Pongid Dentitions

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Evolution of Dentitions
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Microwear Patterns

• The amount of wear and tear on fossil teeth has
  always provided a clue to diet, but work with
  scanning electron microscopes has revealed tiny
  pits and scratches on the surfaces of tooth
  enamel--called microwear patterns--that provide
  further evidence of dietary conditions.
• It has been observed that grasses leave linear
  scratches on the teeth, leaves produce a polished
  effect, and the bone crunching of carnivores
  gouges out tiny pits in the enamel.

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Human Tooth Pongid Tooth
A. afarensis
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Pongid Dentitions

• Progressive increase in the size of incisors
• Widening of the mandible with the eventual
  formation of the simian shelf
• Strong, conical, sexually dimorphic canines
• Cutting function of the first lower premolar is
  accentuated by the development of a strong
  anterior root
• Postcanine teeth preserve parallel or slightly
  divergent alignment in relatively straight rows
• First deciduous molars remain predominantly
  unicuspid

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Pongid Dentition
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Australopithecines Dentitions

• Robust australopithecines show dental
  specializations of a high order in that there is
  gross disproportion between anterior and
  posterior dentition.
• Small incisors and canines.
• Premolars and molars are extremely large.(for
  crushing)
• Microwear patterns on the teeth of early
  australopithecines indicates that unlike pongids
  their diet did not consist of tough plant
  material.
• Australopithecine diet had more in common with
  that of modern fruit-eating forms such as
  chimpanzees.

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Australopithecine Dentition
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Hominid Dentitions

• Reduction of incisors and canines
• Appearance of bicuspid premolars
• Canines have diminished to a spatulate form
• There is no pronounced sexual dimorphism of the
  canines
• Spaces between teeth have largely vanished
• Dental arcade is even and rounded

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Homo Habilis Dentitions

• Incisors become more spatulate
• Molars become smaller in size and proportion
• This possibly indicates another dietary shift

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Homo Erectus Dentitions

• Show heavy wear patterns that include pits,
  scratches, and polish
• All of these indicate an unspecialized,
  omnivorous dietary preference.

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Homo Sapien Dentitions

• Dental characteristics revolve around the reduced
  jaw bone size
• The dentitions as a whole shows tooth crowding
• Accompanied by smallness of the individual teeth
  and marked reduction is size of the third
  molar(wisdom teeth)

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Human Dentition
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Use of Isotopes in Evidence of Hominid Diet

• Studies have shown that the ratio of 13C to 12C
  in tooth enamel can be used to provide dietary
  information about extinct fauna.
• The foundation of this approach is our knowledge
  of photosynthesis in plants.
• Trees, bushes, shrubs,and forbs are C3 plants
• Tropical grasses and sedges are C4 plants
• The relative proportions of C3 and C4 vegetation
  in an animals diet can be determined by
  analyzing its tooth enamel with stable isotope
  mass spectrometry

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Aaron Berger Jason Lawson