The appendix mystery, solved: My Times Year in Ideas piece

A couple of weeks ago, the New York Times Magazine published its 2007 “Year in Ideas” issue — their annual compendium of the year’s most interesting and offbeat research. I wrote up five of their scientific and technological entries. The entire issue is online here for free, but I’m also archiving my pieces here for posterity’s sake.

This one’s about a new theory for why the appendix exists! That lovely image above, by Bryan Christie Design, accompanied it.

The Appendix Rationale

For years, the appendix got no respect. Doctors regarded it as nothing but a source of trouble: It didn’t seem to do anything, and it sometimes got infected and required an emergency removal. Plus, nobody ever suffered from not having an appendix. So human biologists assumed that the tiny, worm-shaped organ is vestigial — a shrunken remainder of some organ our ancestors required. In a word: Useless.

Now that old theory has been upended. In a December issue of The Journal of Theoretical Biology, a group of scientists announce they have solved the riddle of the appendix. The organ, they claim, is in reality a ”safe house” for healthful bacteria — the stuff that makes our digestive system function. When our gut is ravaged by diseases like diarrhea and dysentery, the appendix quietly goes to work repopulating the gut with beneficial bacteria.

”In essence,” says William Parker, a chemist who co-wrote the paper, ”after our system crashes, the appendix reboots it.” The theory may explain the location of the appendix: Positioned at the beginning of the colon, it often escapes being voided when a sick colon violently empties itself out the bottom.

If the appendix is indeed crucial, why don’t people who have their appendixes removed die? Because in the modern world hygiene and medicine can keep our levels of healthy bacteria adequate. The appendix may have evolved its rebooting function back when our ancestors lived a more vulnerable life — and an entire village might suffer catastrophic diarrhea. In that situation, each gut had to rely on its own resources to recover after a collapse, so the appendix was crucial.

Parker admits the argument is ”deductive.” There’s no way to test it other than performing ”some heinous experiment” — like going to an isolated tribal village, removing half the population’s appendixes and seeing whether that half dies during the next bout of dysentery. Even so, anatomists have been receptive to Parker’s theory. CLIVE THOMPSON

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I'm Clive Thompson, the author of Smarter Than You Think: How Technology is Changing Our Minds for the Better (Penguin Press). You can order the book now at Amazon, Barnes and Noble, Powells, Indiebound, or through your local bookstore! I'm also a contributing writer for the New York Times Magazine and a columnist for Wired magazine. Email is here or ping me via the antiquated form of AOL IM (pomeranian99).

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