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Homininae

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For an explanation of very similar terms, seeHominidaeandHominini.

Homininae
Temporal range:12.5–0Ma
Three hominines – an adulthuman male(Leonard Carmichael) holding a juvenilegorilla(left) and a juvenilechimpanzee(right).
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Homininae
Gray,1825
Type species
Homo sapiens
Linnaeus, 1758
Tribes

Homininae(thehominines), is a subfamily of the familyHominidae(hominids). (The Homininae—/hɒmɪˈnaɪniː/—encompass humans, and are also called "African hominids"or"African apes".)[1][2]This subfamily includes two tribes,HomininiandGorillini,both havingextant(or living) species as well asextinctspecies.

TribeHomininiincludes: the extant genusHomo,which comprises only one extant species—the modernhumans(Homosapiens), and numerous extinct human species; and the extant genusPan,which includes two extant species,chimpanzeesandbonobos.TribeGorillini(gorillas) contains one extant genus, Gorilla, with two extant species, with variants, and one known extinct genus. Alternatively, the genusPanis considered by some to belong, instead of to a subtribePanina,to its own separate tribe, (so-called) "Panini" —which would be a third tribe for Homininae.

Some classification schemes provide a more comprehensive account of extinct groups—(see section "Taxonomic Classification", below). For example, tribe Hominini shows two subtribes: subtribeHominina,which contains at least two extinctgenera;and subtribe Panina, which presents only the extant genus,Pan(chimpanzees/bonobos), as fossils of extinct chimpanzees/bonobos are very rarely found.

The Homininae comprise allhominidsthat arose after the subfamilyPonginae(orangutans} split from the line of thegreat apes.The Homininaecladogramhas three main branches leading: to gorillas (via the tribe Gorillini); to humans and to chimpanzees (via the tribe Hominini and subtribes Hominina and Panina―(see graphic "Evolutionary tree", below). There are two living species of Panina, chimpanzees and bonobos, and two living species of gorillas and one that is extinct. Traces of extinctHomospecies, includingHomo floresiensis,have been found with dates as recent as 40,000 years ago. Individual members of this subfamily are calledhominineorhominines—not to be confused with the termshomininsorHominini.[Note 1]

History of discoveries and classification

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See also:List of human evolution fossils
Evolutionary treeof the superfamilyHominoidea,emphasizing the subfamily Homininae: after an initial separation from the main line (some 18 million years ago) ofHylobatidae(currentgibbons), the line of subfamilyPonginaebroke away—leading to the current orangutan; and later the Homininae split into the tribeHominini(with subtribes Hominina and Panina), and the tribeGorillini.

Until 1970, the family (and term) Hominidae meant humans only; the non-humangreat apeswere assigned to the then-familyPongidae.[3]Later discoveries led to revised classifications, with the greatapesthen united with humans (now in subfamily Homininae)[4]as members of family Hominidae[5] By 1990, it was recognized thatgorillasandchimpanzeesare more closely related tohumansthan they are toorangutans,leading to their (gorillas' and chimpanzees') placement in subfamily Homininae as well.[6]

The subfamily Homininae can be further subdivided into three branches, the tribeGorillini(gorillas), the tribeHomininiwith subtribesPanina(chimpanzees/bonobos) andHominina(humans and their extinct relatives), and the extinct tribeDryopithecini.TheLate MiocenefossilNakalipithecus nakayamai,described in 2007, is abasalmember of thisclade,as is, perhaps, its contemporaryOuranopithecus;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 (seeHuman evolutionary genetics).

Today, chimpanzees and gorillas live intropical forestswith 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 (KapthurinFormation, Kenya), where many fossils from the human lineage (hominins)[Note 1]have been found.[7]This shows that some chimpanzees lived close toHomo(H. erectusorH. rhodesiensis) at the time; the same is likely true for gorillas.[4]

Taxonomic classification

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Hominina(Humans, Chimpanzees, and Gorillas)
Hominoidea(Apes)
Hylobatidae(gibbons)
Hominidae (great apes)
Ponginae
(Orangutans)
Homininae
Gorillini
(Gorilla)
Hominini
Panina
(chimpanzees)
Hominina(Humans)

