Australopithecus

{{short description|Genus of hominin ancestral to modern humans}}

{{for|the collective tribe|Australopithecine}}

{{Automatic taxobox

| display_parents = 3

| taxon = Australopithecus

| authority = R.A. Dart, 1925

| fossil_range = {{fossilrange|4.5|1.5|ZancleanGelasian, 4.5–1.9/1.2 mya}}

| image = Mrs Ples Face.jpg

| image_caption = Mrs. Ples, an Australopithecus africanus specimen

| type_species = {{extinct}}Australopithecus africanus

| type_species_authority = Dart, 1925

| subdivision_ranks = Species

| subdivision = *†A. afarensis

Classically excluded but cladistically included:

}}

Australopithecus ({{IPAc-en|ˌ|ɒ|s|t|r|ə|l|ə|ˈ|p|ɪ|θ|ᵻ|k|ə|s|,_|-|l|oʊ|-}}, {{respell|OS|trə|lə|PITH|i|kəs|,_|-|loh|-}};{{refn|{{Citation |last=Jones |first=Daniel |author-link=Daniel Jones (phonetician) |title=English Pronouncing Dictionary |editor=Peter Roach |editor2=James Hartmann |editor3=Jane Setter |place=Cambridge |publisher=Cambridge University Press |orig-year=1917 |year=2003 |isbn=978-3-12-539683-8 }}}} or ({{IPAc-en|ɒ|s|ˌ|t|r|ə|l|ə|p|ɪ|ˈ|θ|iː|k|ə|s|}}, {{respell|os|TRA|lə|pi|THEE|kəs|}}Pronunciation with stressed penultimate syllable and long-E is used by anthropologists such as Lee Berger (https://www.youtube.com/watch?v=rm_tWwZSRzU) and Raymond Dart (https://www.youtube.com/watch?v=b9A2tpvXkWQ&t=2297s) (time 38:20) and conforms to ALA-LC Romanization tables (https://www.loc.gov/catdir/cpso/romanization/greek.pdf) and classical scholarship (Kelly, H.A., 1986. Pronouncing Latin words in English. The Classical World, 80(1), pp.33-37). {{ety|la|australis|southern|grc|πίθηκος (pithekos)|ape}}{{cite web|url=https://research.amnh.org/paleontology/perissodactyl/concepts/glossary|archive-url=https://web.archive.org/web/20211120123130/https://research.amnh.org/paleontology/perissodactyl/concepts/glossary|archive-date=20 November 2021|title=Glossary. American Museum of Natural History}}) is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera Homo (which includes modern humans), Paranthropus, and Kenyanthropus evolved from some Australopithecus species. Australopithecus is a member of the subtribe Australopithecina,{{Sfn|Wood|Richmond|2000|p=}}{{Sfn|Briggs|Crowther|2008|p=124}} which sometimes also includes Ardipithecus,{{Sfn|Wood|2010|p=}} though the term "australopithecine" is sometimes used to refer only to members of Australopithecus. Species include A. garhi, A. africanus, A. sediba, A. afarensis, A. anamensis, A. bahrelghazali, and A. deyiremeda. Debate exists as to whether some Australopithecus species should be reclassified into new genera, or if Paranthropus and Kenyanthropus are synonymous with Australopithecus, in part because of the taxonomic inconsistency.{{cite journal |author=Haile-Selassie, Y |date=27 October 2010 |title=Phylogeny of early Australopithecus: new fossil evidence from the Woranso-Mille (central Afar, Ethiopia)|journal=Philosophical Transactions of the Royal Society B: Biological Sciences |volume=365 |issue=1556 |pages=3323–3331 |pmid=20855306 |pmc=2981958 |doi=10.1098/rstb.2010.0064}}

Furthermore, because e.g. A. africanus is more closely related to humans, or their ancestors at the time, than e.g. A. anamensis and many more Australopithecus branches, Australopithecus cannot be consolidated into a coherent grouping without also including the genus Homo and other genera.

The earliest known member of the genus, A. anamensis, existed in eastern Africa around 4.2 million years ago. Australopithecus fossils become more widely dispersed throughout eastern and southern Africa (the Chadian A. bahrelghazali indicates that the genus was much more widespread than the fossil record suggests), before eventually becoming extinct 1.9 million years ago (or 1.2 to 0.6 million years ago if Paranthropus is included). While none of the groups normally directly assigned to this group survived, Australopithecus gave rise to living descendants, as the genus Homo emerged from an Australopithecus species{{cite journal | last1 = Asfaw | first1 = B | last2 = White | first2 = T | last3 = Lovejoy | first3 = O | last4 = Latimer | first4 = B | last5 = Simpson | first5 = S | last6 = Suwa | first6 = G | title = Australopithecus garhi: a new species of early hominid from Ethiopia | journal =Science | volume = 284 | issue = 5414 | pages = 629–35 | year = 1999 | pmid = 10213683 | doi = 10.1126/science.284.5414.629 | bibcode = 1999Sci...284..629A}}{{Cite web|url=http://www.bradshawfoundation.com/origins/australopithecus_africanus.php|title=Exploring the fossil record: Australopithecus africanus|website=Bradshaw Foundation|language=en|access-date=2019-11-11}}{{Cite journal |last1=Berger |first1=L. R. |last2=de Ruiter |first2=D. J. |last3=Churchill |first3=S. E. |last4=Schmid |first4=P. |last5=Carlson |first5=K. J. |last6=Dirks |first6=P. H. G. M. |last7=Kibii |first7=J. M. |year=2010 |title=Australopithecus sediba: a new species of Homo-like australopith from South Africa |journal=Science |volume=328 |issue=5975 |pages=195–204 |doi=10.1126/science.1184944 |pmid=20378811|citeseerx=10.1.1.729.7802 |bibcode=2010Sci...328..195B |s2cid=14209370 }}Toth, Nicholas and Schick, Kathy (2005). "African Origins" in The Human Past: World Prehistory and the Development of Human Societies (Editor: Chris Scarre). London: Thames and Hudson. Page 60. {{ISBN|0-500-28531-4}}{{overcite|date=April 2024}} at some time between 3 and 2 million years ago.{{cite journal |author1=Kimbel, W.H. |author2=Villmoare, B. |date=5 July 2016 |title=From Australopithecus to Homo: the transition that wasn't|journal=Philosophical Transactions of the Royal Society of London B: Biological Sciences |volume=371 |issue=1698|pages=20150248 |doi=10.1098/rstb.2015.0248 |pmid=27298460 |pmc=4920303 }}

