Date: October 8, 2007 Source: Duke University Medical Center Summary: Long denigrated as vestigial or useless, the appendix now appears to have a reason to be - as a "safe house" for the beneficial bacteria living in the human gut. The gut is populated with different microbes that help the digestive system break down the foods we eat. In return, the gut provides nourishment and safety to the bacteria. Parker now believes that the immune system cells found in the appendix are there to protect, rather than harm, the good bacteria.