Search results
Results from the WOW.Com Content Network
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]
In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype. [5] Atavisms are often seen as evidence of evolution. [6] 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.
These additional EPMs are the by-product traits of a species’ evolutionary development (see spandrels), as well as the vestigial traits that no longer benefit the species’ fitness. It can be difficult to tell whether a trait is vestigial or not, so some literature is more lenient and refers to vestigial traits as adaptations, even though ...
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.
Although Wiedersheim originally published a list of 86, later interpretations enlarged his list to 180 vestiges. Thus the zoologist Newman stated in the Scopes Trial: "There are, according to Wiedersheim, no less than 180 vestigial structures in the human body, sufficient to make of a man a veritable walking museum of antiquities."
The sudden startled arm-jerking response sometimes experienced when on the verge of sleeping is known as the hypnic jerk.. The evolutionary explanation for the existence of the hypnic jerk is unclear, but a possibility is that it is a vestigial reflex humans evolved when they usually slept in trees.
Plants with more than one significant human use may be listed in multiple categories. Plants are considered domesticated when their life cycle , behavior , or appearance has been significantly altered as a result of being under artificial selection by humans for multiple generations (see the main article on domestication for more information).