Australopithecus possessed two of the three duplicated genes derived from SRGAP2 roughly 3.4 and 2.4 million years ago (SRGAP2B and SRGAP2C), the second of which contributed to the increase in number and migration of neurons in the human brain.{{Cite web|url=https://www.newscientist.com/article/dn21777-the-humanity-switch-how-one-gene-made-us-brainier/|title=The humanity switch: How one gene made us brainier|last=Reardon|first=Sara|date=2012-05-03|website=New Scientist|language=en-US|access-date=2020-03-06}}{{Cite journal|last1=Sporny|first1=Michael|last2=Guez-Haddad|first2=Julia|last3=Kreusch|first3=Annett|last4=Shakartzi|first4=Sivan|last5=Neznansky|first5=Avi|last6=Cross|first6=Alice|last7=Isupov|first7=Michail N.|last8=Qualmann|first8=Britta|last9=Kessels|first9=Michael M.|last10=Opatowsky|first10=Yarden|date=June 2017|title=Structural History of Human SRGAP2 Proteins|journal=Molecular Biology and Evolution|volume=34|issue=6|pages=1463–1478|doi=10.1093/molbev/msx094|issn=0737-4038|pmc=5435084|pmid=28333212}} Significant changes to the hand first appear in the fossil record of later A. afarensis about 3 million years ago (fingers shortened relative to thumb and changes to the joints between the index finger and the trapezium and capitate).{{Cite journal |author1=Tocheri, Matthew W. |author2=Orr, Caley M. |author3=Jocofsky, Marc C. |author4=Marzke, Mary W. |author4-link=Mary Marzke|date=April 2008 |title=The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo|journal=Journal of Anatomy|volume=212 |issue=4 |pages=544–562 |doi=10.1111/j.1469-7580.2008.00865.x |pmid=18380869|pmc=2409097 }}

Taxonomy

=Research history=

File:Australopithecus africanus Taung face (University of Zurich).JPG's skull]]

The first Australopithecus specimen, the type specimen, was discovered in 1924 in a lime quarry by workers at Taung, South Africa. The specimen was studied by the Australian anatomist Raymond Dart, who was then working at the University of the Witwatersrand in Johannesburg. The fossil skull was from a three-year-old bipedal primate (nicknamed Taung Child) that he named Australopithecus africanus. The first report was published in Nature in February 1925. Dart realised that the fossil contained a number of humanoid features, and so he came to the conclusion that this was an early human ancestor.{{cite book|title= Human Evolution: An Illustrated Introduction |last=Lewin |first=Roger |chapter=The Australopithecines |year=1999 |publisher= Blackwell Science |isbn=0632043091 |pages=112–113}} Later, Scottish paleontologist Robert Broom and Dart set out to search for more early hominin specimens, and several more A. africanus remains from various sites. Initially, anthropologists were largely hostile to the idea that these discoveries were anything but apes, though this changed during the late 1940s.

In 1950, evolutionary biologist Ernst Walter Mayr said that all bipedal apes should be classified into the genus Homo, and considered renaming Australopithecus to Homo transvaalensis.{{cite journal|author1=Schwartz, Jeffrey H.|author2=Tattersall, Ian|date=2015|title=Defining the genus Homo|journal=Science|volume=349|issue=931|pages=931–932|bibcode=2015Sci...349..931S|doi=10.1126/science.aac6182|pmid=26315422|s2cid=206639783}} However, the contrary view taken by J.T. Robinson in 1954, excluding australopiths from Homo, became the prevalent view. The first australopithecine fossil discovered in eastern Africa was an A. boisei skull excavated by Mary Leakey in 1959 in Olduvai Gorge, Tanzania. Since then, the Leakey family has continued to excavate the gorge, uncovering further evidence for australopithecines, as well as for Homo habilis and Homo erectus. The scientific community took 20 more years to widely accept Australopithecus as a member of the human family tree.

In 1997, an almost complete Australopithecus skeleton with skull was found in the Sterkfontein caves of Gauteng, South Africa. It is now called "Little Foot" and it is around 3.7 million years old. It was named Australopithecus prometheusBruxelles L., Clarke R. J., Maire R., Ortega R., et Stratford D. – 2014. – Stratigraphic analysis of the Sterkfontein StW 573 Australopithecus skeleton and implications for its age. Journal of Human Evolution,{{Cite web |title=New stratigraphic research makes Little Foot the oldest complete Australopithecus |url=http://phys.org/news/2014-03-stratigraphic-foot-oldest-australopithecus.html}} which has since been placed within A. africanus. Other fossil remains found in the same cave in 2008 were named Australopithecus sediba, which lived 1.9 million years ago. A. africanus probably evolved into A. sediba, which some scientists think may have evolved into H. erectus,{{cite news |url= https://www.nytimes.com/2010/04/09/science/09fossil.html |title=New Hominid Species Discovered in South Africa |newspaper=The New York Times |author=Celia W. Dugger |author2=John Noble Wilford |date=April 8, 2010}} though this is heavily disputed.

