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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]
Vestigial structures are anatomical structures of organisms in a species which are considered to have lost much or all of their original function through evolution. [8] These body parts can be classed as additional to the required functioning of the body. In human anatomy, the vermiform appendix is sometimes classed as a vestigial remnant.
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.
"The vestigiality of the human vermiform appendix: A Modern Reappraisal"—evolutionary biology argument that the appendix is vestigial; Smith HF, Fisher RE, Everett ML, Thomas AD, Bollinger RR, Parker W (October 2009). "Comparative anatomy and phylogenetic distribution of the mammalian cecal appendix". Journal of Evolutionary Biology.
Main article: List of systems of the human body. Nervous system in a human body. There are 11 distinct organ systems in human beings, [2] which form the basis of human anatomy and physiology. The 11 organ systems: the respiratory system, digestive and excretory system, circulatory system, urinary system, integumentary system, skeletal system ...
Human trichromatic color vision had its genetic origins in this period. Catarrhines lost the vomeronasal organ (or possibly reduced it to vestigial status). Proconsul was an early genus of catarrhine primates. They had a mixture of Old World monkey and ape characteristics.
The vomeronasal organ plays an important role with its sensitivity toward chemicals that are related to mating or sensing prey. For example, snakes use the organ to detect the presence of prey or predator by gathering chemical cues in the environment through the flicking behavior of the forked tongue.