{"id":159,"date":"2017-09-13T20:20:25","date_gmt":"2017-09-13T20:20:25","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-history-of-our-tribe\/chapter\/18-paranthropus-boisei\/"},"modified":"2017-10-03T16:10:08","modified_gmt":"2017-10-03T16:10:08","slug":"18-paranthropus-boisei","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-history-of-our-tribe\/chapter\/18-paranthropus-boisei\/","title":{"raw":"18. Paranthropus boisei","rendered":"18. Paranthropus boisei"},"content":{"raw":"
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Paranthropus boisei <\/i>(2.5 mya)<\/b><\/h1>\r\n

(\u201cbeside human\u201d \/ Boise: surname of one of the Leakey\u2019s financiers)<\/h2>\r\n[caption id=\"attachment_228\" align=\"aligncenter\" width=\"300\"]\"7.43\" Figure 18.1\u00a0<\/em>Paranthropus boisei. \u201cParanthropus boisei side (University of Zurich)<\/a>\u201d by Nicolas Gu\u00e9rin is licensed under CC BY-SA 3.0<\/a>.[\/caption]\r\n\r\n
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SITES<\/b><\/h3>\r\nEthiopia:<\/b> Shungura Deposits and Konso\r\n\r\nKenya:<\/b> Chesowanja, West Lake Turkana, and Koobi Fora\r\n\r\nTanzania:<\/b> Olduvai and Peninj\r\n

PEOPLE<\/b><\/h3>\r\nMary and Richard Leakey\r\n\r\n<\/div>\r\n

INTRODUCTION<\/strong><\/h2>\r\nIn the first course that I took in physical anthropology, I was most fascinated by the Paranthropus boisei<\/i> face from Olduvai Gorge (see Figures 18.1\u00a0and 18.5) and the Natron\/Peninj mandible from the Peninj site near Lake Natron. I still remember the first time I saw them, and the species has always been for me one of the more interesting discoveries in paleoanthropology. Their faces, jaws, and cheek teeth were massive and truly unforgettable. While the Olduvai material is attributed to Mary Leakey, it was her husband Louis who announced to the world that he had his \u201cman.\u201d He had been finding tools of what are now termed the Oldowan tradition and was hoping to discover who had made them when Mary discovered the first P. boisei<\/i> fossils. They were assigned to a new genus and species: Zinjanthropus boisei<\/i>, or \u201chuman from East Africa.\u201d \u201cZinj\u201d is a derivation of the archaic term \u201cZanj\u201d for an area of the East African coast, and Boise was the surname of one of the Leakeys\u2019 financial supporters (Wikipedia contributors 2015g). Louis claimed that they had their toolmaker, but many did not agree with his conclusion. They thought he had found a big, dumb, herbivorous, bipedal ape that would not have had the cognitive abilities to produce stone tools. Hand bones have been attributed to the species by some researchers. If they are correct in their assignment, the species may have been capable of tool manufacture and efficient use. However, while their brains were somewhat larger than earlier species, we still do not know if they had the cognitive abilities and thus whether tools from East African sites can be attributed to them.\r\n
\r\n\r\n[caption id=\"attachment_972\" align=\"aligncenter\" width=\"500\"]\"\" Figure 18.2\u00a0<\/em>Olduvai Gorge, by David Berkowitz, CC BY 2.0<\/a>[\/caption]\r\n\r\n<\/div>\r\nFossils from more than 100 individuals have been recovered in the last 55 years. Over time, the genus has changed from Zinjanthropus<\/i> to Australopithecus<\/i> to Paranthropus<\/i>, but some researchers are still using genus: Australopithecus<\/i>.\r\n

PHYLOGENY<\/b><\/h2>\r\nSupport for P. boisei<\/i> being descended from Au. aethiopicus<\/i> has steadily increased. However, some still group P. boisei<\/i> as a sister species of P. robustus<\/i> and believe that they descended from Au. africanus<\/i>. The two more derived forms share a molar trait with Au. africanus<\/i>, in that the second molar (M2) is larger than the third (M3). Members of the latter group, such as Henry McHenry, contend that the more primitive Au. aethiopicus<\/i> is an example of homoplasy<\/b> or convergent evolution, making the robust traits homoplasies. Paleoanthropologists have tended to be conservative in their acceptance of homoplasies; common ancestry is more parsimonious.\r\n\r\nExcept for the possible Au. aethiopicus<\/i> \u2192 P. boisei<\/i> scenario, the robust australopiths were evolutionary dead-ends as far as we know.\r\n\r\n[caption id=\"attachment_230\" align=\"aligncenter\" width=\"300\"]\"7.46\" Figure 18.3\u00a0<\/em>Scientific reconstruction of Paranthropus boisei. \u201cParanthropus boisei<\/a>\u201d by Lillyundfreya is licensed under CC BY-SA 3.0<\/a>.[\/caption]\r\n

