''Paranthropus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of extinct

hominin The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas). The ...

which contains two widely accepted

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

: '' P. robustus'' and '' P. boisei''. However, the validity of ''Paranthropus'' is contested, and it is sometimes considered to be

synonymous A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with ''

Australopithecus ''Australopithecus'' (, ; ) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genus ''Homo'' (which includes modern humans) emerged within ''Australopithecus'', as sister to e.g. ''Australo ...

''. They are also referred to as the robust australopithecines. They lived between approximately 2.6 and 1.2 million years ago (mya) from the end of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Middle Pleistocene. ''Paranthropus'' is characterised by robust skulls, with a prominent

gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four ...

-like

sagittal crest A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exception ...

along the midline—which suggest strong chewing muscles—and broad, herbivorous teeth used for grinding. However, they likely preferred soft food over tough and hard food. ''Paranthropus'' species were generalist feeders, but ''P. robustus'' was likely an

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nu ...

, whereas ''P. boisei'' was likely herbivorous and mainly ate bulbotubers. They were

bipeds Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' a ...

. Despite their robust heads, they had comparatively small bodies. Average weight and height are estimated to be at for ''P. robustus'' males, at for ''P. boisei'' males, at for ''P. robustus'' females, and at for ''P. boisei'' females. They were possibly

polygamous Crimes Polygamy (from Late Greek (') "state of marriage to many spouses") is the practice of marrying multiple spouses. When a man is married to more than one wife at the same time, sociologists call this polygyny. When a woman is marri ...

and patrilocal, but there are no modern analogues for australopithecine societies. They are associated with bone tools and contested as the earliest evidence of fire usage. They typically inhabited woodlands, and coexisted with some early human species, namely '' A. africanus'', '' H. habilis'' and '' H. erectus''. They were preyed upon by the large carnivores of the time, specifically crocodiles, leopards, sabertoothed cats and hyenas.

Taxonomy

Species

''P. robustus''

The genus ''Paranthropus'' was first erected by Scottish-South African

palaeontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

Robert Broom Robert Broom FRS FRSE (30 November 1866 6 April 1951) was a British- South African doctor and palaeontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow. From 1903 to 1910, he ...

in 1938, with the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specim ...

'' P. robustus''. "''Paranthropus''" derives from

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

παρα ''para'' beside or alongside; and άνθρωπος ''ánthropos'' man. The

type specimen In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...

, a male braincase, TM 1517, was discovered by schoolboy Gert Terblanche at the

Kromdraai fossil site Kromdraai (means crooked turn in afrikaans) is a fossil-bearing breccia-filled cave located about east of the well-known South African hominid-bearing site of Sterkfontein and about northwest of Johannesburg, South Africa. It is situated wit ...

, about southwest of

Pretoria Pretoria () is South Africa's administrative capital, serving as the seat of the executive branch of government, and as the host to all foreign embassies to South Africa. Pretoria straddles the Apies River and extends eastward into the foothi ...

, South Africa. By 1988, at least six individuals were unearthed in around the same area, now known as the

Cradle of Humankind The Cradle of Humankind is a paleoanthropological site and is located about northwest of Johannesburg, South Africa, in the Gauteng province. Declared a World Heritage Site by UNESCO in 1999, the site is home to the largest concentration of h ...

. In 1948, at Swartkrans Cave, in about the same vicinity as Kromdraai, Broom and South African palaeontologist

John Talbot Robinson John Talbot Robinson FRSSAf (10 January 1923 – 12 October 2001) was a distinguished South African hominin paleontologist. His most famous discovery (with Robert Broom) was the nearly complete fossil skull of the hominin species ''Australop ...

described ''P. crassidens'' based on a subadult jaw, SK 6. He believed later ''Paranthropus'' were morphologically distinct from earlier ''Paranthropus'' in the cave—that is, the Swartkrans ''Paranthropus'' were reproductively isolated from Kromdraai ''Paranthropus'' and the former eventually

speciate Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

d. By 1988, several specimens from Swartkrans had been placed into ''P. crassidens''. However, this has since been synonymised with ''P. robustus'' as the two populations do not seem to be very distinct.

''P. boisei''

In 1959, '' P. boisei'' was discovered by Mary Leakey at

Olduvai Gorge The Olduvai Gorge or Oldupai Gorge in Tanzania is one of the most important paleoanthropological localities in the world; the many sites exposed by the gorge have proven invaluable in furthering understanding of early human evolution. A steep-si ...

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...

