Paranthropus boisei is aspecies ofaustralopithecine from theEarly Pleistocene of East Africa about 2.5 to 1.15 million years ago.^[1] Theholotype specimen,OH 5, was discovered by palaeoanthropologistMary Leakey in 1959 at Olduvai Gorge, Tanzania anddescribed by her husbandLouis a month later. It was originally placed into its owngenus as "Zinjanthropus boisei", but is now relegated toParanthropus along with other robust australopithecines. However, it is also argued thatParanthropus is an invalid grouping andsynonymous withAustralopithecus, so the species is also often classified asAustralopithecus boisei.

Paranthropus boisei Temporal range:Early Pleistocene,2.5–1.15 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Reconstruction of theholotype specimenOH 5
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. boisei
Binomial name
†Paranthropus boisei (Louis Leakey, 1959)
Synonyms
Zinjanthropus boisei Australopithecus boisei P. aethiopicus?

Robust australopithecines are characterised by heavily built skulls capable of producing highstresses andbite forces, and some of the largestmolars with the thickestenamel of any known ape.P. boisei is the most robust of this group. Brain size was about 450–550 cc (27–34 cu in), similar to other australopithecines. Some skulls are markedly smaller than others, which is taken as evidence ofsexual dimorphism where females are much smaller than males, though body size is difficult to estimate given only one specimen, OH 80, definitely provides any bodily elements. The presumed male OH 80 may have been 156 cm (5 ft 1 in) tall and 61.7 kg (136 lb) in weight, and the presumed female KNM-ER 1500 124 cm (4 ft 1 in) tall (though its species designation is unclear). The arm and hand bones of OH 80 and KNM-ER 47000 suggestP. boisei wasarboreal to a degree.

P. boisei was originally believed to have been aspecialist species of hard foods, such as nuts, due to its heavily built skull, but it was more likely a generalist feeder of predominantly abrasiveC4 plants, such asgrasses or undergroundstorage organs. Likegorillas, the apparently specialised adaptations of the skull may have only been used with less desirable fallback foods, allowingP. boisei to inhabit a wider range of habitats than gracile australopithecines.P. boisei may have been able to makeOldowanstone tools and butcher carcasses.P. boisei mainly inhabited wet, wooded environments, and coexisted withH. habilis,H. rudolfensis andH. ergaster/erectus. These were likely preyed upon by the large carnivores of the time, includingbig cats,crocodiles andhyenas.

PalaeoanthropologistsMary andLouis Leakey had conducted excavations in Tanzania since the 1930s, though work was postponed with the start ofWorld War II. They returned in 1951, finding mostly ancient tools andfossils of extinctmammals for the next few years.^[2] In 1955, they unearthed ahomininbabycanine and largemolar tooth inOlduvai Gorge, catalogue ID Olduvai Hominin (OH) 3.^[3]

On the morning of July 17, 1959, Louis felt ill and stayed at camp while Mary went out to Bed I'sFrida Leakey Gully.^[4] Sometime around 11:00 AM, she noticed what appeared to be a portion of a skull poking out of the ground, OH 5.^[5] The dig team created a pile of stones around the exposed portion to protect it from further weathering.^[6] Active excavation began the following day; they had chosen to wait for photographer Des Bartlett to document the entire process.^[6] The partial cranium was fully unearthed August 6, though it had to be reconstructed from its fragments which were scattered in thescree.^[7] Louis published a short summary of the find and context the following week.^[8]

Louis determined OH 5 to be a subadult or adolescent based on dental development, and he and Mary nicknamed it "Dear Boy".^[9] After they reconstructed the skull and jaws, newspapers began referring to it as "Nutcracker Man" due to the large back teeth and jaws which gave it a resemblance to vintagenutcrackers.^[10] South African palaeoanthropologistPhillip Tobias, a colleague of the Leakeys, has also received attribution for this nickname.^[11] The cranium was taken to Kenya after its discovery and was there until January 1965 when it was placed on display in the Hall of Man at theNational Museum of Tanzania in Dar es Salaam.^[12]

Louis preliminarily supposed OH 5 was about half a million years old, but in 1965, American geologistsGarniss Curtis and Jack Evernden dated OH 5 to 1.75 million years ago usingpotassium–argon dating ofanortoclase crystals from an overlyingtuff (volcanic ash) bed.^[13] Such an application ofgeochronology was unprecedented at the time.^[14]

