Paranthropus robustus is a species of robust australopithecine from the Early and possibly Middle Pleistocene of the Cradle of Humankind, South Africa, about 2.27 to 0.87 (or, more conservatively, 2 to 1) million years ago.

Robust australopithecines—as opposed to gracile australopithecines—are characterised by heavily built skulls capable of producing high stresses and bite forces, as well as inflated cheek teeth (molars and premolars).

It is typically found in what were mixed open and wooded environments, and may have gone extinct in the Mid-Pleistocene Transition characterised by the continual prolonging of dry cycles and subsequent retreat of such habitat.

The first remains, a partial skull including a part of the jawbone (TM 1517), were discovered in June 1938 at the Kromdraai cave site, South Africa, by local schoolboy Gert Terblanche.

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.

[7] At this point in time, humans and allies were classified into the family Hominidae, and non-human great apes into "Pongidae"; in 1950, Broom suggested separating early hominins into the subfamilies Australopithecinae (Au.

[12] 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".

[19] It was long assumed that if Paranthropus is a valid genus then P. robustus was the ancestor of P. boisei, but in 1985, anthropologists Alan Walker and 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|A.

The skulls of males have a well-defined sagittal crest on the midline of the skullcap and inflated cheek bones, which likely supported massive temporal muscles important in biting.

[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.

[30] 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.

[47] 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.

[48] The textural complexity of the kneecap SKX 1084, which reflects cartilage thickness and thus usage of the knee joint and bipedality, is midway between modern humans and chimps.

[49] 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 gait cycle.

[17] Robinson's estimation of P. robustus size was soon challenged in 1974 by American palaeontologist Stephen Jay Gould and English palaeoanthropologist David Pilbeam, who guessed from the available skeletal elements a weight of about 40.5 kg (89 lb).

[58] 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.

[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.

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.

[68] 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.

Australopithecine bone technology was first proposed by Dart in the 1950s with what he termed the "osteodontokeratic culture", which he attributed to A. africanus at Makapansgat dating to 3–2.6 million years ago.

[72][73][74] 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.

[72] 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 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.

"[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.

[87] Based on a sample of 402 teeth, P. robustus seems to have had a low incidence rate of about 12–16% for tertiary dentin, which forms to repair tooth damage caused by excessive wearing or dental cavities.

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.

[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.

[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.

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?

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.