(specimen OH 5). Her husband Louis named it ''Zinjanthropus boisei'' because he believed it differed greatly from ''Paranthropus'' and ''Australopithecus''. The name derives from " Zinj", an ancient Arabic word for the coast of East Africa, and "boisei", referring to their financial benefactor Charles Watson Boise. However, this genus was rejected at Mr. Leakey's presentation before the 4th Pan-African Congress on Prehistory, as it was based on a single specimen. The discovery of the Peninj Mandible made the Leakey's reclassify their species as ''Australopithecus (Zinjanthropus) boisei'' in 1964, but in 1967, South African palaeoanthropologist

Phillip V. Tobias Phillip Vallentine Tobias (14 October 1925 – 7 June 2012) was a South African palaeoanthropologist and Professor Emeritus at the University of the Witwatersrand in Johannesburg. He was best known for his work at South Africa's hominid fossil ...

subsumed it into ''Australopithecus'' as ''A. boisei''. However, as more specimens were found, the combination ''Paranthropus boisei'' became more popular. It is debated whether the wide range of variation in jaw size indicates simply

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

or a grounds for identifying a new species. It could be explained as

groundmass The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or clasts are embedded. The matrix of an igneous rock consists of finer-grained, often microscopic, crystals in which larger crystals, ...

filling in cracks naturally formed after death, inflating the perceived size of the bone. ''P. boisei'' also has a notably wide range of variation in skull anatomy, but these features likely have no taxonomic bearing.

''P. aethiopicus''

In 1968, French palaeontologists

Camille Arambourg Camille Arambourg ( February 3, 1885– November 19, 1969) was a French vertebrate paleontologist. He conducted extensive field work in North Africa. In the 1950s he argued against the prevailing model of Neanderthals as brutish and simian. Du ...

and Yves Coppens described "''Paraustralopithecus aethiopicus''" based on a toothless mandible from the Shungura Formation, Ethiopia (Omo 18). In 1976, American anthropologist Francis Clark Howell and Breton anthropologist Yves Coppens reclassified it as ''A. africanus''. In 1986, after the discovery of the skull KNM WT 17000 by English anthropologist

Alan Walker Alan Olav Walker (born 24 August 1997) is a British-born Norwegian music producer and DJ primarily known for the critically acclaimed single " Faded" (2015), which was certified platinum in 14 countries. He has also made several songs including ...

and Richard Leakey classified it into ''Paranthropus'' as '' P. aethiopicus''. There is debate whether this is synonymous with ''P. boisei'', the main argument for separation being the skull seems less adapted for chewing tough vegetation. In 1989, palaeoartist and zoologist Walter Ferguson reclassified KNM WT 17000 into a new species, ''walkeri'', because he considered the skull's species designation questionable as it comprised the skull whereas the holotype of ''P. aethiopicus'' comprised only the mandible. Ferguson's classification is almost universally ignored, and is considered to be synonymous with ''P. aethiopicus''.

Others

In 1963, while in the Congo, French ethnographer Charles Cordier assigned the name "P. congensis" to a super-strong, monstrous ape-man cryptid called "Kikomba", "Apamándi", "Abanaánji", "Zuluzúgu", or "Tshingómbe" by various native tribes which he heard stories about. In 2015, Ethiopian palaeoanthropologist Yohannes Haile-Selassie and colleagues described the 3.5–3.2 Ma '' A. deyiremeda'' based on three jawbones from the Afar Region, Ethiopia. They noted that, though it shares many similarities with ''Paranthropus'', it may not have been closely related because it lacked enlarged molars which characterize the genus. Nonetheless, in 2018, independent researcher Johan Nygren recommended moving it to ''Paranthropus'' based on dental and presumed dietary similarity.

Validity

In 1951, American anthropologists Sherwood Washburn and Bruce D. Patterson were the first to suggest that ''Paranthropus'' should be considered a

junior synonym The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linn ...

of ''Australopithecus'' as the former was only known from fragmentary remains at the time, and dental differences were too minute to serve as justification. In face of calls for subsumation, Leakey and Robinson continued defending its validity. Various other authors were still unsure until more complete remains were found. ''Paranthropus'' is sometimes classified as a

subgenus In biology, a subgenus (plural: subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between ...

of ''Australopithecus''. Paranthropus robustus top (University of Zurich)

There is currently no clear consensus on the validity of ''Paranthropus''. The argument rests upon whether the genus is

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gr ...