The first identified jawbone,Peninj 1, was discoveredLake Natron just north of Olduvai Gorge in 1964.^{[15]: 107 [16][17]} Especially from 1966 to 1975, several more specimens revealing facial elements were reported from theShungura Formation, Ethiopia;Koobi Fora andChesowanja, Kenya; andOmo andKonso, Ethiopia. Among the notable specimens found include the well preserved skullKNM-ER 406 from Koobi Fora in 1970.^{[15]: 108–109} In 1997, the first specimen with both the skull and jawbone (and also one of the largest specimens), KGA10-525, was discovered in Konso.^[18] In 1999, a jawbone was recovered from Malema, Malawi, extending the species' southernmost range over 2,000 km (1,200 mi) from Olduvai Gorge.^[15]: 109 The first definitive bodily elements ofP. boisei associated with facial elements, OH 80 (isolated teeth with an arm and a leg), were discovered in 2013. Previously, body remains lacking unambiguous diagnostic skull elements had been dubiously assigned to the species, namely the partial skeleton KNM-ER 1500 associated with a small jawbone fragment.^[19] In 2015, based on OH 80, American palaeoanthropologist Michael Lague recommended assigning the isolated humerus specimens KNM-ER 739, 1504, 6020 and 1591 from Koobi Fora toP. boisei.^[20] In 2020, the first associated hand bones were reported, KNM-ER 47000 (which also includes a nearly complete arm), fromIleret, Kenya.^[21]

The remains were clearlyaustralopithecine (not of the genusHomo), and at the time, the only australopithecine genera described wereAustralopithecus byRaymond Dart andParanthropus (the South AfricanP. robustus) byRobert Broom, and there were arguments thatParanthropus wassynonymous withAustralopithecus. Louis believed the skull had a mix of traits from both genera, briefly listing 20 differences, and so used OH 5 as the basis for the new genus and species "Zinjanthropus boisei" on August 15, 1959. The genus name derives from the medieval term for East Africa, "Zanj", and the specific name was in honour ofCharles Watson Boise, the Leakeys' benefactor.^[22] He initially considered the name "Titanohomo mirabilis" ("wonderful Titan-like man").^[23]

Soon after, Louis presented "Z."boisei to the 4th Pan-African Congress on Prehistory in Léopoldville,Belgian Congo (nowKinshasa, Democratic Republic of the Congo).^[3] Dart made his now famous joke, "... what would have happened if [theA. africanus specimen]Mrs. Ples had met Dear Boy one dark night." At the time of discovery, there was resistance to erecting completely new genera based on single specimens, and the Congress largely rejected "Zinjanthropus".^[24] In 1960, American anthropologistJohn Talbot Robinson pointed out that the supposed differences between "Zinjanthropus" andParanthropus are due to OH 5 being slightly larger, and so recommended the species be reclassified asP. boisei. Louis rejected Robinson's proposal.^[25] Following this, it was debated ifP. boisei was simply an East African variant ofP. robustus until 1967 when South African palaeoanthropologistPhillip V. Tobias gave a far more detailed description of OH 5 in amonograph (edited by Louis). Tobias and Louis still retained "Zinjanthropus", but recommended demoting it tosubgenus level asAustralopithecus ("Zinjanthropus") boisei, consideringParanthropus to be synonymous withAustralopithecus.^[3] SynonymisingParanthropus withAustralopithecus was first suggested by anthropologistsSherwood Washburn and Bruce D. Patterson in 1951, who recommended limiting hominin genera to onlyAustralopithecus andHomo.^[26]

The genusParanthropus (otherwise known as "robust australopithecines") typically includesP. boisei,P. aethiopicus andP. robustus. It is debated ifParanthropus is a valid natural grouping (monophyletic) or an invalid grouping of similar-looking hominins (paraphyletic). Because skeletal elements are so limited in these species, theiraffinities with each other and to other australopithecines is difficult to gauge with accuracy. The jaws are the main argument for monophyly, but such anatomy is strongly influenced by diet and environment, and could in all likelihood have evolved independently inP. boisei andP. robustus. Proponents of monophyly considerP. aethiopicus to be ancestral to the other two species, or closely related to the ancestor. Proponents of paraphyly allocate these three species to the genusAustralopithecus asA. boisei,A. aethiopicus andA. robustus.^{[15]: 117–121}

