View source for Biology:Paranthropus robustus

{{short description|Extinct species of hominin of South Africa}}
{{Speciesbox
| fossil_range = [[Earth:Pleistocene|Pleistocene]], {{fossilrange|2.27/2|1/0.87}}
| image = Original of Paranthropus robustus Face.jpg
| image_caption = Cast of the presumed-male SK 48 skull
| image_alt = a skull in face-view, lacking a forehead, and having large and rectangular eye sockets, an even larger triangular opening for the nose, flaring cheeks strongly angled inward, and missing the front teeth
| genus = Paranthropus
| species = robustus
| authority = Broom, 1938
| synonyms = *''P. crassidens''<br/><small>Broom and Robinson, 1948</small>
*''Australopithecus robustus''<br/><small>[[Biography:Sherwood Washburn|Washburn]] and Patterson, 1951</small>
}}
'''''Paranthropus robustus''''' is a [[Biology:Species|species]] of [[Biology:Robustness (morphology)|robust]] [[Biology:Australopithecine|australopithecine]] from the [[Earth:Early Pleistocene|Early]] and possibly [[Earth:Middle Pleistocene|Middle]] Pleistocene of the [[History:Cradle of Humankind|Cradle of Humankind]], {{wipe|South Africa}}, about 2.27 to 0.87 (or, more conservatively, 2 to 1) million years ago.<ref>{{cite web |last1=Wood|first1=Bernard|last2=Doherty|first2=Dandy|last3=Boyle|first3=Eve|date=2020-05-29|title=Hominin Taxic Diversity|url=https://oxfordre.com/anthropology/view/10.1093/acrefore/9780190854584.001.0001/acrefore-9780190854584-e-194|access-date=2021-04-19|website=Oxford Research Encyclopedia of Anthropology|language=en|doi=10.1093/acrefore/9780190854584.013.194|isbn=9780190854584}}</ref> It has been identified in Kromdraai, Swartkrans, [[Earth:Sterkfontein|Sterkfontein]], Gondolin, [[Earth:Cooper's Cave|Cooper's]], and Drimolen Caves. Discovered in 1938, it was among the first early hominins described, and became the [[Biology:Type species|type species]] for the [[Biology:Genus|genus]] ''[[Biology:Paranthropus|Paranthropus]]''. However, it has been argued by some that ''Paranthropus'' is an invalid grouping and [[Biology:Synonym (taxonomy)|synonymous]] with ''[[Biology:Australopithecus|Australopithecus]]'', so the species is also often classified as '''''Australopithecus robustus'''''.

Robust australopithecines—as opposed to [[Biology:Gracility|gracile]] australopithecines—are characterised by heavily built skulls capable of producing high [[Physics:Stress|stresses]] and bite forces, as well as inflated [[Biology:Cheek teeth|cheek teeth]] (molars and premolars). Males had more heavily built skulls than females. ''P. robustus'' may have had a genetic susceptibility for pitting enamel hypoplasia on the teeth, and seems to have had a dental [[Medicine:Tooth decay|cavity]] rate similar to non-agricultural modern humans. The species is thought to have exhibited marked [[Biology:Sexual dimorphism|sexual dimorphism]], with males substantially larger and more robust than females. Based on 3 specimens, males may have been {{cvt|132|cm|ftin}} tall and females {{cvt|110|cm|ftin}}. Based on 4 specimens, males averaged {{cvt|40|kg}} in weight and females {{cvt|30|kg}}. The brain volume of the specimen SK 1585 is estimated to have been 476 cc, and of DNH 155 about 450 cc (for comparison, the brain volume of contemporary ''[[Biology:Homo|Homo]]'' varied from 500 to 900 cc). ''P. robustus'' limb anatomy is similar to that of other australopithecines, which may indicate a less efficient walking ability than modern humans, and perhaps some degree of arboreality (movement in the trees).

''P. robustus'' seems to have consumed a high proportion of [[Biology:C4 carbon fixation|C<sub>4</sub> savanna plants]]. In addition, it may have also eaten fruits, underground [[Biology:Storage organ|storage organ]]s (such as roots and tubers), and perhaps [[Chemistry:Honey|honey]] and [[Biology:Termite|termite]]s. ''P. robustus'' may have used bones as tools to extract and process food. It is unclear if ''P. robustus'' lived in a [[Biology:Harem (zoology)|harem]] society like [[Biology:Gorilla|gorilla]]s or a multi-male society like [[Biology:Baboon|baboon]]s. ''P. robustus'' society may have been patrilocal, with adult females more likely to leave the group than males, but males may have been more likely to be evicted as indicated by higher male mortality rates and assumed increased risk of predation to solitary individuals. ''P. robustus'' contended with sabertooth cats, [[Biology:Leopard|leopard]]s, and [[Biology:Hyena|hyena]]s on the mixed, open-to-closed landscape, and ''P. robustus'' bones probably accumulated in caves due to big cat predation. It is typically found in what were mixed open and wooded environments, and may have gone extinct in the [[Earth:Mid-Pleistocene Transition|Mid-Pleistocene Transition]] characterised by the continual prolonging of dry cycles and subsequent retreat of such habitat.

==Taxonomy==
===Research history===
[[File:TM 1517.jpg|thumb|Cast of the face of TM 1517, the holotype specimen of ''P. robustus''|alt=Preserved left half of the skull and right half of the jaw mounted on a wall]]
====Discovery====
The first remains, a partial skull including a part of the jawbone (TM 1517), were discovered in June 1938 at the [[Earth:Kromdraai fossil site|Kromdraai cave site]], South Africa, by local schoolboy Gert Terblanche. He gave the remains to South African conservationist Charles Sydney Barlow, who then relayed them to South African palaeontologist Robert Broom.<ref name=Broom1938/> Broom began investigating the site, and, a few weeks later, recovered a right distal [[Biology:Humerus|humerus]] (the lower part of the upper arm bone), a proximal right [[Biology:Ulna|ulna]] (upper part of a lower arm bone) and a distal phalanx bone of the big toe, all of which he assigned to TM 1517. He also identified a distal toe phalanx which he believed belonged to a [[Biology:Baboon|baboon]], but has since been associated with TM 1517.<ref name=Cazenave2019>{{cite conference|first1=M.|last1=Cazenave|first2=C.|last2=Zanolli|first3=D.|last3=Clément|display-authors=et al.|year=2019|title=The TM 1517 odontoskeletal assemblage from Kromdraai B, South Africa, and the maturational pattern of ''Paranthropus robustus''|conference=9th Meeting of the European Society for the Study of Human Evolution|pages=19–21|url=https://kar.kent.ac.uk/id/eprint/79902}}</ref> Broom noted the Kromdraai remains were especially [[Biology:Robustness (morphology)|robust]] compared to other hominins.<ref name=Broom1938/> In August 1938, Broom classified the robust Kromdraai remains into a new [[Biology:Genus|genus]], as ''Paranthropus robustus''.<ref name=Broom1938>{{cite journal|first=R.|last=Broom|year=1938|title=The Pleistocene Anthropoid Apes of South Africa|journal=Nature|volume=142|issue=3591|pages=377–339|doi=10.1038/142377a0|bibcode=1938Natur.142..377B|doi-access=free}}</ref> "''[[Biology:Paranthropus|Paranthropus]]''" derives from the [[Social:Ancient Greek|Ancient Greek]] παρα ''para'', beside or alongside; and άνθρωπος ''ánthropos'', man.<ref>{{cite web|url=https://www.merriam-webster.com/dictionary/Paranthropus|title=''Paranthropus''|publisher=Merriam–Webster Dictionary|access-date=20 June 2020}}</ref>

At this point in time, Australian anthropologist [[Biography:Raymond Dart|Raymond Dart]] had made the very first claim (quite controversially at the time) of an early [[Biology:Ape|ape]]-like human ancestor in 1924 from South Africa, ''[[Biology:Australopithecus africanus|Australopithecus africanus]]'', based on the Taung child.<ref name=Tobias1998>{{cite journal|first=P. V.|last=Tobias|year=1998|title=Ape-Like ''Australopithecus'' After Seventy Years: Was It a Hominid?|journal=The Journal of the Royal Anthropological Institute|volume=4|issue=2|pages=283–308|doi=10.2307/3034503|jstor=3034503}}</ref>{{rp|285–288}} In 1936, Broom had described "''Plesianthropus transvaalensis''" (now [[Biology:Synonym (taxonomy)|synonymised]] with ''A. africanus'') from the [[Earth:Sterkfontein|Sterkfontein]] Caves only {{cvt|2|km}} west from Kromdraai. All these species dated to the [[Earth:Pleistocene|Pleistocene]] and were found in the same general vicinity (now called the "[[History:Cradle of Humankind|Cradle of Humankind]]"). Broom considered them evidence of a greater diversity of hominins in the Pliocene from which they and modern humans descended, and consistent with several hominin taxa existing alongside human ancestors.<ref name=Broom1938/>

The Kromdraii taxon, classified as ''Paranthropus robustus'', was later discovered at the nearby Swartkrans Cave in 1948. ''P. robustus'' was only definitively identified at Kromdraai and Swartkrans until around the turn of the century when the species was reported elsewhere in the Cradle of Humankind at Sterkfontein, Gondolin, [[Earth:Cooper's Cave|Cooper's]], and Drimolen Caves. The species has not been found outside this small area.<ref name=Constantino2004/>

===="''P. crassidens''"====
In 1948, at the nearby Swartkrans Cave, Broom described "''P. crassidens''" (distinct from ''P. robustus'') based on a subadult jaw, SK 6,<ref name=Constantino2004/> because Swartkrans and Kromdraai clearly dated to different time intervals based on the diverging animal assemblages in these caves.<ref>{{cite journal|first=R.|last=Broom|year=1948|title=Another new type of fossil ape-man|journal=Nature|volume=162|issue=4132|page=57|doi=10.1038/163057a0|pmid=18106151|s2cid=4126221|doi-access=free}}</ref> At this point in time, humans and allies were classified into the family [[Biology:Hominidae|Hominidae]], and non-human great apes into "[[Biology:Pongidae|Pongidae]]"; in 1950, Broom suggested separating early hominins into the subfamilies Australopithecinae (''Au. africanus'' and "''Pl. transvaalensis''"), "Paranthropinae" (''Pa. robustus'' and "''Pa. crassidens''"), and "Archanthropinae" ("''Au. prometheus''").<ref>{{cite journal|first=R.|last=Broom|year=1950|title=The genera and species of the South African fossil ape-men|journal=American Journal of Physical Anthropology|volume=8|issue=1|pages=1–14|doi=10.1002/ajpa.1330080109|pmid=15410860}}</ref> This scheme was widely criticised for being too liberal in demarcating species.<ref name=Robinson1954/> Further, the remains were not firmly dated, and it was debated if there were indeed multiple hominin lineages or if there was only a single one leading to humans. Most prominently, Broom and South African palaeontologist John Talbot Robinson continued arguing for the validity of ''Paranthropus''.<ref name=Johanson>{{cite journal|first1=D. C.|last1=Johanson|first2=T. D.|last2=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|pmid=104384|bibcode=1979Sci...203..321J}}</ref>

Anthropologists [[Biography:Sherwood Washburn|Sherwood Washburn]] and Bruce D. Patterson were the first to recommend synonymising ''Paranthropus'' with ''[[Biology:Australopithecus|Australopithecus]]'' in 1951, wanting to limit hominin genera to only that and ''[[Biology:Homo|Homo]]'',<ref>{{cite journal|first1=S. L.|last1=Washburn|first2=B.|last2=Patterson|year=1951|title=Evolutionary Importance of the South African 'Man-apes'|journal=Nature|volume=167|issue=4251|pages=650–651|doi=10.1038/167650a0|pmid=14826894|bibcode=1951Natur.167..650W|s2cid=4207075}}</ref> and it has since been debated whether or not ''Paranthropus'' is a junior synonym of ''Australopithecus''.<ref name=Constantino2004>{{cite book|first1=P. J.|last1=Constantino|first2=B. A.|last2=Wood|year=2004|chapter=''Paranthropus'' Paleobiology|title=Miscelanea en Homenaje a Emiliano Aguirre|volume=III|series=Paleoantropologia|publisher=Museo Arqueológico Regional|url=https://mds.marshall.edu/cgi/viewcontent.cgi?article=1028&=&context=bio_sciences_faculty&=&sei-redir=1&referer=https%253A%252F%252Fscholar.google.com%252Fscholar%253Fhl%253Den%2526as_sdt%253D0%25252C44%2526q%253Dparanthropus%252Baethiopicus%2526oq%253DParanthropus#search=%22paranthropus%20aethiopicus%22}}</ref> In the spirit of tightening splitting criteria for hominin taxa, in 1954, Robinson suggested demoting "''P. crassidens''" to subspecies level as "''P. r. crassidens''", and also moved the Indonesian ''[[Biology:Meganthropus|Meganthropus]]'' into the genus as "''P. palaeojavanicus''".<ref name=Robinson1954>{{cite journal|first=J. T.|last=Robinson|author-link=John Talbot Robinson|year=1954|title=The genera and species of the australopithecinae|journal=American Journal of Physical Anthropology|volume=12|issue=2|pages=181–200|doi=10.1002/ajpa.1330120216|pmid=13188956}}</ref> ''Meganthropus'' has since been variously reclassified as a synonym of the Asian ''[[Biology:Homo erectus|Homo erectus]]'', "''[[Biology:Anthropopithecus|Pithecanthropus dubius]]''", ''Pongo'' ([[Biology:Orangutan|orangutan]]s), and so on, and in 2019 it was again argued to be a valid genus.<ref>{{cite journal |last1=Zanolli|first1=C.|last2=Kullmer|first2=O.|last3=Kelley|first3=J.|display-authors=et al.|year=2019|title=Evidence for increased hominid diversity in the Early to Middle Pleistocene of Indonesia|journal=Nature Ecology and Evolution|volume=3|issue=5|pages=755–764|doi=10.1038/s41559-019-0860-z|pmid=30962558|bibcode=2019NatEE...3..755Z |s2cid=102353734|url=https://kar.kent.ac.uk/72814/1/01-Indonesian_hominid_paleobiodiversity_v2.pdf}}</ref>

