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| synonyms=
| synonyms=
*''Homo antiquus''</br><small>[[Walter Ferguson|Ferguson]], 1984</small>
*''Homo antiquus''</br><small>[[Walter Ferguson|Ferguson]], 1984</small>
*''Praeanthropus afarensis'' </br><small>[[Camilo José Cela Conde|Cela Conde]] and [[Francisco J. Ayala|Ayala]], 2003</small>
| synonyms_ref=<ref>{{cite journal|last1=White|first1=Tim D.|last2=Suwa|first2=Gen|last3=Asfaw|first3=Berhane|title=''Australopithecus ramidus'', a new species of early hominid from Aramis, Ethiopia|journal=Nature|date=1994|volume=371|issue=6495|pages=306–312|doi=10.1038/371306a0|pmid=8090200|url=http://www.tarha.ulpgc.es/ramidus_94.pdf|bibcode=1994Natur.371..306W}}</ref>
}}
}}
'''''Australopithecus afarensis''''' ([[Latin]]: "Southern ape from [[Afar Region|Afar]]") is an extinct [[hominin]] that lived between 3.9 and 2.9 million years ago <ref name="EvolutionAndPrehistory">{{cite book |url=https://books.google.com/books?id=LfYirloa_rUC&pg=PA134&lpg=PA134&q=lucy%20australopithecus%20potassium%20argon
'''''Australopithecus afarensis''''' ([[Latin]]: "Southern ape from [[Afar Region|Afar]]") is an extinct [[hominin]] that lived between 3.9 and 2.9 million years ago <ref name="EvolutionAndPrehistory">{{cite book |url=https://books.google.com/books?id=LfYirloa_rUC&pg=PA134&lpg=PA134&q=lucy%20australopithecus%20potassium%20argon
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==Taxonomy==
==Taxonomy==
===Research history===
===Research history===
Beginning in the 1930s, some of the most ancient [[hominin]] remains of the time dating to 3.8–2.9 million years ago were recovered from [[Laetoli]], Tanzania, and [[Hadar, Ethiopia|Hadar]], Ethiopia. In 1948, German palaeontologist [[Edwin Hennig]] proposed classifying these remains into a new [[genus]], "''Praeanthropus''", but he failed to give a species name. In 1950, German anthropologist Hans Weinhert proposed classifying a jawbone from the headwaters of the Gerusi River (near Laetoli) as ''Meganthropus africanus'', but this was largely ignored. In 1955, S. Şenyüruk proposed the combination ''Praeanthropus africanus''.<ref name=Johanson1978/> Major collections were made in Laetoli on an expedition beginning in 1974 directed by British palaeoanthropologist [[Mary Leakey]], and in Hadar from 1972–1977 by the International Afar Research Expedition (IARE) formed by French geologist [[Maurice Taieb]], American palaeoanthropologist [[Donald Johanson]], and Breton anthropologist [[Yves Coppens]]. These fossils were remarkably well-preserved and many had associated skeletal aspects.<ref name=Kimbel2009>{{cite journal|first=W. H.|last=Kimbel|first2=L. K.|last2=Delezene|year=2009|title="Lucy" Redux: A Review of Research on ''Australopithecus afarensis''|journal=American Journal of Physical Anthropology|volume=49|doi=10.1002/ajpa.21183|pmid=19890859}}</ref>{{rp|5}} Because ''[[Australopithecus africanus]]'' fossils were commonly being discovered throughout the 1920s and 40s in South Africa, these remains were provisionally classified as [[Australopithecus africanus|''Australopithecus'' aff. ''africanus'']], but Mary and [[Louis Leakey|Louis]] Leakey also classified some into ''[[Homo]]'' spp.<ref name=Johanson1978/> In 1973, the IARE team unearthed the first [[knee joint]], [[AL 129-1]], and showed the earliest evidence at the time of [[bipedalism]]. In 1974, Johanson and graduate student Tom Gray discovered the partial skeleton AL 288-1, commonly referred to as "[[Lucy (Australopithecus)|Lucy]]" (named after [[The Beatles]] song ''[[Lucy in the Sky with Diamonds]]'' which was playing on their [[tape recorder]] that evening).<ref name=Johanson1990>{{cite book|first=D.|last=Johanson|authorlink=Donald Johanson|year=1990|chapter=Prologue|title=Lucy: The Beginnings of Humankind|publisher=Simon and Schuster|isbn=978-0-671-72499-3}}</ref> In 1975, the IARE recovered 216 specimens belonging to 13 individuals, [[AL 333]] "the First Family".<ref>{{cite journal|first=D. C.|last=Johanson|authorlink=Donald Johanson|year=2004|title=Lucy, Thirty Years Later: An Expanded View of ''Australopithecus afarensis''|journal=Journal of Anthropological Research|volume=60|issue=4|doi=10.1086/jar.60.4.3631138|jstor=3631138}}</ref>{{rp|471–472}}
