The appendix has long been thought of as a pretty useless organ. But now, researchers suggest there's more to it than we know of. Says LiveScience:

Not only was it recently proposed to actually possess a critical function, but scientists now find it appears in nature a lot more often than before thought. And it's possible some of this organ's ancient uses could be recruited by physicians to help the human body fight disease more effectively.

The appendix, which is referred to as a "vestigial organ" by many textbooks, is a slimy dead-end sac between the small and large intestines. The theory was that the appendix used to be from an ancestor that ate leaves, and is an evolutionary remain of a "cecum" which was used for digesting food.

"Everybody likely knows at least one person who had to get their appendix taken out - slightly more than 1 in 20 people do - and they see there are no ill effects, and this suggests that you don't need it," said William Parker, an immunologist at Duke University Medical Center in Durham.

But Parker and his team recently suggested that the appendix was vital, serving as a safehouse where good bacteria could lie and wait until they were needed to repopulate the gut after a bad case of diarrhea. Previous studies have also shown that the appendix can help make, direct and train white blood cells.

"The appendix has been around for at least 80 million years, much longer that we would estimate if [Charles] Darwin's ideas about the appendix were correct," Parker said. It appears that the appendix has evolved at least twice, once among Australian marsupials like the wombat, and another time among rodents, as well as humans and some primates.

Parker added: "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."

As for appendicitis, Parker said, the deadly inflammation of the organ may not be fully due to a faulty appendix, but rather cultural changes associated with industrialized society and improved sanitation.

"Those changes left out immune systems with too little work and too much time their hands - a recipe for trouble," he said. "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."

Parker added if modern medicine could find a way to prevent appendicitis, like how human immune systems were challenged back in the Stone Age, we would see less cases of allergies, autoimmune disease and appendicitis.

[via LiveScience]