Homininae

Evolution

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See also:Human evolutionandHuman evolutionary genetics

The age of the subfamily Homininae (of theHomininae–Ponginae last common ancestor) is estimated at some 14[10]to 12.5 million years (Sivapithecus).[11][12] Its separation into Gorillini and Hominini (the "gorilla–human last common ancestor", GHLCA) is estimated to have occurred at about8 to 10million years ago(TGHLCA) during the lateMiocene,close to the age ofNakalipithecus nakayamai.[13]

There is evidence there was interbreeding of Gorillas and the Pan–Homo ancestors until right up to the Pan–Homo split.[14]

Evolution of bipedalism

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See also:Human skeletal changes due to bipedalism

Recent studies ofArdipithecus ramidus(4.4 million years old) andOrrorin tugenensis(6 million years old) suggest some degree of bipedalism.Australopithecusand earlyParanthropusmay have beenbipedal.Very early hominins such asArdipithecus ramidusmay have possessed an arboreal type of bipedalism.[15]

The evolution ofbipedalismencouraged multiple changes among hominins especially when it came tobipedalismin humans as they were now able to do many other things as they began to walk with their feet. These changes included the ability to now use their hands to create tools or carry things with their hands, the ability to travel longer distances at a faster speed, and the ability to hunt for food. According to researchers, humans were able to be bipedalists due to Darwin's Principle ofnatural selection.Darwin himself believed that larger brains in humans made an upright gait necessary, but had no hypothesis for how the mechanism evolved.

The first major theory attempting to directly explanation the origins ofbipedalismwas theSavannah hypothesis(Dart 1925.) This theory hypothesized that hominins became bipedalists due to the environment of the Savanna such as the tall grass and dry climate. This was later proven to be incorrect due to fossil records that showed that hominins were still climbing trees during this era.

AnthropologistOwen Lovejoyhas suggested thatbipedalismwas a result ofsexual dimorphismin efforts to help with the collecting of food. In his Male Provisioning Hypothesis introduced in 1981, lowered birth rates in early hominids increased pressure on males to provide for females and offspring. While females groomed and cared for their children with the family group, males ranged to seek food and returned bipadally with full arms. Males who could better provide for females in this model were more likely to mate and produce offspring.[16]

Anthropologist Yohannes Haile-Selassie, an expert onAustralopithecus anamensis,discusses the evidence that Australopithecus were one of the first hominins to evolve into obligate bipedalists. The remains of this subfamily are very important in the field of research as it presents possible information regarding how these primates adapted from tree life to terrestrial life. This was a huge adaptation as it encouraged many evolutionary changes within hominins including the ability to use their hand to make tools and gather food, as well as a larger brain development due to their change in diet.[17]

Brain size evolution

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There has been a gradual increase in brain volume (brain size) as the ancestors of modern humans progressed along thetimeline of human evolution,starting from about 600 cm3inHomo habilisup to 1500 cm3inHomo neanderthalensis.However, modernHomo sapienshave a brain volume slightly smaller (1250 cm3) than Neanderthals, women have a brain slightly smaller than men and the Flores hominids (Homo floresiensis), nicknamed hobbits, had a cranial capacity of about 380 cm3(considered small for a chimpanzee), about a third of theHomo erectusaverage. It is proposed that they evolved fromH. erectusas a case of insular dwarfism.[citation needed]In spite of their smaller brain, there is evidence thatH. floresiensisused fire and made stone tools at least as sophisticated as those of their proposed ancestorsH. erectus.[18]In this case, it seems that for intelligence, the structure of the brain is more important than its size.[19]

The current size of the human brain is a big distinguishing factor that separates humans from other primates. Recent examination of the human brain shows that the brain of a human is about more than four times the size ofgreat apesand 20 times larger than the brain size ofold world monkeys.A study[20]was conducted to help determine the evolution of the brain size within the sub family Homininae that tested the genes ASPM (abnormal spindle-like microcephalyassociated) and MCHP1(microcephalin-1) and their association with the human brain. In this study researchers discovered that the increase in brain size is correlated to the increase of both ASP and MCPH1. MCPH1 is very polymorphic in humans compared togibbons,Old World monkeys.This gene helps encourage the growth of the brain. Further research indicated that the MCPH1 gene in humans could have also been an encouraging factor of population expansion. Other researchers have included that the diet was an encouraging factor to brain size as protein intake increased this helped brain development.[20]

