Paranthropus robustus
Paranthropus robustus | |
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Cast of the presumed-male SK 48 skull | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Primates |
Suborder: | Haplorhini |
Infraorder: | Simiiformes |
Family: | Hominidae |
Subfamily: | Homininae |
Tribe: | Hominini |
Genus: | †Paranthropus |
Species: | †P. robustus
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Binomial name | |
†Paranthropus robustus Broom, 1938
| |
Synonyms | |
Paranthropus robustus is a
Robust australopithecines—as opposed to
P. robustus seems to have consumed a high proportion of
Taxonomy
million years ago ) |
Research history
Discovery
The first remains, a partial skull including a part of the jawbone (
At this point in time, Australian anthropologist
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, Cooper's, and Drimolen Caves. The species has not been found outside this small area.[6]
"P. crassidens"
In 1948, at the nearby Swartkrans Cave, Broom described "P. crassidens" (distinct from P. robustus) based on a subadult jaw, SK 6,
Anthropologists
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.
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.[6]
Gigantopithecus
In 1939, Broom hypothesised that P. robustus was closely related to the similarly large-toothed ape Gigantopithecus from Asia (extinct apes were primarily known from Asia at the time) believing Gigantopithecus to have been a hominin.[15] Primarily influenced by the mid-century opinions of Jewish German anthropologist 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.[16]
In 1972, Robinson suggested including Gigantopithecus in "Paranthropinae", with the
P. boisei
In 1959, another and much more robust australopithecine was discovered in East Africa,
In 1979, a year after describing
It was long assumed that if Paranthropus is a valid genus then P. robustus was the ancestor of P. boisei, but in 1985, anthropologists
Classification
The genus Paranthropus (otherwise known as "robust australopithecines", in contrast to the "
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.[23]
Anatomy
Head
Skull
Typical of Paranthropus, P. robustus exhibits
P. robustus has a tall face with slight
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
The 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 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.[27]
Brain
Upon describing the species, Broom estimated the fragmentary braincase of TM 1517 as 600 cc,[2] and he, along with South African anthropologist Gerrit Willem Hendrik Schepers, revised this to 575–680 cc in 1946.[28] For comparison, the brain volume of contemporary Homo varied from 500 to 900 cc.[29] A year later, British primatologist Wilfrid Le Gros Clark commented that, since only a part of the temporal bone on one side is known, brain volume cannot be accurately measured for this specimen.[28] 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.[30]
In 1972, American physical anthropologist
In 2020, the nearly complete skull DNH 155 was discovered and was measured to have had a brain volume of 450 cc.[22]
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.[33] 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.[34]
Regarding the
Torso
Few vertebrae 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.[37] Modern humans who suffer from spinal disc herniation often have vertebrae that are more similar to those of chimpanzees 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.[38] The shape of the lumbar vertebrae is much more similar to that of 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.[37]
The
Limbs
The distal (lower)
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).
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 140–150 cm (4 ft 7 in – 4 ft 11 in) and a weight of 68–91 kg (150–201 lb). 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 1.2–1.4 m (4–4.5 ft) tall and 18–27 kg (40–60 lb) in weight, and to have also been completely bipedal.[17]
Robinson's estimation of P. robustus size was soon challenged in 1974 by American palaeontologist
In 2001, palaeoanthropologist Randall L. Susman and colleagues, using two recently discovered proximal femoral fragments from Swartkrans, estimated an average of 42 kg (93 lb) for males and 30 kg (66 lb) 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 humans and chimpanzees, but less than orangutans and gorillas. 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 55 kg (121 lb).[56] In 2012, American anthropologist Trenton Holliday, using the same equation as McHenry on 3 specimens, reported an average of 37 kg (82 lb) with a range of 30–43 kg (66–95 lb).[57] In 2015, biological anthropologist Mark Grabowski and colleagues, using 9 specimens, estimated an average of 32.3 kg (71 lb) for males and 24 kg (53 lb) for females.[58]
Palaeobiology
Diet
In 1954, Robinson suggested that the heavily built skull of P. robustus and resultantly exorbitant bite force was indicative of a 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.[59] 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 mandrills, chimps, and orangutans.[60] 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.[59]
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 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.[59] 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.[61] In 1980, anthropologists Tom Hatley and John Kappelman suggested that early hominins (convergently with bears and pigs) adapted to eating abrasive and calorie-rich underground storage organs (USOs), such as roots and tubers.[62] Since then, hominin exploitation of USOs has gained more support. In 2005, biological anthropologists Greg Laden and 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.[61]
A 2006 carbon isotope analysis suggested that P. robustus subsisted on mainly C4 savanna plants or C3 forest plants depending on the season, which could indicate either seasonal shifts in diet or seasonal migration from forest to savanna.[63] H. ergaster/H. erectus appears to have consumed about the same proportion of C3 to C4 based foods as P. robustus.[64] 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).[63][65] A high cavity rate could indicate honey consumption.[66] Juvenile P. robustus may have relied more on tubers than adults, given the elevated levels of strontium compared to adults in teeth from Swartkrans Cave, which, in the area, was most likely sourced from tubers. Dentin 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 instead less capable of removing grit from dug-up food rather than purposefully seeking out more abrasive foods.[67]
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.[68][69]
In 2007, anthropologist Charles Lockwood and colleagues pointed out that P. robustus appears to have had pronounced
However, in 2011, palaeoanthropologist Sandi Copeland and colleagues studied the
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
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 "
