JOIN USCharles Darwin was wrong when he theorised that the appendix in humans and other primates was the evolutionary remains of a larger structure, called a cecum, which was used by now-extinct ancestors for digesting food, according to research collaborators from three US institutions.
Researchers at Duke University Medical Centre, the University of Arizona, and Arizona State University have observed that not only does the appendix appear in nature much more frequently than previously acknowledged, but it has been around much longer than anyone had suspected.
“Maybe it’s time to correct the textbooks. Many biology texts today still refer to the appendix as a ‘vestigial organ’,” says Dr William Parker, assistant professor of Surgical Sciences at Duke.
He revealed that his research team used a modern approach to evolutionary biology called cladistics, which utilises genetic information in combination with a variety of other data to evaluate biological relationships that emerge over the ages, for their study.
He said that his study has shown 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,” he said.
Parker says that his study shows two major problems with Darwin’s idea of the appendix being a ‘biological remnant’.
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 per cent of all primate and rodent groups contain species with an appendix,” the researcher said.
Parker further pointed out that Darwin had thought that appendices appeared in only a small handful of animals.
“Darwin simply didn’t have access to the information we have. 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,” said Parker.
The study report further states that Darwin was not aware of the fact that appendicitis, also known as inflammation of the appendix, is not due to a faulty appendix, but rather due to cultural changes associated with industrialised society and improved sanitation.
“Those changes left our immune systems with too little work and too much time their hands — a recipe for trouble,” said Parker.
The researcher added that that notion wasn’t proposed until the early 1900s, and “we didn’t really have a good understanding of that principle until the mid 1980s”.
“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,” Parker said.
Given that scientists these days understand the normal function of the appendix, Parker stresses that a critical question to ask is whether we can do anything to prevent appendicitis.
He thinks the answer may lie in devising ways to challenge our immune systems today in much the same manner that they were challenged back in the Stone Age.
“If modern medicine could figure out a way to do that, we would see far fewer cases of allergies, autoimmune disease, and appendicitis,” he said.