The Appendix: More Useful Than Once Thought

For a long time, it was thought that the human appendix had no use. Instead, it was thought of as a vestigial organ, that is, an organ that functioned in an earlier ancestor, but no longer held that same use. However, new research indicates that the appendix is far from pointless. In fact, it may have an important role in survival.

The appendix is a pinky-finger sized organ located just below the junction between the small and large intestines. Though its function has been debated over the years, scientists have known for a while that the appendix is formed from immune system tissue.


The appendix is a pinky-finger sized organ located just below the junction of the large and small intestines.

According to Dr. Bill Parker, the appendix serves as a natural reserve for beneficial bacteria in our guts. Parker, an associate professor of surgery at Duke University’s School of Medicine, has spent a portion of his career studying the role of immunity in the gut, and through this research formed his hypothesis about the function of the appendix.

Our guts are full of beneficial bacteria. These bacteria help us to digest the food we eat by helping to break down food particles into nutrients our bodies can absorb. They also help to prevent the growth of harmful bacteria. The relationship between these bacteria and our gut is not one-sided; in return for their role in helping to maintain overall gut health, the bacteria have a safe place to live and get the nutrients they need to survive.

Parkers initial studies related to the function of the appendix were theoretical, given that it is difficult to study the appendix’s function in situ (and any such experiment would have serious ethical issues). In addition, though some other animals, such as great apes, rabbits, wombats, and opossums also have appendixes, their appendixes are significantly different from the human appendix, and would not make a valid substitution in an experiment.

However, a recent study appears to corroborate Parkers hypothesis. A team of researchers, led by Dr. James Grendell, chief of the Gastroenterology, Hepatology and Nutrition division at Winthrop University Hospital, studied the histories of 254 patients known to have experienced gut infections caused by Clostridium difficile. This bacterium, commonly referred to as C. diff, is a particularly deadly pathogen that is known to infect hospital patients who have been put on extended courses of antibiotics. Such long courses of antibiotics are known to completely deplete all of the good bacteria from a patients gastrointestinal tract. As a result, C. diff can infect the patients gut, causing severe gastrointestinal distress.

According to Parker’s hypothesis, if the patients appendix is still intact, it should be able to replenish the guts population of good bacteria after a case of C. diff, preventing a recurrence. If a patient has had their appendix removed, they would likely be more susceptible to a recurrence of C. diff infection. Grendell and his colleagues found exactly these results–patients who lacked an appendix had nearly double the chance of a recurrence of a C. diff infection, while those patients who still had their appendix has less than a 20 percent chance of infection recurrence.

Parker thinks that the appendix evolved for a lifestyle that was much less sanitary than the one many of us experience today. In parts of the world where clean water is a luxury and cholera is still a problem, the appendix is likely a vital organ that helps to repopulate the gut with good bacteria after such an infection occurs. In fact, in the developing world, appendix removal is much less common than it is in developed countries.

Though far from conclusive, the results of Grendell’s study indicate that Parker’s hypothesis may be correct. Up until recently, appendixes were routinely removed during abdominal surgeries given their supposed uselessness as a measure to prevent complications or a possible future bout of appendicitis. However, given the appendix’s apparent role as a reservoir of good bacteria, such removals may soon be a thing of the past.

More to Explore

What Do You Think?