In 1949, also in Swartkrans Cave, Broom and Robinson found a mandible which they preliminary described as "intermediate between one of the ape-men and true man," classifying it as a new genus and species "''Telanthropus capensis''". Most immediate reactions favoured synonymising "''T. capensis''" with "''P. crassidens''", whose remains were already abundantly found in the cave.<ref>{{cite journal|first=J. T.|last=Robinson|year=1953|title=The Nature of ''Telanthropus capensis''|journal=Nature|volume=171|issue=4340|page=33|doi=10.1038/171033a0|pmid=13025468|bibcode=1953Natur.171...33R|s2cid=76346|doi-access=free}}</ref> In 1957, though, Italian biologist Alberto Simonetta moved it to the genus "''Pithecanthropus''", and Robinson (without a specific reason why) decided to synonymise it with ''H. erectus'' (African ''H. erectus'' are sometimes called ''H. ergaster'' today). In 1965, South African palaeoanthropologist [[Biography:Phillip V. Tobias|Phillip V. Tobias]] questioned whether this classification is completely sound or not.<ref>{{cite journal|first=P. V.|last=Tobias|year=1965|title=New Discoveries in Tanganyika: Their Bearing on Hominid Evolution|journal=Current Anthropology|volume=6|issue=4|page=393|doi=10.1086/200622|jstor=2740331|s2cid=84325204}}</ref>

By the 21st century, "''P. crassidens''" had more or less fallen out of use in favour of ''P. robustus''. American palaeoanthropologist Frederick E. Grine is the primary opponent of synonymisation of the two species.<ref name=Constantino2004/>

====''Gigantopithecus''====
In 1939, Broom hypothesised that ''P. robustus'' was closely related to the similarly large-toothed ape ''[[Biology:Gigantopithecus|Gigantopithecus]]'' from Asia (extinct apes were primarily known from Asia at the time) believing ''Gigantopithecus'' to have been a hominin.<ref>{{cite journal|last=Broom|first=R.|year=1939|title=The dentition of the Transvaal Pleistocene anthropoids, ''Plesianthropus'' and ''Paranthropus''|journal=Annals of the Transvaal Museum|volume=19|issue=3|pages=303–314|url=https://journals.co.za/docserver/fulltext/nfi_annalstm/19/3/484.pdf?expires=1587575563&id=id&accname=guest&checksum=2AB75E7DD6F91D015A8D2145BD8137F9}}</ref> Primarily influenced by the mid-century opinions of Jewish German anthropologist [[Biography:Franz Weidenreich|Franz Weidenreich]] and German-Dutch palaeontologist Ralph von Koenigswald that ''Gigantopithecus'' was, respectively, the direct ancestor of the Asian ''H. erectus'' or closely related, much debate followed over whether ''Gigantopithecus'' was a hominin or a non-human ape.<ref name=ZhangHarrison2017>{{cite journal|last1= Zhang|first1= Y.|last2= Harrison|first2= T.|title= ''Gigantopithecus blacki'': a giant ape from the Pleistocene of Asia revisited|journal= American Journal of Physical Anthropology|volume= 162|issue= S63|year= 2017|page=170|doi= 10.1002/ajpa.23150|doi-access= free|pmid= 28105715}}</ref>

In 1972, Robinson suggested including ''Gigantopithecus'' in "Paranthropinae", with the Miocene Pakistani "''G. bilaspurensis''" (now ''[[Biology:Indopithecus|Indopithecus]]'') as the ancestor of ''Paranthropus'' and the Chinese ''G. blacki''. He also believed that they both had a massive build. In contrast, he reported a very small build for ''A. africanus'' (which he referred to as "''Homo''" ''africanus'') and speculated it had some cultural and hunting abilities, being a member of the human lineage, which "paranthropines" lacked.<ref name=Wolpoff1974/> With the popularisation of cladistics by the late 1970s to 1980s, and better resolution on how Miocene apes relate to later apes, ''Gigantopithecus'' was entirely removed from [[Biology:Homininae|Homininae]], and is now placed in the subfamily [[Biology:Ponginae|Ponginae]] with orangutans.<ref name=ZhangHarrison2017/>

====''P. boisei''====
[[File:Australophithecus boisei (cast), Olduvai Gorge - Springfield Science Museum - Springfield, MA - DSC03368.JPG|thumb|OH 5 (reconstructed skull above) was made the holotype specimen of the 2nd ''Paranthropus'' species, ''P. boisei''.|alt=Large, white, complete skull in three-quarter view facing left]]
In 1959, another and much more robust australopithecine was discovered in East Africa, ''P. boisei'', and in 1975, the ''P. boisei'' skull KNM-ER 406 was demonstrated to have been contemporaneous with the ''H. ergaster/H. erectus'' skull KNM ER 3733 (which is considered a human ancestor). This is generally taken to show that ''Paranthropus'' was a sister taxon to ''Homo'', both developing from some ''Australopithecus'' species, which at the time only included ''A. africanus''.<ref name="Johanson"/>

In 1979, a year after describing ''A. afarensis'' from East Africa, anthropologists [[Biography:Donald Johanson|Donald Johanson]] and [[Biography:Tim D. White|Tim D. White]] suggested that ''A. afarensis'' was instead the last common ancestor between ''Homo'' and ''Paranthropus'', and ''A. africanus'' was the earliest member of the ''Paranthropus'' lineage or at least was ancestral to ''P. robustus'', because ''A. africanus'' inhabited South Africa before ''P. robustus'', and ''A. afarensis'' was at the time the oldest known hominin species at roughly 3.5 million years old.<ref name="Johanson"/> Now, the earliest-known South African australopithecine ("Little Foot") dates to 3.67 million years ago, contemporaneous with ''A. afarensis''.<ref>{{cite journal|first1=R. J.|last1=Clarke|first2=K.|last2=Kuman|year=2019|title=The skull of StW 573, a 3.67 Ma ''Australopithecus prometheus'' skeleton from Sterkfontein Caves, South Africa|journal=Journal of Human Evolution|volume=134|page=102634|doi=10.1016/j.jhevol.2019.06.005|pmid=31446970|s2cid=201209318}}</ref> The matter is still debated.<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>

It was long assumed that if ''Paranthropus'' is a valid genus then ''P. robustus'' was the ancestor of ''P. boisei'', but in 1985, anthropologists [[Biography:Alan Walker (anthropologist)|Alan Walker]] and [[Biography:Richard Leakey|Richard Leakey]] found that the 2.5-million-year-old East African skull KNM WT 17000—which they assigned to a new species ''A. aethiopicus''—was ancestral to ''A. boisei'' (they considered ''Paranthropus'' synonymous with ''Australopithecus''), thus establishing the ''boisei'' lineage as beginning long before ''robustus'' had existed.<ref name=Walker1986>{{cite journal|first1=A.|last1=Walker|first2=R. E.|last2=Leakey|first3=J. M.|last3=Harris|first4=F. H.|last4=Brown|year=1986|title=2.5-Myr Australopithecus boisei from west of Lake Turkana, Kenya|journal=Nature|volume=322|issue=6079|pages=517–522|doi=10.1038/322517a0|bibcode=1986Natur.322..517W|s2cid=4270200}}</ref>

===Classification===
The genus ''Paranthropus'' (otherwise known as "robust australopithecines", in contrast to the "gracile australopithecines") now also includes the East African ''P. boisei'' and ''P. aethiopicus''. It is still debated if this is a valid natural grouping ([[Biology:Monophyletic|monophyletic]]) or an invalid grouping of similar-looking hominins (paraphyletic). Because skeletal elements are so limited in these species, their [[Affinity (taxonomy)|affinities]] with each other and with other [[Biology:Australopithecine|australopithecine]]s are difficult to gauge with accuracy. The jaws are the main argument for monophyly, but jaw anatomy is strongly influenced by diet and environment, and could have evolved independently in ''P. robustus'' and ''P. boisei''. Proponents of monophyly consider ''P. aethiopicus'' to be ancestral to the other two species, or closely related to the ancestor. Proponents of paraphyly allocate these three species to the genus ''Australopithecus'' as ''A. boisei'', ''A. aethiopicus'', and ''A. robustus''.<ref name=wood2>{{cite journal |first1=Bernard |last1=Wood |first2=Paul |last2=Constantino |year=2007 |title=''Paranthropus boisei'': Fifty years of evidence and analysis |journal=American Journal of Physical Anthropology |volume=134|issue=Suppl 45 |pages=117–121 |pmid=18046746 |doi=10.1002/ajpa.20732|url=https://mds.marshall.edu/cgi/viewcontent.cgi?article=1035&context=bio_sciences_faculty |doi-access=free }}</ref> In 2020, palaeoanthropologist Jesse M. Martin and colleagues' phylogenetic analyses reported the monophyly of ''Paranthropus'', but also that ''P. robustus'' had branched off before ''P. aethiopicus'' (that ''P. aethiopicus'' was ancestral to only ''P. boisei'').<ref name=Martin2020/> The exact classification of ''Australopithecus'' species with each other is quite contentious.<ref name=McNulty2016/>

{{clade gallery
|align=centre |height=225px|main-borders= 
|main-footer=Three examples of family trees with ''P. robustus'' (note, they are not absolute)
|caption1=Monophyly<ref name=wood2/>{{rp|119}}
|caption2=Paraphyly<ref name=wood2/>{{rp|119}}
|caption3=Monophyly<ref name=Martin2020/>
|cladogram1=
{{clade
 |1={{clade
  |1=''[[Biology:Australopithecus africanus|A. africanus]]''
  |2={{clade
   |1=''P. aethiopicus''
   |2={{clade
    |1=''P. boisei''
    |2='''''P. robustus'''''
    }}
   }}
  }}
 }}
|cladogram2=
{{clade
|1={{clade
 |1={{clade
  |1=''[[Biology:Australopithecus africanus|A. africanus]]''
  |2='''''P. robustus'''''
  }}
 |2={{clade
  |1=''P. aethiopicus''
  |2=''P. boisei''
  }}
 }}
}}
|cladogram3=
{{clade
 |1={{clade
  |1=''[[Biology:Australopithecus africanus|A. africanus]]''
  |2={{clade
   |1=''[[Biology:Homo|Homo]]''
   |2=''[[Biology:Kenyanthropus|Kenyanthropus]]''
   |3={{clade
    |1='''''P. robustus'''''
    |2={{clade
     |1=''P. aethiopicus''
     |2=''P. boisei''
     }}
    }}
   }}
  }}
 }}
}}In 2023, fragmentary genetic material belonging to this species was reported from 2 million year-old teeth, being the oldest genetic evidence to be retrieved from a human.<ref>{{Cite journal |last=Callaway |first=Ewen |date=2023-07-10 |title=Oldest genetic data from a human relative found in 2-million-year-old teeth |url=https://www.nature.com/articles/d41586-023-02242-z |journal=Nature |language=en |volume=619 |issue=7970 |pages=446 |doi=10.1038/d41586-023-02242-z|pmid=37430164 |bibcode=2023Natur.619..446C |s2cid=259657320 }}</ref>

==Anatomy==
===Head===
====Skull====
{{Multiple image|width=200|image1=DNH7.jpg|image2=Paranthropus robustus top (University of Zurich).JPG|footer=Female DNH 7 (left) and cast of male SK 48 (right) skulls|alt=DNH 7 has a complete jaw and almost-complete skull, missing the left margins of the left eye socket, as well as the left half of the braincase. SK 48 does not have the jaw, and only has 2 right incisors for teeth visible. DNH 7 has rounded eye sockets, but SK 48 has rectangular ones.}}
Typical of ''Paranthropus'', ''P. robustus'' exhibits [[Biology:Post-canine megadontia|post-canine megadontia]] with enormous [[Biology:Cheek teeth|cheek teeth]] but human-sized incisors and [[Biology:Canine tooth|canines]]. The premolars are shaped like molars.<ref name=Cartmill2009/> The [[Biology:Tooth enamel|enamel]] thickness on the cheek teeth is relatively on par with that of modern humans, though australopithecine cheek tooth enamel thickens especially at the tips of the cusps, whereas in humans it thickens at the base of the cusps.<ref>{{cite journal|first1=A. J.|last1=Olejniczak|first2=T. M.|last2=Smith|first3=M. M.|last3=Skinner|first4=F. E.|last4=Grine|author4-link=Frederick E. Grine|display-authors=et al.|year=2008|title=Three-dimensional molar enamel distribution and thickness in ''Australopithecus'' and ''Paranthropus''|journal=Biology Letters|volume=4|issue=4|pages=406–410|doi=10.1098/rsbl.2008.0223|pmc=2610159|pmid=18522924}}</ref>

''P. robustus'' has a tall face with slight [[Medicine:Prognathism|prognathism]] (the jaw jutted out somewhat). The skulls of males have a well-defined sagittal crest on the midline of the skullcap and inflated [[Medicine:Cheek|cheek]] bones, which likely supported massive temporal muscles important in biting. The cheeks project so far from the face that, when in top-view, the nose appears to sit at the bottom of a concavity (a dished face). This displaced the eye sockets forward somewhat, causing a weak brow ridge and receding forehead. The inflated cheeks also would have pushed the masseter muscle (important in biting down) forward and pushed the tooth rows back, which would have created a higher bite force on the premolars. The ramus of the jawbone, which connects the lower jaw to the upper jaw, is tall, which would have increased lever arm (and thereby, torque) of the masseter and medial pterygoid muscles (both important in biting down), further increasing bite force.<ref name=Cartmill2009>{{cite book|first1=M.|last1=Cartmill|first2=F.H.|last2=Smith|year=2009|title=The Human Lineage|publisher=John Wiley and Sons|pages=152–157|isbn=978-0-471-21491-5|url={{google books|plainurl=yes|id=5TRHOmTUTP4C|page=152}}}}</ref>