In 2003, Spanish writer Camilo José Cela Conde and evolutionary biologist Francisco J. Ayala proposed resurrecting the genus Praeanthropus to house Orrorin, A. afarensis, A. anamensis, A. bahrelghazali, and A. garhi,{{Cite journal | last1 = Cela-Conde | first1 = C. J.| last2 = Ayala | first2 = F. J. | 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| doi-access = free}} but this genus has been largely dismissed.{{cite journal|last=Tattersall|first=I.|author-link=Ian Tattersall|year=2017|title=Species, genera, and phylogenetic structure in the human fossil record: a modest proposal|journal=Evolutionary Anthropology: Issues, News, and Reviews|volume=26|issue=3|pages=116–118|doi=10.1002/evan.21523|pmid=28627785|s2cid=43487900|quote=Forms such as Ardipithecus, Sahelanthropus, and Orrorin have also been admitted to the pantheon, though this has clearly been facilitated by their great age. And in a nod to history, the venerable genus Paranthropus has been grandfathered in for use by those who think it useful. But except for the widely dismissed revival of Praeanthropus, there has been little real rethinking of the hugely minimalist hominid taxonomy, generic as well as specific, that Mayr foisted on us all those years ago...}}

=Classification=

With the apparent emergence of the genera Homo, Kenyanthropus, and Paranthropus in the genus Australopithecus, taxonomy runs into some difficulty, as the name of species incorporates their genus. According to cladistics, groups should not be left paraphyletic, where it is kept not consisting of a common ancestor and all of its descendants.{{Citation|last=Kimbel|first=William H.|chapter=The Species and Diversity of Australopiths|date=2015|pages=2071–2105|editor-last=Henke|editor-first=Winfried|publisher=Springer Berlin Heidelberg|language=en|doi=10.1007/978-3-642-39979-4_50|isbn=9783642399787|editor2-last=Tattersall|editor2-first=Ian|title=Handbook of Paleoanthropology}}{{Cite book|url= https://books.google.com/books?id=--PNXm0q2O8C&pg=PA364 |page=364 |title=Primate Adaptation and Evolution|last=Fleagle|first=John G.|date=2013-03-08|publisher=Academic Press|isbn=9780123786333|language=en}}{{Cite journal|last=Schwarz|first=J.H.|s2cid=12944654|date=2004|title=Barking up the wrong ape--australopiths and the quest for chimpanzee characters in hominid fossils|journal=Collegium Antropologicum|volume=28|issue=Suppl 2 |pages=87–101|pmid=15571084}}{{Cite journal|last=Cartmill|first=Matt|title=A sort of revolution: Systematics and physical anthropology in the 20th century|journal=American Journal of Physical Anthropology|language=en|volume=165|issue=4|pages=677–687|doi=10.1002/ajpa.23321|pmid=29574829|hdl=2144/29233|year=2018|doi-access=free|hdl-access=free}}{{Cite journal|last=Villmoare|first=Brian|date=2018-01-30|title=Early Homo and the role of the genus in paleoanthropology|journal=American Journal of Physical Anthropology|language=en|volume=165|pages=72–89|doi=10.1002/ajpa.23387|pmid=29380889|issn=0002-9483|doi-access=free}}{{Cite web|url= https://www.researchgate.net/publication/267552437|title=2 @BULLET Enhanced cognitive capacity as a contingent fact of hominid phylogeny|website=ResearchGate|language=en|access-date=2019-01-12}} Resolving this problem would cause major ramifications in the nomenclature of all descendent species. Possibilities suggested have been to rename Homo sapiens to Australopithecus sapiens{{Cite journal|last=Flegr|first=Jaroslav|date=2013-11-27|title=Why Drosophila is not Drosophila any more, why it will be worse and what can be done about it?|journal=Zootaxa|language=en|volume=3741|issue=2|pages=295–300|doi=10.11646/zootaxa.3741.2.8|pmid=25112991|issn=1175-5334}} (or even Pan sapiens{{Cite book |last1=Pietrzak-Franger |first1=Monika |url=https://books.google.com/books?id=k1m8AgAAQBAJ&pg=PA118 |title=Reflecting on Darwin |last2=Schaff |first2=Barbara |last3=Voigts |first3=Eckart |date=2014-02-28 |publisher=Ashgate Publishing, Ltd. |isbn=9781472414090 |page=118 |language=en}}{{Cite book|url= https://books.google.com/books?id=DCUD9E-x8iEC |title=Science: A History: A History|last=Gribbin|first=John|date=2009-08-27|publisher=Penguin Books Limited|isbn=9780141042220|language=en}}), or to move some Australopithecus species into new genera.{{Cite web|url= https://medium.com/@johnhawks/the-plot-to-kill-homo-habilis-94a33bee2adf|title=The plot to kill Homo habilis|last=Hawks|first=John|date=2017-03-20|website=Medium|access-date=2019-03-24}} A study reported in 2025 reported preliminary success in extracting ancient proteins from an Australopithic tooth, suggesting that paleoproteomics has the potential to provide information about the genetic affinities of the species.{{cite journal| last=Madupe |first=Palesa |display-authors=etal| journal= South African Journal of Science|title=Results from an Australopithecus africanus dental enamel fragment confirm the potential of palaeoproteomics for South African Plio-Pleistocene fossil sites|volume= 121|number=1/2 |url= |doi=10.17159/sajs.2025/18571 |date=2025 |pages= |issn= |doi-access=free}}