Beginning in the 1930s, some of the most ancient [[hominin]] remains of the time dating to 3.8–2.9 million years ago were recovered from [[Laetoli]], Tanzania, and [[Hadar, Ethiopia|Hadar]], Ethiopia. Because ''[[Australopithecus africanus]]'' fossils were commonly being discovered throughout the 1920s and 40s in South Africa, these remains were provisionally classified as [[Australopithecus africanus|''Australopithecus'' aff. ''africanus'']]. In 1948, German palaeontologist [[Edwin Hennig]] proposed classifying these remains into a new [[genus]], "''Praeanthropus''", but he failed to give a species name. In 1950, German anthropologist Hans Weinhert proposed classifying a jawbone from the headwaters of the Gerusi River (near Laetoli) as ''Meganthropus africanus'', but this was largely ignored. In 1955, S. Şenyüruk proposed the combination ''Praeanthropus africanus''.<ref name=Johanson1978/> Major collections were made in Laetoli on an expedition beginning in 1974 directed by British palaeoanthropologist [[Mary Leakey]], and in Hadar from 1972–1977 by the International Afar Research Expedition (IARE) formed by French geologist [[Maurice Taieb]], American palaeoanthropologist [[Donald Johanson]], and Breton anthropologist [[Yves Coppens]]. These fossils were remarkably well-preserved and many had associated skeletal aspects.<ref name=Kimbel2009>{{cite journal|first=W. H.|last=Kimbel|first2=L. K.|last2=Delezene|year=2009|title="Lucy" Redux: A Review of Research on ''Australopithecus afarensis''|journal=American Journal of Physical Anthropology|volume=49|doi=10.1002/ajpa.21183|pmid=19890859}}</ref>{{rp|5}} In 1976, Leakey and colleagues preliminarily classified Laetoli remains into ''[[Homo]]'' spp., and attributing ''Australopithecus''-like traits as evidence of them being [[transitional fossil]]s.<ref>{{cite journal|first=M.|last=Leakey|authorlink=Mary Leakey|first2=R. H.|last2=Ray|first3=G. H.|last3=Curtis|first4=R. E.|last4=Drake|first5=M. K.|last5=Jackes|first6=T. D.|last6=White|author6-link=Tim D. White|year=1976|title=Fossil hominids from the Laetolil Beds|journal=Nature|volume=262|pages=460–466|doi=10.1038/262460a0}}</ref> In 1973, the IARE team unearthed the first [[knee joint]], [[AL 129-1]], and showed the earliest evidence at the time of [[bipedalism]]. In 1974, Johanson and graduate student Tom Gray discovered the partial skeleton AL 288-1, commonly referred to as "[[Lucy (Australopithecus)|Lucy]]" (named after [[The Beatles]] song ''[[Lucy in the Sky with Diamonds]]'' which was playing on their [[tape recorder]] that evening).<ref name=Johanson1990>{{cite book|first=D.|last=Johanson|authorlink=Donald Johanson|year=1990|chapter=Prologue|title=Lucy: The Beginnings of Humankind|publisher=Simon and Schuster|isbn=978-0-671-72499-3}}</ref> In 1975, the IARE recovered 216 specimens belonging to 13 individuals, [[AL 333]] "the First Family".<ref>{{cite journal|first=D. C.|last=Johanson|authorlink=Donald Johanson|year=2004|title=Lucy, Thirty Years Later: An Expanded View of ''Australopithecus afarensis''|journal=Journal of Anthropological Research|volume=60|issue=4|doi=10.1086/jar.60.4.3631138|jstor=3631138}}</ref>{{rp|471–472}}


