Why You Might Want to Keep Your Appendix Study: It has evolved in 32 different mammals, might protect gut By John Johnson, Newser Staff Posted Feb 13, 2013 5:46 PM CST 21 comments Comments (Shutterstock) (Newser) – A new study lends weight to the theory that the appendix has been getting a bad rap for centuries. Researchers determined that the organ had evolved independently in at least 32 different mammals, which wouldn't make a lot of evolutionary sense if it served no purpose, reports Science. Conventional wisdom, made popular by Darwin himself, holds that the appendix was important eons ago when human ancestors ate mostly leaves, but fell out of service when our diet and digestion needs changed. The new research refutes this theory, finding scant evidence of a link to the appendix and diet in the mammals studied. So what might the appendix do? The article floats an interesting "safe house" theory that's been around for a few years: On the rare occasion when beneficial bacteria in the gut is overrun by its dangerous brethren, the good stuff can "retreat to the safety of the appendix, which remains unaffected," it says. "Once the immune system has beaten the infection, the beneficial bacteria emerge from the appendix to quickly recolonize the gut."