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The human appendix averages 9 cm (3.5 in) in length, ranging from 5 to 35 cm (2.0 to 13.8 in). The diameter of the appendix is 6 mm (0.24 in), and more than 6 mm (0.24 in) is considered a thickened or inflamed appendix. The longest appendix ever removed was 26 cm (10 in) long. [3]
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 the 1970s palaeontologists Niles Eldredge and Stephen Jay Gould developed a theoretical model that suggests that evolution, although a slow process in human terms, undergoes periods of relatively rapid change (ranging between 50,000 and 100,000 years) [80] alternating with long periods of relative stability.
The last common ancestor between humans and other apes possibly had a similar method of locomotion. 12-8 Ma The clade currently represented by humans and the genus Pan (chimpanzees and bonobos) splits from the ancestors of the gorillas between c. 12 to 8 Ma. [31] 8-6 Ma Sahelanthropus tchadensis
The 126 bones of the appendicular skeleton and the 80 bones of the axial skeleton together form the complete skeleton of 206 bones in the human body. Unlike the axial skeleton, the appendicular skeleton is made up of significantly more long bones and predominantly articulated via synovial joints , which allow for a much greater range of motion .
Reconstruction of early Homo sapiens from Jebel Irhoud, Morocco c. 315 000 years BP. Early modern human (EMH), or anatomically modern human (AMH), [1] are terms used to distinguish Homo sapiens (sometimes Homo sapiens sapiens) that are anatomically consistent with the range of phenotypes seen in contemporary humans, from extinct archaic human species (of which some are at times also identified ...
Human evolution is the evolutionary process within the history of primates that led to the emergence of Homo sapiens as a distinct species of the hominid family that ...