—is composed of a common ancestor and all of its descendants—and the argument against monophyly (that the genus is

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

) says that ''P. robustus'' and ''P. boisei'' evolved similar gorilla-like heads independently of each other by coincidence (

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

), as chewing adaptations in hominins evolve very rapidly and multiple times at various points in the family tree ( homoplasy). In 1999, a chimp-like

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

forearm bone was assigned to ''P. boisei'', the first discovered ulna of the species, which was markedly different from ''P. robustus'' ulnae, which could suggest paraphyly.

Evolution

''P. aethiopicus'' is the earliest member of the genus, with the oldest remains, from the Ethiopian Omo Kibish Formation, dated to 2.6 mya at the end of the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Malema, Malawi. ''P. boisei'' changed remarkably little over its nearly one-million-year existence. ''Paranthropus'' had spread into South Africa by 2 mya with the earliest ''P. robustus'' remains. It is sometimes suggested that ''Paranthropus'' and ''Homo'' are sister taxa, both evolving from ''

''. This may have occurred during a drying trend 2.8–2.5 mya in the Great Rift Valley, which caused the retreat of woodland environments in favor of open savanna, with forests growing only along rivers and lakes. ''Homo'' evolved in the former, and ''Paranthropus'' in the latter riparian environment. However, the classifications of ''Australopithecus'' species is problematic. Paranthropus boisei face (University of Zurich)

Paranthropus boisei face (University of Zurich)

Evolutionary tree according to a 2019 study:

Description

Skull

''Paranthropus'' had a massively built, tall and flat skull, with a prominent

-like

along the midline which anchored massive temporalis muscles used in chewing. Like other australopithecines, ''Paranthropus'' exhibited sexual dimorphism, with males notably larger than females. They had large molars with a relatively thick

tooth enamel Tooth enamel is one of the four major tissues that make up the tooth in humans and many other animals, including some species of fish. It makes up the normally visible part of the tooth, covering the crown. The other major tissues are dentin, ...

coating ( post-canine megadontia), and comparatively small incisors (similar in size to modern

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...

s), possibly adaptations to processing abrasive foods. The teeth of ''P. aethiopicus'' developed faster than those of ''P. boisei''. ''Paranthropus'' had adaptations to the skull to resist large bite loads while feeding, namely the expansive

squamosal suture The squamosal suture, or squamous suture, arches backward from the pterion and connects the temporal squama with the lower border of the parietal bone: this suture is continuous behind with the short, nearly horizontal parietomastoid suture, whic ...

s. The notably thick palate was once thought to have been an adaptation to resist a high bite force, but is better explained as a byproduct of facial lengthening and nasal anatomy. In ''P. boisei'', the jaw hinge was adapted to grinding food side-to-side (rather than up-and-down in modern humans), which is better at processing the

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human die ...

y abrasive foods that likely made up the bulk of its diet. ''P. robustus'' may have chewed in a front-to-back direction instead, and had less exaggerated (less

derived Derive may refer to: *Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguation ...

) anatomical features than ''P. boisei'' as it perhaps did not require them with this kind of chewing strategy. This may have also allowed ''P. robustus'' to better process tougher foods. The braincase volume averaged about , comparable to gracile australopithecines, but smaller than ''Homo''. Modern human brain volume averages for men and for women.

Limbs and locomotion

Unlike ''P. robustus'', the forearms of ''P. boisei'' were heavily built, which might suggest habitual suspensory behaviour as in

orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...

s and

gibbon Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforest from eastern Bangladesh to Northeast Indi ...

s. A ''P. boisei'' shoulder blade indicates long infraspinatus muscles, which is also associated with suspensory behavior. A ''P. aethiopicus'' ulna, on the other hand, shows more similarities to ''Homo'' than ''P. boisei''. ''Paranthropus'' were bipeds, and their hips, legs and feet resemble ''A. afarensis'' and modern humans. The pelvis is similar to ''A. afarensis'', but the hip joints are smaller in ''P. robustus''. The physical similarity implies a similar walking gait. Their modern-humanlike big toe indicates a modern-humanlike foot posture and range of motion, but the more distal ankle joint would have inhibited the modern human toe-off gait cycle. By 1.8 mya, ''Paranthropus'' and '' H. habilis'' may have achieved about the same grade of bipedality.

