For generations, children have been taught that the appendix is useless-at most, causing a trip to the emergency room and an impressive scar.
But that may not be correct, according to a team of surgeons and immunologists at the Duke University Medical Center who stumbled upon the function of the appendix while researching the immune system and bacteria in the gut.
In a study published online in the Journal of Theoretical Biology last week, researchers proposed that the appendix serves as a "safe house" for commensal bacteria-"good bacteria" that aid in food digestion and prevents disease.
The gut is normally populated with these commensal bacteria, but in the case of diseases such as cholera or amoebic dysentery, the large intestine is purged of these helpful microorganisms, said study co-author Bill Parker, an assistant professor of experimental surgery at DUMC.
"The idea is that your flora gets contaminated and your body tries to flush it out," he said.
As a result, the appendix cultivates and repopulates the gut with these commensal bacteria, essentially restarting the digestive system.
But this does not happen often in industrialized countries, Parker added.
"Modern medical care and sanitation practices have pretty much rendered the function of the appendix obsolete," he said.
In less developed nations, where the appendix may still serve a purpose, the rate of appendicitis-a life-threatening condition in which the appendix becomes inflamed and must be surgically removed-is also much lower than that of the United States, Parker said.
According to statistics compiled by the Centers for Disease Control and Prevention, in 2005-the most recent year for which statistics were available-321,000 Americans were hospitalized with appendicitis. Researchers attributed this high incidence to a lack of fiber in the Western diet, as well as the so-called "hygiene hypothesis," Parker said.
"We are so clean that our immune system never gets challenged by the things that it is adapted to be challenged with," he said. "It begins to overreact with things that it shouldn't overreact with, causing allergies, autoimmune diseases and of course appendicitis."
Despite these new developments, Parker said individuals should seek medical attention when appendicitis may have occurred.
Further direct studies of the appendix's function are not planned.
"We're more focused on the immune system and how it can be affected to cause inflammatory bowel disease and how we can prevent inflammatory bowel disease and other things like that," Parker said.
Although many students said they were unaware of the results of the study, those that have said they were shocked.
"The appendix has a function-that's the craziest thing I've ever heard!" freshman Tuhin Chakraborty said.
Daniel Schmitt, an associate professor and chair of the Department of Biological Anthropology and Anatomy, said there are even larger lessons to be derived from such a study.
"I am glad that these researchers kept looking and didn't just default to the idea that [the appendix] is vestigial," he said. "These guys identified a function and showed how it can contribute to fitness. Their study speaks to the importance of understanding function in order to understand evolution."
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