In 1978, Johanson, [[Tim D. White]], and Coppens classified the hundreds of specimens collected thus far into a new species, ''A. afarensis'', and considered the apparently wide range of variation (resulting in the previous classification of the remains into two different genera) a result of [[sexual dimorphism]]. The [[species name]] honours the [[Afar Region]] of Ethiopia where the majority of the specimens had been recovered from. They later selected the jawbone [[LH 4]] has the [[lectotype specimen]] because of its preservation quality and because White had already fully described and illustrated it the year before.<ref name=Johanson1978/> In 1979, Johanson and White proposed that ''A. afarensis'' was the last common ancestor between ''Homo'' and ''[[Paranthropus]]'', supplanting ''A. africanus'' in this role.<ref>{{cite journal|first=D. C.|last=Johanson|authorlink=Donald Johanson|first2=T. D.|last2=White|author2-link=Tim D. White|year=1979|title=A Systematic Assessment of Early African Hominids|journal=Science|volume=203|issue=4378|pages=321–330|doi=10.1126/science.104384}}</ref> Considerable debate of the validity of this species followed, with proposals for [[synonym (taxonomy)|synonymising]] them with ''A. africanus'' or recognising multiple species from the Laetoli and Hadar remains. The skull KNM-ER 1470 (now ''[[Homo rudolfensis|H. rudolfensis]]'') was at first dated to 2.9 mya, which cast doubt on the ancestral position of both ''A. afarensis'' or ''A. africanus'', but it has since been re-dated to about 2 mya.<ref name=Delson2004>{{cite book|first=E.|last=Delson|first2=I.|last2=Tattersall|author2-link=Ian Tattersall|first3=J.|last3=Van Couvering|first4=A. S.|last4=Brooks|year=2004|title=Encyclopedia of Human Evolution and Prehistory|edition=2nd|publisher=Routledge|pages=118–120|isbn=978-1-135-58228-9}}</ref> Palaeoartist [[Walter Ferguson]] has proposed splitting ''A. afarensis'' into "''H. antiquus''", a [[relict population|relict]] [[dryopithecine]] "''Ramapithecus''" (now ''[[Sivapithecus]]''), and a subspecies of ''A. africanus''. His recommendations have largely been ignored.<ref name=White1994>{{Cite journal|last1=White |first1=T. D.|authorlink=Tim D. White|last2=Suwa |first2=G.|authorlink2=Gen Suwa|last3=Asfaw |first3=B. |authorlink3=Berhane Asfaw|title=''Australopithecus ramidus'', a new species of early hominid from Aramis, Ethiopia |journal=Nature |volume=371 |pages=306–312 |year=1994 |pmid=8090200 |doi=10.1038/371306a0|bibcode=1994Natur.371..306W|issue=6495}}</ref><ref name=Delson2004/> In 2003, Spanish writer [[Camilo José Cela Conde]] and evolutionary biologist [[Francisco J. Ayala]] proposed reinstating "''Praeanthropus''" including ''A. afarensis'' alongside ''[[Sahelanthropus]]'', ''[[Australopithecus anamensis|A. anamensis]]'', ''[[Australopithecus bahrelghazali|A. bahrelghazali]]'', and ''[[Australopithecus garhi|A. garhi]]''.<ref name="Cela-CondeAyala2003">{{Cite journal | last1 = Cela-Conde | first1 = C. J.|author1-link=Camilo José Cela Conde| last2 = Ayala | first2 = F. J. |author2-link=Francisco J. Ayala| title = Genera of the human lineage | doi = 10.1073/pnas.0832372100 | journal = Proceedings of the National Academy of Sciences | volume = 100 | issue = 13 | pages = 7684–7689 | year = 2003 | pmid = 12794185| pmc = 164648 | bibcode = 2003PNAS..100.7684C}}</ref>
In 1978, Johanson, [[Tim D. White]], and Coppens classified the hundreds of specimens collected thus far into a new species, ''A. afarensis'', and considered the apparently wide range of variation a result of [[sexual dimorphism]]. The [[species name]] honours the [[Afar Region]] of Ethiopia where the majority of the specimens had been recovered from. They later selected the jawbone [[LH 4]] has the [[lectotype specimen]] because of its preservation quality and because White had already fully described and illustrated it the year before.<ref name=Johanson1978/> In 1979, Johanson and White proposed that ''A. afarensis'' was the last common ancestor between ''Homo'' and ''[[Paranthropus]]'', supplanting ''A. africanus'' in this role.<ref>{{cite journal|first=D. C.|last=Johanson|authorlink=Donald Johanson|first2=T. D.|last2=White|author2-link=Tim D. White|year=1979|title=A Systematic Assessment of Early African Hominids|journal=Science|volume=203|issue=4378|pages=321–330|doi=10.1126/science.104384}}</ref> Considerable debate of the validity of this species followed, with proposals for [[synonym (taxonomy)|synonymising]] them with ''A. africanus'' or recognising multiple species from the Laetoli and Hadar remains. The skull KNM-ER 1470 (now ''[[Homo rudolfensis|H. rudolfensis]]'') was at first dated to 2.9 mya, which cast doubt on the ancestral position of both ''A. afarensis'' or ''A. africanus'', but it has since been re-dated to about 2 mya.<ref name=Delson2004>{{cite book|first=E.|last=Delson|first2=I.|last2=Tattersall|author2-link=Ian Tattersall|first3=J.|last3=Van Couvering|first4=A. S.|last4=Brooks|year=2004|title=Encyclopedia of Human Evolution and Prehistory|edition=2nd|publisher=Routledge|pages=118–120|isbn=978-1-135-58228-9}}</ref> Palaeoartist [[Walter Ferguson]] has proposed splitting ''A. afarensis'' into "''H. antiquus''", a [[relict population|relict]] [[dryopithecine]] "''Ramapithecus''" (now ''[[Sivapithecus]]''), and a subspecies of ''A. africanus''. His recommendations have largely been ignored.<ref name=White1994>{{Cite journal|last1=White |first1=T. D.|authorlink=Tim D. White|last2=Suwa |first2=G.|authorlink2=Gen Suwa|last3=Asfaw |first3=B. |authorlink3=Berhane Asfaw|title=''Australopithecus ramidus'', a new species of early hominid from Aramis, Ethiopia |journal=Nature |volume=371 |pages=306–312 |year=1994 |pmid=8090200 |doi=10.1038/371306a0|bibcode=1994Natur.371..306W|issue=6495}}</ref><ref name=Delson2004/> In 2003, Spanish writer [[Camilo José Cela Conde]] and evolutionary biologist [[Francisco J. Ayala]] proposed reinstating "''Praeanthropus''" including ''A. afarensis'' alongside ''[[Sahelanthropus]]'', ''[[Australopithecus anamensis|A. anamensis]]'', ''[[Australopithecus bahrelghazali|A. bahrelghazali]]'', and ''[[Australopithecus garhi|A. garhi]]''.<ref name="Cela-CondeAyala2003">{{Cite journal | last1 = Cela-Conde | first1 = C. J.|author1-link=Camilo José Cela Conde| last2 = Ayala | first2 = F. J. |author2-link=Francisco J. Ayala| title = Genera of the human lineage | doi = 10.1073/pnas.0832372100 | journal = Proceedings of the National Academy of Sciences | volume = 100 | issue = 13 | pages = 7684–7689 | year = 2003 | pmid = 12794185| pmc = 164648 | bibcode = 2003PNAS..100.7684C}}</ref>


