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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]
This phenomenon is an automatic-response mechanism that activates even before a human becomes consciously aware that a startling, unexpected or unknown sound has been "heard". [2] That this vestigial response occurs even before becoming consciously aware of a startling noise would explain why the function of ear-perking had evolved in animals.
Vestigial-like family member 3 is a protein that in humans is encoded by the VGLL3 gene. [ 5 ] This protein is one of four mammalian homologs (VGLL1-4) of the vestigial gene found in the fruit fly Drosophila . [ 6 ]
In females, the mesonephros degenerates entirely, though vestigial structures such as Gartner's ducts, the epoophoron, and paroophoron are common. In males, a few of the more caudal tubules will survive and give rise to the efferent ductules of the testis , [ 1 ] the epididymis , vas deferens , seminal vesicle , as well as vestigial structures ...
A notable example of a bird with a pseudo-penis is the red-billed buffalo weaver, which do not use their pseudo-penis for direct insertion during copulation; however it does play a part in successful mating and stimulation. [15] Similarly to the red-billed buffalo weaver, the cassowary, a ratite, exhibits a pseudo-penis in both males and females.
The classic example of a unitary pseudogene is the gene that presumably coded the enzyme L-gulono-γ-lactone oxidase (GULO) in primates. In all mammals studied besides primates (except guinea pigs), GULO aids in the biosynthesis of ascorbic acid (vitamin C), but it exists as a disabled gene (GULOP) in humans and other primates.
The flat human face helps to maintain balance on the occipital condyles. Because of this, the erect position of the head is possible without the prominent supraorbital ridges and the strong muscular attachments found in, for example, apes. As a result, in humans the muscles of the forehead (the occipitofrontalis) are only used for facial ...