Deciduous Dentition of Fossil Hominins

Abstract

The deciduous dentition is the first of two successive sets of teeth in humans. It consists of 20 teeth that are shed and replaced by the permanent teeth, of which there are 32. The most significant differences in the teeth of fossil hominins and great apes are the reduction of canine size, the change in canine shape and the increased complexity of the deciduous lower first molar. At about 2.5 million years ago, one hominin lineage – Paranthropus – continued to increase size and complexity of molars, and reduce canine and incisor size, while the lineage leading to our species Homo sapiens underwent dental reduction and simplification. Compared to earlier hominins, the deciduous teeth of recent humans are greatly reduced in size and complexity. However, the range of size and morphological variation among geographic populations is very wide, especially for deciduous first molars.

Key Concepts

  • Hominin deciduous teeth differ from those of great apes primarily in the size and shape of the upper and lower canines and shape of lower first molar.
  • Hominin deciduous incisors are smaller than those of great apes and early hominin upper incisors are more heteromorphic (greater differences in size between lateral and central incisors).
  • Hominin deciduous canines are shorter, smaller and less pointed than those of great apes.
  • Hominin deciduous canines are more diamond shaped and less conical than those of great apes.
  • Hominin deciduous lower first molars are nonsectorial and have more cusps than those of great apes.
  • Hominin deciduous molars are larger and may be morphologically more complex than those of great apes.
  • The genus Homo is characterised by incisor expansion, further canine diminution and molar reduction.
  • Neanderthals can be statistically distinguished from Homo sapiens in the shape and cusp size of deciduous molars.
  • Recent humans are highly variable compared to their fossil relatives, but tend to have even smaller and more simplified canines and postcanine teeth.

Keywords: deciduous dentition; Australopithecus; Paranthropus; Homo; dental morphology

Figure 1. Comparison of permanent and deciduous dentitions: d, deciduous; superscript, upper dentition; subscript, lower dentition. i/I, incisor; c/C, canine, P, premolar and m/M, molar.
Figure 2. Variation in the lower deciduous canine in fossil hominins (modified from Grine, : 563, with permission). (a) Australopithecus afarensis (East African Australopithecus); (b) Australopithecus africanus (South African Australopithecus); (c) Paranthropus robustus (South African Paranthropus) and (d) Homo erectus (buccal view, mesial is to the left).
Figure 3. Illustration of morphological terms used: 1: protoconid; 2: metaconid; 3: hypoconid; 4: entoconid; 5: hypoconulid (Cusp 5); 6: tuberculum sextum (cusp 6); 7: trigonid crest; 8: anterior fovea; 9: mesial marginal ridge; 10: protostylid; 11: protocone; 12: paracone; 13: metacone; 14: hypocone; 15: Carabelli's feature; 16: mesial marginal ridge; 17: anterior fovea; 18: posterior fovea; 19: epicrista; 20: distal trigone crest; 21: parastyle and 22: tuberculum molare.
Figure 4. Range of morphological complexity in hominin molars. (a) Paranthropus robustus; (b) recent Homo sapiens. Clockwise from the left: 1: lower dm1; 2: upper dm1; 3: lower dm2 and 4: upper dm2. All teeth represent the left side, and mesial is to the top.
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Further Reading

Bailey SE (2006) Beyond shovel shaped incisors: Neandertal dental morphology in a comparative context. Periodicum Biologorum 108 (3): 253–267.

Bailey SE, Skinner MM and Hublin J‐J (2011) What lies beneath? An evaluation of lower molar trigonid crest patterns based on both dentine and enamel expression. American Journal of Physical Anthropology 45: 505–518.

Bailey SE and Hublin J‐J (2013) What does it mean to be dentally ‘modern’? In: Scott GR and Irish JD (eds) Anthropological Perspectives on Tooth Morphology: Genetics, Evolution, Variation. Cambridge, UK: Cambridge University Press.

Grine FE (1985) Australopithecine evolution: the deciduous dental evidence. In: Delson E (ed) Ancestors: The Hard Evidence, pp. 153–167. New York, NY: Alan R. Liss, Inc.

Grine FE (1986) Dental evidence for dietary differences in Australopithecus and Paranthropus: a quantitative analysis of permanent molar microwear. Journal of Human Evolution 15: 783–822.

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Martinón‐Torres M, Bermúdez de Castro JM, Gómez‐Robles A, Prado‐Simón L and Arsuaga JL (2012) Morphological description and comparison of the dental remains from Atapuerca‐Sima de los Huesos site (Spain). Journal of Human Evolution 62 (1): 7–58.

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Weidenreich F (1937) The dentition of Sinanthropus pekenensis: a comparative odontography of the hominids. Paleontologia Sinica n.s. D (1): 1–180.

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How to Cite close
Bailey, Shara E(Jan 2017) Deciduous Dentition of Fossil Hominins. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0027069]