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Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function. Vestigiality is the retention, during the process of evolution , of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [ 1 ]
The young Robert Ernst Eduard Wiedersheim, probably in early 1874 by Alfredo Noack in Genoa. [1]Robert Ernst Eduard Wiedersheim (21 April 1848 – 12 July 1923) was a German anatomist who is famous for publishing a list of 86 "vestigial organs" in his book The Structure of Man: An Index to His Past History.
Scientific literature concerning vestigial structures abounds. One study compiled 64 examples of vestigial structures found in the literature across a wide range of disciplines within the 21st century. [73] The following non-exhaustive list summarizes Senter et al. alongside various other examples:
The cecum is a pouch-like structure of the large intestine, located at the junction of the small and the large intestines. The term "vermiform" comes from Latin and means "worm-shaped". The appendix was once considered a vestigial organ, but this view has changed since the early 2000s.
In social sciences, atavism is the tendency of reversion: for example, people in the modern era reverting to the ways of thinking and acting of a former time. The word atavism is derived from the Latin atavus—a great-great-great-grandfather or, more generally, an ancestor.
This phenomenon agrees with the accepted scientific explanation: the incidence of tubercles of the auricle among humans, are vestigial structures testifying to our evolutionary past. They are a throwback to the pointed ears of many mammals and just one more vestigial trace of human evolutionary history.
The formation of goose bumps in humans under stress is considered by some to be a vestigial reflex, [4] though visible piloerection is associated with changes in skin temperature in humans. [5] The reflex of producing goose bumps is known as piloerection or the pilomotor reflex , or, more traditionally, [ 6 ] horripilation .