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Bite force and occlusal stress production in hominin evolution
Carolyn M Eng1, Daniel E Lieberman, Katherine D Zink
1Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA. cmeng@fas.harvard.edu
American Journal of Physical Anthropology
|June 12, 2013
Summary
Modern humans evolved lower maximum bite forces than predicted, suggesting a shift towards non-thermal food processing before cooking. This impacts our understanding of human craniofacial evolution and dietary adaptations.
Area of Science:
- Paleoanthropology
- Biomechanics
- Evolutionary Biology
Background:
- Maximum bite force influences craniofacial morphology and food processing capabilities.
- Humans are thought to have lower bite forces than apes due to advanced food processing techniques.
- The timing of regular consumption of mechanically processed or cooked diets in hominins is unknown.
Purpose of the Study:
- To estimate maximum bite forces and stresses at the second molar in modern humans, nonhuman primates, and hominins.
- To investigate the relationship between bite force, molar area, and jaw muscle architecture.
- To test the hypothesis of isometry in bite force scaling across species.
Main Methods:
- Application of a validated model for estimating maximum bite forces and stresses.
- Incorporation of skeletal data and species-specific jaw muscle architecture estimates.
- Analysis of modern human, nonhuman primate, and hominin skulls, focusing on second molar dimensions.
Main Results:
- A significant relationship exists between second molar bite force and second molar area across species, but isometry was not confirmed.
- Homo species exhibit maximum bite forces below the regression line for nonhuman anthropoids and australopiths.
- Australopiths demonstrated ape-like bite force capabilities.
Conclusions:
- Homo species likely evolved lower bite forces before the advent of cooking, possibly due to increased reliance on nonthermal food processing.
- Environmental factors and variations in food mechanical properties may contribute to observed bite force variability in humans.
- The findings suggest a significant dietary shift in early Homo, impacting craniofacial evolution.
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