''A. afarensis'' is known only from [[East Africa]]. Beyond Laetoli and Hadar, it has been recorded in [[Omo]], Maka, Fejej, and Belohdelie in Ethiopia, and [[Koobi Fora]] and Lothagam in [[Kenya]].{{cn|date=June 2020}}
''A. afarensis'' is known only from [[East Africa]]. Beyond Laetoli and Hadar, the species has been recorded in [[Omo]], Maka, Fejej, and Belohdelie in Ethiopia, and [[Koobi Fora]] and Lothagam in [[Kenya]].{{cn|date=June 2020}}


===Classification===
===Classification===
''A. afarensis'' is now a widely accepted species, and it is now generally thought that ''Homo'' and ''Paranthropus'' are [[sister taxa]] deriving from ''Australopithecus'', but the classification of ''Australopithecus'' species is in disarray. ''Australopithecus'' is considered a [[wastebasket taxon]] whose members are united by their similar physiology rather than close relations with each other over other hominin genera.<ref>{{cite journal|last=Cartmill|first=M.|title=A sort of revolution: Systematics and physical anthropology in the 20th century|journal=American Journal of Physical Anthropology|volume=165|issue=4|pages=677–687|doi=10.1002/ajpa.23321|pmid=29574829|hdl=2144/29233|year=2018|doi-access=free}}</ref> Several ''Australopithecus'' species have been postulated to represent the ancestor to ''Homo'', but the 2013 discovery of the earliest ''Homo'' specimen, [[LD 350-1]], 2.8 million years old (older than almost all other ''Australopithecus'' species) from the Afar Region could potentially affirm ''A. afarensis''{{'}} ancestral position.<ref name=Villmoare2015>{{cite journal|first=B.|last=Villmoare|first2=W. H.|last2=Kimbel|first3=C.|last3=Seyoum|display-authors=et al.|year=2015|title=Early ''Homo'' at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia|journal=Science|volume=347|issue=6228|pages=1352–1355|doi=10.1126/science.aaa1343|doi-access=free}}</ref>
''A. afarensis'' is now a widely accepted species, and it is now generally thought that ''Homo'' and ''Paranthropus'' are [[sister taxa]] deriving from ''Australopithecus'', but the classification of ''Australopithecus'' species is in disarray. ''Australopithecus'' is considered a [[wastebasket taxon]] whose members are united by their similar physiology rather than close relations with each other over other hominin genera. It is unclear how any ''Australopithecus'' species relate to each other,<ref name=McNulty2016>{{cite journal|first=K. P.|last=McNulty|year=2016|title=Hominin Taxonomy and Phylogeny: What's In A Name?|journal=Nature Education Knowledge|volume=7|issue=1|page=2|url=https://www.nature.com/scitable/knowledge/library/hominin-taxonomy-and-phylogeny-what-s-in-142102877/}}</ref> but it is generally thought that a population of ''[[Australopithecus anamensis|A. anamensis]]'' evolved into ''A. afarensis''.<ref name="Kimbel">{{cite journal |last1=Kimbel |first1=W. H. |last2=Lockwood |first2=C. A. |first3=C. V. |last3=Ward |first4=M. G. |last4=Leakey |author4-link=Meave G. Leakey |first5=Y. |last5=Rake |first6=D. C. |last6=Johanson |author6-link=Donald Johanson|title=Was ''Australopithecus anamensis'' ancestral to ''A. afarensis''? A case of anagenesis in the hominin fossil record |journal=Journal of Human Evolution |year=2006 |volume=51 |issue=2 |pages=134–152 |doi=10.1016/j.jhevol.2006.02.003 |pmid=16630646}}</ref><ref>{{cite journal|last1=Haile-Selassie|first1=Y.|author1-link=Yohannes Haile-Selassie|last2=M. Melillo|first2=S.|last3=Vazzana|first3=A.|last4=Benazzi|first4=S.|last5=T.|first5=M. Ryan|year=2019|title=A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia|journal=Nature|volume=573|issue=7773|pages=214–219|doi=10.1038/s41586-019-1513-8|bibcode=2019Natur.573..214H|pmid=31462770|hdl=11585/697577|hdl-access=free}}</ref><ref name=McNulty2016/> Several ''Australopithecus'' species have been postulated to represent the ancestor to ''Homo'', but the 2013 discovery of the earliest ''Homo'' specimen, [[LD 350-1]], 2.8 million years old (older than almost all other ''Australopithecus'' species) from the Afar Region could potentially affirm ''A. afarensis''{{'}} ancestral position.<ref name=Villmoare2015>{{cite journal|first=B.|last=Villmoare|first2=W. H.|last2=Kimbel|first3=C.|last3=Seyoum|display-authors=et al.|year=2015|title=Early ''Homo'' at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia|journal=Science|volume=347|issue=6228|pages=1352–1355|doi=10.1126/science.aaa1343|doi-access=free}}</ref>


