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Root growth during molar eruption in extant great apes
Frontiers of Oral Biology
|October 16, 2009
Summary
Great ape molar root lengths vary, with gorillas showing the longest roots at emergence. Human molar root growth comprises a larger percentage of eruption timing compared to great apes.
Area of Science:
- Primatology
- Paleoanthropology
- Developmental Biology
Background:
- Molar crown formation and eruption timing in great apes are increasingly understood.
- However, knowledge regarding molar root formation during eruption remains limited.
Purpose of the Study:
- To investigate and compare mandibular first and second molar root lengths during eruption in extant great apes.
- To assess the contribution of root growth to differences in first molar emergence timing between humans and great apes.
Main Methods:
- Measurement of mandibular first and second molar root lengths in osteological specimens of great apes (Gorilla, Pongo, Pan).
- Direct tooth measurement or radiographic analysis was employed based on specimen condition.
- Eruption stages were categorized by protein-stained cusps, with 1-2 stained cusps indicating immediate post-gingival emergence.
Main Results:
- At the early eruption stage, Gorilla exhibited the longest first molar roots, followed by Pongo and Pan.
- Variation in mesial root lengths of first molars at this stage was minimal in Gorilla and Pan, representing a few months of growth.
- Root growth constitutes a greater proportion of the time between birth and first molar emergence in humans than in any great ape species.
Conclusions:
- Molar root length at emergence is a significant factor in understanding primate dental development.
- Comparative analysis reveals distinct patterns of root development and eruption timing across great ape species and humans.
- These findings contribute to a more comprehensive understanding of hominoid dental evolution.
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