Genetics and the evolution of primate enamel thickness: a baboon model

Area of Science:

• Primate paleontology
• Evolutionary biology
• Quantitative genetics

Background:

• Tooth enamel thickness is a key indicator of diet and evolutionary history in primates.
• Previous studies focused on hominids, leaving nonhominoid primate enamel thickness largely unexplored.
• The genetic mechanisms driving enamel thickness variation remain unclear.

Purpose of the Study:

• To conduct the first quantitative genetic analysis of primate enamel thickness.
• To investigate the heritability and genetic basis of enamel thickness variation in baboons.
• To provide insights into the evolution of tooth enamel in the primate fossil record.

Main Methods:

• Computed tomography (CT) analysis of 44 Papio mandibular molars to identify uniform enamel thickness zones.
• Development of a caliper metric measurement protocol for worn molars.
• Quantitative genetic analysis of enamel thickness in 506 pedigreed baboons.

Main Results:

• A significant portion of phenotypic variance in enamel thickness is attributable to additive genetic effects.
• Enamel thickness variation is independent of sex and tooth size.
• Enamel thickness shows potential for rapid evolutionary tracking of dietary shifts.

Conclusions:

• Additive gene effects provide a mechanism for rapid adaptation of enamel thickness to dietary changes.
• The high heritability of enamel thickness suggests potential for homoplasy in fossil analyses.
• This study establishes a foundation for exploring enamel thickness evolution in the papionin fossil record.