Height and weight

In comparison to the large, robust head, the body was rather small. Average weight for ''P. robustus'' may have been for males and for females; and for ''P. boisei'' for males and for females. At Swartkrans Cave Members 1 and 2, about 35% of the ''P. robustus'' individuals are estimated to have weighed , 22% about , and the remaining 43% bigger than the former but less than . At Member 3, all individuals were about . Female weight was about the same in contemporaneous ''H. erectus'', but male ''H. erectus'' were on average heavier than ''P. robustus'' males. ''P. robustus'' sites are oddly dominated by small adults, which could be explained as heightened predation or mortality of the larger males of a group. The largest-known ''Paranthropus'' individual was estimated at . According to a 1991 study, based on

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...

length and using the dimensions of modern humans, male and female ''P. robustus'' are estimated to have stood on average , respectively, and ''P. boisei'' . However, the latter estimates are problematic as there were no positively identified male ''P. boisei'' femurs at the time. In 2013, a 1.34 Ma male ''P. boisei'' partial skeleton was estimated to be at least and .

Pathology

''Paranthropus'' seems to have had notably high rates of

pitting enamel hypoplasia Enamel hypoplasia can take a variety of forms, but all types are associated with a reduction of enamel formation due to disruption in ameloblast production. One of the most common types, Pitting Enamel Hypoplasia (PEH), ranges from small circular pi ...

(PEH), where

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, in any other tested hominin species. The condition of these holes covering the entire tooth is consistent with the modern human ailment amelogenesis imperfecta. However, since circular holes in enamel coverage are uniform in size, only present on the

molar teeth The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...

, and have the same severity across individuals, the PEH may have been a genetic condition. It is possible that the coding-DNA concerned with thickening enamel also left them more vulnerable to PEH. There have been 10 identified cases of cavities in ''P. robustus'', indicating a rate similar to modern humans. A molar from

Drimolen The Drimolen Palaeocave System consists of a series of terminal Pliocene to early Pleistocene hominin-bearing palaeocave fills located around north of Johannesburg, South Africa, and about north of Sterkfontein in the UNESCO World Heritage Site ...

, South Africa, 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 had to have also presented either alveolar resportion, which is commonly associated with gum disease; or super-eruption of teeth which occurs when teeth become worn down and have to erupt a bit more in order to maintain a proper bite, and this exposed the root. 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, which may have been caused by a change in diet or mouth microbiome, or the loss of the adjacent molar.

Palaeobiology

Diet

Paranthropus boisei side (University of Zurich)

It was once thought ''P. boisei'' cracked open nuts with its powerful teeth, giving OH 5 the nickname "Nutcracker Man". However, like gorillas, ''Paranthropus'' likely preferred soft foods, but would consume tough or hard food during leaner times, and the powerful jaws were used only in the latter situation. In ''P. boisei'', thick enamel was more likely used to resist abrasive gritty particles rather than to minimize chipping while eating hard foods. In fact, there is a distinct lack of tooth fractures which would have resulted from such activity. ''Paranthropus'' were generalist feeders, but diet seems to have ranged dramatically with location. The South African ''P. robustus'' appears to have been an omnivore, with a diet similar to contemporaneous ''Homo'' and nearly identical to the later ''

H. ergaster ''Homo ergaster'' is an extinct species or subspecies of archaic humans who lived in Africa in the Early Pleistocene. Whether ''H. ergaster'' constitutes a species of its own or should be subsumed into ''H. erectus'' is an ongoing and unresolv ...

'', and subsisted on mainly C4 savanna plants and C3 forest plants, which could indicate either seasonal shifts in diet or seasonal migration from forest to savanna. In leaner times it may have fallen back on brittle food. It likely also consumed seeds and possibly

tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...

s or

termite Termites are small insects that live in colonies and have distinct castes ( eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blat ...

s. A high cavity rate could indicate

honey Honey is a sweet and viscous substance made by several bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of plants (primar ...

consumption. The East African ''P. boisei'', on the other hand, seems to have been largely herbivorous and fed on C4 plants. Its powerful jaws allowed it to consume a wide variety of different plants, though it may have largely preferred nutrient-rich bulbotubers as these are known to thrive in the well-watered woodlands it is thought to have inhabited. Feeding on these, ''P. boisei'' may have been able to meet its daily caloric requirements of approximately 9,700 kJ after about 6 hours of foraging. Juvenile ''P. robustus'' may have relied more on tubers than adults, given the elevated levels of

strontium Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is e ...

compared to adults in teeth from Swartkrans Cave, which, in the area, was most likely sourced from tubers.