For a long time, ''A. afarensis'' was the oldest known hominin until the 1994 description of the 4.4 Ma ''[[Ardipithecus ramidus]]'',<ref name="Suwa_2009">{{cite journal | title=The ''Ardipithecus ramidus skull'' and its implications for hominid origins | journal=Science | last=Suwa | first=G | date=2 October 2009| volume=326 | issue=5949 | pages=68, 68e1–68e7 | doi=10.1126/science.1175825 | last2=Asfaw | first2=B. | last3=Kono | first3=R. T. | last4=Kubo | first4=D. | last5=Lovejoy | first5=C. O. | last6=White | first6=T. D. | pmid=19810194|bibcode = 2009Sci...326...68S |display-authors=et al.| url=http://doc.rero.ch/record/211453/files/PAL_E4442.pdf }}</ref> and a few earlier or contemporary taxa have been described since, including the 3.5 Ma ''[[Kenyanthropus platyops]]'' in 2001,<ref>{{cite journal | last1 = Leakey | first1 = M. G. | display-authors = et al. | year = 2001 | title = New hominin genus from eastern Africa shows diverse middle Pliocene lineages | url = | journal = Nature | volume = 410 | issue = | pages = 433–440 }}</ref> the 6 Ma ''[[Orrorin tugenensis]]'' in 2001,<ref>{{cite journal |last1=Senut |first1=B. |last2=Pickford |first2=M. |last3=Gommery |first3=D.|last4=Mein |first4=P. |last5=Cheboi |first5=K. |last6=Coppens |first6=Y.|author6-link=Yves Coppens |title=First hominid from the Miocene (Lukeino Formation, Kenya) |journal=Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science |year= 2001 |volume=332 |issue=2 |pages=137–144 |doi=10.1016/S1251-8050(01)01529-4 }}</ref> and the 7–6 Ma ''Sahelanthropus tchadensis'' in 2002.<ref name=klages>{{cite journal |last1=Brunet |first1=M. |last2=Guy |first2=F. |last3=Pilbeam |first3=D. |author3-link=David Pilbeam|last4=Mackaye |first4=H. T.|display-authors=et al.|year=2002 |title=A new hominid from the Upper Miocene of Chad, Central Africa |journal=[[Nature (journal)|Nature]] |volume=418 |issue=6894| pages=145–151 |doi=10.1038/nature00879 |pmid=12110880|bibcode=2002Natur.418..145B}}</ref>
For a long time, ''A. afarensis'' was the oldest known hominin until the 1994 description of the 4.4 Ma ''[[Ardipithecus ramidus]]'',<ref name="Suwa_2009">{{cite journal | title=The ''Ardipithecus ramidus skull'' and its implications for hominid origins | journal=Science | last=Suwa | first=G | date=2 October 2009| volume=326 | issue=5949 | pages=68, 68e1–68e7 | doi=10.1126/science.1175825 | last2=Asfaw | first2=B. | last3=Kono | first3=R. T. | last4=Kubo | first4=D. | last5=Lovejoy | first5=C. O. | last6=White | first6=T. D. | pmid=19810194|bibcode = 2009Sci...326...68S |display-authors=et al.| url=http://doc.rero.ch/record/211453/files/PAL_E4442.pdf }}</ref> and a few earlier or contemporary taxa have been described since, including the the 4 Ma ''A. anamensis'' in 1995,<ref>{{cite journal |first1=M. G. |last1=Leakey |author-link=Meave G. Leakey |first2=C. S. |last2=Feibel |first3=I. |last3=MacDougall |first4=A. |author3-link=Ian McDougall (geologist) |last4=Walker |author4-link=Alan Walker (anthropologist) |year=1995 |title=New four-million-year-old hominid species from Kanapoi and Allia Bay, Kenya |journal=Nature |pmid=7637803 |volume=376 |issue=6541 |pages=565–571 |doi=10.1038/376565a0 |bibcode=1995Natur.376..565L}}</ref> the 3.5 Ma ''[[Kenyanthropus platyops]]'' in 2001,<ref>{{cite journal | last1 = Leakey | first1 = M. G. | display-authors = et al. | year = 2001 | title = New hominin genus from eastern Africa shows diverse middle Pliocene lineages | url = | journal = Nature | volume = 410 | issue = | pages = 433–440 }}</ref> the 6 Ma ''[[Orrorin tugenensis]]'' in 2001,<ref>{{cite journal |last1=Senut |first1=B. |last2=Pickford |first2=M. |last3=Gommery |first3=D.|last4=Mein |first4=P. |last5=Cheboi |first5=K. |last6=Coppens |first6=Y.|author6-link=Yves Coppens |title=First hominid from the Miocene (Lukeino Formation, Kenya) |journal=Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science |year= 2001 |volume=332 |issue=2 |pages=137–144 |doi=10.1016/S1251-8050(01)01529-4 }}</ref> and the 7–6 Ma ''Sahelanthropus tchadensis'' in 2002.<ref name=klages>{{cite journal |last1=Brunet |first1=M. |last2=Guy |first2=F. |last3=Pilbeam |first3=D. |author3-link=David Pilbeam|last4=Mackaye |first4=H. T.|display-authors=et al.|year=2002 |title=A new hominid from the Upper Miocene of Chad, Central Africa |journal=[[Nature (journal)|Nature]] |volume=418 |issue=6894| pages=145–151 |doi=10.1038/nature00879 |pmid=12110880|bibcode=2002Natur.418..145B}}</ref>


==Anatomy==
==Anatomy==

Revision as of 19:08, 15 June 2020

Australopithecus afarensis
Temporal range: Pliocene, 3.9–2.9 Ma
↓
The partial skeleton AL 288-1 ("Lucy")
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Homininae
Tribe: Hominini
Genus: †Australopithecus
Species:
†A. afarensis
Binomial name
†Australopithecus afarensis
Synonyms

Australopithecus afarensis (Latin: "Southern ape from Afar") is an extinct hominin that lived between 3.9 and 2.9 million years ago [2] in Africa.[3][4][5] A. afarensis was slenderly built, like the younger Australopithecus africanus. A. afarensis is thought to be more closely related to the genus Homo (which includes the modern human species Homo sapiens), whether as a direct ancestor or a close relative of an unknown ancestor, than any other known primate from the same time.[6]