The well-defined sagittal crest and inflated cheeks are absent in the presumed-female skull DNH-7, so Keyser suggested that male ''P. robustus'' may have been more heavily built than females (''P. robustus'' was sexually dimorphic).<ref name=Keyser2000/> The Drimolen material, being more basal, is comparatively more gracile and consequently probably had a smaller bite force than the younger Swartkrans and Kromdraii ''P. robustus''. The brows of the former also are rounded off rather than squared, and the sagittal crest of the presumed-male DNH 155 is more posteriorly (towards the back of the head) positioned.<ref name=Martin2020>{{cite journal|first1=J. M.|last1=Martin|first2=A. B.|last2=Leece|first3=S.|last3=Neubauer|display-authors=et al.|year=2020|title=Drimolen cranium DNH 155 documents microevolution in an early hominin species|journal=Nature Ecology and Evolution|volume=5|issue=1|pages=38–45|doi=10.1038/s41559-020-01319-6|pmid=33168991|bibcode=2020NatEE...5...38M |hdl=11568/1066411 |s2cid=226296091}}</ref>

The [[Biology:Semicircular canals#Posterior semicircular canal|posterior semicircular canals]] in the inner ear of SK 46 and SK 47 are unlike those of the apelike ''Australopithecus'' or ''Homo'', suggesting different locomotory and head movement patterns, since inner ear anatomy affects the [[Biology:Vestibular system|vestibular system]] (sense of balance). The posterior semicircular canals of modern humans are thought to aid in stabilisation while running, which could mean ''P. robustus'' was not an endurance runner.<ref>{{cite journal|last1=Beaudet|first1=A.|last2=Clarke|first2=R. J.|last3=Bruxelles|first3=L.|display-authors=et al.|year=2019|title=The bony labyrinth of StW 573 ("Little Foot"): Implications for early hominin evolution and paleobiology|journal=Journal of Human Evolution|volume=127|pages=67–80|doi=10.1016/j.jhevol.2018.12.002|pmid=30777359|s2cid=73466797}}</ref>
[[File:Paranthropus robustus female.jpg|thumb|Reconstruction of a female ''P. robustus'']]

====Brain====
Upon describing the species, Broom estimated the fragmentary braincase of TM 1517 as 600 cc,<ref name=Broom1938/> and he, along with South African anthropologist Gerrit Willem Hendrik Schepers, revised this to 575–680 cc in 1946.<ref name=Clark1947/> For comparison, the brain volume of contemporary ''Homo'' varied from 500 to 900 cc.<ref name=Spoor2015>{{cite journal |author1=F. Spoor |author2=P. Gunz |author3=S. Neubauer |author4=S. Stelzer |author5=N. Scott |author6=A. Kwekason |author7=M. C. Dean | year = 2015 | title = Reconstructed ''Homo habilis'' type OH 7 suggests deep-rooted species diversity in early ''Homo'' | journal = Nature | volume = 519 |issue= 7541 | pages =83–86 | doi= 10.1038/nature14224 | pmid=25739632 | bibcode=2015Natur.519...83S|s2cid=4470282 }}</ref> A year later, British primatologist [[Biography:Wilfrid Le Gros Clark|Wilfrid Le Gros Clark]] commented that, since only a part of the [[Medicine:Temporal bone|temporal bone]] on one side is known, brain volume cannot be accurately measured for this specimen.<ref name=Clark1947>{{cite journal|first=W. E.|last=Le Gros Clark|year=1947|title=Observations on the anatomy of the fossil Australopithecinae|journal=Journal of Anatomy|volume=81|issue=Pt 3|page=321|pmc=1272827|pmid=17105037}}</ref> In 2001, Polish anthropologist Katarzyna Kaszycka said that Broom quite often artificially inflated brain size in early hominins, and the true value was probably much lower.<ref>{{cite journal|first=K.|last=Kaszycka|year=2001|title=A new graphic reconstruction of the type specimen of ''Australopithecus robustus'' from Kromdraai, South Africa - TM 1517|journal=South African Journal of Science|volume=91|url=https://www.researchgate.net/publication/255730212}}</ref>

In 1972, American physical anthropologist Ralph Holloway measured the skullcap SK 1585, which is missing part of the frontal bone, and reported a volume of about 530 cc. He also noted that, compared to other australopithecines, ''Paranthropus'' seems to have had an expanded [[Biology:Cerebellum|cerebellum]] like ''Homo'', echoing what Tobias said while studying ''P. boisei'' skulls in 1967.<ref>{{cite journal|first=R. L.|last=Holloway|year=1972|title=New australopithecine endocast, SK 1585, from Swartkrans, South Africa|journal=American Journal of Physical Anthropology|volume=37|issue=2|pages=173–185|doi=10.1002/ajpa.1330370203}}</ref> In 2000, American neuroanthropologist Dean Falk and colleagues filled in frontal bone anatomy of SK 1585 using the ''P. boisei'' specimens KNM-ER 407, OH 5, and KNM-ER 732, and recalculated the brain volume to about 476 cc. They stated overall brain anatomy of ''P. robustus'' was more like that of non-human apes.<ref>{{cite journal|first1=D.|last1=Falk|first2=J. C.|last2=Redmond, Jr.|first3=J.|last3=Guyer|display-authors=et al.|year=2000|title=Early hominid brain evolution: a new look at old endocasts|journal=Journal of Human Evolution|volume=38|issue=5|pages=695–717|doi=10.1006/jhev.1999.0378|pmid=10799260|s2cid=18886132|url=https://pdfs.semanticscholar.org/6167/bf468c614ca4bbdb080a7fa7b5e55dec61c6.pdf|archive-url=https://web.archive.org/web/20200623010953/https://pdfs.semanticscholar.org/6167/bf468c614ca4bbdb080a7fa7b5e55dec61c6.pdf|url-status=dead|archive-date=2020-06-23}}</ref>

In 2020, the nearly complete skull DNH 155 was discovered and was measured to have had a brain volume of 450 cc.<ref name=Martin2020/>

====Blood vessels====
In 1983, while studying SK 1585 (''P. robustus'') and KNM-ER 407 (''P. boisei'', which he referred to as ''robustus''), French anthropologist Roger Saban stated that the parietal branch of the middle meningeal artery originated from the posterior branch in ''P. robustus'' and ''P. boisei'' instead of the anterior branch as in earlier hominins, and considered this a derived characteristic due to increased brain capacity.<ref>{{cite journal|first=R.|last=Saban|year=1983|title=Les veines méningées moyennes des Australopithèques|journal=Bulletins et Mémoires de la Société d'Anthropologie de Paris|language=fr|volume=13|issue=3|pages=313–323|doi=10.3406/bmsap.1983.3905|url=https://www.persee.fr/doc/bmsap_0037-8984_1983_num_10_3_3905}}</ref> It has since been demonstrated that, at least for ''P. boisei'', the parietal branch could originate from either the anterior or posterior branches, sometimes both in a single specimen on opposite sides of the skull.<ref>{{cite journal|first1=B.|last1=Brown|first2=A.|last2=Walker|first3=C. V.|last3=Ward|first4=R. E.|last4=Leakey|author4-link=Richard Leakey|year=1993|title=New ''Australopithecus boisei'' calvaria from East Lake Turkana, Kenya|journal=American Journal of Physical Anthropology|volume=91|issue=2|page=157|doi=10.1002/ajpa.1330910202|pmid=8317557}}</ref>

Regarding the dural venous sinuses, in 1983, Falk and anthropologist Glenn Conroy suggested that, unlike ''A. africanus'' or modern humans, all ''Paranthropus'' (and ''A. afarensis'') had expanded occipital and marginal (around the foramen magnum) sinuses, completely supplanting the transverse and sigmoid sinuses. They suggested the setup would have increased blood flow to the internal vertebral venous plexuses or [[Medicine:Internal jugular vein|internal jugular vein]], and was thus related to the reorganisation of the blood vessels supplying the head as an immediate response to bipedalism, which relaxed as bipedalism became more developed.<ref>{{cite journal|first1=D.|last1=Falk|first2=G. C.|last2=Conroy|year=1983|title=The cranial venous sinus system in ''Australopithecus afarensis''|journal=Nature|volume=306|issue=5945|pages=779–781|doi=10.1038/306779a0|bibcode=1983Natur.306..779F|s2cid=34922603}}</ref> In 1988, Falk and Tobias demonstrated that early hominins (at least ''A. africanus'' and ''P. boisei'') could have both an occipital/marginal and transverse/sigmoid systems concurrently or on opposite halves of the skull.<ref>{{cite book|first=D.|last=Falk|chapter=Enlarged occipital/marginal sinuses and emissary foramina: Their significance in hominid evolution|editor-first=F. E.|editor-last=Grine|title=Evolutionary History of the "Robust" Australopithecines|year=1988|pages=133–148|publisher=Routledge |isbn=978-1-351-52126-0}}</ref>

===Torso===
Few [[Biology:Vertebra|vertebra]]e are assigned to ''P. robustus''. The only thoracolumbar series (thoracic and lumbar series) preserved belongs to the juvenile SKW 14002, and either represents the 1st to the 4th lumbar vertebrae, or the 2nd to the 5th. SK 3981 preserves a 12th thoracic vertebra (the last in the series), and a lower lumbar vertebra. The 12th thoracic vertebra is relatively elongated, and the articular surface (where it joins with another vertebra) is kidney-shaped. The T12 is more compressed in height than that of other australopithecines and modern apes.<ref name=Sanders1998/> Modern humans who suffer from spinal disc herniation often have vertebrae that are more similar to those of [[Biology:Chimpanzee|chimpanzee]]s than healthy humans. Early hominin vertebrae are similar to those of a pathological human, including the only other 12th thoracic vertebra known for ''P. robustus'', the juvenile SK 853. Conversely, SK 3981 is more similar to those of healthy humans, which could be explained as: SK 3981 is abnormal, the vertebrae took on a more humanlike condition with maturity, or one of these specimens is assigned to the wrong species.<ref>{{cite journal|first1=K. A.|last1=Plomp|first2=K.|last2=Dobney|first3=D. A.|last3=Weston|first4=U. S.|last4=Viðarsdóttir|first5=M.|last5=Collard|year=2019|title=3D shape analyses of extant primate and fossil hominin vertebrae support the ancestral shape hypothesis for intervertebral disc herniation|journal=BMC Evolutionary Biology|volume=19|issue=226|page=226|doi=10.1186/s12862-019-1550-9|pmid=31842740|pmc=6916256|bibcode=2019BMCEE..19..226P |doi-access=free}}</ref> The shape of the lumbar vertebrae is much more similar to that of [[Earth:Turkana Boy|Turkana Boy]] (''H. ergaster''/''H. erectus'') and humans than other australopithecines. The pedicles (which jut out diagonally from the vertebra) of the lower lumbar vertebra are much more robust than in other australopithecines and are within the range of humans, and the transverse processes (which jut out to the sides of the vertebra) indicate powerful iliolumbar ligaments. These could have bearing on the amount of time spent upright compared to other australopithecines.<ref name=Sanders1998>{{cite journal|first=W. J.|last=Sanders|year=1998|title=Comparative morphometric study of the australopithecine vertebral series Stw-H8/H41|journal=Journal of Human Evolution|volume=34|issue=3|pages=249–302|url=http://pdfs.semanticscholar.org/6e8b/ecb745a170622037db8db61735ec45512da7.pdf|archive-url=https://web.archive.org/web/20190226075230/http://pdfs.semanticscholar.org/6e8b/ecb745a170622037db8db61735ec45512da7.pdf|url-status=dead|archive-date=2019-02-26|doi=10.1006/jhev.1997.0193|pmid=9547457|s2cid=13290661}}</ref>

[[File:DNH 43 ventral.jpg|thumb|Illustration of the pelvis of DNH 43 (front view)|alt=Pelvis in face-view preserving the sacrum and the right ilium and the upper portion of the ischium]]
The [[Biology:Pelvis|pelvis]] is similar to the pelvises of ''A. africanus'' and ''A. afarensis'', but it has a wider iliac blade and smaller acetabulum and hip joint.<ref name=Wood2000/> Like modern humans, the ilium of ''P. robustus'' features development of the surface and thickening of the posterior superior iliac spine, which are important in stabilising the [[Biology:Sacrum|sacrum]], and indicates lumbar lordosis (curvature of the lumbar vertebrae) and thus bipedalism. The anatomy of the sacrum and the first lumbar vertebra (at least the vertebral arch), preserved in DNH 43, are similar to those of other australopithecines.<ref>{{cite journal|first1=D.|last1=Gommery|first2=B.|last2=Senut|first3=A.|last3=Keyser|year=2002|title=A fragmentary pelvis of ''Paranthropus robustus'' of the Plio-Pleistocene site of Drimolen Republic of South Africa|language=fr|journal=Geobios|volume=35|issue=2|pages=265–281|doi=10.1016/S0016-6995(02)00022-0}}</ref> The pelvis seems to indicate a more-or-less humanlike hip joint consistent with bipedalism, though differences in overall pelvic anatomy may indicate ''P. robustus'' used different muscles to generate force and perhaps had a different mechanism to direct force up the spine. This is similar to the condition seen in ''A. africanus''. This could potentially indicate the lower limbs had a wider range of motion than those of modern humans.<ref>{{cite journal |vauthors=Macchiarelli R, Bondioli L, Galichon V, Tobias PV |title=Hip bone trabecular architecture shows uniquely distinctive locomotor behaviour in South African australopithecines |journal=Journal of Human Evolution |volume=36 |issue=2 |pages=211–32 |date=February 1999 |pmid=10068067 |doi=10.1006/jhev.1998.0267}}</ref>