Dentin Dentin () (American English) or dentine ( or ) (British English) ( la, substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by e ...

exposure on juvenile teeth could indicate early weaning, or a more abrasive diet than adults which wore away the cementum and enamel coatings, or both. It is also possible juveniles were less capable of removing grit from dug-up food rather than purposefully seeking out more abrasive foods.

Technology

Bone tools dating between 2.3 and 0.6 mya have been found in abundance in Swartkrans, Kromdraai and

caves, and are often associated with ''P. robustus''. Though ''Homo'' is also known from these caves, their remains are comparatively scarce to ''Paranthropus'', making ''Homo''-attribution unlikely. The tools also cooccur with ''Homo''-associated Oldawan and possibly

Acheulian Acheulean (; also Acheulian and Mode II), from the French ''acheuléen'' after the type site of Saint-Acheul, is an archaeological industry of stone tool manufacture characterized by the distinctive oval and pear-shaped "hand axes" associated ...

stone tool industries. The bone tools were typically sourced from the

shaft Shaft may refer to: Rotating machine elements * Shaft (mechanical engineering), a rotating machine element used to transmit power * Line shaft, a power transmission system * Drive shaft, a shaft for transferring torque * Axle, a shaft around whi ...

long bone The long bones are those that are longer than they are wide. They are one of five types of bones: long, short, flat, irregular and sesamoid. Long bones, especially the femur and tibia, are subjected to most of the load during daily activities ...

s from medium- to large-sized mammals, but tools made sourced from

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

s and horn cores have also been found. Bone tools have also been found at Oldawan Gorge and directly associated with ''P. boisei'', the youngest dating to 1.34 mya, though a great proportion of other bone tools from here have ambiguous attribution. Stone tools from Kromdraai could possibly be attributed to ''P. robustus'', as no ''Homo'' have been found there yet. The bone tools were not manufactured or purposefully shaped for a task. However, since the bones display no weathering (and were not scavenged randomly), and there is a preference displayed for certain bones, raw materials were likely specifically hand-picked. This could indicate a similar cognitive ability to contemporary Stone Age ''Homo''. Bone tools may have been used to cut or process vegetation, or dig up

s or

s, The form of ''P. robustus'' incisors appear to be intermediate between ''H. erectus'' and modern humans, which could indicate less food processing done by the teeth due to preparation with simple tools. Burnt bones were also associated with the inhabitants of Swartkrans, which could indicate some of the earliest fire usage. However, these bones were found in Member 3, where ''Paranthropus'' remains are rarer than ''H. erectus'', and it is also possible the bones were burned in a wildfire and washed into the cave as it is known the bones were not burned onsite.

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 will not be entirely accurate. ''Paranthropus'' had pronounced

, with males notably larger than females, which is commonly correlated with a male-dominated

society. ''P. robustus'' may have had a harem society similar to modern forest-dwelling silverback gorillas, where one male has exclusive breeding rights to a group of females, as male-female size disparity is comparable to gorillas (based on facial dimensions), and younger males were less robust than older males (delayed maturity is also exhibited in gorillas). However, if ''P. robustus'' preferred a savanna habitat, a multi-male society would have been more productive to better defend the troop from predators in the more exposed environment, much like savanna baboons. Further, 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. A 2011

strontium isotope The alkaline earth metal strontium (38Sr) has four stable, naturally occurring isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%). Its standard atomic weight is 87.62(1). Only 87Sr is radiogenic; it is produced by decay from the ...

study of ''P. robustus'' teeth from the

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

Sterkfontein Sterkfontein (Afrikaans for ''Strong Spring'') is a set of limestone caves of special interest to paleo-anthropologists located in Gauteng province, about northwest of Johannesburg, South Africa in the Muldersdrift area close to the town of ...

Valley found that, like other

s, but unlike other great apes, ''P. robustus'' females were more likely to leave their place of birth ( patrilocal). This also 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.

Life history

Dental development seems to have followed about the same timeframe as it does in modern humans and most other hominins, but, since ''Paranthropus'' molars are markedly larger, rate of tooth eruption would have been accelerated. Their life history may have mirrored that of gorillas as they have the same brain volume, which (depending on the subspecies) reach physical maturity from 12–18 years and have birthing intervals of 40–70 months.

Palaeoecology

Habitat

Upper Omo River Valley, Ethiopia (12562049655)

It is generally thought that ''Paranthropus'' preferred to inhabit wooded, riverine landscapes. The teeth of ''Paranthropus'', ''H. habilis'' and '' H. erectus'' are all known from various overlapping beds in East Africa, such as at Olduvai Gorge and the

Turkana Basin An '' Acacia'' tree in the Kokiselei river, northern Kenya The greater Turkana Basin in East Africa (mainly northwestern Kenya and southern Ethiopia, smaller parts of eastern Uganda and southeastern South Sudan) determines a large endorheic bas ...

