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Paranthropus boisei

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Paranthropus boisei
Temporal range: Pleistocene, 2.3–1.2 Ma
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Photograph of KNM ER 406, a male specimen.
Scientific classification Edit this 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
(Mary Leakey, 1959)
Synonyms
  • Australopithecus boisei
    (Dart, 1938)
  • Zinjanthropus boisei
    (Louis Leakey, 1959) P E N I D

Paranthropus boisei or Australopithecus boisei was an early hominin, described as the largest of the genus Paranthropus (robust australopithecines). It lived in Eastern Africa during the Pleistocene epoch from about 2.4 until about 1.4 million years ago.[1]

Discovery

First discovered by anthropologist Mary Leakey on July 17, 1959, at Olduvai Gorge, Tanzania, the well-preserved cranium (nicknamed "Nutcracker Man") was dated to 1.75 million years ago and had characteristics distinctive of the robust australopithecines. Mary and her husband Louis Leakey classified the find as Zinjanthropus boisei: "Zinj" for the medieval East African region of Zanj, "anthropus" (from Greek: ἄνθρωπος, anthropos) for "human being", and "boisei" for Charles Watson Boise, the anthropologist team’s benefactor.[2]

Paranthropus boisei (as the species was eventually categorized) proved to be a treasure, especially when the anthropologists' son Richard Leakey suggested it was the first hominin species to use stone tools. Bernard Wood of the University of Liverpool, England, posits that tools discovered in Ethiopia and dated to 2.5 million years ago could have been made by Paranthropus boisei.[3] A well-preserved jaw, known as the Peninj Mandible, was found by Richard's colleague Kamoya Kimeu in 1964 in Peninj, Tanzania.[4][5] Another skull, specimen KNM ER 406, was unearthed in 1969 by Richard at Koobi Fora near Lake Turkana, in Kenya.

Morphology and interpretations

File:Paranthropus boisei.JPG
Paranthropus boisei reconstruction

The brain volume is quite small, about 500 to 550 cm3, not much larger than that of Australopithecus afarensis and Australopithecus africanus or modern-day chimpanzees. In P. boisei the foramen magnum is much shorter than in P. robustus. In addition, the cranial variation of P. boisei is remarkably high.[6] The adult males were larger on average than females (sexual dimorphism), as was the case in virtually all australopithecine species. Males weighed some 49 kg (108 lb) and stood about 1.37 m (4 ft 6 in) tall, while females weighed about 34 kg (75 lb) and were 1.24 m (4 ft 1 in) tall.[1]

It had a skull highly specialized for heavy chewing and several traits seen in modern-day gorillas. The molar teeth were very large, with an area over twice that of modern humans.[7] The species is sometimes referred to as "Nutcracker Man" because it had the biggest, flattest cheek teeth and the thickest enamel of any known hominin.[8] P. boisei had large chewing muscles attached to a pronounced sagittal crest. To accommodate their enormous cheek teeth (four times the size of modern human teeth[6]), P. boisei had a wide face, although the front teeth were much smaller than in similar species.

Some argue that the craniodental morphology of this taxon (e.g. large postcanine dentition, thick enamel, robust mandibles, sagittal cresting, flaring zygomatic region) is indicative of a diet of hard or tough foods such as ground tubers, nuts and seeds.[9] However, research on the molar microwear of P. boisei [10][11] has found a pattern very different from that observed in P. robustus in South Africa, which is thought to have fed on hard foods as a fallback resource.[12] This work suggests that hard foods were an infrequent part of P. boisei's diet. Carbon isotope ratios suggest P. boisei had a diet dominated by C4 vegetation, unlike P. robustus in South Africa.

Fossils

In 1993, A. Amzaye found fossils of P. boisei at Konso, Ethiopia. The partial skull is designated as KGA10-525 and is dated to 1.4 million years ago. It is the biggest skull specimen ever found of P. boisei. The oldest specimen of P. boisei was found in Omo, Ethiopia, and dates to 2.3 million years ago, classified as (L. 74a-21), while the youngest specimen from Olduvai Gorge dates to 1.2 million years ago and is classified as OH 3 and OH 38.[citation needed]

Other well-preserved specimens

Lifestyle

Diet

Casts of the skull sometimes known as "Nutcracker Man", found by Mary Leakey in 1959, and the jaw known as the Peninj Mandible, found by Kamoya Kimeu in 1964.

Almost all primates and hominids are or were dietary generalists, meaning that they ate a wide variety of foods and did not depend on a single, specific food source.[14]

The most widely accepted theory about what foods P. boisei ate suggests that it fed on hard objects as its primary source of nutrition.[15] Strong jaw muscles are believed to be an evolutionary adaptation of P. boisei for a diet of nuts, seeds and hard fruit.[16] Analysis of the wear on the molars of P. boisei showed fine striations[10] indicating constant chewing of small, hard food items, like nuts and seeds.

The foods that P. boisei would have ingested can be determined by means of carbon isotope measurements (not to be confused with radiocarbon dating).[16] Along with fruits and nuts, carbon isotope data on P. boisei fossils suggest that their diet was largely based on C4 resources, probably grasses or sedges. One study has concluded that the diet of P. boisei actually consisted mostly of grasses and sedges such as tigernut and that it rarely ate fruits and nuts.[17][18] According to another, the addition of tubers to its diet helped P. boisei to meet its daily caloric intake requirement.[19] In any case, it would appear that P. boisei consumed larger quantities of plant matter than any other hominin studied to date.[10]

The diet of fruits and nuts that P. boisei would have eaten is reflected by its classification as a cosmopolitan species, meaning that its wide geographic range would result in a diverse diet of different foods.[16] The data suggest that this C4 resource centered diet was present over a wide range of period and region,[16] with Paranthropus in eastern Africa and southern Africa having different diets.[20]

