阑尾并非可有可无
两年前，来自杜克大学医学中心(Duke University Medical Center)的研究人员说，以前被认为没有作用的阑尾实际上有用，因为在肠内环境不好的时分，体内好的肠菌正是躲藏在那里。
目前该研究小组从进化论历史的角度来研究阑尾。他们发现动物有阑尾的工夫超过了8千万年。阑尾至少有两次独立地进化过，一次是在澳大利亚的有袋类动物身上，这令人感到有些希奇。另外一次是在通常的古老哺乳类动物身上，而我们人类就属于哺乳类动物。
达尔文认为，仅仅只有少部分动物具有阑尾，他还认为人的阑尾是盲肠进化过程中残留下来的部分。但是，这项新的研究发现，70%的啮齿动物和灵长目动物的物种具有阑尾。有些活着的动物既有盲肠又有阑尾。研究者们说，如果达尔文明白有这样的物种的话，他或许会改变他对阑尾的观点。
具有讽刺意味的是，正是自然选择使得人类的阑尾没有完全消失掉。因为阑尾越小，它越轻易被感染。这样就可以把人类的基因保持下来。
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.