The most famous fossil is the partial skeleton named Lucy (3.2 million years old) found by Donald Johanson, who was playing the Beatles song "Lucy in the Sky with Diamonds" (where the name Lucy comes from) while at the dig site.[7][8][9]

Taxonomy

Research history

Beginning in the 1930s, some of the most ancient hominin remains of the time dating to 3.8–2.9 million years ago were recovered from Laetoli, Tanzania, and Hadar, Ethiopia. Because Australopithecus africanus fossils were commonly being discovered throughout the 1920s and 40s in South Africa, these remains were provisionally classified as Australopithecus aff. africanus. In 1948, German palaeontologist Edwin Hennig proposed classifying these remains into a new genus, "Praeanthropus", but he failed to give a species name. In 1950, German anthropologist Hans Weinhert proposed classifying a jawbone from the headwaters of the Gerusi River (near Laetoli) as Meganthropus africanus, but this was largely ignored. In 1955, S. Şenyüruk proposed the combination Praeanthropus africanus.[1] Major collections were made in Laetoli on an expedition beginning in 1974 directed by British palaeoanthropologist Mary Leakey, and in Hadar from 1972–1977 by the International Afar Research Expedition (IARE) formed by French geologist Maurice Taieb, American palaeoanthropologist Donald Johanson, and Breton anthropologist Yves Coppens. These fossils were remarkably well-preserved and many had associated skeletal aspects.[10]: 5  In 1976, Leakey and colleagues preliminarily classified Laetoli remains into Homo spp., and attributing Australopithecus-like traits as evidence of them being transitional fossils.[11] In 1973, the IARE team unearthed the first knee joint, AL 129-1, and showed the earliest evidence at the time of bipedalism. In 1974, Johanson and graduate student Tom Gray discovered the partial skeleton AL 288-1, commonly referred to as "Lucy" (named after The Beatles song Lucy in the Sky with Diamonds which was playing on their tape recorder that evening).[12] In 1975, the IARE recovered 216 specimens belonging to 13 individuals, AL 333 "the First Family".[13]: 471–472 

In 1978, Johanson, Tim D. White, and Coppens classified the hundreds of specimens collected thus far into a new species, A. afarensis, and considered the apparently wide range of variation a result of sexual dimorphism. The species name honours the Afar Region of Ethiopia where the majority of the specimens had been recovered from. They later selected the jawbone LH 4 has the lectotype specimen because of its preservation quality and because White had already fully described and illustrated it the year before.[1] In 1979, Johanson and White proposed that A. afarensis was the last common ancestor between Homo and Paranthropus, supplanting A. africanus in this role.[14] Considerable debate of the validity of this species followed, with proposals for synonymising them with A. africanus or recognising multiple species from the Laetoli and Hadar remains. The skull KNM-ER 1470 (now H. rudolfensis) was at first dated to 2.9 mya, which cast doubt on the ancestral position of both A. afarensis or A. africanus, but it has since been re-dated to about 2 mya.[15] Palaeoartist Walter Ferguson has proposed splitting A. afarensis into "H. antiquus", a relict dryopithecine "Ramapithecus" (now Sivapithecus), and a subspecies of A. africanus. His recommendations have largely been ignored.[16][15] In 2003, Spanish writer Camilo José Cela Conde and evolutionary biologist Francisco J. Ayala proposed reinstating "Praeanthropus" including A. afarensis alongside Sahelanthropus, A. anamensis, A. bahrelghazali, and A. garhi.[17]

A. afarensis is known only from East Africa. Beyond Laetoli and Hadar, the species has been recorded in Omo, Maka, Fejej, and Belohdelie in Ethiopia, and Koobi Fora and Lothagam in Kenya.[citation needed]

Classification

A. afarensis is now a widely accepted species, and it is now generally thought that Homo and Paranthropus are sister taxa deriving from Australopithecus, but the classification of Australopithecus species is in disarray. Australopithecus is considered a wastebasket taxon whose members are united by their similar physiology rather than close relations with each other over other hominin genera. It is unclear how any Australopithecus species relate to each other,[18] but it is generally thought that a population of A. anamensis evolved into A. afarensis.[19][20][18] Several Australopithecus species have been postulated to represent the ancestor to Homo, but the 2013 discovery of the earliest Homo specimen, LD 350-1, 2.8 million years old (older than almost all other Australopithecus species) from the Afar Region could potentially affirm A. afarensis' ancestral position.[21]

For a long time, A. afarensis was the oldest known hominin until the 1994 description of the 4.4 Ma Ardipithecus ramidus,[22] and a few earlier or contemporary taxa have been described since, including the the 4 Ma A. anamensis in 1995,[23] the 3.5 Ma Kenyanthropus platyops in 2001,[24] the 6 Ma Orrorin tugenensis in 2001,[25] and the 7–6 Ma Sahelanthropus tchadensis in 2002.[26]

Anatomy

Body mass

A lack of complete skeletons hinders estimations of body mass,[27] but a 2017 work by Brassey et al. calculates a body mass of 20.4 kilograms for Australopithecus afarensis fossil AL 288–1, with a range of between 13.5 and 30.9 kilograms.[27] (By comparison, Walpole et al. (2012) estimate average adult human body mass in 2005 to have been 62 kilograms).[28]

Craniodental features and brain size

File:Australopithecus afarensis adult male - head model - Smithsonian Museum of Natural History - 2012-05-17.jpg
A. afarensis, forensic facial reconstruction[29]

Compared to the modern and extinct great apes, A. afarensis has reduced canines and molars, although they are still larger than those of modern humans. A. afarensis also has a relatively small brain size (about 380–430 cm3) (Holloway, 1983) and a prognathic face (i.e. a face with forward-projecting jaws).