===Limbs===
The distal (lower) [[Biology:Humerus|humerus]] of ''P. robustus'' falls within the variation of both modern humans and chimps, as the distal humerus is quite similar between humans and chimpanzees.<ref>{{cite journal|first=W. L.|last=Straus, Jr.|year=1948|title=The humerus of ''Paranthropus robustus''|journal=American Journal of Physical Anthropology|volume=6|issue=3|pages=285–313|doi=10.1002/ajpa.1330060305|pmid=18884223}}</ref> The [[Biology:Radius (bone)|radius]] of ''P. robustus'' is comparable in form to ''Australopithecus'' species. The wrist joint had the same maneuverability as that of modern humans rather than the greater flexion achieved by non-human apes, but the head of radius (the [[Medicine:Elbow|elbow]]) seems to have been quite capable of maintaining stability when the forearm was flexed like non-human apes. It is possible this reflects some arboreal activity (movement in the trees) as is controversially postulated in other australopithecines.<ref>{{cite journal|first1=F. E.|last1=Grine|first2=R. L.|last2=Susman|year=1991|title=Radius of ''Paranthropus robustus'' from member 1, Swartkrans Formation, South Africa|journal=American Journal of Physical Anthropology|volume=84|issue=3|pages=229–248|doi=10.1002/ajpa.1330840302|pmid=2024712}}</ref> SKX 3602 exhibits robust radial styloid processes near the hand which indicate strong brachioradialis muscles and [[Medicine:Extensor retinaculum of the hand|extensor retinaculae]]. Like humans, the finger bones are uncurved and have weaker muscle attachment than non-human apes, though the proximal phalanges are smaller than in humans. The intermediate phalanges are stout and straight like humans, but have stouter bases and better developed flexor impressions. The distal phalanges seem to be essentially humanlike. These could indicate a decreased climbing capacity compared to non-human apes<ref>{{cite journal|first=R. L.|last=Susman|year=1989|title=New hominid fossils from the Swartkrans formation (1979–1986 excavations): Postcranial specimens|journal=American Journal of Physical Anthropology|volume=79|issue=4|pages=451–474|doi=10.1002/ajpa.1330790403|pmid=2672829}}</ref> and ''P. boisei''.<ref>{{cite journal|first1=M.|last1=Domínguez-Rodrigo|first2=T. R.|last2=Pickering|first3=E.|last3=Baquedano|display-authors=et al.|year=2013|title=First Partial Skeleton of a 1.34-Million-Year-Old ''Paranthropus boisei'' from Bed II, Olduvai Gorge, Tanzania|journal=PLOS ONE|volume=8|issue=12|page=e80347|doi=10.1371/journal.pone.0080347|pmid=24339873|pmc=3855051|bibcode=2013PLoSO...880347D|doi-access=free}}</ref> The ''P. robustus'' hand is consistent with a humanlike precision grip which would have made possible the production or usage of tools requiring greater motor functions than [[Biology:Tool use by animals#Primates|non-human primate tools]].<ref name=Susman1988>{{cite journal|first=R. L.|last=Susman|year=1988|title=Hand of ''Paranthropus robustus'' From Member 1, Swartkrans: Fossil Evidence for Tool Behavior|journal=Science|volume=240|issue=4853|pages=781–784|doi=10.1126/science.3129783|jstor=1701549|pmid=3129783|bibcode=1988Sci...240..781S}}</ref>

The femur, as in ''P. boisei'' and ''H. habilis'', is flattened anteroposteriorly (on the front and back side). This may indicate a walking gait more similar to early hominins than to modern humans (less efficient gait).<ref name=Wood2000>{{cite journal |vauthors=Wood B, Richmond BG |title=Human evolution: taxonomy and paleobiology |journal=Journal of Anatomy |volume=197 |issue=1 |pages=35–36 |year=2000 |pmid=10999270 |pmc=1468107 |doi=10.1046/j.1469-7580.2000.19710019.x}}</ref> Four femora assigned to ''P. robustus''—SK 19, SK 82, SK 97, and SK 3121—exhibit an apparently high [[Anisotropy|anisotropic]] trabecular bone (at the hip joint) structure, which could indicate reduced mobility of the hip joint compared to non-human apes, and the ability to produce forces consistent with humanlike bipedalism.<ref>{{cite journal|first1=T. M.|last1=Ryan|first2=K. J.|last2=Carlson|first3=A. D.|last3=Gordon|display-authors=et al.|year=2018|title=Human-like hip joint loading in ''Australopithecus africanus'' and ''Paranthropus robustus''|journal=Journal of Human Anthropology|volume=121|pages=12–24|doi=10.1016/j.jhevol.2018.03.008|pmid=29706230|s2cid=14060188|url=https://www.repository.cam.ac.uk/handle/1810/277557|doi-access=free}}</ref> The femoral head StW 311, which either belongs to ''P. robustus'' or early ''Homo'', seems to have habitually been placed in highly flexed positions based on the wearing patterns, which would be consistent with frequent climbing activity. It is unclear if frequent squatting could be a valid alternative interpretation.<ref>{{cite journal|first1=L.|last1=Georgiou|first2=C. J.|last2=Dunmore|first3=A.|last3=Bardo|year=2020|title=Evidence for habitual climbing in a Pleistocene hominin in South Africa|journal=Proceedings of the National Academy of Sciences|volume=117|issue=15|pages=8416–8423|doi=10.1073/pnas.1914481117|pmid=32229560|pmc=7165455|bibcode=2020PNAS..117.8416G |doi-access=free}}</ref> The textural complexity of the [[Biology:Patella|kneecap]] SKX 1084, which reflects [[Biology:Cartilage|cartilage]] thickness and thus usage of the knee joint and bipedality, is midway between modern humans and chimps.<ref>{{cite journal|first1=M.|last1=Cazenave|first2=A.|last2=Oettlê|first3=J. F.|last3=Thackerey|display-authors=et al.|year=2019|title=The SKX 1084 hominin patella from Swartkrans Member 2, South Africa: An integrated analysis of its outer morphology and inner structure|journal=Comptes Rendus Palevol|volume=18|issue=2|pages=223–235|doi=10.1016/j.crpv.2018.06.002|bibcode=2019CRPal..18..223C |doi-access=free|hdl=2263/71976|hdl-access=free}}</ref> The big toe bone of ''P. robustus'' is not dextrous, which indicates a humanlike foot posture and range of motion, but the more distal ankle joint would have inhibited the modern human toe-off [[Biology:Bipedal gait cycle|gait cycle]]. ''P. robustus'' and ''H. habilis'' may have achieved about the same grade of bipedality.<ref>{{cite journal|first1=R. L.|last1=Susman|first2=T. M.|last2=Brain|year=1988|title=New first metatarsal (SKX 5017) from Swartkrans and the gait of ''Paranthropus robustus''|journal=American Journal of Physical Anthropology|volume=77|issue=1|pages=7–15|doi=10.1002/ajpa.1330770103|pmid=3189526}}</ref>

===Size===
Broom had noted that the ankle bone and humerus of the holotype TM 1517 were about the same dimensions as that of a modern San woman, and so assumed humanlike proportions in ''P. robustus''. In 1972, Robinson estimated ''Paranthropus'' as having been massive. He calculated the humerus-to-femur ratio of ''P. robustus'' by using the presumed female humerus of STS 7 and comparing it with the presumed male femur of STS 14. He also had to estimate the length of the humerus using the femur assuming a similar degree of sexual dimorphism between ''P. robustus'' and humans. Comparing the ratio to humans, he concluded that ''P. robustus'' was a heavily built species with a height of {{cvt|140–150|cm|ftin}} and a weight of {{cvt|68–91|kg}}. Consequently, Robinson had described its locomotory habits as, "a compromise between erectness and facility for quadrupedal climbing." In contrast, he estimated ''A. africanus'' (which he called "''H.''" ''africanus'') to have been {{cvt|4–4.5|ft|order=flip}} tall and {{cvt|40–60|lb|order=flip}} in weight, and to have also been completely bipedal.<ref name=Wolpoff1974>{{cite journal|first=M. H.|last=Wolpoff|year=1974|title=Reviewed Work: Early Hominid Posture and Locomotion by John T. Robinson|journal=Human Biology|volume=46|issue=4|pages=719–724|jstor=41462378}}</ref>

Robinson's estimation of ''P. robustus'' size was soon challenged in 1974 by American palaeontologist [[Biography:Stephen Jay Gould|Stephen Jay Gould]] and English palaeoanthropologist David Pilbeam, who guessed from the available skeletal elements a weight of about {{cvt|40.5|kg}}.<ref>{{cite journal|last1=Pilbeam|first1=D.|last2=Gould|first2=S. J.|year=1974|title=Size and Scaling in Human Evolution|journal=Science|volume=186|issue=4167|pages=892–901|doi=10.1126/science.186.4167.892|pmid=4219964|bibcode=1974Sci...186..892P|s2cid=23346637}}</ref> Similarly, in 1988, American anthropologist Henry McHenry reported much lighter weights as well as notable sexual dimorphism for ''Paranthropus''. McHenry plotted body size vs. the cross sectional area of the femoral head for a sample of just humans and a sample with all great apes including humans, and calculated [[Linear regression|linear regression]]s for each one. Based on the average of these two regressions, he reported an average weight of {{cvt|47.1|kg}} for ''P. robustus'' using the specimens SK 82 and SK 97.<ref>{{cite book|first=H. M.|last=McHenry|chapter=New estimates of body weight in early hominids and their significance to encephalization and megadontia in robust australopithecines|editor-first=F. E.|editor-last=Grine|title=Evolutionary History of the "Robust" Australopithecines|year=1988|pages=133–148|publisher=Routledge |isbn=978-1-351-52126-0}}</ref> In 1991, McHenry expanded his sample size, and also estimated the living size of Swartkrans specimens by scaling down the dimensions of an average modern human to meet a preserved leg or foot element (he considered the arm measurements too variable among hominins to give accurate estimates). At Members 1 and 2, about 35% of the ''P. robustus'' leg or foot specimens were the same size as those in a {{cvt|28|kg}} human, 22% in a {{cvt|43|kg}} human, and the remaining 43% bigger than the former but less than a {{cvt|54|kg}} human except for KNM‐ER 1464 (an ankle bone). At Member 3, all individuals were consistent with a {{cvt|45|kg}} human.<ref name=McHenry1991a>{{cite journal|first=H. M.|last=McHenry|author-link=Henry McHenry|year=1991|title=Petite bodies of the "robust" australopithecines|journal=American Journal of Physical Anthropology|volume=86|issue=4|pages=445–454|doi=10.1002/ajpa.1330860402}}</ref> Smaller adults thus seem to have been more common.<ref name=Braga2017>{{cite journal|first1=J.|last1=Braga|first2=J. F.|last2=Thackeray|first3=L.|last3=Bruxelles|first4=J.|last4=Dumoncel|first5=J.-P.|last5=Fourvel|year=2017|title=Stretching the time span of hominin evolution at Kromdraai (Gauteng, South Africa): Recent discoveries|journal=Comptes Rendus Palevol|volume=16|issue=1|pages=58–70|doi=10.1016/j.crpv.2016.03.003|bibcode=2017CRPal..16...58B |doi-access=free}}</ref> McHenry also estimated the living height of 3 ''P. robustus'' specimens (male SK 82, male SK 97, and female or subadult SK 3155), by scaling down an average human to meet the estimated size of the preserved femur, as {{cvt|126|cm|ftin}}, {{cvt|137|cm|ftin}}, and {{cvt|110|cm|ftin}}, respectively. Based on just these three, he reported an average height of {{cvt|132|cm|ftin}} for ''P. robustus'' males and {{cvt|110|cm|ftin}} for females.<ref name=McHenry1991b>{{cite journal|first=H. M.|last=McHenry|author-link=Henry McHenry|year=1991|title=Femoral lengths and stature in Plio-Pleistocene hominids|journal=American Journal of Physical Anthropology|volume=85|issue=2|pages=149–158|doi=10.1002/ajpa.1330850204|pmid=1882979}}</ref>

In 2001, palaeoanthropologist Randall L. Susman and colleagues, using two recently discovered proximal femoral fragments from Swartkrans, estimated an average of {{cvt|42|kg}} for males and {{cvt|30|kg}} for females. If these four proximal femur specimens—SK 82, SK 97, SKW 19, and SK 3121—are representative of the entire species, they said that this degree of sexual dimorphism is greater than what is exhibited in [[Biology:Human|human]]s and [[Biology:Chimpanzee|chimpanzee]]s, but less than [[Biology:Orangutan|orangutan]]s and [[Biology:Gorilla|gorilla]]s. Female ''P. robustus'' were about the same estimated weight as female ''H. ergaster/H. erectus'' in Swartkrans, but they estimated male ''H. ergaster/H. erectus'' as much bigger at {{cvt|55|kg}}.<ref name=Susman2001>{{cite journal|first1=R. L.|last1=Susman|first2=D.|last2=de Ruiter|first3=C. K.|last3=Brain|year=2001|title=Recently identified postcranial remains of ''Paranthropus'' and Early ''Homo'' from Swartkrans Cave, South Africa|journal=Journal of Human Evolution|volume=41|issue=6|pages=607–629|doi=10.1006/jhev.2001.0510|pmid=11782111|s2cid=26326715}}</ref> In 2012, American anthropologist Trenton Holliday, using the same equation as McHenry on 3 specimens, reported an average of {{cvt|37|kg}} with a range of {{cvt|30–43|kg}}.<ref>{{cite journal|first=T. W.|last=Holliday|year=2012|title=Body Size, Body Shape, and the Circumscription of the Genus ''Homo''|journal=Current Anthropology|volume=53|issue=6|page=338|doi=10.1086/667360|s2cid=83620946}}</ref> In 2015, biological anthropologist Mark Grabowski and colleagues, using 9 specimens, estimated an average of {{cvt|32.3|kg}} for males and {{cvt|24|kg}} for females.<ref>{{cite journal|first1=M.|last1=Grabowski|first2=K. G.|last2=Hatala|first3=W. L.|last3=Jungers|first4=B. G.|last4=Richmond|year=2015|title=Body mass estimates of hominin fossils and the evolution of human body size|journal=Journal of Human Evolution|volume=85|pages=75–93|doi=10.1016/j.jhevol.2015.05.005|pmid=26094042}}</ref>