BeforeP. boisei was described (andP. robustus was the only member ofParanthropus), Broom and Robinson continued arguing thatP. robustus andA. africanus (the then only known australopithecines) were two distinct lineages. However, remains were not firmly dated, and it was debated if there were indeed multiple hominin lineages or if there was only 1 leading to humans. In 1975, theP. boisei skull KNM-ER 406 was demonstrated to have been contemporaneous with theH. ergaster/erectus skullKNM ER 3733, which is generally taken to show thatParanthropus was asister taxon toHomo, both developing from someAustralopithecus species, which at the time only includedA. africanus. In 1979, a year after describingA. afarensis from East Africa, anthropologistsDonald Johanson andTim D. White suggested thatA. afarensis was instead the last common ancestor betweenHomo andParanthropus, andA. africanus was the earliest member of theParanthropus lineage or at least was ancestral toP. robustus, becauseA. africanus inhabited South Africa beforeP. robustus, andA. afarensis was at the time the oldest-known hominin species at roughly 3.5 million years old.^[27] Now, the earliest known South African australopithecine ("Little Foot") dates to 3.67 million years ago, contemporaneous withA. afarensis.^[28]

Such arguments are based on how one draws the hominin family tree, and the exact classification ofAustralopithecus species with each other is quite contentious. For example, if the South AfricanA. sediba (which evolved fromA. africanus) is considered the ancestor or closely related to the ancestor ofHomo, then this could allow forA. africanus to be placed more closely related toHomo than toParanthropus. This would leave the EthiopianA. garhi as the ancestor ofP. aethiopicus instead ofA. africanus (assumingParanthropus is monophyletic, and thatP. aethiopicus evolved at a time in East Africa when onlyA. garhi existed there).^[29]

BecauseP. boisei andP. aethiopicus are both known from East Africa andP. aethiopicus is only confidently identified from the skullKNM WT 17000 and a few jaws and isolated teeth, it is debated ifP. aethiopicus should be subsumed underP. boisei or if the differences stemming from archaicness justifies species distinction. The termsP. boiseisensu lato ("in the broad sense") andP. boiseisensu stricto ("in the strict sense") can be used to respectively include and excludeP. aethiopicus fromP. boisei when discussing the lineage as a whole.^{[15]: 106–107}

Africanhominin timeline(in mya)
View references

P. aethiopicus is the earliest member of the genus, with the oldest remains, from the EthiopianOmo Kibish Formation, dated to 2.6 million years ago (mya) at the end of thePliocene.^[30] It is possible thatP. aethiopicus evolved even earlier, up to 3.3 mya, on the expansive Kenyan floodplains of the time.^[31] The oldestP. boisei remains date to about 2.3 mya from Malema.^[30] The youngest record ofP. boisei comes Olduvai Gorge (OH 80) about 1.34 mya;^[19] however, due a large gap in the hominin fossil record,P. boisei may have persisted until 1 mya.^[15]: 109P. boisei changed remarkably little over its nearly one-million-year existence.^[32]

P. boisei is the most robust of the robust australopithecines, whereas the South AfricanP. robustus is smaller with comparatively more gracile features.^[15]: 120 TheP. boisei skull is heavily built, and features a definedbrow ridge, receding forehead, rounded bottom margins of theeye sockets, inflated and concavecheek bones, a thickpalate, and a robust and deep jawbone. This is generally interpreted as having allowedP. boisei to resist high stresses while chewing,^[33] though the thick palate could instead be a byproduct of facial lengthening.^[34] The skull features large rough patches (rugosities) on the cheek and jawbones, and males have pronouncedsagittal (on the midline) and temporonuchal (on the back) crests, which indicate a massivemasseter muscle (used in biting down) placed near the front of the head (increasingmechanical advantage). This is typically considered to be evidence of a highbite force.^[33]

Theincisors and canines are reduced, which would hinder biting off chunks of large food pieces. In contrast, thecheek teeth of both sexes are enormous (postcanine megadontia), and the greater surface area would have permitted the processing of larger quantities of food at once.^[33] In the upper jaw, the 1st molar averages roughly 250 mm² (0.39 sq in), the 2nd molar 320 mm² (0.50 sq in), and the 3rd molar 315 mm² (0.488 sq in); in the lower jaw, the 1st molar averages roughly 260 mm² (0.40 sq in), the 2nd molar 315 mm² (0.488 sq in), and the 3rd molar 340 mm² (0.53 sq in).^[35] The molars arebunodont, featuring low and roundedcusps. Thepremolars resemble molars (are molarised), which may indicateP. boisei required an extended chewing surface for processing a lot of food at the same time. Theenamel on the cheek teeth are among the thickest of any known ape, which would help resist high stresses while biting.^{[33]: 128–132}

