Researchers believe that they may have uncovered the function for the appendix, which has long been thought to be superfluous: the organ may act as an incubator for beneficial bacteria that aid the body in digestion.
Writing in the Journal of Theoretical Biology, researchers from Duke University Medical School speculate that the appendix provides a reservoir of beneficial microbes so that the body can replenish its supply in case a disease such as cholera or amoebic dysentery causes the bacteria in the lower gut to be purged.
The researchers observed that the appendix is located just beneath the large intestine, in a spot that food and bacteria usually flow past in only one direction. This would be an ideal location for the hypothesized function.
According to the researchers, the dense populations found in modern cities make it easy for people to be re-exposed to digestive flora after losing them. But in earlier times, the researchers say, a cholera epidemic might have devastated a whole region and necessitated an internal replenishing source.
The researchers noted that appendicitis is significantly less common in Third World countries, where epidemics of diseases targeting the digestive system are more common. They theorized that appendicitis may be a disease of affluence, triggered by an environment more sterile than that in which the body evolved.
Appendicitis occurs when the appendix becomes infected and inflamed. Appendicitis can lead to inflammation of the abdominal cavity, which is nearly always fatal if not treated. According to the Centers for Disease Control and Prevention, 321,000 people in the United States were hospitalized for appendicitis in 2005, and 300 to 400 people die from the condition each year.