Hominini
Encyclopedia
Hominini is the tribe
of Homininae
that comprises Homo
, and the two species of the genus Pan
(the Common Chimpanzee
and the Bonobo
), their ancestors, and the extinct lineages of their common ancestor (but see the discussion below for alternative views). Members of the tribe are called hominins (cf. Hominidae
, "hominids"). The subtribe Hominina
is the "human" branch, including genus Homo and its close relatives, but not Pan. All species in this tribe carry the same four blood type
s which can be exchanged between species.
The creation of this taxon is the result of the current idea that the least similar species of a trichotomy
should be separated from the other two. Through DNA
comparison, scientists believe the Pan/Homo divergence occurred between 5.4 and 6.3 million years ago, after an unusual process of speciation
that ranged over 4 million years. Few fossil specimens on the Pan side of the split have been found, the first fossil chimpanzee discovery being published in 2005, dating to between 545 ± 3 kyr (thousand years) and 284 ± 12 kyr via 40Ar/39Ar, from Kenya's East African Rift Valley. All of the extinct genera listed in the table to the right are ancestral to Homo, or are offshoots of such. However, both Orrorin and Sahelanthropus existed around the time of the split, and so may be ancestral to all three extant species.
In the proposal of Mann and Weiss (1996), the tribe Hominini includes Pan as well as Homo, but as separate subtribes. Homo (and, by inference, all bipedal apes) is in the subtribe Hominina
, while Pan is in the subtribe Panina. However, there are alternative definitions: some researchers use the term Hominini to include humans and fossil ancestors, but not chimpanzees. Wood (2010) discusses the different views of this taxonomy.
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
of Homininae
Homininae
Homininae is a subfamily of Hominidae, which includes humans, gorillas and chimpanzees, and some extinct relatives; it comprises all those hominids, such as Australopithecus, that arose after the split from orangutans . Our family tree, which has 3 main branches leading to chimpanzees, humans and...
that comprises Homo
Homo (genus)
Homo is the genus that includes modern humans and species closely related to them. The genus is estimated to be about 2.3 to 2.4 million years old, evolving from australopithecine ancestors with the appearance of Homo habilis....
, and the two species of the genus Pan
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...
(the Common Chimpanzee
Common Chimpanzee
The common chimpanzee , also known as the robust chimpanzee, is a great ape. Colloquially, the common chimpanzee is often called the chimpanzee , though technically this term refers to both species in the genus Pan: the common chimpanzee and the closely related bonobo, formerly called the pygmy...
and the Bonobo
Bonobo
The bonobo , Pan paniscus, previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee...
), their ancestors, and the extinct lineages of their common ancestor (but see the discussion below for alternative views). Members of the tribe are called hominins (cf. Hominidae
Hominidae
The Hominidae or include them .), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees , gorillas , humans , and orangutans ....
, "hominids"). The subtribe Hominina
Hominina
The more anthropomorphic primates of the Hominini tribe are placed in the Hominina subtribe. Referred to as hominans, they are characterized by the evolution of an increasingly erect bipedal locomotion. The only extant species is Homo sapiens...
is the "human" branch, including genus Homo and its close relatives, but not Pan. All species in this tribe carry the same four blood type
Blood type
A blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...
s which can be exchanged between species.
The creation of this taxon is the result of the current idea that the least similar species of a trichotomy
Trichotomy
In mathematics, the Law of Trichotomy states that every real number is either positive, negative, or zero. More generally, trichotomy is the property of an order relation...
should be separated from the other two. Through DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
comparison, scientists believe the Pan/Homo divergence occurred between 5.4 and 6.3 million years ago, after an unusual process of speciation
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
that ranged over 4 million years. Few fossil specimens on the Pan side of the split have been found, the first fossil chimpanzee discovery being published in 2005, dating to between 545 ± 3 kyr (thousand years) and 284 ± 12 kyr via 40Ar/39Ar, from Kenya's East African Rift Valley. All of the extinct genera listed in the table to the right are ancestral to Homo, or are offshoots of such. However, both Orrorin and Sahelanthropus existed around the time of the split, and so may be ancestral to all three extant species.
In the proposal of Mann and Weiss (1996), the tribe Hominini includes Pan as well as Homo, but as separate subtribes. Homo (and, by inference, all bipedal apes) is in the subtribe Hominina
Hominina
The more anthropomorphic primates of the Hominini tribe are placed in the Hominina subtribe. Referred to as hominans, they are characterized by the evolution of an increasingly erect bipedal locomotion. The only extant species is Homo sapiens...
, while Pan is in the subtribe Panina. However, there are alternative definitions: some researchers use the term Hominini to include humans and fossil ancestors, but not chimpanzees. Wood (2010) discusses the different views of this taxonomy.