Homininae (/hɒmɪˈnaɪniː/), also called "African hominids" or "African apes", is a subfamily of Hominidae.[1][2] It includes two tribes, with their extant as well as extinct species: 1) the tribe Hominini (with the genus Homo including modern humans and numerous extinct species; the subtribe Australopithecina, comprising at least two extinct genera; and the subtribe Panina, represented only by the genus Pan, which includes chimpanzees and bonobos)―and 2) the tribe Gorillini (gorillas). Alternatively, the genus Pan is sometimes considered to belong to its own third tribe, Panini. Homininae comprises all hominids that arose after orangutans (subfamily Ponginae) split from the line of great apes. The Homininae cladogram has three main branches, which lead to gorillas (through the tribe Gorillini), and to humans and chimpanzees via the tribe Hominini and subtribes Hominina and Panina (see the evolutionary tree below). There are two living species of Panina (chimpanzees and bonobos) and two living species of gorillas, but only one extant human species. Traces of extinct Homo species, including Homo floresiensis have been found with dates as recent as 40,000 years ago. Organisms in this subfamily are described as hominine or hominines (not to be confused with the terms hominins or hominini).
Until 1970, the family (and term) Hominidae meant humans only; the non-human great apes were assigned to the family Pongidae.[3] Later discoveries led to revised classifications, with the great apes then united with humans (now in subfamily Homininae) as members of family Hominidae [4] By 1990, it was recognized that gorillas and chimpanzees are more closely related to humans than they are to orangutans, leading to their (gorillas' and chimpanzees') placement in subfamily Homininae as well.[5]
The subfamily Homininae can be[year needed][by whom?] further subdivided into three branches: the tribe Gorillini (gorillas), the tribe Hominini with subtribes Panina (chimpanzees) and Hominina (humans and their extinct relatives), and the extinct tribe Dryopithecini. The Late Miocene fossil Nakalipithecus nakayamai, described in 2007, is a basal member of this clade, as is, perhaps, its contemporary Ouranopithecus; that is, they are not assignable to any of the three extant branches. Their existence suggests that the Homininae tribes diverged not earlier than about 8 million years ago (see Human evolutionary genetics).
Today, chimpanzees and gorillas live in tropical forests with acid soils that rarely preserve fossils. Although no fossil gorillas have been reported, four chimpanzee teeth about 500,000 years old have been discovered in the East-African rift valley (Kapthurin Formation, Kenya), where many fossils from the human lineage (hominins)[Note 1] have been found.[6] This shows that some chimpanzees lived close to Homo (H. erectus or H. rhodesiensis) at the time; the same is likely true for gorillas.[citation needed]
The age of the subfamily Homininae (of the Homininae–Ponginae last common ancestor) is estimated at some 14[11] to 12.5 million years (Sivapithecus).[12][13] Its separation into Gorillini and Hominini (the "gorilla–human last common ancestor", GHLCA) is estimated to have occurred at about 8 to 10 million years ago (TGHLCA) during the late Miocene, close to the age of Nakalipithecus nakayamai.[14]
There is evidence there was interbreeding of Gorillas and the Pan–Homo ancestors until right up to the Pan–Homo split.[15]