Humble appendix, long regarded as a useless evolutionary artifact, has regained the respect, about 3 years ago, when researchers at the University Duck suggested that it fulfills a critical function.
They say that appendix is a haven for good bacteria, where they can shelter until they are needed to repopulate the intestine after a severe case of diarrhea, for example.
Using a modern approach of biological evolution, which uses genetic information in combination with other information to assess the biological connections that emerged over the years, Parker and his colleagues discovered that the appendix has been modified at least twice, once in Australian marsupials and the second time in rats and other rodents, primates and humans.
Darwin theorized that the appendix in humans and other primates is an evolutionary remnant of a larger structure called the caecum, which was part of the digestive system of the ancestors. The latest study shows two major mistakes in this theory. First, some living species, including some lemurs, rodents and a kind of flying squirrel, still have an appendix attached to a larger caecum which is used in digestion. Second, Parker says that currently there are very many species in nature that have appendix.
Darwin also was not aware that appendicitis, or inflammation of the appendix, is not caused by a defective appendix, but rather is caused by cultural changes associated with an industrialized society and improving of sanitation.
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