. ''P. robustus'' and ''H. erectus'' also appear to have coexisted. ''P. boisei'', known from the Great Rift Valley, may have typically inhabited wetlands along lakes and rivers, wooded or arid

shrubland Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It ...

s, and semiarid woodlands, though their presence in the savanna-dominated Malawian Chiwondo Beds implies they could tolerate a range of habitats. During the Pleistocene, there seems to have been coastal and montane forests in Eastern Africa. More expansive river valleys—namely the Omo River Valley—may have served as important refuges for forest-dwelling creatures. Being cut off from the forests of Central Africa by a savanna corridor, these East African forests would have promoted high rates of

endemism Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

, especially during times of climatic volatility. The Cradle of Humankind, the only area ''P. robustus'' is known from, was mainly dominated by the springbok ''Antidorcas recki'', but other antelope, giraffes and

elephants Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae ...

were also seemingly abundant megafauna. Other known primates are early ''Homo'', the

hamadryas baboon The hamadryas baboon (''Papio hamadryas'' ) is a species of baboon within the Old World monkey family. It is the northernmost of all the baboons, being native to the Horn of Africa and the southwestern region of the Arabian Peninsula. These re ...

, and the extinct colobine monkey '' Cercopithecoides williamsi''.

Predators

The left foot of a ''P. boisei'' specimen (though perhaps actually belonging to ''H. habilis'') from Olduvai Gorge seems to have been bitten off by a crocodile, possibly ''

Crocodylus anthropophagus ''Crocodylus anthropophagus'' is an extinct species of crocodile from the Pleistocene of Tanzania. It lived 1.84 million years ago. It was a large-sized predator reaching a length of . Etymology ''Crocodylus anthropophagus'' was first named by ...

'', and another's leg shows evidence of leopard predation. Other likely Olduvan predators of great apes include the hunting hyena ''Chasmaporthetes nitidula'', and the sabertoothed cats ''

Dinofelis ''Dinofelis'' is a genus of extinct sabre-toothed cats belonging to the tribe Metailurini or possibly Smilodontini. They were widespread in Europe, Asia, Africa and North America at least 5 million to about 1.2 million years ago (Early Pliocene ...

'' and '' Megantereon''. The carnivore assemblage at the Cradle of Humankind comprises the two sabertooths, and the hyena '' Lycyaenops silberbergi''. Male ''P. robustus'' appear to have had a higher mortality rate than females. It is possible that males were more likely to be kicked out of a group, and these lone males had a higher risk of predation.

Extinction

It was once thought that ''Paranthropus'' had become a specialist feeder, and were inferior to the more adaptable tool-producing ''Homo'', leading to their extinction, but this has been called into question. However, smaller brain size may have been a factor in their extinction along with gracile australopithecines. ''P. boisei'' may have died out due to an arid trend starting 1.45 mya, causing the retreat of woodlands, and more competition with savanna baboons and ''Homo'' for alternative food resources. South African ''Paranthropus'' appear to have outlasted their East African counterparts. The youngest record of ''P. boisei'' comes from

Konso Konso (also known as Karati) is a town on the Sagan River in south-western Ethiopia. The administrative center of the Konso special woreda of the Southern Nations, Nationalities, and Peoples Region, this town has a latitude and longitude of and ...

, Ethiopia about 1.4 mya; however, there are no East African sites dated between 1.4 and 1 mya, so it may have persisted until 1 mya. ''P. robustus'', on the other hand, was recorded in Swartkrans until Member 3 dated to 1–0.6 mya (the Middle Pleistocene), though more likely the younger side of the estimate.

References

External links

Reconstructions of ''P. boisei''
by

John Gurche John Gurche is an American artist known for his paintings, sculptures, and sketches of prehistoric life, especially dinosaurs and early humans. Gurche is currently an Artist in Residence at the Museum of the Earth in Ithaca, New York. Gurche stu ...

*
Human Timeline (Interactive)
– Smithsonian,

National Museum of Natural History The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7. ...

(August 2016). {{Taxonbar, from=Q111463 Prehistoric primate genera Pliocene primates Pleistocene primates Pleistocene extinctions Cenozoic mammals of Africa Pleistocene genus extinctions Fossil taxa described in 1938