(rèn)為的不一樣，更多動(dòng)物具有闌尾。該研究認(rèn)為闌尾不僅僅是消化器官盲腸進(jìn)化后的殘留部分。所有這些研究結(jié)果意味著闌尾可能有用。

That's No Vestigial Organ, That's My Appendix

Two years ago, Duke University Medical Center researchers said that the supposedly useless appendix is actually where good gut bacteria safely hide out during some unpleasant intestinal conditions.

Now the research team has looked at the appendix over evolutionary history. They found that animals have had appendixes for about 80 million years. And the organ has evolved separately at least twice, once among the weird Australian marsupials and another time in the regular old mammal lineage that we belong to.

Darwin thought that only a few animals have an appendix and that the human version was what was left of a digestive organ called the cecum. But the new study found that 70 percent of rodent and primate groups have species with an appendix. And some living animals have a cecum and an appendix. If Darwin had known about species that had both organs, he probably would have revised his views of the appendix, the researchers note.

Ironically, it's natural selection that keeps the human appendix from shrinking away completely. Because smaller ones are more likely to become infected. And keep your genes out of the pool.

闌尾并非可有可無(wú)

兩年前，來(lái)自杜克大學(xué)醫(yī)學(xué)中心（Duke University Medical Center）的研究人員說(shuō)，以前被認(rèn)為沒(méi)有作用的闌尾實(shí)際上有用，因?yàn)樵谀c內(nèi)環(huán)境不好的時(shí)候，體內(nèi)好的腸菌正是躲藏在那里。

目前該研究小組從進(jìn)化論歷史的角度來(lái)研究闌尾。他們發(fā)現(xiàn)動(dòng)物有闌尾的時(shí)間超過(guò)了8千萬(wàn)年。闌尾至少有兩次獨(dú)立地進(jìn)化過(guò)，一次是在澳大利亞的有袋類動(dòng)物身上，這令人感到有些奇怪。另外一次是在通常的古老哺乳類動(dòng)物身上，而我們?nèi)祟惥蛯儆诓溉轭悇?dòng)物。

達(dá)爾文認(rèn)為，僅僅只有少部分動(dòng)物具有闌尾，他還認(rèn)為人的闌尾是盲腸進(jìn)化過(guò)程中殘留下來(lái)的部分。但是，這項(xiàng)新的研究發(fā)現(xiàn)，70%的嚙齒動(dòng)物和靈長(zhǎng)目動(dòng)物的物種具有闌尾。有些活著的動(dòng)物既有盲腸又有闌尾。研究者們說(shuō)，如果達(dá)爾文知道有這樣的物種的話，他或許會(huì)改變他對(duì)闌尾的觀點(diǎn)。

具有諷刺意味的是，正是自然選擇使得人類的闌尾沒(méi)有完全消失掉。因?yàn)殛@尾越小，它越容易被感染。這樣就可以把人類的基因保持下來(lái)。

Vocabulary:

Evolutionary:進(jìn)化論的

Appendix:闌尾；（書(shū)、文件的）附錄

Remnant:剩余部分；殘余部分

Digestive:消化的

Organ:器官

Cecum:盲腸

Useless:無(wú)用的

Vestigial:殘余的；退化的；殘留的

Supposedly:據(jù)信；據(jù)傳；據(jù)說(shuō)

Gut:消化道；腸道