Modulation of mandibular loading and bite force in mammals during mastication

Area of Science:

• Biomechanics
• Mammalian Physiology
• Evolutionary Biology

Background:

• Mastication is a complex, rhythmic behavior crucial for feeding in mammals.
• Understanding how bite force is modulated offers insights into the control of cyclic movements.

Purpose of the Study:

• To investigate whether bite force modulation in mammalian mastication is achieved by altering force duration or force production rate.
• To analyze in vivo bone strain data from the mandibular corpus to test these hypotheses.

Main Methods:

• Collected rosette strain data from 40 experiments across 11 mammalian species (primates, goats, pigs, horses, alpacas).
• Utilized bivariate correlation and multiple regression analyses to assess relationships between principal strain magnitudes and temporal variables (loading/unloading time, rate, cycle duration, duty factor).

Main Results:

• Strain magnitudes were significantly correlated with strain loading and unloading rates, but not consistently with loading/unloading times.
• Multiple regression indicated that loading rate, not loading time or other temporal variables, best explained variations in strain magnitude.
• Weak correlations were observed between strain magnitude and overall chew cycle time or duty factor.

Conclusions:

• Mammalian bite force modulation during rhythmic mastication is predominantly achieved by altering the rate of force generation.
• Rate modulation, rather than temporal adjustments, likely facilitates a stable chewing frequency and simplifies motor control.
• These findings highlight the importance of force application dynamics in the biomechanics of feeding.