Vestigial No More: The Function of the Appendix

Researchers from Duke, Arizona, and Arizona State have concluded that Charles Darwin was wrong.

No, not about natural selection or speciation.

He was wrong to believe that the human appendix was a vestigial organ with no modern function. Not only does the appendix have functionality (namely, it provides a reservoir for healthy bacteria to hide out during digestive or intestinal issues such as diarrhea), the researchers have determined that the appendix has evolved at least two seperate times and has only recently (for humans) developed problems such as severe inflammation.

The latest study demonstrates two major problems with that idea. First, several living species, including certain lemurs, several rodents and a type of flying squirrel, still have an appendix attached to a large cecum which is used in digestion. Second, Parker says the appendix is actually quite widespread in nature. "For example, when species are divided into groups called 'families', we find that more than 70 percent of all primate and rodent groups contain species with an appendix." Darwin had thought that appendices appeared in only a small handful of animals.

"Darwin simply didn't have access to the information we have," explains Parker. "If Darwin had been aware of the species that have an appendix attached to a large cecum, and if he had known about the widespread nature of the appendix, he probably would not have thought of the appendix as a vestige of evolution."

He also was not aware that appendicitis, or inflammation of the appendix, is not due to a faulty appendix, but rather due to cultural changes associated with industrialized society and improved sanitation. "Those changes left our immune systems with too little work and too much time their hands – a recipe for trouble," says Parker.

That notion wasn't proposed until the early 1900's, and "we didn't really have a good understanding of that principle until the mid 1980's," Parker said. "Even more importantly, Darwin had no way of knowing that the function of the appendix could be rendered obsolete by cultural changes that included widespread use of sewer systems and clean drinking water."