==Palaeobiology==
===Diet===
[[File:SK 46.jpg|thumb|Cast of SK 46 skull|alt=Skull in three-quarter view facing left, with the right side of the face missing (though the right dental row is still there)]]
In 1954, Robinson suggested that the heavily built skull of ''P. robustus'' and resultantly exorbitant bite force was indicative of a [[Earth:Generalist and specialist species|specialist]] diet adapted for frequently cracking hard foods such as nuts. Because of this, the predominant model of ''Paranthropus'' extinction for the latter half of the 20th century was that they were unable to adapt to the volatile climate of the Pleistocene, unlike the much more adaptable ''Homo''. Subsequent researchers reinforced this model studying the musculature of the face, dental wearing patterns, and primate ecology.<ref name=Wood2004/> In 1981, English anthropologist Alan Walker, while studying the ''P. boisei'' skulls KNM-ER 406 and 729, pointed out that bite force is a measure of not only the total pressure exerted but also the surface area of the tooth over which the pressure is being exerted, and ''Paranthropus'' teeth are 4–5 times the size of modern human teeth. Because the chewing muscles are arranged the same way, Walker postulated that the heavy build was instead an adaptation to chew a large quantity of food at the same time. He also found that microwearing on 20 ''P. boisei'' molar specimens were indistinguishable from patterning recorded in [[Biology:Mandrill|mandrill]]s, chimps, and orangutans.<ref>{{cite journal|first=A.|last=Walker|year=1981|title=Diet and teeth. Dietary hypotheses and human evolution|journal=Philosophical Transactions of the Royal Society B|volume=292|issue=1057|pages=57–64|doi=10.1098/rstb.1981.0013|pmid=6115407|doi-access=free}}</ref> Despite subsequent arguments that ''Paranthropus'' were not specialist feeders, the predominant consensus in favour of Robinson's initial model did not change for the remainder of the 20th century.<ref name=Wood2004/>

In 2004, in their review of ''Paranthropus'' dietary literature, anthropologists Bernard Wood and David Strait concluded that ''Paranthropus'' were most definitely generalist feeders, and that ''P. robustus'' was an [[Biology:Omnivore|omnivore]]. They found that the microwear patterns in ''P. robustus'' suggest hard food was infrequently consumed, and therefore the heavy build of the skull was only relevant when eating less desirable fallback foods.<ref name=Wood2004>{{cite journal|first1=B.|last1=Wood|first2=D.|last2=Strait|year=2004|title=Patterns of resource use in early ''Homo'' and ''Paranthropus''|journal=Journal of Human Evolution|volume=46|issue=2|pages=119–162|doi=10.1016/j.jhevol.2003.11.004|pmid=14871560}}</ref> Such a strategy is similar to that used by modern gorillas, which can sustain themselves entirely on lower quality fallback foods year-round, as opposed to lighter built chimpanzees (and presumably gracile australopithecines) which require steady access to high quality foods.<ref name=Laden2005>{{cite journal|first1=G.|last1=Laden|first2=R.|last2=Wrangham|year=2005|title=The rise of the hominids as an adaptive shift in fallback foods: Plant underground storage organs (USOs) and australopith origins|journal=Journal of Human Evolution|volume=49|issue=4|pages=482–498|doi=10.1016/j.jhevol.2005.05.007|pmid=16085279}}</ref> In 1980, anthropologists Tom Hatley and John Kappelman suggested that early hominins ([[Biology:Convergent evolution|convergently]] with bears and pigs) adapted to eating abrasive and calorie-rich underground [[Biology:Storage organ|storage organ]]s (USOs), such as roots and tubers.<ref>{{cite journal|first1=T.|last1=Hatley|first2=J.|last2=Kappelman|year=1980|title=Bears, pigs, and Plio-Pleistocene hominids: A case for the exploitation of belowground food resources|journal=Human Ecology|volume=8|issue=4|pages=371–387|doi=10.1007/BF01561000|jstor=4602571|s2cid=86632664}}</ref> Since then, hominin exploitation of USOs has gained more support. In 2005, biological anthropologists Greg Laden and [[Biography:Richard Wrangham|Richard Wrangham]] proposed that ''Paranthropus'' relied on USOs as a fallback or possibly primary food source, and noted that there may be a correlation between high USO abundance and hominin occupation.<ref name=Laden2005/>

A 2006 [[Physics:Isotope analysis#Carbon-13|carbon isotope analysis]] suggested that ''P. robustus'' subsisted on mainly [[Biology:C4 carbon fixation|C<sub>4</sub> savanna plants]] or [[Biology:C3 carbon fixation|C<sub>3</sub> forest plants]] depending on the season, which could indicate either seasonal shifts in diet or seasonal migration from forest to savanna.<ref name=Sponheimer2006/> ''H. ergaster/H. erectus'' appears to have consumed about the same proportion of C<sub>3</sub> to C<sub>4</sub> based foods as ''P. robustus''.<ref name=Lee2000>{{cite journal|first1=J.|last1=Lee-Thorp|first2=J. F.|last2=Thackeray|first3=N. V.|last3=der Merwe|year=2000|title=The hunters and the hunted revisited|journal=Journal of Human Evolution|volume=39|issue=6|pages=565–576|doi=10.1006/jhev.2000.0436|pmid=11102267}}</ref> ''P. robustus'' likely also commonly cracked hard foods such as seeds or nuts, as it had a moderate tooth-chipping rate (about 12% in a sample of 239 individuals, as opposed to little to none for ''P. boisei'').<ref name=Sponheimer2006>{{cite journal|first1=M.|last1=Sponheimer|first2=B. H.|last2=Passey|first3=D. J.|last3=de Ruiter|display-authors=et al.|year=2006|title=Isotopic Evidence for Dietary Variability in the Early Hominin ''Paranthropus robustus''|journal=Science|volume=314|issue=5801|pages=980–982|doi=10.1126/science.1133827|pmid=17095699|bibcode=2006Sci...314..980S|s2cid=22291574}}</ref><ref>{{cite journal|first1=P. J.|last1=Constantino|first2=O.|last2=Borrero-Lopez|first3=B. R.|last3=Lawn|year=2018|title=Mechanisms of Tooth Damage in ''Paranthropus'' Dietary Reconstruction|journal= Biosurface and Biotribology|volume=4|issue=3|pages=73–78|doi=10.1049/bsbt.2018.0017|doi-access=free}}</ref> A high cavity rate could indicate [[Chemistry:Honey|honey]] consumption.<ref name=Towle2019/> Juvenile ''P. robustus'' may have relied more on tubers than adults, given the elevated levels of [[Chemistry:Strontium|strontium]] compared to adults in teeth from Swartkrans Cave, which, in the area, was most likely sourced from tubers. [[Biology:Dentin|Dentin]] exposure on juvenile teeth could indicate early weaning, or a more abrasive diet than adults which wore away the [[Medicine:Cementum|cementum]] and [[Biology:Tooth enamel|enamel]] coatings, or both. It is also possible juveniles were instead less capable of removing grit from dug-up food rather than purposefully seeking out more abrasive foods.<ref name=Williams2015/>

===Social structure===
Given the marked anatomical and physical differences with modern great apes, there may be no modern analogue for australopithecine societies, so comparisons drawn with modern primates are highly speculative.<ref name=Copeland2011/><ref name=Kaszycka2016/>

In 2007, anthropologist Charles Lockwood and colleagues pointed out that ''P. robustus'' appears to have had pronounced [[Biology:Sexual dimorphism|sexual dimorphism]], with males notably larger than females. This is commonly correlated with a male-dominated polygamous society, such as the harem society of modern forest-dwelling silverback gorillas where one male has exclusive breeding rights to a group of females. Estimated male-female size disparity in ''P. robustus'' is comparable to gorillas (based on facial dimensions), and younger males were less robust than older males (delayed maturity is also exhibited in gorillas). Because the majority of sexed ''P. robustus'' specimens are male (or at least presumed male), males seem to have had a higher mortality rate than females. In a harem society, males are more likely to be evicted from the group given higher male–male competition over females, and lone males may have been put at a higher risk of predation. By this hypothesis, a female moving out of her birth group may have spent little time alone and transferred immediately to another established group.<ref name=Lockwood2007>{{cite journal|first1=C. A.|last1=Lockwood|first2=C. G.|last2=Menter|first3=J.|last3=Moggi-Cecchi|first4=A. W.|last4=Keyser|year=2007|title=Extended male growth in a fossil hominin species|journal=Science|volume=318|issue=5855|pages=1443–1446|doi=10.1126/science.1149211|pmid=18048687|bibcode=2007Sci...318.1443L|s2cid=32900905|url=http://doc.rero.ch/record/15464/files/PAL_E2851.pdf }}</ref>

[[File:20070819 Dierenpark Emmen (20).JPG|thumb|upright=1.3|''P. robustus'' could have lived in multi-male groups like Hamadryas baboons (above troop at Dierenpark Emmen).<ref name=Kaszycka2016/>|alt=A large troop of Hamadrayas baboons. The females are brown and shorthaired, whereas the males are white and longhaired.]]
However, in 2011, palaeoanthropologist Sandi Copeland and colleagues studied the strontium isotope ratio of ''P. robustus'' teeth from the [[Earth:Dolomite (rock)|dolomite]] Sterkfontein Valley, and found that like other hominins, but unlike other great apes, ''P. robustus'' females were more likely to leave their place of birth (patrilocal). This discounts the plausibility of a harem society, which would have resulted in a matrilocal society due to heightened male–male competition. Males did not seem to have ventured very far from the valley, which could either indicate small home ranges, or that they preferred dolomitic landscapes due to perhaps cave abundance or factors related to vegetation growth.<ref name=Copeland2011>{{cite journal|first1=S. R.|last1=Copeland|first2=M.|last2=Sponheimmer|first3=D. J.|last3=de Ruiter|first4=J.|last4=Lee-Thorp|year=2011|title=Strontium isotope evidence for landscape use by early hominins|journal=Nature|volume=474|issue=7349|pages=76–78|doi=10.1038/nature10149|pmid=21637256|s2cid=205225222}}</ref> Similarly, in 2016, Polish anthropologist Katarzyna Kaszycka rebutted that, among primates, delayed maturity is also exhibited in the rhesus monkey which has a multi-male society, and may not be an accurate indicator of social structure. If ''P. robustus'' preferred a savanna habitat, a multi-male society would have been more conducive in defending the troop from predators in the more exposed environment, much like baboons which live in the savanna. Even in a multi-male society, it is still possible that males were more likely to be evicted, explaining male-skewed mortality with the same mechanism.<ref name=Kaszycka2016>{{cite journal|first=K. A.|last=Kaszycka|year=2016|title=''Australopithecus robustus'' societies - one-male or multimale?|journal=South African Journal of Science|volume=112|issue=1–2|pages=124–131|doi=10.17159/sajs.2016/20150165|doi-access=free}}</ref>

In 2017, anthropologist Katharine Balolia and colleagues postulated that, because male non-human great apes have a larger sagittal crest than females (particularly gorillas and orangutans), the crest may be influenced by [[Biology:Sexual selection|sexual selection]] in addition to supporting chewing muscles. Further, the size of the sagittal crest (and the gluteus muscles) in male [[Biology:Western lowland gorilla|western lowland gorilla]]s has been correlated with reproductive success. Balolia ''et al.'' extended their interpretation of the crest to the males of ''Paranthropus'' species, with the crest and resultantly larger head (at least in ''P. boisei'') being used for some kind of [[Biology:Display (zoology)|display]]. This contrasts with other primates which flash the typically enlarged canines in agonistic display (''Paranthropus'' likely did not do this as the canines are comparatively small), though it is also possible that the crest is only so prominent in male gorillas and orangutans because they require larger temporalis muscles to achieve a wider gape to better display the canines.<ref>{{cite journal|first1=K. L.|last1=Balolia|first2=C.|last2=Soligo|first3=B.|last3=Wood|year=2017|title=Sagittal crest formation in great apes and gibbons|journal=Journal of Anatomy|volume=230|issue=6|pages=820–832|doi=10.1111/joa.12609|pmid=28418109|pmc=5442144|doi-access=free}}</ref>

===Technology===
Cave sites in the Cradle of Humankind often have stone and bone tools, with the former attributed to early ''Homo'' and the latter generally to ''P. robustus'', as bone tools are most abundant when ''P. robustus'' remains far outnumber ''Homo'' remains. Australopithecine bone technology was first proposed by Dart in the 1950s with what he termed the "[[History:Osteodontokeratic culture|osteodontokeratic culture]]", which he attributed to ''A. africanus'' at [[Earth:Makapansgat|Makapansgat]] dating to 3–2.6 million years ago. These bones are no longer considered to have been tools, and the existence of this culture is not supported. The first probable bone tool was reported by Robinson in 1959 at Sterkfontein Member 5. Excavations led by South African palaeontologist Charles Kimberlin Brain at Swartkrans in the late 1980s and early 1990s recovered 84 similar bone tools, and excavations led by Keyser at Drimolen recovered 23. These tools were all found alongside [[Engineering:Acheulean|Acheulean]] [[Engineering:Stone tool|stone tool]]s, except for those from Swartkrans Member 1 which bore [[History:Oldowan|Oldowan]] stone tools. Thus, there are 108 bone tool specimens from the region in total, and possibly an additional two from Kromdraai B. The two stone tools (either "Developed Oldowan" or "Early Acheulean") from Kromdraai B could possibly be attributed to ''P. robustus'', as ''Homo'' has not been confidently identified in this layer, though it is possible that the stone tools were reworked (moved into the layer after the inhabitants had died). Bone tools may have been used to cut or process vegetation,<ref name=Stammers2018/> process fruits (namely marula fruit), strip tree bark,<ref name=Errico2009>{{cite journal|first1=F.|last1=d'Errico|first2=L.|last2=Backwell|year=2009|title=Assessing the function of early hominin bone tools|journal=Journal of Archaeological Science|volume=36|issue=8|pages=1764–1773|doi=10.1016/j.jas.2009.04.005|bibcode=2009JArSc..36.1764D }}</ref> or dig up tubers or termites.<ref name=Stammers2018/><ref name=Errico2009/><ref name=Backwell2001>{{cite journal|first1=L. R.|last1=Backwell|first2=F.|last2=d'Errico|year=2001|title=Evidence of termite foraging by Swartkrans early hominids|journal=Proceedings of the National Academy of Sciences|volume=98|issue=4|pages=1358–1363|doi=10.1073/pnas.021551598|pmid=11171955|pmc=29261|doi-access=free}}</ref> The form of ''P. robustus'' incisors appears to be intermediate between ''H. erectus'' and modern humans, which could possibly mean it did not have to regularly bite off mouthfuls of a large food item due to preparation with simple tools.<ref name=Williams2015>{{cite journal|first=F. L.|last=Williams|year=2015|title=Dietary proclivities of ''Paranthropus robustus'' from Swartkrans, South Africa|journal=Anthropological Review|volume=78|issue=1|pages=1–19|doi=10.1515/anre-2015-0001|doi-access=free}}</ref> The bone tools were typically sourced from the [[Biology:Diaphysis|shaft]] of [[Biology:Long bone|long bone]]s from medium- to large-sized mammals, but tools sourced from mandibles, [[Biology:Rib|rib]]s, and horn cores have also been found. They were not manufactured or purposefully shaped for a task, but since they display no weathering, and there is a preference displayed for certain bones, raw materials were likely specifically hand picked. This contrasts with East African bone tools which appear to have been modified and directly cut into specific shapes before using.<ref name=Stammers2018>{{cite journal|first1=R. C.|last1=Stammers|first2=M.|last2=Caruana|first3=A. I. R.|last3=Herries|year=2018|title=The first bone tools from Kromdraai and stone tools from Drimolen, and the place of bone tools in the South African Earlier Stone Age|journal= Quaternary International|volume=495|pages=87–101|doi=10.1016/j.quaint.2018.04.026|bibcode=2018QuInt.495...87S|s2cid=135196415|doi-access=free}}</ref>