In a sample of 10P. boisei specimens, brain size varied from 444–545 cc (27.1–33.3 cu in) with an average of 487.5 cc (29.75 cu in).^[36] However, the lower-end specimen, Omo L338‐y6, is a juvenile, and many skull specimens have a highly damaged or missingfrontal bone which can alter brain volume estimates.^[37] The brain volume of australopithecines generally ranged from 400–500 cc (24–31 cu in), and for contemporaryHomo 500–900 cc (31–55 cu in).^[38]

Regarding thedural venous sinuses, in 1983, American neuroanthropologistDean Falk and anthropologist Glenn Conroy suggested that, unlikeA. africanus or modern humans, allParanthropus (andA. afarensis) had expandedoccipital and marginal (around theforamen magnum) sinuses, completely supplanting thetransverse andsigmoid sinuses. In 1988, Falk and Tobias demonstrated that hominins can have both an occipital/marginal and transverse/sigmoid systems concurrently or on opposite halves of the skull, such as with theP. boisei specimen KNM-ER 23000.^[39]

In 1983, French anthropologist Roger Saban stated that the parietal branch of themiddle meningeal artery originated from the posterior branch inP. boisei andP. robustus instead of the anterior branch as in earlier hominins, and considered this a derived characteristic due to increased brain capacity.^[40] It has since been demonstrated that the parietal branch could originate from either the anterior or posterior branches, sometimes both in a single specimen on opposite sides of the skull as in KNM-ER 23000 and OH 5.^[41]

The wide range of size variation in skull specimens seems to indicate a great degree ofsexual dimorphism with males being notably bigger than females. However, it is difficult to predict with accuracy the true dimensions of living males and females due to the lack of definitiveP. boisei skeletal remains, save for the presumed male OH 80. Based on an approximation of 400 mm (1.3 ft) for thefemur before it was broken and using modern humanlike proportions (which is probably an unsafe assumption), OH 80 was about 156.3 cm (5 ft 1.5 in) tall in life.^[19] For comparison, modern human men and women in the year 1900 averaged 163 cm (5 ft 4 in) and 152.7 cm (5.01 ft), respectively.^[42] Thefemoral head, the best proxy for estimating body mass, is missing, but using the shaft, OH 80 weighed about 50 kg (110 lb) assuming humanlike proportions, and 61.7 kg (136 lb) using the proportions of a non-human ape.^[19] The ambiguously attributed, presumed female femur KNM-ER 1500 is estimated to have been of an individual about 124 cm (4 ft 1 in) tall^[43] which would be consistent with the argument of sexual dimorphism,^[19] but if the specimen does indeed belong toP. boisei, it would show a limb anatomy quite similar to that of the contemporaryH. habilis.^[15]: 116

Instead, the OH 80 femur, more likeH. erectus femora, is quite thick, features a laterally flattened shaft, and indicates similarly arrangedgluteal,pectineal andintertrochanteric lines around thehip joint. Nonetheless, the intertrochanteric line is much more defined in OH 80, thegluteal tuberosity is more towards the midline of the femur, and the mid-shaft in side-view is straighter, which likely reflect some difference in load-bearing capabilities of the leg. UnlikeP. robustus, the arm bones of OH 80 are heavily built, and theelbow joint shows similarities to that of moderngibbons andorangutans. This could either indicate thatP. boisei used a combination of terrestrial walking as well assuspensory behaviour, or was completely bipedal but retained an ape-like upper body condition from some ancestor species due to a lack of selective pressure to lose them. In contrast, theP. robustus hand is not consistent with climbing.^[19] The hand of KNM-ER 47000 showsAustralopithecus-like anatomy lacking thethird metacarpal styloid process (which allows the hand to lock into the wrist to exert more pressure), a weak thumb compared to modern humans, and curvedphalanges (finger bones) which are typically interpreted as adaptations for climbing. Nonetheless, despite lacking a particularly forcefulprecision grip likeHomo, the hand was still dextrous enough to handle and manufacture simple tools.^[21]

