Written by: Kevin Cann
The godfather of evolution, Charles Darwin, predicted that our appendix was an organ of past times and as we continued to evolve as human beings the appendix would slowly go away. The appendix is a 3.5 inch tube that is connected to our colon, right where the small and large intestine meet, by way of the cecum.
Throughout undergraduate and graduate studies all that I knew about the appendix was how big of a nuisance it could be to some people. In fact, you have a 5-10% chance of developing appendicitis depending on your age, race, and sex. Why would natural selection not rid our bodies of something that can negatively affect such a high percentage of the population?
70% of all mammals and primates have an appendix. The caecum and the appendix allow them to eat large amounts of fibrous plants. Many researchers believe this was the purpose of our appendix before our diet changed. As our diet changed, our appendix shrank to its current size today.
A smaller appendix is more prone to infection. Perhaps this is why between the ages of 10-19 we have the highest likelihood of developing appendicitis. Our appendix is largest during childhood and shrinks as we age. The shrinking of the appendix, from an evolutionary standpoint, might be the reason we see an increase in the rates of appendicitis.
Why the appendix shrinks over time I am not sure. It seems as though other members of the mammal and primate communities that have large appendixes also have a diet rich in high fibrous foods. Perhaps to digest these foods, more gut bacteria are needed. Since we do not eat foods such as twigs anymore, will our appendix continue to shrink until we no longer have one?
I do not think this is the case for a couple of reasons (although I am no expert in this arena). For one, a smaller appendix has a higher risk of infection. An infection that could potentially be deadly. This does not seem like a path natural selection would take.
The other reason, our appendix may play a crucial role in our gastrointestinal immune system. For one there are a plethora of lymphoid tissue housed within the appendix. This suggests that the appendix plays a role with our immune system. The lymphatic tissue might serve a different purpose within the appendix though.
The appendix is also a home for over 4,000 species of beneficial gut bacteria. Some of these bacteria feed off of the lymphoid tissue. Presence of the lymphoid tissue in the appendix might be primarily as a food source to keep these bacteria alive, since they are tucked away from all of the food we eat.
This makes the appendix a safe house for beneficial bacteria. This makes sense as we can lose species of bacteria and/or shift the optimal balance of bacteria within the gut after an intestinal infection. In this case the appendix can release those species into the intestinal tract and help us recover from illness. Perhaps the loss of a bacterial safe house after an appendectomy is why people without an appendix are at a higher risk of developing Crohn’s disease (1).
With all of this said, this does not mean you should hold onto your appendix at all costs. If your appendix is inflamed and at a risk of rupturing, you might want to have it removed, as it can be fatal. Appendicitis results in roughly 400 deaths per year in the United States, and those figures would be much higher if the 320,000 people suffering from appendicitis did not have their appendix removed.
There was a time period where doctors would just take someone’s appendix as a precautionary procedure. This is unwarranted and may actually be harmful. Others will argue that we do not have a need for a storage unit of beneficial bacteria. They point to people who have had their appendixes removed and suffer no negative consequences as evidence.
Before we make these definitive claims we need to be sure we understand the full function of the appendix. I can say with confidence that we do not understand the full function of the appendix. We are just uncovering the first layer of importance.
I do not think it is farfetched to think that this organ plays an even bigger role in our health than we already know. We are 10 times more bacteria than we are human. Putting that into perspective and understanding the many roles that our gut bacteria play in our health, from our weight, mood, and digestion, to all of the issues an imbalance can cause from autism, allergies, and even cancer.
The keys to our health and well-being lie in our guts with the health of all the beneficial gut bugs residing there. It is inevitable that life will at times leave a negative impact on these beneficial bacterium. In these cases it is a good thing we have an appendix to help reestablish our health and get back on track. If you do not have an appendix, do not worry. A quality dose of probiotics following an illness and/or infection can probably help reestablish that same balance.