Evolution of family structure and sexuality

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See also:Human sexuality

Sexuality is related to family structure and partly shapes it. The involvement of fathers in education is quite unique to humans, at least when compared to other Homininae.Concealed ovulationandmenopausein women both also occur in a few other primates however, but are uncommon in other species.Testisandpenis sizeseems to be related to family structure:monogamyorpromiscuity,orharem,in humans, chimpanzees or gorillas, respectively.[21][22]The levels ofsexual dimorphismare generally seen as a marker ofsexual selection.Studies have suggested that the earliest hominins were dimorphic and that this lessened over the course of the evolution of the genusHomo,correlating with humans becoming more monogamous, whereas gorillas, who live in harems, show a large degree of sexual dimorphism. Concealed (or "hidden" ) ovulation means that the phase of fertility is not detectable in women, whereas chimpanzees advertise ovulation via an obvious swelling of the genitals. Women can be partly aware of their ovulation along the menstrual phases, but men are essentially unable to detect ovulation in women. Most primates have semi-concealed ovulation, thus one can think that the common ancestor had semi-concealed ovulation, that was inherited by gorillas, and that later evolved in concealed ovulation in humans and advertised ovulation in chimpanzees. Menopause also occurs inrhesus monkeys,and possibly in chimpanzees, but does not in gorillas and is quite uncommon in other primates (and other mammal groups).[22]

See also

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Notes

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  1. ^abAhomininis a member of the tribe Hominini, ahominineis a member of the subfamily Homininae, ahominidis a member of the family Hominidae, and ahominoidis a member of the superfamily Hominoidea.

