No not a book appendix, silly. The one in your belly. It's been dissed all these years—everyone says it's superfluous, has no function, tits on a boar, that kinda thing—but it's actually useful, it turns out. And not just the way Alfred Sherwood Romer and Thomas S. Parsons suggest in The Vertebrate Body (1986), p. 389: "Its major importance would appear to be financial support of the surgical profession.”
Docs at Duke University Medical School published a report this week that say it produces and protects good germs for your gut.
But it can kill ya. In fact, over 300,000 were hospitalized in the U.S. with appendicitis in 2005, and about 300 to 400 Americans die of appendicitis each year.
Remember, there are more bacteria cells than human cells in your body—10 to 1, actually. (Ewww.) But what happens if the bacteria in your intestines die or are, to use a delicate word, purged? Diseases such as cholera or amoebic dysentery clear your guts of useful bacteria (oh yeah, been there done that, from both ends). The appendix's job is to reboot your digestive system. Kinda like rebooting your computer from one of those keychain memory sticks.
Your appendix, it turns out, is a safe cul-de-sac for bacteria, located just below the normal one-way flow of food and germs in the large intestine. Today, if your gut bacteria die, it can usually be repopulated easily with germs they pick up from other people. (Wash your hands!) But before modern-day dense populations, and during regional cholera epidemics, it wasn't as easy to cultivate another batch of bacteria, so the appendix came in handy.
Interestingly, in less developed countries, where the appendix may be still useful, the rate of appendicitis is lower than in the U.S.. Prostate cancer is lower among people who, um, use that more too. Both may be examples of an overly hygienic society producing an over reaction by the body's immune system.
I wonder if eventually we'll find the same sort of thing about the tonsils?