Not So Useless After All

The Appendix’s Function is to “Re-Boot” the Digestive System

Appendix, the "useless" organ that has been the butt (heh) of jokes for ages (like the function of the appendix is to rupture, thus ensuring your doctor would be able to pay for his summer vacation - bursting with laughter yet?), turns out not to be so useless after all:

The US scientists found that the appendix acted as a "good safe house" for bacteria essential for healthy digestion, in effect re-booting the digestive system after the host has contracted diseases such as amoebic dysentery or cholera, which kill off helpful germs and purge the gut.
This function has been made obsolete by modern, industrialised society; populations are now so dense that people pick up essential bacteria from each other, allowing gut organisms to regrow without help from the appendix, the researchers said.
But in earlier centuries, when vast tracts of land were more sparsely populated and whole regions could be wiped out by an epidemic of cholera, the appendix provided survivors with a vital individual stockpile of suitable bacteria.

More