In 1988, Brain and South African archaeologist A. Sillent analysed the 59,488 bone fragments from Swartkrans Member 3, and found that 270 had been burnt, mainly belonging to medium-sized antelope, but also zebra, warthog, baboon, and ''P. robustus''. They were found across the entire depth of Member 3, so fire was a regular event throughout its deposition. Based on colour and structural changes, they found that 46 were heated to below {{cvt|300|C}}, 52 to {{cvt|300–400|C}}, 45 to {{cvt|400–500|C}}, and 127 above this. They concluded that these bones were, "the earliest direct evidence of fire use in the fossil record," and compared the temperatures with those achieved by experimental campfires burning [[Biology:Celtis africana|white stinkwood]] which commonly grows near the cave. Though some bones had cut marks consistent with butchery, they said it was also possible hominins were making fire to scare away predators or for warmth instead of cooking. Because both ''P. robustus'' and ''H. ergaster''/''H. erectus'' were found in the cave, they were unsure which species to attribute the fire to.<ref name=Brain1988>{{cite journal|first1=C. K.|last1=Brain|first2=A.|last2=Sillent|year=1988|title=Evidence from the Swartkrans cave for the earliest use of fire|journal=Nature|volume=336|issue=6198|pages=464–466|doi=10.1038/336464a0|bibcode=1988Natur.336..464B|s2cid=4318364}}</ref> As an alternative to hominin activity, because the bones were not burnt inside the cave, it is possible that they were naturally burnt in cyclically occurring [[Biology:Wildfire|wildfire]]s (dry savanna grass as well as possible [[Earth:Guano|guano]] or plant accumulation in the cave may have left it susceptible to such a scenario), and then washed into what would become Member 3.<ref name=Pickering>{{cite journal|last=Pickering|first=T. R.|year=2012|title=What's new is old: comments on (more) archaeological evidence of one-million-year-old fire from South Africa|journal=South African Journal of Science|volume=108|issue=5–6|pages=1–2|doi=10.4102/sajs.v108i5/6.1250|url=https://www.researchgate.net/publication/262749300|doi-access=free}}</ref><ref>{{cite journal|first1=J. A. J.|last1=Gowlett|first2=R. W.|last2=Wrangham|year=2013|title=Earliest fire in Africa: towards the convergence of archaeological evidence and the cooking hypothesis|journal=Azania: Archaeological Research in Africa|volume=48|issue=1|pages=16–17|doi=10.1080/0067270X.2012.756754|s2cid=163033909}}</ref> The now-earliest claim of fire usage is 1.7 million years ago at Wonderwerk Cave, South Africa, made by South African archaeologist Peter Beaumont in 2011, which he attributed to ''H. ergaster''/''H. erectus''.<ref name=Beaumont2011>{{cite journal|first=P. B.|last=Beaumont|year=2011|title=The Edge: More on Fire-Making by about 1.7 Million Years Ago at Wonderwerk Cave in South Africa|journal=Current Anthropology|volume=52|issue=4|pages=585–595|doi=10.1086/660919|s2cid=144176681}}</ref>

===Development===
[[File:SK11 Global.jpg|thumb|250px|left|SKX 11 tooth|alt=A tooth inside-view, top-view, and bottom-view]]
Australopithecines are generally considered to have had a faster, apelike growth rate than modern humans largely due to dental development trends. Broadly speaking, the emergence of the first permanent molar in early hominins has been variously estimated anywhere from 2.5 to 4.5 years, which all contrast markedly with the modern human average of 5.8 years. The 1st permanent molar of SK 63, which may have died at 3.4–3.7 years of age, possibly erupted at 2.9–3.2 years. In modern apes (including humans), dental development trajectory is strongly correlated with life history and overall growth rate, but it is possible that early hominins simply had a faster dental trajectory but a slower life history due to environmental factors, such as early weaning age as is exemplified in modern [[Biology:Indriidae|indriid]] lemurs.<ref name=Kelley2012>{{cite journal|first1=J.|last1=Kelley|first2=G. T.|last2=Schwartz|year=2012|title=Life-History Inference in the Early Hominins ''Australopithecus'' and ''Paranthropus''|journal=International Journal of Primatology|volume=33|issue=6|pages=1332–1363|doi=10.1007/s10764-012-9607-2|s2cid=16288970}}</ref> In TM 1517, fusion of the elements of the distal humerus (at the elbow joint) occurred before the fusion of the elements in the distal big toe phalanx, much like in chimps and [[Biology:Bonobo|bonobo]]s, but unlike humans, which could also indicate an apelike growth trajectory.<ref name=Cazenave2019/>

While growing, the front part of the jaw in ''P. robustus'' is depository (so it grows) whereas the sides are resorptive (so they recede). For comparison, chimp jaws are generally depository reflecting prognathism, and modern humans resorptive reflecting a flat face. In ''Paranthropus'', this may have functioned to thicken the palate. Unlike other apes and gracile australopithecines, but like humans, the premaxillary [[Biology:Suture (anatomy)|suture]] between the premaxilla and the [[Biology:Maxilla|maxilla]] (on the palate) formed early in development. At early stages, the ''P. robustus'' jawbone was somewhat similar to that of modern humans, but the breadth grew in ''P. robustus'', as to be expected from its incredible robustness in adulthood. By the time the first permanent molar erupts, the body of the mandible and the front jaw broadened, and the ramus of the mandible elongated, diverging from the modern human trajectory. Because the ramus was so tall, it is suggested that ''P. robustus'' experienced more anterior face rotation than modern humans and apes. Growth was most marked between the eruptions of the first and second permanent molars, most notably in terms of the distance from the back of the mouth to the front of the mouth, probably to make room for the massive postcanine teeth. Like humans, jaw robustness decreased with age, though it decreased slower in ''P. robustus''.<ref name=Cofran2014>{{cite journal|last=Cofran|first=Z.|year=2014|title=Mandibular development in ''Australopithecus robustus''|journal=American Journal of Physical Anthropology|volume=154|issue=3|pages=436–446|doi=10.1002/ajpa.22527|pmid=24820665}}</ref> Regardless if ''P. robustus'' followed a human or non-human ape dental development timeframe, the premolars and molars would have had an accelerated growth rate to achieve their massive size. In contrast, the presence of perikymata on the incisors and canines (growth lines which typically are worn away after eruption) could indicate these teeth had a reduced growth rate.<ref>{{cite journal|first=M. C.|last=Dean|year=1985|title=The eruption pattern of the permanent incisors and first permanent molars in ''Australopithecus (Paranthropus) robustus''|journal=American Journal of Physical Anthropology|volume=67|issue=3|pages=251–257|doi=10.1002/ajpa.1330670310|pmid=3933358}}</ref> The tooth roots of ''P. robustus'' molars may have grown at a faster rate than gracile australopithecines; the root length of SK 62's 1st molar, which was reaching emergence from the dental alveolus, is about {{cvt|6|mm}}. In contrast, those of other hominins reach {{cvt|5–6|mm}} after the tooth has emerged not only from the gums (a later stage of dental development). SK 62's growth trajectory is more similar to that of gorillas, whose roots typically measure {{cvt|7|mm}} when emerging from the gums.<ref name=Kelley2012/>

Females may have reached skeletal maturity by the time the third molar erupted, but males appear to have continued growing after reaching dental maturity, during which time they become markedly more robust than females (sexual bimaturism). Similarly, male gorillas complete dental development about the same time as females, but continue growing for up to 5 or 6 years; and male mandrills complete dental development before females, but continue growing for several years more.<ref name=Lockwood2007/> It is debated whether or not ''P. robustus'' had a defined growth spurt in terms of overall height during adolescence, an event unique to humans among modern apes.<ref name=Cofran2014/>

===Life history===
In 1968, American anthropologist Alan Mann, using dental maturity, stratified ''P. robustus'' specimens from Swartkrans into different ages, and found an average of 17.2 years at death (they did not necessarily die from old age), and the oldest specimen was 30–35 years old. He also reported an average of 22.2 years for ''A. africanus''. Using these, he argued these hominins had a humanlike prolonged childhood.<ref>{{cite thesis|first=A. E.|last=Mann|year=1968|title=The Paleodemography of Australopithecus|type=PhD|publisher=University of California, Berkeley}}</ref> In response, in 1971, biologist Kelton McKinley repeated Mann's process with more specimens, and (including ''P. boisei'') reported an average of 18 years. McKinley agreed with Mann that ''P. robustus'' may have had a prolonged childhood. McKinley also speculated that [[Biology:Sexual maturity|sexual maturity]] was reached at approximately 11 years because it is about halfway between the averages for chimps (9 years) and humans (13). Based on this, he concluded babies were birthed at intervals of 3 to 4 years using a statistical test to maximise the number of children born.<ref>{{cite journal|first=K. R.|last=McKinley|year=1971|title=Survivorship in gracile and robust ''Australopithecines'': A demographic comparison and a proposed birth model|journal=American Journal of Physical Anthropology|volume=34|issue=3|pages=417–426|doi=10.1002/ajpa.1330340311|pmid=5120556}}</ref>

In 1972, after estimating a foetal size of {{cvt|1230–1390|g|lb|1}} based on an adult female weight of {{cvt|50|kg}}, anthropologist Walter Leutenegger estimated foetal head size at about {{cvt|110–160|cc}}, similar to a chimp.<ref>{{cite journal|first=W.|last=Leutenegger|year=1972|title=Newborn Size and Pelvic Dimensions of ''Australopithecus''|journal=Nature|volume=240|issue=5383|pages=568–569|doi=10.1038/240568a0|pmid=4568405|bibcode=1972Natur.240..568L|s2cid=4151860}}</ref> In 1973, using this and an equation between foetal head size and gestation (assuming foetal growth rate of 0.6 for all mammals), biologist John Frazer estimated a gestation of 300 days for ''P. robustus''.<ref>{{cite journal|first=J. F. D.|last=Frazer|year=1973|title=Gestation Period for ''Australopithecus''|journal=Nature|volume=242|issue=5396|page=347|doi=10.1038/242347a0|pmid=4699060|bibcode=1973Natur.242..347F|s2cid=4289836|doi-access=free}}</ref> In response, Leutenegger pointed out that apes have highly variable foetal growth rates, and "estimates on gestation periods based on this rate and birth weight are useless."<ref>{{cite journal|first=W.|last=Leutenegger|year=1973|title=Gestation Period and Birth Weight of ''Australopithecus''|journal=Nature|volume=243|issue=5383|pages=568–9|doi=10.1038/240568a0|pmid=4568405|bibcode=1972Natur.240..568L |s2cid=4151860}}</ref>

In 1985, British biologists [[Biography:Paul H. Harvey|Paul H. Harvey]] and Tim Clutton-Brock came up with equations relating body size to life history events for primates, which McHenry applied to australopithecines in 1994. For ''P. robustus'', he reported newborn brain size of 175 cc and weight of {{cvt|1.9|kg}}, gestation 7.6 months, weaning after 30.1 months of age, maturation age 9.7 years, breeding age 11.4 years, birth interval 45 months, and lifespan 43.3 years. These roughly aligned with other australopithecines and chimps. However, for chimps, he got strongly inaccurate results when compared to actual data for newborn brain size, weaning age, and birth interval, and for humans all metrics except birth interval.<ref>{{cite journal|first=H. M.|last=McHenry|year=1994|title=Behavioral ecological implications of early hominid body size|journal=Journal of Human Evolution|volume=27|issue=1–3|page=84|doi=10.1006/jhev.1994.1036}}</ref>

===Pathology===
[[File:SK 57.png|thumb|The left upper 1st molar of SK 57 with tertiary dentin (white arrow)|alt=A tooth still in the jawbone which has numerous cracks all over, and the bottom left is chipped off. There is a white arrow pointing to a prominent black circle on the upper left tooth]]
Based on a sample of 402 teeth, ''P. robustus'' seems to have had a low incidence rate of about 12–16% for [[Medicine:Tertiary dentin|tertiary dentin]], which forms to repair tooth damage caused by excessive wearing or dental cavities. This is similar to what was found for ''A. africanus'' and ''H. naledi'' (all three inhabited the Cradle of Humankind at different points in time). In contrast, chimpanzees have an incidence rate of 47%, and gorillas as much as 90%, probably due to a diet with a much higher content of tough plants.<ref>{{cite journal|last=Towle|first=I.|year=2019|title=Tertiary Dentine Frequencies in Extant Great Apes and Fossil Hominins|journal=Open Quaternary|volume=5|issue=1|page=2|doi=10.5334/oq.48|doi-access=free}}</ref>