Skeletal morphology and locomotion

Considerable debate surrounds the locomotor behaviour of A. afarensis. Some studies suggest that A. afarensis was almost exclusively bipedal, while others propose that the creatures were partly arboreal. The anatomy of the hands, feet, and shoulder joints in many ways favour the latter interpretation. In particular, the morphology of the scapula appears to be ape-like and very different from modern humans.[30] The curvature of the finger and toe bones (phalanges) approaches that of modern-day apes, and is suggestive of their ability to efficiently grasp branches and climb. Alternatively, the loss of an abductable great toe and therefore the ability to grasp with the foot (a feature of all other primates) suggests A. afarensis was no longer adapted to climbing.[31]

Lucy skeleton reconstruction exhibit at the Cleveland Natural History Museum

A number of traits in the A. afarensis skeleton strongly reflect bipedalism, to the extent some researchers have suggested bipedality evolved long before A. afarensis.[32] In overall anatomy, the pelvis is far more human-like than ape-like. The iliac blades are short and wide, the sacrum is wide and positioned directly behind the hip joint, and evidence of a strong attachment for the knee extensors is clear. While the pelvis is not wholly human-like (being markedly wide, or flared, with laterally oriented iliac blades), these features point to a structure that can be considered radically remodeled to accommodate a significant degree of bipedalism in the animals' locomotor repertoire.[citation needed]

Importantly, the femur also angles in toward the knee from the hip. This trait would have allowed the foot to have fallen closer to the midline of the body, and is a strong indication of habitual bipedal locomotion. The feet also feature adducted big toes, making it difficult if not impossible to grasp branches with the hindlimbs. The loss of a grasping hindlimb also increases the risk of an infant being dropped or falling, as primates typically hold onto their mothers while the mother goes about her daily business. Without the second set of grasping limbs, the infant cannot maintain as strong a grip and likely had to be held with help from the mother. The problem of holding the infant would be multiplied if the mother also had to climb trees. Bones of the foot (such as the calcaneus) also indicate bipedality.[33][34]

Computer simulations using dynamic modeling of the skeleton's inertial properties and kinematics suggest A. afarensis was able to walk in the same way modern humans walk, with a normal erect gait or with bent hips and knees, but could not walk in the same way as chimpanzees. The upright gait would have been much more efficient than the bent knee and hip walking, which would have taken twice as much energy.[35][36]

A. afarensis probably was quite an efficient bipedal walker over short distances, and the spacing of the footprints at Laetoli indicates they were walking at 1.0 m/s or above, which matches human small-town walking speeds.[37] Yet, this can be questioned, as finds of Australopithecus foot bones indicate the Laetoli footprints may not have been made by Australopithecus.[38] Many scientists also doubt the suggestion of bipedalism, and argue that even if Australopithecus really did walk on two legs, it did not walk in the same way as humans.[39][40][41]

The presence of a wrist-locking mechanism, though, might suggest they engaged in knuckle-walking.[42] (However, these conclusions have been questioned on the basis of close analysis of knuckle-walking and the comparison of wrist bones in different species of primates).[43] The shoulder joint is also oriented much more cranially (i.e. towards the skull) than that in modern humans, but similar to that in the present-day apes.[30] Combined with the relatively long arms Au. afarensis is thought to have had, this is thought by many to be reflective of a heightened ability to use the arm above the head in climbing behavior. Furthermore, scans of the skulls reveal a canal and bony labyrinth morphology, which is not supportive to proper bipedal locomotion.[44]

Upright bipedal walking is commonly thought to have evolved from knuckle-walking with bent legs, in the manner used by chimpanzees and gorillas to move around on the ground, but fossils such as Orrorin tugenensis indicate bipedalism around 5 to 8 million years ago, in the same general period when genetic studies suggest the lineage of chimpanzees and humans diverged. Modern apes and their fossil ancestors show skeletal adaptations to an upright posture used in tree-climbing, and upright, straight-legged walking has been proposed to have originally evolved as an adaptation to tree-dwelling.

Studies of modern orangutans in Sumatra have shown these apes use four legs when walking on large, stable branches and when swinging underneath slightly smaller branches, but are bipedal and maintain their legs very straight when using multiple small, flexible branches under 4 cm in diameter, while also using their arms for balance and additional support. This enables them to get nearer to the edge of the tree canopy to grasp fruit or cross to another tree.

