The Appendix: Not so useless?

Here's some recent news from the field of theoretical biology: Long described in high school biology classes as a vestigial structure - an evolutionary remnant with no functional use - the appendix may have a purpose after all (other than getting inflamed and keeping surgeons busy with appendectomies). The function, it turns out, may be to repopulate the gut with bacteria. Illnesses or antibiotic treatment can purge many of the "good" bacteria that aid in digestion and vitamin K production, and this new theory proposes that the appendix serves as a 'safe house' for commensal bacteria, and re-inoculates the intestinal tract after such a purge. The reason an appendix can be removed without ill effect may be due to our living conditions - in a highly populated, industrialized environment we're more likely to re-acquire these bacteria from our neighbours, but the appendix may still be important in less developed countries. Link to the full paper here [pdf, subscription may be required]