''P. robustus'' seems to have had notably high rates of pitting enamel hypoplasia (PEH), where tooth enamel formation is spotty instead of mostly uniform. In ''P. robustus'', about 47% of baby teeth and 14% of adult teeth were affected, in comparison to about 6.7% and 4.3%, respectively, for the combined teeth of ''A. africanus'', ''A. sediba'', early ''Homo'', and ''H. naledi''. The condition of these holes covering the entire tooth is consistent with the modern human ailment amelogenesis imperfecta. Since circular holes in enamel coverage are uniform in size, only present on the molar teeth, and have the same severity across individuals, the PEH may have been a genetic condition. It is possible that the [[Biology:Coding region|coding region]] concerned with thickening enamel also increased the risk of developing PEH.<ref>{{cite journal|first1=I.|last1=Towle|first2=J. D.|last2=Irish|year=2019|title=A probable genetic origin for pitting enamel hypoplasia on the molars of ''Paranthropus robustus''|journal=Journal of Human Evolution|volume=129|pages=54–61|doi=10.1016/j.jhevol.2019.01.002|pmid=30904040|s2cid=85502058|url=http://researchonline.ljmu.ac.uk/id/eprint/10289/1/Towle_Irish_JHE%202019.pdf}}</ref>

As many as four ''P. robustus'' individuals have been identified as having had dental [[Medicine:Tooth decay|cavities]], indicating a rate similar to non-agricultural modern humans (1–5%). This is odd as ''P. robustus'' is thought to have had a diet high in gritty foods, and gritty foods should decrease cavity incidence rate, so ''P. robustus'' may have often consumed high-sugar cavity-causing foods. PEH may have also increased susceptibility to cavities.<ref>{{cite journal|first1=I.|last1=Towle|first2=J. D.|last2=Irish|display-authors=et al.|year=2019|title=Dental caries in human evolution: frequency of carious lesions in South African fossil hominins|journal=bioRxiv|doi=10.1101/597385|s2cid=132416831}}</ref> A molar from Drimolen showed a cavity on the tooth root, a rare occurrence in fossil great apes. In order for cavity-creating bacteria to reach this area, the individual would have also presented either alveolar resportion, which is commonly associated with gum disease; or super-eruption of the tooth which occurs when it becomes worn down and has to erupt a bit more in order to maintain a proper bite, exposing the root in the process. The latter is most likely, and the exposed root seems to have caused hypercementosis to anchor the tooth in place. The cavity seems to have been healing, possibly due to a change in diet or [[Biology:Oral microbiology|mouth microbiome]], or the loss of the adjacent molar.<ref name=Towle2019>{{cite journal|first1=I.|last1=Towle|first2=A.|last2=Riga|first3=J. D.|last3=Irish|display-authors=et al.|year=2019|title=Root caries on a ''Paranthropus robustus'' third molar from Drimolen|journal=American Journal of Physical Anthropology|volume=170|issue=2|pages=319–323|doi=10.1002/ajpa.23891|pmid=31265762|s2cid=195786562|url=https://www.biorxiv.org/content/biorxiv/early/2019/04/11/573964.full.pdf}}</ref>

In a sample of 15 ''P. robustus'' specimens, all of them exhibited mild to moderate [[Medicine:Bone destruction patterns in periodontal disease|alveolar bone loss resulting from periodontal disease]] (the wearing away of the bone which supports the teeth due to gum disease). In contrast, in a sample of 10 ''A. africanus'' specimens, three exhibited no pathologies of the alveolar bone. Measuring the distance between the alveolar bone and the [[Medicine:Cementoenamel junction|cementoenamel junction]], ''P. robustus'' possibly suffered from a higher rate of [[Medicine:Tooth mobility|tooth-attachment loss]], unless ''P. robustus'' had a higher cervical height (the slightly narrowed area where the crown meets the root) in which case these two species had the same rate of tooth-attachment loss. If the former is correct, then the difference may be due to different dietary habits, chewing strategies, more pathogenic mouth microflora in ''P. robustus'', or some immunological difference which made ''P. robustus'' somewhat more susceptible to gum disease.<ref>{{cite journal|last=Ripamonti|first=U.|year=1989|title=The Hard Evidence of Alveolar Bone Loss in Early Hominids of Southern Africa|journal=Journal of Periodontology|volume=60|issue=2|pages=118–120|doi=10.1902/jop.1989.60.2.118|pmid=2656976}}</ref>

While removing the [[Earth:Matrix (geology)|matrix]] encapsulating TM 1517, Schepers noted a large rock, which would have weighed {{cvt|75|g}}, which had driven itself into the braincase through the [[Biology:Parietal bone|parietal bone]]. He considered this evidence that another individual had killed TM 1517 by launching the rock as a projectile in either defense or attack, but the most parsimonious explanation is that the rock was deposited during the fossilisation process after TM 1517 had died. In 1961, science writer [[Biography:Robert Ardrey|Robert Ardrey]] noted two small holes about 2.5&nbsp;cm (an inch) apart on the child skullcap SK 54, and believed this individual had been killed by being struck twice on the head in an assault; in 1970<!--not 1972-->, Brain reinterpreted this as evidence of a leopard attack.<ref>{{cite journal|first=C. K.|last=Brain|year=1972|title=An Attempt to Reconstruct the Behaviour of Australopithecines: The Evidence for Interpersonal Violence|journal=Zoologica Africana|volume=7|pages=389–391|doi=10.1080/00445096.1972.11447451|doi-access=free}}</ref>

==Palaeoecology==
The Pleistocene Cradle of Humankind was mainly dominated by the [[Biology:Springbok|springbok]] ''Antidorcas recki'', but other antelope, [[Biology:Giraffidae|giraffes]], and [[Biology:Elephantidae|elephants]] were also seemingly abundant megafauna. The carnivore assemblage comprises the sabertoothed cats ''[[Biology:Dinofelis|Dinofelis]] spp.'' and ''[[Biology:Megantereon|Megantereon]] spp.'', and the hyena ''Lycyaenops silberbergi''. Overall, the animal assemblage of the region broadly indicates a mixed, open-to-closed landscape featuring perhaps montane grasslands and shrublands.<ref name=Adams>{{cite journal|first1=J. W.|last1=Adams|first2=D. S.|last2=Rovinsky|first3=A. I. R.|last3=Herries|first4=C. G.|last4=Menter|year=2016|title=Macromammalian faunas, biochronology and palaeoecology of the early Pleistocene Main Quarry hominin-bearing deposits of the Drimolen Palaeocave System, South Africa|journal=PeerJ|volume=4|page=e1941|pmid=27114884|pmc=4841245|doi=10.7717/peerj.1941 |doi-access=free }}</ref> Australopithecines and early ''Homo'' likely preferred cooler conditions than later ''Homo'', as there are no australopithecine sites that were below {{cvt|1000|m}} in elevation at the time of deposition. This would mean that, like chimps, they often inhabited areas with an average diurnal temperature of {{cvt|25|C}}, dropping to {{cvt|10|or|5|C}} at night.<ref name=David2016>{{cite journal|first1=T.|last1=Dávid-Barrett|first2=R. I. M.|last2=Dunbar|year=2016|title=Bipedality and hair loss in human evolution revisited: The impact of altitude and activity scheduling|journal=Journal of Human Evolution|volume=94|pages=72–82|doi=10.1016/j.jhevol.2016.02.006|pmc=4874949|pmid=27178459}}</ref>

''P. robustus'' also cohabited the Cradle of Humankind with ''H. ergaster''/''H. erectus''.<ref name=Susman2001/><ref name=Pickering/><ref name=Herries2020>{{cite journal|first1=A. I. R.|last1=Herries|first2=J. M.|last2=Martin|display-authors=et al.|year=2020|title=Contemporaneity of ''Australopithecus'', ''Paranthropus'', and early ''Homo erectus'' in South Africa|journal=Science|volume=368|issue=6486|page=eaaw7293|doi=10.1126/science.aaw7293|pmid=32241925|hdl=11568/1040368|s2cid=214763272|hdl-access=free}}</ref> In addition, these two species resided alongside ''Australopithecus sediba'' which is known from about 2 million years ago at [[Earth:Malapa Fossil Site, Cradle of Humankind|Malapa]]. The most recent ''A. africanus'' specimen, Sts 5, dates to about 2.07 million years ago, around the arrival of ''P. robustus'' and ''H. erectus''.<ref name=Herries2020/> It has been debated whether or not ''P. robustus'' would have had symbiotic, neutral, or antagonist relations with contemporary ''Australopithecus'' and ''Homo''.<ref>{{cite journal|first=N. T.|last=Boaz|year=1977|title=Paleoecology of Early Hominidae in Africa|journal=Kroeber Anthropological Society|volume=50|pages=39–40|s2cid=201632920|url=https://pdfs.semanticscholar.org/ecc2/e167a8946cdb37aca18f6b7aba870a1a2097.pdf|archive-url=https://web.archive.org/web/20200227082959/https://pdfs.semanticscholar.org/ecc2/e167a8946cdb37aca18f6b7aba870a1a2097.pdf|url-status=dead|archive-date=2020-02-27}}</ref> It is possible that South Africa was a [[Earth:Refuge (ecology)|refugium]] for ''Australopithecus'' until about 2 million years ago with the beginning of major climatic variability and volatility, and potentially competition with ''Homo'' and ''Paranthropus''.<ref name=Herries2020/>

===Fossil-bearing deposits===
{{multiple image
| align = left
| direction = horizontal
| image1 = Paranthropus robustus Africa.jpg
| width1 = 160
| caption1 = Location of the [[History:Cradle of Humankind|Cradle of Humankind]]
| alt1 = A map of the African continent with a red dot indicating the Cradle of Humankind in the northeast region of South Africa
| image2 = Cradle of Humankind plan.jpg
| width2 = 190
| caption2 = Fossil-bearing caves (''P. robustus'' is known from 1, 7, and 11–14)
| alt2 = A map of the Cradle of Humankind with 15 blue dots indicating various fossil-bearing caves. Paranthropus is known from Kromdraai, Swartkrans, Sterkfontein, Gondolin, Cooper's, and Drimolen Caves
}}
;Swartkrans
At Swartkrans, ''P. robustus'' has been identified from Members 1–3.<ref name=Herries2009/> ''Homo'' is also found in these deposits, but species identification in Members 1 and 2 is debated between ''H. ergaster/H. erectus'', ''H. habilis'', ''H. rudolfensis'', or multiple species. In total, over 300 ''P. robustus'' specimens representing over 130 individuals,<ref>{{cite journal|first=F. E.|last=Grine|year=2005|title=Early ''Homo'' at Swartkrans, South Africa : a review of the evidence and an evaluation of recently proposed morphs|journal=South African Journal of Science|volume=101|issue=1–2|pages=43–52|hdl=10520/EJC96341}}</ref> predominantly isolated teeth, have been recovered from Swartkrans.<ref name=Constantino2004/>

Member 1 and Member 3 have several mammal species in common, making dating by animal remains ([[Earth:Biostratigraphy|biostratigraphy]]) yield overlapping time intervals. Like the East African Olduvai Bed I (2.03–1.75 million years ago) and Lower Bed II (1.75–1.70 million years ago), Member 1 preserved the antelope ''[[Biology:Parmularius|Parmularius angusticornis]]'', the [[Biology:Wildebeest|wildebeest]], and the Cape buffalo. The presence of the Hamadryas baboon and ''[[Biology:Dinopithecus|Dinopithecus]]'' could mean Members 1–3 were deposited 1.9–1.65 million years ago, though the presence of [[Biology:Warthog|warthog]]s suggests some sections of the deposits could date to after 1.5 million years ago. [[Physics:Uranium–lead dating|Uranium–lead dating]] reports intervals of 3.21–0.45 million years ago for Member 1 (a very large error range), 1.65–1.07 million years ago for Member 2, and 1.04–0.62 million years ago for Member 3, though more likely the younger side of the estimate; this could mean ''P. robustus'' outlived ''P. boisei''.<ref name=Herries2009>{{cite journal|first1=A. I. R.|last1=Herries|first2=D.|last2=Curnoe|first3=J. W.|last3=Adams|year=2009|title=A multi-disciplinary seriation of early ''Homo'' and ''Paranthropus'' bearing palaeocaves in southern Africa|journal=Quaternary International|volume=202|issue=1–2|pages=14–28|doi=10.1016/j.quaint.2008.05.017|bibcode=2009QuInt.202...14H}}</ref>

[[Physics:Cosmogenic nuclide|Cosmogenic nuclide]] geochronology has reported much more constrained dates of 2.2–1.8 million years ago for Member 1, and 0.96 million years ago for Member 3. No suitable section of Member 2 could be identified to date.<ref>{{cite journal|first1=R. J.|last1=Gibbon|first2=T.|last2=Pickering|first3=M. B.|last3=Sutton|first4=J. L.|last4=Heaton|year=2014|title=Comogenic nuclide burial dating of hominin-bearing Pleistocene cave deposits at Swartkrans, South Africa|journal=Quaternary Geochronology|volume=24|pages=10–15|doi=10.1016/j.quageo.2014.07.004|bibcode=2014QuGeo..24...10G }}</ref>

;Sterkfontein
[[File:The cranium of an Australopithecus africanus (3967774317).jpg|thumb|Ronald J. Clarke suggested StW 505 (above) is ancestral to ''P. robustus'']]
At Sterkfontein, only the specimens StW 566 and StW 569 are firmly assigned to ''P. robustus'', coming from the "Oldowan infill" dating to 2–1.7 million years ago in a section of Member 5. Earlier members yielded ''A. africanus''. In 1988, palaeoanthropologist Ronald J. Clarke suggested StW 505 from the earlier Member 4 was an ancestor to ''P. robustus''. The specimen is still generally assigned to ''A. africanus'', though the Sterkfontein hominins are known to have an exceedingly wide range of variation, and it is debated whether or not the materials represent multiple species instead of just ''A. africanus''.<ref name=Constantino2004/>