References

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  1. ^Grabowski M, Jungers WL (October 2017)."Evidence of a chimpanzee-sized ancestor of humans but a gibbon-sized ancestor of apes".Nature Communications.8(1): 880.Bibcode:2017NatCo...8..880G.doi:10.1038/s41467-017-00997-4.PMC5638852.PMID29026075.
  2. ^Fuss J, Spassov N, Begun DR, Böhme M (2017-05-22)."Potential hominin affinities of Graecopithecus from the Late Miocene of Europe".PLOS ONE.12(5): e0177127.Bibcode:2017PLoSO..1277127F.doi:10.1371/journal.pone.0177127.PMC5439669.PMID28531170.
  3. ^Goodman M(1964)."Man's place in the phylogeny of the primates as reflected in serum proteins".In Washburn SL (ed.).Classification and Human Evolution.Transaction Publishers. pp. 204–234.ISBN978-0-202-36487-2.
  4. ^ab"Homininae Gray, 1825".Global Biodiversity Information Facility.Retrieved2024-08-02.
  5. ^Goodman M (1974). "Biochemical Evidence on Hominid Phylogeny".Annual Review of Anthropology.3:203–228.doi:10.1146/annurev.an.03.100174.001223.
  6. ^Goodman M, Tagle DA, Fitch DH, Bailey W, Czelusniak J, Koop BF, Benson P, Slightom JL (March 1990). "Primate evolution at the DNA level and a classification of hominoids".Journal of Molecular Evolution.30(3): 260–6.Bibcode:1990JMolE..30..260G.doi:10.1007/BF02099995.PMID2109087.S2CID2112935.
  7. ^McBrearty S, Jablonski NG (September 2005). "First fossil chimpanzee".Nature.437(7055): 105–8.Bibcode:2005Natur.437..105M.doi:10.1038/nature04008.PMID16136135.S2CID4423286.
  8. ^Fuss, J; Spassov, N; Begun, DR; Böhme, M (2017). "Potential hominin affinities of Graecopithecus from the Late Miocene of Europe". PLOS One. 12 (5).
  9. ^Sevim-Erol, Ayla; Begun, D. R.; Sözer, Ç Sönmez; Mayda, S.; van den Hoek Ostende, L. W.; Martin, R. M. G.; Alçiçek, M. Cihat (2023-08-23)."A new ape from Türkiye and the radiation of late Miocene hominines".Communications Biology.6(1): 842.doi:10.1038/s42003-023-05210-5.ISSN2399-3642.PMC10447513.PMID37612372.
  10. ^Hill A, Ward S (1988)."Origin of the Hominidae: The Record of African Large Hominoid Evolution Between 14 My and 4 My".Yearbook of Physical Anthropology.31(59): 49–83.doi:10.1002/ajpa.1330310505.
  11. ^Finarelli JA, Clyde WC (2004)."Reassessing hominoid phylogeny: Evaluating congruence in the morphological and temporal data"(PDF).Paleobiology.30(4): 614–651.Bibcode:2004Pbio...30..614F.doi:10.1666/0094-8373(2004)030<0614:RHPECI>2.0.CO;2.S2CID86034107.Archived fromthe original(PDF)on 2010-07-21.Retrieved2017-12-04.
  12. ^Chaimanee Y, Suteethorn V, Jintasakul P, Vidthayanon C, Marandat B, Jaeger JJ (January 2004)."A new orang-utan relative from the Late Miocene of Thailand"(PDF).Nature.427(6973): 439–41.Bibcode:2004Natur.427..439C.doi:10.1038/nature02245.PMID14749830.S2CID4349664.Archived fromthe original(PDF)on 2012-01-17.Retrieved2017-12-04.
  13. ^Jha A (March 7, 2012)."Gorilla genome analysis reveals new human links".The Guardian.RetrievedMay 8,2015. Jha A (March 9, 2012)."Scientists unlock genetic code for gorillas - and show the human link".The Sydney Morning Herald.RetrievedMay 8,2015. Hansford, Dave (November 13, 2007)."New Ape May Be Human-Gorilla Ancestor".National Geographic News.RetrievedMay 8,2015.
  14. ^Popadin, Konstantin; Gunbin, Konstantin; Peshkin, Leonid; Annis, Sofia; Fleischmann, Zoe; Kraytsberg, Genya; Markuzon, Natalya; Ackermann, Rebecca R.; Khrapko, Konstantin (2017-10-19)."Mitochondrial pseudogenes suggest repeated inter-species hybridization in hominid evolution".bioRxiv:134502.doi:10.1101/134502.hdl:11427/36660.
  15. ^Kivell TL, Schmitt D (August 2009)."Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor".Proceedings of the National Academy of Sciences of the United States of America.106(34): 14241–6.Bibcode:2009PNAS..10614241K.doi:10.1073/pnas.0901280106.PMC2732797.PMID19667206.
  16. ^"Origins of Bipedalism".NOVA.Retrieved2023-06-25.
  17. ^Haile-Selassie, Yohannes (2021-12-01)."From Trees to the Ground: The Significance of Australopithecus anamensis in Human Evolution".Journal of Anthropological Research.77(4): 457–482.doi:10.1086/716743.ISSN0091-7710.S2CID240262976.
  18. ^Brown P, Sutikna T, Morwood MJ, Soejono RP, Saptomo EW, Due RA (October 2004)."A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia"(PDF).Nature.431(7012): 1055–61.Bibcode:2004Natur.431.1055B.doi:10.1038/nature02999.PMID15514638.S2CID26441.
  19. ^Davidson, I. (2007)."As large as you need and as small as you can—implications of the brain size ofHomo floresiensis".In Schalley, A.C.; Khlentzos, D. (eds.).Mental States: Evolution, function, nature; 2. Language and cognitive structure.Studies in language companion. Vol. 92–93. John Benjamins. pp. 35–42.ISBN978-9027231055.
  20. ^abWang, Yin-qiu; Su, Bing (2004-06-01)."Molecular evolution of microcephalin, a gene determining human brain size".Human Molecular Genetics.13(11): 1131–1137.doi:10.1093/hmg/ddh127.ISSN1460-2083.PMID15056608.
  21. ^Diamond J(1991).The Third Chimpanzee.
  22. ^abDiamond J (1997).Why is Sex Fun?.

Further reading

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The WikibookDichotomous Keyhas a page on the topic of:Homininae
Wikispecieshas information related toHomininae.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Homininae&oldid=1253190516"