Climate changes around 11 to 10 million years ago affected forests in East and Central Africa, establishing periods where openings in forest lands prevented travel through the tree canopy. During such times proto-hominins could have adopted upright walking behavior for ever-increasing ground travel, while the ancestors of gorillas and chimpanzees continued to specialize in climbing vertical tree trunks and lianas with a bent-hip and bent-knee posture—which ultimately lead them also to adopt knuckle-walking for minimal ground travel. This differential development within the larger hominid community would result in A. afarensis being adapted to upright bipedalism for extensive ground travel while still using arms well adapted for climbing smaller trees. Still, the proto-hominins and the ancestors of chimpanzees and gorillas were the closest of relatives, and they shared anatomical features including a fused wrist bone, which may suggest that knuckle-walking was used for a time by human ancestors.[45][46][47]

Other studies suggest an upright spine and a primarily vertical body plan in primates dates back to Morotopithecus bishopi in the Early Miocene of 21.6 Mya, the earliest human-like primates.[48][49] Known from fossil remains found in Africa, australopithecines represent the group from which the ancestors of modern humans emerged. As generally used, the term "australopithecine" covers all early hominin fossils dated from about 7 million to 2.5 million years ago—and some others dated later, i.e., from 2.5 million to 1.4 million years ago. Australopithecines became extinct after that time.[citation needed]

Behaviour

File:A.afarensis.jpg
A reconstruction of a female A. afarensis

One of the best indicators of social behavior in extinct fossil species is the patterns of the size differences between males and females (sexual dimorphism). By comparisons to the behaviors to modern apes and other animals, reproductive behaviors and social structure in A. afarensis can be inferred. One difficulty is that the average difference in body size between male and female A. afarensis is considerably debated. Some propose that males were substantially larger than females similar to gorillas and orangutans. If observations on the relationship between sexual dimorphism and social group structure from modern gorillas are applied to A. afarensis, then these creatures may have lived in small family groups containing a single dominant male and a number of breeding females.[50] Other studies have shown there could have been substantial overlap between males and females in size more similar to the pattern observed in modern humans.[51] This, along with the reduction of the canine teeth, has been argued to suggest A. afarensis males and females were monogamous.[52] Males may have engaged in provisioning behavior, and the need for carrying may have led to the evolution of bipedalism.

For a long time, no known stone tools were associated with A. afarensis, and paleoanthropologists commonly thought stone artifacts only dated back to about 2.5 Mya.[53] However, a 2010 study suggests the hominin species ate meat by carving animal carcasses with stone implements. This finding pushes back the earliest known use of stone tools among hominins to about 3.4 Mya.[54]

Specimens

A. afarensis skull reconstruction, displayed at Museum of Man, San Diego, California
  • LH 4
Main article: LH 4
The type specimen for A. afarensis is an adult mandible from the site of Laetoli, Tanzania.[55]
  • AL 129-1
Main article: AL 129-1
The first A. afarensis knee joint was discovered in November 1973 by Donald Johanson as part of a team involving Maurice Taieb, Yves Coppens, and Tim White in the Middle Awash of Ethiopia's Afar Depression.
  • AL 200-1
Main article: AL 200-1
An upper palate with teeth found in October 1974
  • AL 288-1 (Lucy)
Main article: Lucy (Australopithecus)
The first A. afarensis skeleton was discovered on November 24, 1974 near Hadar in Ethiopia by Tom Gray in the company of Donald Johanson, as part of a team involving Maurice Taieb, Yves Coppens and Tim White in the Middle Awash of Ethiopia's Afar Depression.
  • AL 333
Main article: AL 333
In 1975, a year after the discovery of Lucy, Donald Johanson's team discovered another site in Hadar which included over 200 fossil specimens from at least 13 individuals, both adults and juveniles. This site, AL 333, is commonly referred to as the "First Family". The close alignment of the remains indicates that all the individuals died at the same time, a unique finding.
  • AL 333-160
In February 2011, the discovery of AL 333-160 in Hadar, Ethiopia, at the AL 333 site was announced.[56] The foot bone shows that the species had arches in its feet, which Ward et al. claimed confirmed that the species walked upright for the majority of the time.[57] The foot bone is one of 49 new bones discovered, and indicates that A. afarensis is "a lot more human-like than we had ever supposed before," according to the lead scientist on the study.[58] In a follow-up study by Mitchell et al. that included a more comprehensive sampling than the Ward et al. study, the authors concluded that "Comparisons of the Hadar 4th MT characters to those of statistically representative samples of humans, all five great ape species, baboons and proboscis monkeys show that none of the correlations Ward et al. make to localized foot function were supported by this analysis."[59] They furthermore noted that "Overall, AL 333-160 is most similar to the 4th MT of eastern gorillas, a slow moving quadruped that sacrifices arboreal behaviors for terrestrial ones."
  • AL 444-2
This is the cranium of a male found at Hadar in 1992.[60] By the time it was found, it was the first complete skull of A. afarensis.[61] The rarity of relatively complete craniofacial remains in the A. afarensis samples before the discovery of AL 444-2 seriously hampered prior meaningful analysis of those samples' evolutionary significance. In light of AL 444-2 and other new craniofacial remains, Kimbel, Rak, and Johanson argue in favor of the taxonomic unity of A. afarensis.
  • Kadanuumuu
Main article: KSD-VP-1/1
Also called Big Man, this is a partial skeleton believed to be a male.
  • Selam
Main article: Selam (Australopithecus)
Skeleton of "Selam"
In 2000, the skeleton of a 3-year-old A. afarensis female, which comprised almost the entire skull and torso, and most parts of the limbs, was discovered in Dikika, Ethiopia, a few miles from the place where Lucy was found. The features of the skeleton suggested adaptation to walking upright (bipedalism) as well as tree-climbing, features that match the skeletal features of Lucy and fall midway between human and hominid ape anatomy. "Baby Lucy" has officially been named Selam (meaning "peace" in the Amharic/Ethiopian Language).[62]

See also

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Further reading

External links

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