DISCOVERY AND GEOGRAPHIC RANGE<\/b><\/h2>\r\nMary Leakey discovered the first material in 1959 at Olduvai Gorge, Tanzania (see Figure 18.2). Nicknamed \u201cNutcracker Man,\u201d \u201cZinj,\u201d or \u201cDear Boy,\u201d the skull and face were dated to 1.7 mya. Fossils attributed to the species have since been found at other sites in Tanzania (Peninj), Kenya (Chesowanja, West Lake Turkana, and Koobi Fora in the East Lake Turkana area), and Ethiopia (the Shungura Deposits and Konso). Richard Leakey discovered the Koobi Fora fossils. Thus, like Au. afarensis<\/i>, the species had a broad geographic range and survived for over a million years.\r\n\r\n[caption id=\"attachment_298\" align=\"aligncenter\" width=\"732\"]\"image\" Figure 18.4\u00a0<\/em>Paranthropus boisei by Keenan Taylor.[\/caption]\r\n

PHYSICAL CHARACTERISTICS<\/b><\/h2>\r\nWhile the robust forms are somewhat larger than the gracile forms, they do not differ much postcranially. It is their skulls that set them apart; P. boisei<\/i> had the most pronounced masticatory adaptations, so that relative to the other two species, they are termed \u201chyper-robust.\u201d Along with the other robust forms, they shared a buttressed skull, face, and mandible; large molars and premolars; a compound sagittal-nuchal crest (not compound in P. robustus<\/i>); large muscles of mastication and nuchal muscles to support their heavy skulls; large, flared zygomatic arches; and a supraorbital torus to absorb the stress generated by chewing. According to some researchers, they shared the following with P. robustus<\/i> and Homo<\/i>: flexed skull base; more orthognathic face; lower face tucked under the braincase, thus increasing chewing force on the molars; a more parabolic dental arcade; and a longer thumb with broad, flat, distal phalanges that gave them better opposition and gripping power. The sagittal crest in P. boisei<\/i> and P. robustus<\/i> was more anteriorly positioned relative to Au. aethiopicus<\/i>. In combination with less prognathism and the fact that their face was tucked under the braincase, the action and strength of the temporalis muscle was concentrated on the cheek teeth. The degree of robusticity and the size of craniofaciodental characteristics were unique to P. boisei<\/i>. The zygomatics were large, heavy, and widely flared, making their faces very broad and the temporal fossa (the space between the zygomatic and the temporal bone) very deep. Again, this facilitated the passage of the temporalis muscle to insert on the mandible and expanded the attachment and anchoring of the masseter muscle. The mandible was massive, with a very robust and deep body and tall rami (vertical side portions), and the temporomandibular (jaw) joint was exceptionally large. Their front teeth were so dwarfed by their enormous cheek teeth, they almost look juvenile. Their premolars were molarized, and some had a third root. The third molar exhibited a unique wrinkling pattern. Their megadontia quotient<\/b> (MQ) was 2.7, meaning that their teeth were 2.7 times larger than would be expected. P. boisei<\/i> had the largest supraorbital torus of the robust forms. They were somewhat more encephalized than past species, with a cranial capacity of 514 cc (range = 494\u2013537 cc). Like all australopiths, the species was sexually dimorphic, with males at 4'6\" (137 cm) tall and 108 lb (49 kg) and with more pronounced sagittal-nuchal crests and females at 4'1\" (124 cm) and 70 lb (34 kg).\r\n\r\n[caption id=\"attachment_231\" align=\"aligncenter\" width=\"250\"]\"7.47\" Figure 18.5\u00a0<\/em>Natron mandible. \u201cPeninj mandible. Paranthropus boisei<\/a>\u201d by Matt Celeskey is licensed under CC BY-SA 2.0<\/a>.[\/caption]\r\n\r\n
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Review of Derived Characteristics<\/h3>\r\n