In 1954, Robinson suggested that the heavily built skull ofParanthropus (at the time only includingP. robustus) was indicative of aspecialist diet specifically adapted for processing a narrow band of foods. Because of this, the predominant model ofParanthropus extinction for the latter half of the 20th century was that it was unable to adapt to the volatile climate of thePleistocene, unlike the much more adaptableHomo.^[33] It was also once thoughtP. boisei cracked open nuts and similar hard foods with its powerful teeth, giving OH 5 the nickname "Nutcracker Man".^[44]

However, in 1981, English anthropologistAlan Walker found that the microwearing patterns on the molars were inconsistent with a diet high in hard foods, and were effectively indistinguishable from the pattern seen in the molars of fruit-eating (frugivorous)mandrills,chimpanzees andorangutans.^[45] The microwearing onP. boisei molars is different from that onP. robustus molars, and indicates thatP. boisei, unlikeP. robustus, very rarely ever ate hard foods.Carbon isotope analyses report a diet of predominantlyC4 plants, such as low quality and abrasive grasses and sedges.^[46][47][48] Thick enamel is consistent with grinding abrasive foods.^[33] The microwear patterns inP. robustus have been thoroughly examined, and suggest that the heavy build of the skull was only relevant when eating less desirable fallback foods. A similar scheme may have been in use byP. boisei.^[33] Such a strategy is similar to that used by moderngorillas, which can sustain themselves entirely on lower quality fallback foods year-round, as opposed to lighter built chimps (and presumably gracile australopithecines) which require steady access to high quality foods.^[49]

In 1980, anthropologists Tom Hatley and John Kappelman suggested that early hominins (convergently withbears andpigs) adapted to eating abrasive and calorie-rich undergroundstorage organs (USOs), such as roots and tubers.^[50] Since then, hominin exploitation of USOs has gained more support. In 2005, biological anthropologistsGreg Laden andRichard Wrangham proposed thatParanthropus 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.^[49] In this model,P. boisei may have been a generalist feeder with a predilection for USOs,^[51][48] and may have gone extinct due to an aridity trend and a resultant decline in USOs in tandem with increasing competition withbaboons andHomo.^[52] Like modern chimps and baboons, australopithecines likely foraged for food in the cooler morning and evening instead of in the heat of the day.^[53]

By the time OH 5 was discovered, the Leakeys had spent 24 years excavating the area for early hominin remains, but had instead recovered mainly other animal remains as well as theOldowanstone toolindustry.^[3] Because OH 5 was associated with the tools and processed animal bones, they presumed it was the toolmaker. Attribution of the tools was promptly switched to the bigger-brainedH. habilis upon its description in 1964.^[3] In 2013, OH 80 was found associated with a mass of Oldowan stone tools and animal bones bearing evidence of butchery. This could potentially indicateP. boisei was manufacturing this industry and ate meat to some degree.^[19]

Additionally, theEarly Stone Age of Africa coincides with simplebone tools. In South Africa, these are unearthed in theCradle of Humankind and are largely attributed toP. robustus. In East Africa, a few have been encountered at Olduvai Gorge Beds I–IV, occurring over roughly 1.7 to 0.8 million years ago, and are usually made of limb bones and possibly teeth of large mammals, most notablyelephants. The infrequency of such large animals at this site may explain the relative rarity of bone tools. The toolmakers were modifying bone in much the same way as they did with stone. Though the Olduvan bone tools are normally ascribed toH. ergaster/erectus, the presence of bothP. boisei andH. habilis obfuscates attribution.^[54]

In 1979, American biological anthropologistNoel T. Boaz noticed that the relative proportions between large mammal families at the Shungura Formation are quite similar to the proportion in modern-day across sub-Saharan Africa. Boaz believed that hominins would have had about the same population density as other large mammals, which would equate to 0.006–1.7 individuals per square kilometre (0.4 square mile). Alternatively, by multiplying the density of either bovids, elephants, or hippos by the percentage of hominin remains out of total mammal remains found at the formation, Boaz estimated a density of 0.001–2.58 individuals per square kilometre.^[55] Biologist Robert A. Martin considered population models based on the number of known specimens to be flimsy. In 1981, Martin applied equations formulated by ecologists Alton S. Harestad and Fred L. Bunnel in 1979 to estimate the home range and population density of large mammals based on weight and diet, and, using a weight of 52.4 kg (116 lb), he got: 130 ha (320 acres) and 0.769 individual per square kilometre if herbivorous; 1,295 ha (3,200 acres) and 0.077 individual if omnivorous; and 287,819 ha (711,220 acres) and 0.0004 individual if carnivorous. For comparison, he calculated 953 ha (2,350 acres) and 0.104 individual per square kilometre for omnivorous, 37.5-kilogram (83 lb) chimps.^[56]