In 2002 and again in 2007, Camilo José Cela Conde et al. suggested that A. africanus be moved to Paranthropus. On the basis of craniodental evidence, Strait and Grine (2004) suggest that A. anamensis and A. garhi should be assigned to new genera.{{cite journal|author1=Strait, David S.|author2=Grine, Frederick E.|date=December 2004|title=Inferring hominoid and early hominid phylogeny using craniodental characters: the role of fossil taxa|journal=Journal of Human Evolution|volume=47|issue=6|pages=399–452|doi=10.1016/j.jhevol.2004.08.008|pmid=15566946|bibcode=2004JHumE..47..399S }} It is debated whether or not A. bahrelghazali should be considered simply a western variant of A. afarensis instead of a separate species.{{Cite journal|url=https://www.nature.com/scitable/knowledge/library/australopithecus-and-kin-145077614/|title=Australopithecus and Kin|author1=Ward, Carol V. |author2=Hammind, Ashley S. |date=2016| journal= Nature Education Knowledge |volume=7 |issue=3 |pages=1 |language=en|access-date=2019-11-13}}{{Cite book |last1=White |first1=Tim D.|year=2002 |chapter=Chapter 24 Earliest Hominids| editor1-last=Hartwig |editor1-first=Walter Carl |title=The Primate Fossil Record (Cambridge Studies in Biological and Evolutionary Anthropology)|publisher=Cambridge University Press |isbn=0-521-66315-6}}

{{African hominin timeline}}

Evolution

{{Human timeline}}

File:Map of the fossil sites of the early hominids (4.4-1M BP).svg

A. anamensis may have descended from or was closely related to Ardipithecus ramidus.{{cite journal|last1=Haile-Selassie|first1=Yohannes|last2=Melillo|first2=Stephanie M.|last3=Vazzana|first3=Antonino|last4=Benazzi|first4=Stefano|last5=Ryan|first5=Timothy M.|title=A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia|journal=Nature|volume=573|issue=7773|pages=214–219|year=2019|doi=10.1038/s41586-019-1513-8|pmid=31462770|hdl=11585/697577|hdl-access=free|bibcode=2019Natur.573..214H|s2cid=201656331}} A. anamensis shows some similarities to both Ar. ramidus and Sahelanthropus.

Australopiths shared several traits with modern apes and humans, and were widespread throughout Eastern and Northern Africa by 3.5 million years ago (mya). The earliest evidence of fundamentally bipedal hominins is a (3.6 mya) fossil trackway in Laetoli, Tanzania, which bears a remarkable similarity to those of modern humans. The footprints have generally been classified as australopith, as they are the only form of prehuman hominins known to have existed in that region at that time.{{Cite journal|year=2010 |author=David A. Raichlen |author2=Adam D. Gordon |author3=William E. H. Harcourt-Smith|author4=Adam D. Foster |author5=Wm. Randall Haas Jr |title=Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal Biomechanics |journal=PLOS ONE|pmid=20339543 |volume=5 |issue=3|pmc=2842428 |page= e9769 |doi=10.1371/journal.pone.0009769|editor1-last=Rosenberg|editor1-first=Karen|bibcode=2010PLoSO...5.9769R |doi-access=free }}

According to the Chimpanzee Genome Project, the human–chimpanzee last common ancestor existed about five to six million years ago, assuming a constant rate of mutation. However, hominin species dated to earlier than the date could call this into question.{{cite journal |author=Bower, Bruce |date=May 20, 2006 |title=Hybrid-Driven Evolution: Genomes show complexity of human-chimp split |journal=Science News |volume=169 |issue=20 |pages=308–309 |jstor=4019102 |doi=10.2307/4019102}} Sahelanthropus tchadensis, commonly called "Toumai", is about seven million years old and Orrorin tugenensis lived at least six million years ago. Since little is known of them, they remain controversial among scientists since the molecular clock in humans has determined that humans and chimpanzees had a genetic split at least a million years later.{{citation needed|reason=see no evidence this is fixed or agreed by all scientists|date=November 2019}} One theory suggests that the human and chimpanzee lineages diverged somewhat at first, then some populations interbred around one million years after diverging.

Anatomy

The brains of most species of Australopithecus were roughly 35% of the size of a modern human brain{{Cite web|url=http://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-afarensis|title=Australopithecus afarensis|date=2010-01-25|website=The Smithsonian Institution's Human Origins Program|language=en|access-date=2020-01-09}} with an endocranial volume average of {{cvt|466|cc}}. Although this is more than the average endocranial volume of chimpanzee brains at {{cvt|360|cc}} the earliest australopiths (A. anamensis) appear to have been within the chimpanzee range, whereas some later australopith specimens have a larger endocranial volume than that of some early Homo fossils.

Most species of Australopithecus were diminutive and gracile, usually standing {{convert|1.2|to|1.4|m|abbr=on}} tall. It is possible that they exhibited a considerable degree of sexual dimorphism, males being larger than females.{{cite book|url= https://archive.org/details/mcdougallittellw00beck |url-access= registration |last=Beck |first=Roger B. |author2=Linda Black |author3=Larry S. Krieger |author4=Phillip C. Naylor |author5=Dahia Ibo Shabaka |title=World History: Patterns of Interaction |publisher=McDougal Littell |year=1999 |isbn=978-0-395-87274-1 }} In modern populations, males are on average a mere 15% larger than females, while in Australopithecus, males could be up to 50% larger than females by some estimates. However, the degree of sexual dimorphism is debated due to the fragmentary nature of australopith remains. One paper finds that A. afarensis had a level of dimorphism close to modern humans.Reno, Philip L., Richard S. Meindl, Melanie A. McCollum, and C. Owen Lovejoy. 2003."Sexual Dimorphism in Australopithecus Afarensis Was Similar to That of Modern Humans." Proceedings of the National Academy of Sciences 100 (16): 9404–9. https://doi.org/10.1073/pnas.1133180100.

