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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]
The 10,000 Year Explosion: How Civilization Accelerated Human Evolution is a 2009 book by anthropologists Gregory Cochran and Henry Harpending.Starting with their own take on the conventional wisdom that the evolutionary process stopped when modern humans appeared, the authors explain the genetic basis of their view that human evolution is accelerating, illustrating it with some examples.
Overview map of the peopling of the world by early humans during the Upper Paleolithic, following the Southern Dispersal paradigm. The so-called "recent dispersal" of modern humans took place about 70–50,000 years ago. [60] [61] [62] It is this migration wave that led to the lasting spread of modern humans throughout the world.
The timeline of human evolution outlines the major events in the evolutionary lineage of the modern human species, Homo sapiens, throughout the history of life, beginning some 4 billion years ago down to recent evolution within H. sapiens during and since the Last Glacial Period.
Humans’ impact on biodiversity—via both habitat loss and the effects of man-made climate change—has caused irreversible damage to wildlife, argues a 2023 paper published in the journal PNAS.
For many decades human dissection was thought unnecessary when all the knowledge about a human body could be read about from early authors such as Galen. [35] In the 12th century, as universities were being established in Italy, Emperor Frederick II made it mandatory for students of medicine to take courses on human anatomy and surgery. [36]