The appearance of the baboon ''[[Biology:Theropithecus oswaldi|Theropithecus oswaldi]]'', [[Biology:Zebra|zebra]]s, [[Biology:Lion|lion]]s, [[Biology:Ostrich|ostrich]]es, springhares, and several grazing antelope in Member 5 indicates the predominance of open grasslands, but sediment analysis indicates the cave opening was moist during deposition, which could point to a well-watered wooded grassland.<ref>{{cite journal|first1=K.|last1=Kuman|first2=R. J.|last2=Clarke|year=2000|title=Stratigraphy, artefact industries and hominid associations for Sterkfontein, Member 5|journal=Journal of Human Evolution|volume=38|issue=6|pages=827–847|doi=10.1006/jhev.1999.0392|pmid=10835264}}</ref>

;Kromdraai
At Kromdraai, ''P. robustus'' has been unearthed at Kromdraai B, and almost all ''P. robustus'' fossils discovered in the cave have been recovered from Member 3 (out of 5 members). A total of 31 specimens representing at least 17 individuals have been recovered. The only potential ''Homo'' specimen from Member 3 is KB 5223, but its classification is debated.<ref name=Stammers2018/> The ear bones of the juvenile KB 6067 from Member 3 is consistent with that of ''P. robustus'', but the dimensions of the [[Medicine:Cochlea|cochlea]] and oval window better align with the more ancient StW 53 from Sterkfontein Member 4 with undetermined species designation. KB 6067, therefore, may possibly be basal to (more ancient than) other ''P. robustus'' specimens, at least those for which ear morphology is known.<ref>{{cite journal|first1=J.|last1=Bragá|first2=J. F.|last2=Thackeray|first3=J.|last3=Dumoncel|display-authors=et al.|year=2013|title=A new partial temporal bone of a juvenile hominin from the site of Kromdraai B (South Africa)|journal=Journal of Human Evolution|volume=65|issue=4|pages=447–456|doi=10.1016/j.jhevol.2013.07.013|pmid=24012253}}</ref>

[[Earth:Paleomagnetism|Palaeomagnetism]] suggests Member 3 may date to 1.78–1.6 million years ago, Member 2 to before 1.78 million years ago, and Member 1 to 2.11–1.95 million years ago.<ref name=Herries2009/>

The animal remains of Kromdraai A suggest deposition occurred anywhere between 1.89 and 1.63 million years ago, and the presence of Oldowan or Achulean tools indicates early ''Homo'' activity. The biostratigraphic dating of Kromdraai B is less clear as there are no animal species which are known to have existed in a narrow time interval, and many non-hominin specimens have not been assigned to a species (left at genus level).<ref name=Herries2009/> About 75% of mammalian remains other than ''P. robustus'' are monkeys, including leaf-eating colobine monkeys, possibly the earliest record of the Hamadryas baboon, ''[[Biology:Gorgopithecus|Gorgopithecus]]'', and ''Papio angusticeps'' in South Africa. The absence of the baboons ''T. oswaldi'' and ''Dinopithecus'' could potentially mean Member 3 is older than Sterkfontein Member 5 and Swartkrans Member 1; which, if correct, would invalidate the results from palaeomagnetism, and make these specimens among the oldest representatives of the species.<ref name=Braga2017/>

;Gondolin Cave
[[File:Sterkfontein Caves 69.jpg|thumb|GDA-2 from Gondolin Cave|alt=A tooth in three-quarter view, with the root facing the bottom right and the crown facing the upper left]]
Gondolin Cave has yielded 3 hominin specimens: a right third premolar assigned to early ''Homo'' (G14018), a partial left gracile australopithecine first or second molar (GDA-1), and a robust australopithecine second molar (GDA-2). The first hominin specimen (G14018) was found by German palaeontologist [[Biography:Elisabeth Vrba|Elisabeth Vrba]] in 1979, and the other two specimens were recovered in 1997 by, respectively, South African palaeoanthropologist Andre Keyser and excavator L. Dihasu. GDA-2—measuring {{cvt|18.8x18.1|mm}}, an area of {{cvt|340|mm2}}—is exceptionally large for ''P. robustus'', which has a recorded maximum of {{cvt|290|mm2}}. This falls within the range of ''P. boisei'' {{cvt|278–378|mm2}}, so the discoverers assigned it to an indeterminate species of ''Paranthropus'' rather than ''P. robustus''.<ref>{{cite journal|last1=Menter|first1=C. G.|last2=Kuykendall|first2=K. L.|last3=Keyser|first3=A. W.|last4=Conroy|first4=G. C.|year=1999|title=First record of hominid teeth from the Plio-Pleistocene site of Gondolin, South Africa|journal=Journal of Human Evolution|volume=37|issue=2|pages=299–307|doi=10.1006/jhev.1999.0329|pmid=10444355}}</ref>

GDA-2 was found alongside the pig ''Metridiochoerus andrewsi'', which means the tooth must be 1.9–1.5 million years old.<ref name=Herries2009/> Using this and palaeomagnetism, it may date to roughly 1.8 million years ago.<ref name=Herries2009/>

;Cooper's Cave
Cooper's Cave was first reported to yield ''P. robustus'' remains in 2000 by South African palaeoanthropologists Christine Steininger and Lee Rogers Berger. Specimens include a crushed partial right face (COB 101), three isolated teeth, a juvenile jawbone, and several skull fragments.<ref name=Herries2009/>

The animal remains in the hominin-bearing deposit are similar to those of Swartkrans and Kromdraai A, so the Cooper's Cave deposits may date to 1.87–1.56 million years ago.<ref name=Herries2009/>

;Drimolen Cave
Drimolen Cave was first discovered to have yielded hominin remains by Keyser in 1992, who, in eight years, oversaw the recovery of 79 ''P. robustus'' specimens.<ref name=Keyser2000/> Among these are the most complete ''P. robustus'' skulls: the presumed female DNH-7 (which also preserved articulated jawbone with almost all the teeth), and presumed male DNH 155.<ref name=Martin2020/>  It was also associated with the ''H. ergaster''/''H. erectus'' skull DNH 134.<ref name=Herries2020/> The Drimolen material preserves several basal characteristics relative to the Swartkrans and Kromdraai remains (meaning it may be older).<ref name=Martin2020/>

The site is thought to be roughly 2–1.5 million years old based on animal remains which have also been recovered from Swartkrans Member 1.<ref name=Keyser2000>{{cite journal|first=A. W.|last=Keyser|year=2000|title=The Drimolen skull: the most complete australopithecine cranium and mandible to date|journal=South African Journal of Science|volume=96|pages=189–197|url=https://www.researchgate.net/publication/279710806}}</ref> The animal assemblage is broadly similar to that of Cooper's Cave, meaning they probably are about the same age.<ref name=Herries2009/> In 2020, DNH 152 was palaeomagnetically dated to 2.04–1.95 million years ago, making it the oldest identified ''P. robustus'' specimen.<ref name=Herries2020/>


===Predation===
[[File:Sterkfontein Caves 65.jpg|thumb|SK 54 skullcap with two holes probably inflicted by a leopard attack|alt=A skullcap with two prominent and closely spaced circles at the top]]
Australopithecine bones may have accumulated in caves due to large carnivores dragging in carcasses, which was first explored in detail by Brain in his 1981 book ''The Hunters or the Hunted?: An Introduction to African Cave Taphonomy''. The juvenile ''P. robustus'' skullcap SK 54 has two puncture marks consistent with the lower canines of the [[Biology:Leopard|leopard]] specimen SK 349 from the same deposits. Brain hypothesised that ''Dinofelis'' and perhaps also hunting hyenas specialised on killing australopithecines,<ref name=Brain1983/> but carbon isotope analysis indicates these species predominantly ate large grazers, while the leopard, the sabertoothed ''Megantereon'', and the [[Biology:Spotted hyena|spotted hyena]] were more likely to have regularly consumed ''P. robustus''.<ref>{{cite journal|first1=J.|last1=Lee-Thorp|first2=J. F.|last2=Thackeray|first3=N.|last3=van der Merwe|year=2010|title=The hunters and the hunted revisited|journal=Journal of Human Evolution|volume=39|issue=6|pages=565–576|doi=10.1006/jhev.2000.0436|pmid=11102267}}</ref> Brain was unsure if these predators actively sought them out and brought them back to the cave den to eat, or inhabited deeper recesses of caves and ambushed them when they entered. Modern-day baboons in this region often shelter in [[Earth:Sinkhole|sinkhole]]s especially on cold winter nights, though Brain proposed that australopithecines seasonally migrated out of the [[Place:Highveld|Highveld]] and into the warmer Bushveld, only taking up cave shelters in spring and autumn.<ref name=Brain1983>{{cite book|first=C. K.|last=Brain|author-link=Charles Kimberlin Brain|year=1983|chapter=Who Were the Hunters and Who the Hunted|title=The Hunters Or the Hunted?: An Introduction to African Cave Taphonomy|publisher=University of Chicago Press|isbn=978-0-226-07090-2|url={{google books|plainurl=yes|id=E4JyZgr8y50C|page=266}}}}</ref>

As an antipredator behaviour, baboons often associate themselves with medium-to-large herbivores, most notably [[Biology:Impala|impala]]s, and it is possible that ''P. robustus'' as well as other early hominins which lived in open environments did so also, given they are typically associated with an abundance of medium-to-large bovid and horse remains.<ref>{{cite journal|first=S.|last=Badenhorst|year=2019|title=Possible predator avoidance behaviour of hominins in South Africa|journal=South African Journal of Science|volume=114|issue=7–8|doi=10.17159/sajs.2018/a0274|doi-access=free}}</ref>

===Extinction===
Though ''P. robustus'' was a rather hardy species with a tolerance for environmental variability, it seems to have preferred wooded environments, and similarly most ''P. robustus'' remains date to a wet period in South Africa 2–1.75 million years ago conducive to such biomes. The extinction of ''P. robustus'' coincided with the [[Earth:Mid-Pleistocene Transition|Mid-Pleistocene Transition]], and the doubling of glacial cycle duration. During glacial events, with more ice locked up at the poles, the [[Earth:Tropical rain belt|tropical rain belt]] contracted towards the equator, subsequently causing the retreat of wetland and woodland environments. Before the transition, ''P. robustus'' populations possibly contracted to certain wooded refuge zones over 21,000-year cycles, becoming regionally extinct in certain areas until the wet cycle whereupon it would repopulate those zones. The continual prolonging of dry cycles may have caused its extinction, with the last occurrence in the fossil record 1–0.6 million years ago (though more likely 0.9 million years ago). ''Homo'' possibly was able to survive by inhabiting a much larger geographical range, more likely to find a suitable refuge area during unfavourable climate swings.<ref name=Caley2018/>

However, the geographical range of ''P. robustus'' in the fossil record is roughly {{cvt|500|km2}}, whereas the [[Biology:Critically endangered|critically endangered]] [[Biology:Eastern gorilla|eastern gorilla]] (with the smallest range of any African ape) inhabits {{cvt|70000|km2}}, the critically endangered [[Biology:Western gorilla|western gorilla]] {{cvt|700000|km2}}, and the endangered chimpanzee {{convert|2.6|e6km2|e6mi2|abbr=unit|0}}. Therefore, fossil distribution very unlikely represents the true range of the species; consequently, ''P. robustus'' possibly went extinct much more recently somewhere other than the Cradle of Humankind (Signor–Lipps effect).<ref name=Caley2018>{{cite journal|first1=T.|last1=Caley|first2=T.|last2=Extier|first3=J. A.|last3=Collins|display-authors=et al.|year=2018|title=A two-million-year-long hydroclimatic context for hominin evolution in southeastern Africa|journal=Nature|volume=560|issue=76–79|pages=76–79|doi=10.1038/s41586-018-0309-6|pmid=29988081|bibcode=2018Natur.560...76C|s2cid=49668495|url=http://dro.dur.ac.uk/24690/1/24690.pdf}}</ref>

==See also==
{{columns-list|colwidth=25em|
* [[History:African archaeology|African archaeology]]
* {{annotated link|Biology:Australopithecus africanus|''Australopithecus africanus''}}
* {{annotated link|Biology:Australopithecus sediba|''Australopithecus sediba''}}
* {{annotated link|Biology:Homo habilis|''Homo habilis''}}
* {{annotated link|Biology:Homo naledi|''Homo naledi''}}
* {{annotated link|Biology:Homo rudolfensis|''Homo rudolfensis''}}
* {{annotated link|Biology:Paranthropus aethiopicus|''Paranthropus aethiopicus''}}
* {{annotated link|Biology:Paranthropus boisei|''Paranthropus boisei''}}
}}

== References ==
{{Reflist}}

==Further reading==
*{{cite book|first1=R.|last1=Broom|first2=G. W. H.|last2=Schepers|year=1946|title=The South African Fossil Ape-Men - The Australopithecinae|publisher=The Transvaal Museum}}
*{{cite book|first=J. T.|last=Robinson|year=1972|title=Early Hominid Posture and Locomotion|publisher=University of Chicago Press|isbn=978-0-226-72230-6}}
*{{cite book|first=F. E.|last=Grine|year=1988|title=Evolutionary History of the "Robust" Australopithecines|publisher=Aldine de Gruyter|isbn=978-0-202-02031-0}}
*{{cite book|first1=J.|last1=Bragá|first2=J. F.|last2=Thackeray|year=2017|title=Kromdraai: A Birthplace of Paranthropus in the Cradle of Humankind|publisher=African Sun Media|isbn=978-1-928355-06-9}}

==External links==
* [http://johnhawks.net/explainer/laboratory/meet-robustus.html Meet ''Australopithecus robustus''] — [[Biography:John D. Hawks|John D. Hawks]]' website
* [http://humanorigins.si.edu/evidence/human-fossils/species/paranthropus-robustus ''Paranthropus robustus''] - The Smithsonian's Human Origins Program
* [http://humanorigins.si.edu/evidence/human-evolution-timeline-interactive Human Timeline (Interactive)] – Smithsonian
{{Human_Evolution}}
{{Taxonbar|from=Q310529}}

[[Category:Paranthropus]]
[[Category:Pleistocene primates]]
[[Category:Pliocene primates]]

{{Sourceattribution|Paranthropus robustus}}