According to A. Zihlman, Australopithecus body proportions closely resemble those of bonobos (Pan paniscus),{{cite journal|vauthors=Zihlman AL, Cronin JE, Cramer DL, Sarich VM |year=1978 |title=Pygmy chimpanzee as a possible prototype for the common ancestor of humans, chimpanzees and gorillas |journal=Nature |volume=275 |issue=5682| pages=744–6 |pmid=703839 |doi=10.1038/275744a0 |bibcode=1978Natur.275..744Z |s2cid=4252525 }} leading evolutionary biologist Jeremy Griffith to suggest that bonobos may be phenotypically similar to Australopithecus.{{cite book|last=Griffith|first=Jeremy |author-link=Jeremy Griffith |title=Freedom Book 1|volume= Part 8:4G| year=2013|publisher=WTM Publishing & Communications|isbn=978-1-74129-011-0|url= http://www.worldtransformation.com/freedom-book1-integration-through-love-indoctrination/| access-date=28 March 2013}} Furthermore, thermoregulatory models suggest that australopiths were fully hair covered, more like chimpanzees and bonobos, and unlike humans.{{cite journal |last1=David-Barrett |first1=T. |last2=Dunbar |first2=R.I.M. |year=2016 |title=Bipedality and Hair-loss Revisited: The Impact of Altitude and Activity Scheduling |doi=10.1016/j.jhevol.2016.02.006 |journal=Journal of Human Evolution |volume=94 |pages=72–82 |pmid=27178459 |pmc=4874949}}

File: Australopithecus sediba (Fundort Malapa).jpg by Adrie and Alfons Kennis at the Neanderthal Museum, Germany]]

The fossil record seems to indicate that Australopithecus is ancestral to Homo and modern humans. It was once assumed that large brain size had been a precursor to bipedalism, but the discovery of Australopithecus with a small brain but developed bipedality upset this theory. Nonetheless, it remains a matter of controversy as to how bipedalism first emerged. The advantages of bipedalism were that it left the hands free to grasp objects (e.g., carry food and young), and allowed the eyes to look over tall grasses for possible food sources or predators, but it is also argued that these advantages were not significant enough to cause the emergence of bipedalism.{{citation needed|date=May 2020}} Earlier fossils, such as Orrorin tugenensis, indicate bipedalism around six million years ago, around the time of the split between humans and chimpanzees indicated by genetic studies. This suggests that erect, straight-legged walking originated as an adaptation to tree-dwelling.{{cite journal|last1=Thorpe |first1=SK |last2=Holder |first2=RL |last3=Crompton |first3=RH. |year=2007 |title=Origin of human bipedalism as an adaptation for locomotion on flexible branches |journal=Science |volume=316 |issue=5829| pages=1328–31 |pmid=17540902 |doi=10.1126/science.1140799|bibcode=2007Sci...316.1328T |s2cid=85992565 }} Major changes to the pelvis and feet had already taken place before Australopithecus.{{cite journal |author=Lovejoy, C. O. |title=Evolution of Human walking |journal=Scientific American |volume=259 |issue=5 |pages=82–89 |year=1988 |doi=10.1038/scientificamerican1188-118 |pmid=3212438|bibcode=1988SciAm.259e.118L }} It was once thought that humans descended from a knuckle-walking ancestor,{{cite journal |pmid=11786992 |last1=Richmond |first1=BG |last2=Begun |first2=DR |last3=Strait |first3=DS |title=Origin of human bipedalism: The knuckle-walking hypothesis revisited |journal=American Journal of Physical Anthropology |volume=Suppl 33 |year=2001 |pages=70–105 |doi=10.1002/ajpa.10019|doi-access=free }} but this is not well-supported.{{cite journal|last1=Kivell |first1=TL |last2=Schmitt |first2=D. |date=Aug 2009 |title=Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=106 |issue=34| pages=14241–6 |doi=10.1073/pnas.0901280106 |pmc=2732797 |pmid=19667206 |bibcode=2009PNAS..10614241K |doi-access=free }}

Australopithecines have thirty-two teeth, like modern humans. Their molars were parallel, like those of great apes, and they had a slight pre-canine gap (diastema). Their canines were smaller, like modern humans, and with the teeth less interlocked than in previous hominins. In fact, in some australopithecines, the canines are shaped more like incisors.Kay, R.F., 1985, 'DENTAL EVIDENCE FOR THE DIET OF AUSTRALOPITHECUS', Annual Review of Anthropology, 14, pp. 315-341. The molars of Australopithecus fit together in much the same way those of humans do, with low crowns and four low, rounded cusps used for crushing. They have cutting edges on the crests. However, australopiths generally evolved a larger postcanine dentition with thicker enamel.{{cite book |title=Evolution: The First Four Billion Years |author=McHenry, H. M. |chapter=Human Evolution |editor=Michael Ruse |editor2=Joseph Travis |year=2009 |publisher=The Belknap Press of Harvard University Press |location=Cambridge, Massachusetts |isbn=978-0-674-03175-3 |pages=[https://archive.org/details/evolutionfirstfo00mich/page/261 261–265] |chapter-url=https://archive.org/details/evolutionfirstfo00mich/page/261 }} Australopiths in general had thick enamel, like Homo, while other great apes have markedly thinner enamel. Robust australopiths wore their molar surfaces down flat, unlike the more gracile species, who kept their crests.

Diet

{{Multiple image|align=left|image1=Paranthropus boisei IMG 2933-white.jpg|image2=Australopithecus afarensis Cleveland Museum.jpg|footer=The robust Paranthropus boisei (left) vs the gracile A. anamensis (right)|total_width=400}}

