The appendix does have a function, according to Duke University

The appendix debate has gone on for a long time. And now, it might finally be over according to surgeons from Duke University Medical School. Many people have thought that the appendix is just a vestigial or useless organ, but apparently it is a "good" bacteria factory.

Imagine this, you get cholera or amoebic dysentery, all the useful bacteria dies off as a result. Then what? You need to get some good bacteria back. In modern society, you can pick those up from other people but imagine what it would have been like in the past when the entire region gets infected and the population wasn't so dense? According to the study, that's when the appendix kicks in; it "reboots" the digestive system's good germs.