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The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and ''Pan'' (chimpanzees and bonobos), but excludes the genus ''Gorilla'' (gorillas). The term was originally introduced by Camille Arambourg (1948). Arambourg combined the categories of ''Hominina'' and ''Simiina'' due to Gray (1825) into his new subtribe. This definition is still adhered to in the proposal by Mann and Weiss (1996), which divides Hominini into three subtribes, Panina (containing ''Pan''), Hominina ("homininans", containing ''Homo'' "humans"), and Australopithecina (containing several extinct "australopithecine" genera). Alternatively, Hominini is taken to exclude ''Pan''. In this case, Panini ("panins", Delson 1977) may refer to the tribe containing ''Pan'' as its only genus.Potts (2010). “What Does It Mean to Be Human?”, pp. 34. . National Geographic Society, Washington."Conventionally, taxonomists now refer to the great ape family (including humans) as 'hominids', while all members of the lineage leading to modern humans that arose after the split with the 'Homo''-''Pan''LCA are referred to as 'hominins'. The older literature used the terms hominoids and hominids respectively." Or perhaps place ''Pan'' with other dryopithecine genera, making the whole tribe or subtribe of Panini or Panina together. Minority dissenting nomenclatures include ''Gorilla'' in Hominini and ''Pan'' in ''Homo'' (Goodman et al. 1998), or both ''Pan'' and ''Gorilla'' in ''Homo'' (Watson et al. 2001).

Terminology and definition

By convention, the adjectival term "hominin" (or nominalized "hominins") refers to the tribe Hominini, while the members of the subtribe Hominina (and thus all archaic human species) are referred to as "homininan" ("homininans"). This follows the proposal by Mann and Weiss (1996), which presents tribe Hominini as including both ''Pan'' and ''Homo'', placed in separate subtribes. The genus ''Pan'' is referred to subtribe Panina, and genus ''Homo'' is included in the subtribe Hominina (see above). However, there is an alternative convention which uses "hominin" to exclude members of Panina, i.e. either just for ''Homo'' or for both human and australopithecine species. This alternative convention is referenced in e.g. Coyne (2009)Coyne, Jerry A. (2009) ''Why Evolution Is True'', pp.197-208, 244, 248. (hc), (pbk). Penguin Books Ltd, London. "Anthropologists apply the term ''hominin'' to all the species on the "human" side of our family tree after it split from the branch that became modern chimps." (p.197) and in Dunbar (2014). Potts (2010) in addition uses the name Hominini in a different sense, as excluding ''Pan'', and uses "hominins" for this, while a separate tribe (rather than subtribe) for chimpanzees is introduced, under the name Panini. In this recent convention, ''contra'' Arambourg, the term "hominin" is applied to ''Homo'', ''Australopithecus'', ''Ardipithecus'', and others that arose after the split from the line that led to chimpanzees (see cladogram below); that is, they distinguish fossil members on the human side of the split, as "hominins", from those on the chimpanzee side, as "not hominins" (or "non-hominin hominids").

Cladogram

This cladogram shows the clade of superfamily Hominoidea and its descendent clades, focussed on the division of Hominini (omitting detail on clades not ancestral to Hominini). The family Hominidae ("hominids") comprises the tribes Ponginae (including orangutans), Gorillini (including gorillas) and Hominini, the latter two forming the subfamily of Homininae. Hominini is divided into Panina (chimpanzees) and Australopithecina (australopithecines). The Hominina (humans) are usually held to have emerged within the Australopithecina (which would roughly correspond to the alternative definition of Hominini according to the alternative definition which excludes ''Pan''). Genetic analysis combined with fossil evidence indicates that hominoids diverged from the Old World monkeys about 25 million years ago (Mya), near the Oligocene-Miocene boundary. The most recent common ancestors (MRCA) of the subfamilies Homininae and Ponginae lived about 15 million years ago. In the following cladogram, the approximate time the clades radiated newer clades is indicated in millions of years ago (Mya).

Evolutionary history

Both ''Sahelanthropus'' and ''Orrorin'' existed during the estimated duration of the ancestral chimpanzee-human speciation events, within the range of eight to four million years ago (Mya). Very few fossil specimens have been found that can be considered directly ancestral to genus ''Pan''. News of the first fossil chimpanzee, found in Kenya, was published in 2005. However, it is dated to very recent times—between 545 and 284 thousand years ago. The divergence of a "proto-human" or "pre-human" lineage separate from ''Pan'' appears to have been a process of complex speciation-hybridization rather than a clean split, taking place over the period of anywhere between 13 Mya (close to the age of the tribe Hominini itself) and some 4 Mya. Different chromosomes appear to have split at different times, with broad-scale hybridization activity occurring between the two emerging lineages as late as the period 6.3 to 5.4 Mya, according to Patterson et al. (2006), This research group noted that one hypothetical late hybridization period was based in particular on the similarity of X chromosomes in the proto-humans and stem chimpanzees, suggesting that the final divergence was even as recent as 4 Mya. Wakeley (2008) rejected these hypotheses; he suggested alternative explanations, including selection pressure on the X chromosome in the ancestral populations prior to the chimpanzee–human last common ancestor (CHLCA). Most DNA studies find that humans and ''Pan'' are 99% identical, but one study found only 94% commonality, with some of the difference occurring in noncoding DNA. It is most likely that the australopithecines, dating from 4.4 to 3 Mya, evolved into the earliest members of genus ''Homo''. In the year 2000, the discovery of ''Orrorin tugenensis'', dated as early as 6.2 Mya, briefly challenged critical elements of that hypothesis, as it suggested that ''Homo'' did not in fact derive from australopithecine ancestors.:"The discovery of ''Orrorin'' has ... radically modified interpretations of human origins and the environmental context in which the African apes/hominoid transition occurred, although ... the less likely hypothesis of derivation of ''Homo'' from the australopithecines still holds primacy in the minds of most palaeoanthropologists." All the listed fossil genera are evaluated for: # probability of being ancestral to ''Homo'', and # whether they are more closely related to ''Homo'' than to any other living primate—two traits that could identify them as hominins. Some, including ''Paranthropus'', ''Ardipithecus'', and ''Australopithecus'', are broadly thought to be ancestral and closely related to ''Homo''; others, especially earlier genera, including ''Sahelanthropus'' (and perhaps ''Orrorin''), are supported by one community of scientists but doubted by another.

List of known hominin species



See also

*Human evolution *List of human evolution fossils *History of hominoid taxonomy *Human taxonomy

References

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External links


Human Timeline (Interactive)
Smithsonian, National Museum of Natural History (August 2016). {{Taxonbar|from=Q107588 Category:Homininae Category:Human evolution Category:Mammal tribes