3 Answers

The human appendix is a vestigial structure. A vestigial structure is a structure that has lost all or most of its original function through the process of evolution that has taken place over the years. The vermiform appendage is the shrunken remainder of the cecum that was found in a remote ancestor of humans. Ceca, which are found in the digestive tracts of many extant herbivores, house mutualistic bacteria which help animals digest the cellulose molecules that are found in plants.[4] As the human appendix no longer houses a significant number of these bacteria, and humans are no longer capable of digesting more than a minimal amount of cellulose per day,[5] the human appendix is considered a vestigial structure. This interpretation would stand even if it were found to have a certain use in the human body. Vestigial organs are sometimes pressed into a secondary use when their original function has been lost.[6] See the sections below for possible functions of the appendix that may have evolved more recently after the appendix lost its original function.

A possible scenario for the progression from a fully functional cecum to the current human appendix was put forth by Charles Darwin.[7] He suggested that the appendix was used for digesting leaves as primates. It may be a vestigial organ, evolutionary baggage, of ancient humans that has degraded down to nearly nothing over the course of evolution. The very long cecum of some herbivorous animals, such as found in the horse or the koala, supports this theory. The koala's cecum enables it to host bacteria that specifically help to break down cellulose. Human ancestors may have also relied upon this system when they lived on a diet rich in foliage. As people began to eat more easily digested foods, they became less reliant on cellulose-rich plants for energy. As the cecum became less necessary for digestion, mutations that were previously deleterious (and would have hindered evolutionary progress) were no longer important, so the mutations have survived. These alleles became more frequent and the cecum continued to shrink. After millions of years, the once-necessary cecum has degraded to be the appendix of today.[7] On the other hand, evolutionary theorists have suggested that natural selection selects for larger appendices because smaller and thinner appendices would be more susceptible to inflammation and disease.[8]

In my case nothing it was removed when I was just a wee lad..

So, what is the appendix? The appendix is a small tube at one end of a large intestine. It is closed at one end, like a sort of pocket. The appendix has to be removed when it becomes seriously inflamed by an infection, which is quite common. Substances from the intestine enter the appendix and cannot easily get out again. If they stay there, these substances may harden, forming a plug, which aqueezes the appendix's blood vessels. This can cut off the blood supply to the appendix, and an infection may easily arise. Pain starts in the stomach, and then is concentrated on the right side of the body. Then it is case of calling for the doctor and having the appendix removed by a simple and quick operation.

It is widely believed that the appendix has no function in humans, and that it is an evolutionary remnant. Yet, some say that it functions as a source of digestive bacteria. The fact is that when an appendix is surgically removed, there is no apparent effect on the patients health.