On the evolutionary advantage of multi-cusped teeth

Area of Science:

• Paleontology
• Biomechanics
• Evolutionary Biology

Background:

• Mammalian evolution shows increasing postcanine tooth complexity.
• The evolutionary drivers for this complexity (diet vs. structural integrity) are debated.

Purpose of the Study:

• To quantitatively assess how cusp number, position, and height influence sustainable bite forces in mammalian postcanine teeth.
• To determine the primary factors governing tooth structural integrity under occlusal load.

Main Methods:

• Utilized an extended finite-element methodology.
• Simulated step-by-step crack growth under increasing occlusal load to analyze fracture progression.

Main Results:

• Multi-cusp teeth effectively withstand high bite forces when multiple cusps share the load.
• Contact on a single cusp significantly reduces tooth strength.
• Cusp height and load point location are key factors, more so than cusp number or radius.

Conclusions:

• Complex tooth structures can improve durability.
• Increased cusp number likely evolved for enhanced food manipulation capabilities.
• Optimal structural integrity requires cusps to be distant from side walls and not excessively tall relative to tooth width.