Why you have (or had) an appendix

CT scanThe image of the appendix has been getting a makeover. Two years ago, Duke U. researchers suggested it is not the useless evolutionary vestige that Darwin said it was.

The appendix, they said, is a safe haven where good bacteria could hang out until they were needed to repopulate the gut after a nasty case of diarrhea, for example.

Now some of the team suggest the appendix has been around a lot longer than Darwin thought.

[Surgical sciences professor William] Parker and colleagues found that the appendix has evolved at least twice, once among Australian marsupials and another time among rats, lemmings and other rodents, selected primates and humans. “We also figure that the appendix has been around for at least 80 million years, much longer than we would estimate if Darwin’s ideas about the appendix were correct.”

Parker says Darwin just didn’t have access to enough information about the organ.

“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.

[Story tip: Phoenix New Times blog; CT image by jellywatson]