Development relative to other Hominins

Hominin species during Pleistocene
Homo (genus)AustralopithecusAustralopithecus sedibaAustralopithecus africanusHomo floresiensisHomo neanderthalensisHomo sapiensHomo heidelbergensisHomo erectusHomo nalediHomo habilisHolocenePleistocenePliocene


See also

References

  1. ^ a b "Paranthropus boisei Topics". Smithsonian National Museum of Natural History. Retrieved 11 July 2012.
  2. ^ Watson, Peter (2002). The Modern Mind: An Intellectual History of the 20th Century. New York: Perennial. pp. 486–487. ISBN 0-06-008438-3.
  3. ^ Friend, Tim (January 23, 1997). "Oldest stone tools yet found in Ethiopia". USA Today (LIFE): 1.
  4. ^ Journal of Eastern African Research and Development. East African Literature Bureau. 1974. p. 129. The mandible was discovered by Kamoya Kimeu in 1964, during an expedition conducted by Richard Leakey and Glynn Isaac.
  5. ^ Virginia Morell (11 January 2011). Ancestral Passions: The Leakey Family and the Quest for Humankind's Beginnings. Simon and Schuster. p. 303. ISBN 978-1-4391-4387-2.
  6. ^ a b Wood, Bernard; Lieberman, Daniel E. (2001). "Craniodental variation in Paranthropus boisei: A developmental and functional perspective". American Journal of Physical Anthropology. 116 (1): 13–25. doi:10.1002/ajpa.1097. PMID 11536113.
  7. ^ McHenry, Henry M.; Coffing, Katherine (2000). "Australopithecus to Homo: Transformations in Body and Mind" (PDF). Annual Review of Anthropology. 29 (1): 125–46. doi:10.1146/annurev.anthro.29.1.125. JSTOR 223418. Archived from the original (PDF) on 2008-12-16. {{cite journal}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  8. ^ Findings Challenge Conventional Ideas on Evolution of Human Diet, Natural Selection Newswise, Retrieved on June 26, 2008.
  9. ^ Klein, Richard G. (1999). The Human Career: Human Biological and Cultural Origins (2nd ed.). Chicago: University of Chicago Press. ISBN 0-226-43963-1.[page needed]
  10. ^ a b c Ungar, Peter S.; Grine, Frederick E.; Teaford, Mark F. (April 2008). Petraglia, Michael (ed.). "Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei". PLoS ONE. 3 (4): e2044. Bibcode:2008PLoSO...3.2044U. doi:10.1371/journal.pone.0002044. PMC 2315797. PMID 18446200.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  11. ^ "Gnashers at Work". The Economist. 2008-05-01. Retrieved 2008-05-05.
  12. ^ Scott, Robert S.; Ungar, Peter S.; Bergstrom, Torbjorn S.; Brown, Christopher A.; Grine, Frederick E.; Teaford, Mark F.; Walker, Alan (2005). "Dental microwear texture analysis shows within-species diet variability in fossil hominins". Nature. 436 (7051): 693–5. Bibcode:2005Natur.436..693S. doi:10.1038/nature03822. PMID 16079844.
  13. ^ Daegling, David J.; Judex, Stefan; Ozcivici, Engin; Ravosa, Matthew J.; Taylor, Andrea B.; Grine, Frederick E.; Teaford, Mark F.; Ungar, Peter S. (July 2013). "Viewpoints: feeding mechanics, diet, and dietary adaptations in early hominins". American Journal of Physical Anthropology. 151 (3): 356–71. doi:10.1002/ajpa.22281. PMID 23794331.
  14. ^ Wood, Bernard; Schroer, Kes (2012). "Reconstructing the Diet of an Extinct Hominin Taxon: The Role of Extant Primate Models". International Journal of Primatology. 33 (3): 716–42. doi:10.1007/s10764-012-9602-7.
  15. ^ Ungar, Peter S.; Sponheimer, Matt (2011). "The Diets of Early Hominins". Sciencemag Online. 334 (6053): 190 193. Bibcode:2011Sci...334..190U. doi:10.1126/science.1207701.
  16. ^ a b c d Cerling, Thure E.; Mbua, Emma; Kirera, Francis M.; Manthi, Fredrick Kyalo; Grine, Frederick E.; Leakey, Meave G.; Sponheimer, Matt; Unoa, Kevin T. (2011). "Diet of Paranthropus boisei in the early Pleistocene of East Africa". Proceedings of the National Academy of Sciences. 108 (23): 9337–41. Bibcode:2011PNAS..108.9337C. doi:10.1073/pnas.1104627108. PMC 3111323. PMID 21536914.
  17. ^ New technologies challenge old ideas about early hominid diets[unreliable source?] Archived August 5, 2013, at the Wayback Machine
  18. ^ Macho, Gabriele A. (2014). "Baboon Feeding Ecology Informs the Dietary Niche of Paranthropus boisei". PLoS ONE. 9 (1): 84942. Bibcode:2014PLoSO...984942M. doi:10.1371/journal.pone.0084942. PMC 3885648. PMID 24416315.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  19. ^ Griffith, Cameron S.; Long, Byron L.; Sept, Jeanne M. (2010). "HOMINIDS: An agent-based spatial simulation model to evaluate behavioral patterns of early Pleistocene hominids". Ecological Modelling. 221 (5): 738–60. doi:10.1016/j.ecolmodel.2009.11.009.
  20. ^ Wood, Bernard; Constantino, Paul (2007). "Paranthropus boisei: Fifty years of evidence and analysis". American Journal of Physical Anthropology. 134 (Suppl 45): 106–32. doi:10.1002/ajpa.20732. PMID 18046746.
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