Australopithecus species are thought to have eaten mainly fruit, vegetables, and tubers, and perhaps easy-to-catch animals such as small lizards. Much research has focused on a comparison between the South African species A. africanus and Paranthropus robustus. Early analyses of dental microwear in these two species showed, compared to P. robustus, A. africanus had fewer microwear features and more scratches as opposed to pits on its molar wear facets.{{cite journal|author=Grine FE |year=1986 |title=Dental evidence for dietary differences in Australopithecus and Paranthropus – a quantitative-analysis of permanent molar microwear |journal=Journal of Human Evolution |volume=15 |issue=8| pages=783–822 |doi=10.1016/S0047-2484(86)80010-0 |bibcode=1986JHumE..15..783G }} Microwear patterns on the cheek teeth of A. afarensis and A. anamensis indicate that A. afarensis predominantly ate fruits and leaves, whereas A. anamensis included grasses and seeds (in addition to fruits and leaves).{{cite journal | last1 = Martínez | first1 = L. | last2 = Estebaranz-Sánchez | first2 = F. | last3 = Galbany | first3 = J. | last4 = Pérez-Pérez | first4 = A. | year = 2016 | title = Testing Dietary Hypotheses of East African Hominines Using Buccal Dental Microwear Data | journal = PLOS ONE | volume = 11 | issue = 11| pages = 1–25 | doi = 10.1371/journal.pone.0165447 | pmid = 27851745 | pmc = 5112956 | bibcode = 2016PLoSO..1165447M | doi-access = free }} The thickening of enamel in australopiths may have been a response to eating more ground-bound foods such as tubers, nuts, and cereal grains with gritty dirt and other small particulates which would wear away enamel. Gracile australopiths had larger incisors, which indicates tearing food was important, perhaps eating scavenged meat. Nonetheless, the wearing patterns on the teeth support a largely herbivorous diet.

In 1992, trace-element studies of the strontium/calcium ratios in robust australopith fossils suggested the possibility of animal consumption, as they did in 1994 using stable carbon isotopic analysis.{{cite web |author=Billings, Tom |access-date=2007-01-06 |title=Comparative Anatomy and Physiology Brought Up to Date--continued, Part 3B) |url= http://www.beyondveg.com/billings-t/comp-anat/comp-anat-3b.shtml| archive-url= https://web.archive.org/web/20061215105652/http://beyondveg.com/billings-t/comp-anat/comp-anat-3b.shtml| archive-date= 15 December 2006 | url-status= live}} In 2005, fossil animal bones with butchery marks dating to 2.6 million years old were found at the site of Gona, Ethiopia. This implies meat consumption by at least one of three species of hominins occurring around that time: A. africanus, A. garhi, and/or P. aethiopicus.{{cite web |author=Nature |title=Evidence for Meat-Eating by Early Humans |url= http://www.nature.com/scitable/knowledge/library/evidence-for-meat-eating-by-early-humans-103874273 }} In 2010, fossils of butchered animal bones dated 3.4 million years old were found in Ethiopia, close to regions where australopith fossils were found.{{cite journal |author=Nature |title=Butchering dinner 3.4 million years ago |journal=Nature |url= http://www.nature.com/news/2010/100811/full/news.2010.399.html | doi=10.1038/news.2010.399 |year=2010 }} However, a 2025 study measuring nitrogen isotope ratios in fossilized teeth determined that Australopithecus was almost entirely vegetarian.{{Cite web |title=A Diet Discovery Reveals That Our Ancestors Were Once Vegetarian |url=https://www.discovermagazine.com/the-sciences/a-diet-discovery-reveals-that-our-ancestors-were-once-vegetarian |access-date=2025-01-22 |website=Discover Magazine |language=en}}{{Cite journal |last=Lüdecke |first=Tina |last2=Leichliter |first2=Jennifer N. |last3=Stratford |first3=Dominic |last4=Sigman |first4=Daniel M. |last5=Vonhof |first5=Hubert |last6=Haug |first6=Gerald H. |last7=Bamford |first7=Marion K. |last8=Martínez-García |first8=Alfredo |date=2025-01-17 |title=Australopithecus at Sterkfontein did not consume substantial mammalian meat |url=https://www.science.org/doi/10.1126/science.adq7315 |journal=Science |volume=387 |issue=6731 |pages=309–314 |doi=10.1126/science.adq7315}}

Robust australopithecines (Paranthropus) had larger cheek teeth than gracile australopiths, possibly because robust australopithecines had more tough, fibrous plant material in their diets, whereas gracile australopiths ate more hard and brittle foods. However, such divergence in chewing adaptations may instead have been a response to fallback food availability. In leaner times, robust and gracile australopithecines may have turned to different low-quality foods (fibrous plants for the former, and hard food for the latter), but in more bountiful times, they had more variable and overlapping diets.{{cite journal|first1=P. S.|last1=Ungar|first2=F. E.|last2=Grine|first3=M. F.|last3=Teaford|year=2008|title=Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei|journal=PLOS ONE|volume=3|issue=4|page=e2044|doi=10.1371/journal.pone.0002044|pmc=2315797|pmid=18446200|bibcode=2008PLoSO...3.2044U|doi-access=free}}{{cite journal|vauthors=Scott RS, Ungar PS, Bergstrom TS, Brown CA, Grine FE, Teaford MF, Walker A |year=2005 |title=Dental microwear texture analysis shows within-species diet variability in fossil hominins |journal=Nature |volume=436 |issue=7051| pages=693–695 |doi=10.1038/nature03822 |bibcode=2005Natur.436..693S |pmid=16079844|s2cid=4431062 |url=http://doc.rero.ch/record/15300/files/PAL_E2599.pdf }} In a 1979 preliminary microwear study of Australopithecus fossil teeth, anthropologist Alan Walker theorized that robust australopiths ate predominantly fruit (frugivory).{{cite news |author=Rensberger |first=Boyce |access-date=11 August 2021 |title=Teeth Show Fruit Was The Staple |url= https://www.nytimes.com/1979/05/15/archives/teeth-show-fruit-was-the-staple-no-exceptions-found.html |work=The New York Times |date=1979-05-15}}

