What is our Appendix for?

August 1, 2016 / Humans / 2 Comments /

The appendix is a strange little organ. It can be removed from the host with having no negative effect- something which cannot be said for any other organ. The appendix seems to do nothing for us, but we all have one for some reason. Although no one can say for certain why we have an appendix, there are some pretty good theories about it and modern research, which I will go into in this article.


The Appendix

Image showing the appendix

The appendix is a tiny organ which comes off the large intestine (see image to the right). In the scheme of things it is indeed very small, but it is likely to have shrunk in size as it has become more and more obsolete throughout or evolutionary history. When it was a more valuable organ, many people believe that it would have been much larger.

From its location we can get a good idea of its historic role in the body (even if it no longer is needed for it). Being attached the the large intestine tells us that its role is closely associated with it. The large intestine is home to the vast majority of probiotic bacteria in our body, is responsible for the absorption of some vitamins, large amount of water, and contains a significant amount of immune cells. Although some nutrient absorption goes on here, the vast majority of this occurs in the small intestine, so it’s unlikely the appendix was directly involved in absorption or digestion.

As the appendix is considered to be obsolete in modern man also suggests that there is something about our lifestyle changes in our recent evolutionary history which has resulted in the appendix not being needed.


Theories for the purpose of the appendix

Theory of plants – This theory suggests that our appendix helped us to digest plant matter, particularly cellulose, which we struggle to digest today. breaking down the cell walls of plants would allow vital vitamins and minerals to be released which has obvious health benefits. The reason our appendix has become obsolete is because we cook most of our food which breaks down the tough cellulose. This theory is supported by the fact that some purely herbivorous animals have a large structure similar to an appendix which is thought to help them break down tough plant material (such as koala bears), although there are not many examples of this. Rather than producing enzymes to digest this tough plant material, the appendix most likely contained special bacteria which can break down the cellulose for us. This is quite possible considering the appendix is attached to the most bacteria dense part of the body.

Theory of probiotics – This theory suggests that the appendix served as a kind of probiotic safe house. In any circumstance where the bacteria population of the digestive system would be flushed out or killed (such as diarrhea), the bacteria from the appendix would repopulate the large intestine with beneficial bacteria and prevent pathogenic bacteria populating it (which would cause further illness). The shrinking of the appendix is a result of improved hygiene, farming and the cooking foods, because all of these things reduce the risk of foodborne illness. This again is supported by the proximity of the appendix to the large intestine.

It is very possible that both theories hold some truth as to the historic role of the appendix.


Modern role of the appendix

Yes, the appendix is largely thought of as an obsolete organ, and although you can happily live without, it does still have a role in the body. Relatively recent research has shown that the appendix has a large concentration of immune cells, particularly a group of cells called lymphocytes, which help to eliminate waste from the digestive system and fight infection. The research on this is limited, and so details are quite sparse, but it does look like the appendix still does offer us some benefit after all.



For a long time the appendix has been thought of as a largely redundant and mysterious organ. Its role throughout our evolution is still debated, but is probably related to hosting beneficial bacteria, whether these bacteria are specialised for digesting plant matter or simply a backup for when we have specific illnesses we do not know. Regardless of its historic role, the appendix does still serve a function in the body. Recent research has shown that the appendix has a role in maintaining and protecting the digestive system from pathogens and helping to remove waste, and so it is not as redundant as previously thought.


Images courtesy of Blausen.com staff, Blausen gallery 2014 and AJ Cann

This Youtube video will give an overview of the information found on the article tab. If you want to know more about the topic, or want to see where the information came from, have a read of the article after you watch the video.

The appendix is thought to have acted as a storage of probiotic bacteria for our digestive system in case we ate food that had gone off. There is also evidence that it contains high concentrations of immune cells which can help fight infections and eliminate waste in the digestive system.

  • Letitia

    Thanks for this article!
    I always knew there was a reason we had an appendix! When I was younger, I had to have mine removed. It troubled me to hear the doctors say they did not know what it was for and that I did not need it.
    Now I know!

    • Craig

      Hi Letitia,

      Glad you liked it 🙂 I wouldn’t worry too much – many people live long and happy lives without one.

      Thanks for reading 🙂