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 300 °C (572 °F), 52 to 300–400 °C (572–752 °F), 45 to 400–500 °C (752–932 °F), 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 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.[75] 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 wildfires (dry savanna grass as well as possible 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.[76][77] 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.[78]
Development
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 indriid lemurs.[79] 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 bonobos, but unlike humans, which could also indicate an apelike growth trajectory.[3]
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
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.[70] 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.[80]
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.[82] 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 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.[83]
In 1972, after estimating a foetal size of 1,230–1,390 g (2.7–3.1 lb) based on an adult female weight of 50 kg (110 lb), anthropologist Walter Leutenegger estimated foetal head size at about 110–160 cc (6.7–9.8 cu in), similar to a chimp.[84] 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.[85] 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."[86]
In 1985, British biologists 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 1.9 kg (4.2 lb), 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.[87]
Pathology
Based on a sample of 402 teeth, P. robustus seems to have had a low incidence rate of about 12–16% for
P. robustus seems to have had notably high rates of
As many as four P. robustus individuals have been identified as having had dental
In a sample of 15 P. robustus specimens, all of them exhibited mild to moderate 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 cementoenamel junction, P. robustus possibly suffered from a higher rate of 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.[91]
While removing the matrix encapsulating TM 1517, Schepers noted a large rock, which would have weighed 75 g (2.6 oz), which had driven itself into the braincase through the 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 Robert Ardrey noted two small holes about 2.5 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, Brain reinterpreted this as evidence of a leopard attack.[92]
Palaeoecology
The Pleistocene Cradle of Humankind was mainly dominated by the
P. robustus also cohabited the Cradle of Humankind with H. ergaster/H. erectus.[56][76][95] In addition, these two species resided alongside Australopithecus sediba which is known from about 2 million years ago at 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.[95] It has been debated whether or not P. robustus would have had symbiotic, neutral, or antagonist relations with contemporary Australopithecus and Homo.[96] It is possible that South Africa was a 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.[95]
Fossil-bearing deposits
- Swartkrans
At Swartkrans, P. robustus has been identified from Members 1–3.
Member 1 and Member 3 have several mammal species in common, making dating by animal remains (
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.[99]
- Sterkfontein
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.[6]
The appearance of the baboon
- 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.[72] The ear bones of the juvenile KB 6067 from Member 3 is consistent with that of P. robustus, but the dimensions of the 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.[101]
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.[97]
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).
- Gondolin Cave
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 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 18.8 mm × 18.1 mm (0.74 in × 0.71 in), an area of 340 mm2 (0.53 sq in)—is exceptionally large for P. robustus, which has a recorded maximum of 290 mm2 (0.45 sq in). This falls within the range of P. boisei 278–378 mm2 (0.431–0.586 sq in), so the discoverers assigned it to an indeterminate species of Paranthropus rather than P. robustus.[102]
GDA-2 was found alongside the pig
- Cooper's Cave
Cooper's Cave was first reported to yield P. robustus remains in 2000 by South African palaeoanthropologists Christine Steininger and
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.[97]
- 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.[26] 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.[22] It was also associated with the H. ergaster/H. erectus skull DNH 134.[95] The Drimolen material preserves several basal characteristics relative to the Swartkrans and Kromdraai remains (meaning it may be older).[22]
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.[26] The animal assemblage is broadly similar to that of Cooper's Cave, meaning they probably are about the same age.[97] In 2020, DNH 152 was palaeomagnetically dated to 2.04–1.95 million years ago, making it the oldest identified P. robustus specimen.[95]
Predation
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
As an antipredator behaviour, baboons often associate themselves with medium-to-large herbivores, most notably impalas, 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.[105]
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 Mid-Pleistocene Transition, and the doubling of glacial cycle duration. During glacial events, with more ice locked up at the poles, the 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.[106]
However, the geographical range of P. robustus in the fossil record is roughly 500 km2 (190 sq mi), whereas the
See also
- African archaeology
- Australopithecus africanus – Extinct hominid from South Africa
- Australopithecus sediba – Two-million-year-old hominin from the Cradle of Humankind
- Homo ergaster – Extinct species or subspecies of archaic human
- Homo habilis – Archaic human species from 2.8 to 1.65 mya
- Homo naledi – South African archaic human species
- Homo rudolfensis – Extinct hominin from the Early Pleistocene of East Africa
- Paranthropus aethiopicus – Extinct species of hominin of East Africa
- Paranthropus boisei – Extinct species of hominin of East Africa
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Further reading
- Broom, R.; Schepers, G. W. H. (1946). The South African Fossil Ape-Men - The Australopithecinae. The Transvaal Museum.
- ISBN 978-0-226-72230-6.
- Grine, F. E. (1988). Evolutionary History of the "Robust" Australopithecines. Aldine de Gruyter. ISBN 978-0-202-02031-0.
- Bragá, J.; Thackeray, J. F. (2017). Kromdraai: A Birthplace of Paranthropus in the Cradle of Humankind. African Sun Media. ISBN 978-1-928355-06-9.
External links
- Meet Australopithecus robustus — John D. Hawks' website
- Paranthropus robustus - The Smithsonian's Human Origins Program
- Human Timeline (Interactive) – Smithsonian