A study in 2018 found non-carious cervical lesions, caused by acid erosion, on the teeth of A. africanus, probably caused by consumption of acidic fruit.{{Cite journal|date=2018-09-01|title=Root grooves on two adjacent anterior teeth of Australopithecus africanus|journal=International Journal of Paleopathology|volume=22|pages=163–167|doi=10.1016/j.ijpp.2018.02.004|issn=1879-9817|last1=Towle|first1=Ian|last2=Irish|first2=Joel D.|last3=Elliott|first3=Marina|last4=De Groote|first4=Isabelle|pmid=30126662|s2cid=52056962|url=http://researchonline.ljmu.ac.uk/id/eprint/8352/1/Root%20groove%20article%20JDI.pdf}}

Technology

It is debated if the Australopithecus hand was anatomically capable of producing stone tools.{{Cite journal |last1=Domalain |first1=Mathieu |last2=Bertin |first2=Anne |last3=Daver |first3=Guillaume |date=2017-08-01 |title=Was Australopithecus afarensis able to make the Lomekwian stone tools? Towards a realistic biomechanical simulation of hand force capability in fossil hominins and new insights on the role of the fifth digit |journal=Comptes Rendus Palevol |series=Hominin biomechanics, virtual anatomy and inner structural morphology: From head to toe. A tribute to Laurent Puymerail |language=en |volume=16 |issue=5 |pages=572–584 |doi=10.1016/j.crpv.2016.09.003 |bibcode=2017CRPal..16..572D |issn=1631-0683|doi-access=free }} A. garhi was associated with large mammal bones bearing evidence of processing by stone tools, which may indicate australopithecine tool production.{{cite journal|first1=S.|last1=Semaw|first2=P.|last2=Renne|first3=J. W. K.|last3=Harris|year=1997|title=2.5-million-year-old stone tools from Gona, Ethiopia|journal=Nature|volume=385|issue=6614|pages=333–336|doi=10.1038/385333a0|pmid=9002516|bibcode=1997Natur.385..333S|s2cid=4331652}}{{cite journal|first1=S.|last1=Semaw|first2=M. J.|last2=Rogers|first3=J.|last3=Quade|display-authors=et al.|year=2003|title=2.6-Million-year-old stone tools and associated bones from OGS-6 and OGS-7, Gona, Afar, Ethiopia|journal=Journal of Human Evolution|volume=45|issue=2|pages=169–177|doi=10.1016/s0047-2484(03)00093-9|pmid=14529651|bibcode=2003JHumE..45..169S }}{{cite journal|last1=Asfaw|first1=Berhane|last2=White|first2=Tim|last3=Lovejoy|first3=Owen|last4=Latimer|first4=Bruce|last5=Simpson|first5=Scott|last6=Suwa|first6=Gen|title=Australopithecus garhi: A New Species of Early Hominid from Ethiopia|journal=Science|volume=284|issue=5414|pages=629–635|date=23 April 1999|doi=10.1126/science.284.5414.629|pmid=10213683|bibcode=1999Sci...284..629A}}{{cite journal|last1=de Heinzelin|first1=Jean|last2=Clark|first2=J. Desmond|last3=White|first3=Tim| last4=Hart|first4=William|last5=Renne|first5=Paul|last6=WoldeGabriel|first6=Giday|last7=Beyene|first7=Yonas|last8=Vrba|first8=Elisabeth|title=Environment and Behavior of 2.5-Million-Year-Old Bouri Hominids|journal=Science|volume=284|issue=5414|pages=625–629|date=23 April 1999|doi=10.1126/science.284.5414.625|pmid=10213682|bibcode=1999Sci...284..625D}} Stone tools dating to roughly the same time as A. garhi (about 2.6 mya) were later discovered at the nearby Gona and Ledi-Geraru sites, but the appearance of Homo at Ledi-Geraru (LD 350-1) casts doubt on australopithecine authorship.{{cite journal |first1=D. R. |last1=Braun |first2=V. |last2=Aldeias |first3=W. |last3=Archer |display-authors=et al. |year=2019 |title=Earliest known Oldowan artifacts at >2.58 Ma from Ledi-Geraru, Ethiopia, highlight early technological diversity |journal=Proceedings of the National Academy of Sciences |volume=116 |issue=24 |pages=11,712–11,717 |doi=10.1073/pnas.1820177116 |pmid=31160451 |pmc=6575601 |bibcode=2019PNAS..11611712B |doi-access=free}}

In 2010, cut marks dating to 3.4 mya on a bovid leg were found at the Dikaka site, which were at first attributed to butchery by A. afarensis,{{cite journal|first1=S. P.|last1=McPherron|first2=Z.|last2=Alemseged|first3=C. W.|last3=Marean|display-authors=et al.|year=2010|title=Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia|journal=Nature|volume=466|issue=7308|pages=857–860|doi=10.1038/nature09248|pmid=20703305|bibcode=2010Natur.466..857M|s2cid=4356816}} but because the fossil came from a sandstone unit (and were modified by abrasive sand and gravel particles during the fossilisation process), the attribution to butchery is dubious.{{cite journal|first1=M.|last1=Domínguez-Rodrigo|first2=T. R.|last2=Pickering|first3=H. T.|last3=Bunn|year=2010|title=Configurational approach to identifying the earliest hominin butchers|journal=Proceedings of the National Academy of Sciences|volume=107|issue=49|pages=20929–20934|doi=10.1073/pnas.1013711107|pmid=21078985|pmc=3000273|bibcode=2010PNAS..10720929D|doi-access=free}}

In 2015, the Lomekwi culture was discovered at Lake Turkana dating to 3.3 mya, possibly attributable to Kenyanthropus{{cite journal|first1=S.|last1=Harmand|first2=J. E.|last2=Lewis|first3=C. S.|last3=Feibel|display-authors=et al.|year=2015|title=3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya|journal=Nature|volume=521|issue=7552|pages=310–315|doi=10.1038/nature14464|pmid=25993961|bibcode=2015Natur.521..310H|s2cid=1207285}} or A. deyiremeda.{{cite journal|last1=Spoor|first1=Fred|title=Palaeoanthropology: The middle Pliocene gets crowded|journal=Nature|volume=521|issue=7553|year=2015|pages=432–433|issn=0028-0836|doi=10.1038/521432a|pmid=26017440|bibcode=2015Natur.521..432S|s2cid=4472489|doi-access=free}}