A 2017 study postulated that, because male non-humangreat apes have a larger sagittal crest than females (particularly gorillas and orangutans), the crest may be influenced bysexual selection in addition to supporting chewing muscles. Further, the size of the sagittal crest (and thegluteus muscles) in malewestern lowland gorillas has been correlated with reproductive success. They extended their interpretation of the crest to the males ofParanthropus species, with the crest and resultantly larger head (at least inP. boisei) being used for some kind ofdisplay. This contrasts with other primates which flash the typically engorged canines in agonistic display (the canines ofParanthropus are comparatively small). However, it is also possible that male gorillas and orangutans require larger temporalis muscles to achieve a wider gape to better display the canines.^[57]

Australopithecines are generally considered to have had a faster,apelike growth rate than modernhumans 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 of age, which all contrast markedly with the modern human average of 5.8 years. The tips of the mesial cusps of the 1st molar (on the side closest to the premolar) of KNM-ER 1820 were at about the same level as the cervix (where the enamel meets thecementum) of its non-permanent 2nd premolar. In baboons, this stage occurs when the 1st molar is about to erupt from the gums. Thetooth root is about 5 mm (0.20 in), which is similar to most other hominins at this stage. In contrast, the root of theP. robustus specimen SK 62 was 6 mm (0.24 in) when emerging through thedental alveolus (an earlier stage of development than gum emergence), so, unless either specimen is abnormal,P. robustus may have had a higher tooth-root formation rate. The specimen's 1st molar may have erupted 2–3 months before death, so possibly at 2.7–3.3 years of age. 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 and slower life history due to environmental factors, such as early weaning age exhibited in modernindriidlemurs.^[58]

P. boisei remains have been found predominantly in what were wet, wooded environments, such as wetlands along lakes and rivers, wooded or aridshrublands, and semi-arid woodlands,^[48] with the exception of the savanna-dominated MalawianChiwondo Beds.^[59] Its abundance likely increased duringprecession-driven periods of relative humidity while being more rare during intervals of aridity.^[60] During the Pleistocene, there seems to have been coastal and montane forests in Eastern Africa. More expansive river valleys–namely theOmo 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 ofendemism, especially during times of climatic volatility.^[61] Australopithecines and earlyHomo likely preferred cooler conditions than laterHomo, as there are no australopithecine sites that were below 1,000 m (3,300 ft) in elevation at the time of deposition. This would mean that, like chimps, they often inhabited areas with an average diurnal temperature of 25 °C (77 °F), dropping to 10 or 5 °C (50 or 41 °F) at night.^[53]

P. boisei coexisted withH. habilis,H. rudolfensis andH. ergaster/erectus, but it is unclear how they interacted.^[3] To explain whyP. boisei was associated with Oldowan tools despite not being the tool maker, Louis Leakey and colleagues, when describingH. habilis in 1964, suggested that one possibility wasP. boisei was killed byH. habilis,^[62] perhaps as food.^[63] However, when describingP. boisei 5 years earlier, he said, "There is no reason whatever, in this case, to believe that the skull [OH 5] represents the victim of a cannibalistic feast by some hypothetical more advanced type of man."^[22] OH 80 seems to have been eaten by a big cat.^[64] The leg OH 35, which either belongs toP. boisei orH. habilis, shows evidence ofleopard predation.^[65] Other likely Oldowan predators of great apes include the hunting hyenaChasmaporthetes nitidula, thesabertoothed catsDinofelis andMegantereon,^[66] and thecrocodileCrocodylus anthropophagus.^[67]

• Archaeology InfoArchived 2011-05-16 at theWayback Machine
• Paranthropus boisei - The Smithsonian Institution's Human Origins Program
• Human Timeline (Interactive) –Smithsonian,National Museum of Natural History (August 2016).
• Images of OH 5^[usurped]
• Archaeology Info on OH 5Archived 2011-05-16 at theWayback Machine