In fact, research shows that the appendix has evolved independently over 30 times, indicating its usefulness throughout the evolutionary process.
Every year, approximately 300,000 people are hospitalized due to the pain caused by appendicitis or ruptured appendices, and many have exclaimed: “Why do we even have an appendix?”. This is an intriguing question that science has long tried to answer. In biology, the appendix is seen as a vestigial organ, meaning it has become useless during human evolution. However, the story of the appendix is not that simple.
The Appendix: A Part of Diverse Evolution
The appendix is a small tube located at the junction of the small intestine and the large intestine. Various species of primates, rodents, and even some marsupials in Australia, such as wombats and cuscus, possess an appendix. This shows that the appendix is not exclusive to humans but is also found in many other animal species. In fact, the appendix has evolved independently up to 32 times in different mammalian species.
The appendix is a small tube located at the junction of the small intestine and the large intestine.
Additionally, there are animal species with structures similar to the appendix, even though they lack a cecum—the small pouch where the small intestine opens into the large intestine. These variants are found in certain species of monotremes, birds, and ray-finned fish (Actinopterygians). This raises the question: if the appendix is a vestigial organ, why do so many animal species possess it?
Scientists are currently conducting more in-depth studies on the appendix and its functions. One significant discovery is that the appendix is not a completely useless organ as previously thought. Research has indicated that the appendix plays a role in maintaining the gut microbiota and supports the immune system.
One popular hypothesis is that the appendix contains gut bacteria and plays a certain role in the immune system. Sometimes, diseases related to the gut can devastate the live bacteria residing in our intestines. Scientists believe that the appendix serves as a reservoir for gut bacteria, helping to restore them.
Studies have shown that the appendix in most animal species contains lymphoid tissue—where lymphocytes operate and mature. This suggests that the appendix contributes to immune function. In some animals, such as rabbits and a few other rodents, the appendix aids in digesting tough plant materials by housing bacteria that break down cellulose into digestible nutrients. Among species that consume a lot of hard-to-digest plant matter, the appendix appears larger and more functional.
Rabbits, primates, and cuscus are just a few examples of animals with an appendix. Researchers have discovered that the appendix contains lymphoid tissue, a type of tissue containing lymphocytes.
Lymphocytes are a crucial part of the immune system, helping the body fight infections. This indicates that the appendix plays an important role in maintaining the health of the immune system.
Charles Darwin once posited that the appendix is a vestigial organ, based on the hypothesis that the ancestors of modern humans were herbivores with larger colons for digesting cellulose. However, as humans shifted to a diet lower in plant matter and higher in fruit, the redundant part of the colon shrank into the appendix.
Although Darwin’s theory was compelling in its context, modern technology has provided new evidence regarding the appendix’s function. This evidence supports the hypothesis that the appendix still plays a role in immune function and gut bacteria. However, many questions remain unanswered, such as why only some animal species have an appendix while others do not.
The appendix is not a completely useless organ as once thought.
The appendix may also help restore gut microbiota after being devastated by gut-related diseases. Scientists believe that the appendix serves as a reservoir for gut bacteria and can assist in their regeneration after being wiped out by illnesses like diarrhea.
Unanswered Questions
Despite extensive research on the appendix, many questions remain unresolved. Why do only some animal species have an appendix while others do not? If the appendix plays an essential role in immune function and gut bacteria, why isn’t it present in all animal species?
Surgeons often remove the appendix as a precautionary measure during abdominal surgery. However, new evidence suggests that appendectomy may be harmful. Individuals who have had their appendix removed may face greater difficulties recovering from intestinal infections due to an overgrowth of C. difficile bacteria.
Despite this, if your appendix is about to rupture, you still need to have it removed. This indicates that while the appendix may have an important role in the body, in cases of inflammation or rupture, its removal is necessary to protect your health.
If your appendix is about to rupture, you still need to have it removed.
Although the appendix is considered a vestigial organ, it still holds many mysteries and may play an important role in the immune system and gut bacteria. Ongoing research on the appendix could reveal many secrets about this organ’s true functions and roles in our bodies and those of other animals.
This suggests that in medicine and biology, there is still much to explore and understand about seemingly “useless” parts of the body.