Notable specimens

  • KT-12/H1, an A. bahrelghazali mandibular fragment, discovered 1995 in Sahara, Chad
  • AL 129-1, an A. afarensis knee joint, discovered 1973 in Hadar, Ethiopia
  • Karabo, a juvenile male A. sediba, discovered in South Africa
  • Laetoli footprints, preserved hominin footprints in Tanzania
  • Lucy, a 40%-complete skeleton of a female A. afarensis, discovered 1974 in Hadar, Ethiopia
  • Selam, remains of a three-year-old A. afarensis female, discovered in Dikika, Ethiopia
  • MRD-VP-1/1, first skull of A. anamensis discovered in 2016 in Afar, Ethiopia.
  • STS 5 (Mrs. Ples), the most complete skull of an A. africanus ever found in South Africa
  • STS 14, remains of an A. africanus, discovered 1947 in Sterkfontein, South Africa
  • STS 71, skull of an A. africanus, discovered 1947 in Sterkfontein, South Africa
  • Taung Child, skull of a young A. africanus, discovered 1924 in Taung, South Africa

Gallery

Plaque marking the discovery of Australopithecus in Tanzania.jpg|The spot where the first Australopithecus boisei was discovered in Tanzania.

Mrs Ples.jpg|Original skull of Mrs. Ples, a female A. africanus

Taung child - Skin and Muscles.png|Taung Child by Cicero Moraes, Arc-Team, Antrocom NPO, Museum of the University of Padua.

Lucy blackbg.jpg|Cast of the skeleton of Lucy, an A. afarensis

Australopithecus africanus - Cast of taung child.jpg|Skull of the Taung child

See also

References

{{Reflist|30em}}

=Sources=

  • {{Cite book |editor1-last=Briggs |editor1-first=D. |editor2-first=P. R. |editor2-last=Crowther |title=Palaeobiology II |publisher=John Wiley & Sons |year=2008 |isbn=9780470999288 |page=600}}
  • {{Cite journal |last1=Wood |first1=B. |doi=10.1073/pnas.1001649107 |title=Reconstructing human evolution: Achievements, challenges, and opportunities |journal=Proceedings of the National Academy of Sciences |volume=107 |pages=8902–8909 |year=2010 |issue=Suppl 2 |pmid=20445105 |pmc=3024019 |doi-access=free}}
  • {{Cite journal |last1=Wood |first1=B. |last2=Richmond |first2=B. G. |doi=10.1046/j.1469-7580.2000.19710019.x |title=Human evolution: Taxonomy and paleobiology |journal=Journal of Anatomy |volume=197 |issue=Pt 1 |pages=19–60 |year=2000 |pmid=10999270 |pmc=1468107}}

Further reading

  • {{Cite book |title=Atlas of World History |last=Barraclough |first=G. |edition=3rd |editor-last=Stone |editor-first=N. |year=1989 |publisher=Times Books Limited |isbn=978-0-7230-0304-5 |url=https://archive.org/details/isbn_9780723003045 }}.
  • {{Cite book |title=The Origins of Human Kind |author-link=Richard Leakey |last=Leakey |first=Richard |year=1994 |isbn=978-0-465-03135-1 |publisher=BasicBooks |location=New York |url=https://archive.org/details/originofhumankin00leak }}.
  • {{Cite journal |last1=White |first1=Tim D. |last2=WoldeGabriel |first2=Giday |last3=Asfaw |first3=Berhane |last4=Ambrose |first4=S|last5=Beyene|first5=Y|last6=Bernor |first6=RL|last7=Boisserie |first7=JR|last8=Currie |first8=B |last9=Gilbert|first9=H |last10=Haile-Selassie|first10=Y|last11=Hart|first11=WK |last12=Hlusko|first12=LJ |last13=Howell|first13=FC |last14=Kono|first14=RT |last15=Lehmann|first15=T |last16=Louchart |first16=A|last17=Lovejoy|first17=CO |last18=Renne|first18=PR |last19=Saegusa|first19=H |last20=Vrba|first20=ES |last21=Wesselman|first21=H |last22=Suwa|first22=G |title=Asa Issie, Aramis and the Origin of Australopithecus |journal=Nature |volume=440 |issue=7086 |year=2006 |pages=883–889 |pmid=16612373 |doi=10.1038/nature04629 |bibcode=2006Natur.440..883W|s2cid=4373806 }}.
  • {{cite book|last=Gibbons|first=Ann|year=2006|title=The first human|page=[https://archive.org/details/firsthumanraceto00gibb/page/306 306]|publisher=Doubleday|location=New York|isbn=978-0385512268|url=https://archive.org/details/firsthumanraceto00gibb/page/306}}
  • {{cite book|last=Reader|first=John|year=2011|title=Missing links: in search of human origins|page=[https://archive.org/details/missinglinksinse0000read/page/538 538]|publisher=Oxford University Press|location=New York|isbn=978-0-19-927685-1|url=https://archive.org/details/missinglinksinse0000read/page/538}}
  • {{Cite book |title=Masters of the Planet, the search for our human origins |pages=[https://archive.org/details/mastersofplanets0000tatt/page/1 1–79] |last=Tattersall |first=Ian |author-link=Ian Tattersall |publisher=Palgrave-Macmillan |year=2012 |isbn=978-0-230-10875-2 |url=https://archive.org/details/mastersofplanets0000tatt/page/1 }}
  • {{cite journal |title=100 years of Australopithecus |journal=Nature |date=5 February 2025 |url=https://www.nature.com/collections/bdeahhcgcc |language=en}}