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A functional consequence of an ossified mandibular symphysis
1Department of Oral Anatomy, University of Illinois, Chicago 60612.
American Journal of Physical Anthropology
|September 1, 1988
Summary
Mandibular symphysis fusion in mammals may not be for simple force transmission. Instead, fusion ensures reliable muscle force for incisor biting, preventing force dissipation from independent jaw movements.
Area of Science:
- Comparative anatomy
- Biomechanics
- Mammalian evolution
Background:
- The traditional explanation for fused mandibular symphyses in mammals is enhanced muscle force transmission.
- Recent studies challenge this, showing efficient force transmission across unfused symphyses.
Discussion:
- Symphyseal fusion may be crucial for animals using incisors on tough food.
- An unfused symphysis allows independent movement, potentially dissipating significant muscle force.
- This force dissipation could be a key factor in the evolution of fused symphyses.
Key Insights:
- Fusion ensures consistent bilateral muscle force application during incisor biting.
- Independent lower incisor row movement in unfused symphyses can lead to force loss.
- The necessity of reliable incisor biting force is a strong driver for symphyseal fusion.
Outlook:
- Further research into the biomechanics of incisor occlusion in mammals is warranted.
- Investigating the functional advantages of symphyseal fusion across diverse mammalian clades.
- Exploring the evolutionary pressures that favor fused versus unfused mandibular symphyses.