Molar topography covaries with insectivory in primates

Area of Science:

• Paleontology
• Primate Evolution
• Functional Morphology

Background:

• Traditional primate dietary classification (insectivore, folivore, frugivore, omnivore) is subjective and reductionist.
• Primate diets are complex and vary seasonally, complicating evolutionary studies.
• Understanding dietary shifts, like the early primate shift from insectivory to frugivory, requires refined methods.

Purpose of the Study:

• To develop a more nuanced method for studying primate dietary shifts.
• To investigate the relationship between insectivory and molar topography.
• To treat diet as a continuous variable (% insects) rather than discrete categories.

Main Methods:

• Analyzed 16 non-folivorous primate taxa with available dietary and dental topographic data.
• Quantified molar topography using Dirichlet normal energy (DNE), a measure of surface curvature.
• Employed phylogenetic generalized least squares regression to assess correlations.

Main Results:

• Molar curvature (DNE) significantly increases with the percentage of foraging time spent on insects (%insects).
• The %insects was a significant predictor of molar curvature (P < 0.001, R² = 0.579).
• Diet treated as a continuous variable provided greater insight into molar topography variation.

Conclusions:

• Dirichlet normal energy (DNE) effectively captures molar shape relevant to dietary transitions in primate evolution.
• Treating diet as a continuous variable offers a more nuanced understanding of molar form variation.
• This approach provides valuable insights into primate and mammalian molar evolution.