I am putting the finishing touches on a book about the quest to create artificial life in the lab. Going through this process makes it apparent that some material belongs in the book, but it doesn't quite fit in the main body.
So it winds up relegated to an appendix (defined by Merriam-Webster's dictionary as "supplementary material usually attached at the end of a piece of writing.")
Since Charles Darwin's time, biologists viewed the human vermiform appendix in the much the same way: A supplementary structure attached to the large intestine that isn't really needed. In fact, Darwin and evolutionary biologists since his time have argued that biological structures like the appendix stand as powerful evidence in favor of the theory of evolution. The human appendix is considered to be vestigial—once functional in evolutionary ancestors, but no longer needed by its descendents and experienced decay, losing its utility.
About seven percent of people in developed countries suffer from appendicitis. The inflamed appendix can be removed without any consequence. In fact, appendectomies help prevent ulcerative colitis. These facts seem consistent with the naturalistic view of the appendix as a useless evolutionary feature.
A team of researchers from Duke University recently challenged the idea that the human appendix is vestigial. They suggested that it might function as a storage chamber for bacteria that form beneficial biofilms in the upper part of the large intestine. The microbes stored in the appendix serve as a reservoir to replenish the biofilm that is lost as a result of diarrhea.
Interestingly, a comparative anatomy study published in 1980 (conducted from an evolutionary vantage point) demonstrated that the distribution of appendixes among primates and other mammals doesn't match the expected pattern if it was a vestigial structure. Instead, its occurrence suggests that it plays a useful role.
Revisiting the earlier study, the Duke University scientists confirmed the initial results generated in 1980. These researchers identified an appendix or an appendix-like structure in a number of mammals. From an evolutionary standpoint, it looks as if the appendix has been around for over 80 million years and appears to have originated independently multiple times, suggesting that it indeed is functional.
The human vermiform appendix is one appendix that doesn't belong at the back of the book. The fact that it is not a vestigial structure eliminates another popular argument for biological evolution.