Variation in hominoid molar enamel thickness

Area of Science:

• Paleoanthropology
• Primate dental morphology
• Hominid evolution

Background:

• Enamel thickness is a key trait in hominid origins research.
• Intra-taxon variation in molar enamel thickness remains poorly understood.
• Previous suggestions of posterior molar enamel thickness increase lack rigorous statistical testing.

Purpose of the Study:

• To statistically test posterior trends in enamel thickness variables across molar rows in African apes (Pan) and orangutans (Pongo).
• To investigate variations in enamel thickness between maxillary and mandibular molars.
• To examine differences between mesial and distal cusp sections.

Main Methods:

• Quantified enamel cap area, dentine area, and enamel-dentine junction length in molar sections.
• Calculated average enamel thickness (AET) and relative enamel thickness (RET).
• Tested posterior trends and differences between tooth types and section planes using statistical methods.

Main Results:

• Enamel cap area generally increased posteriorly in mesial sections for both genera.
• Distal sections of maxillary teeth showed decreasing dentine area, potentially due to hypocone reduction.
• Average and relative enamel thickness significantly increased posteriorly in most comparisons, with exceptions noted.

Conclusions:

• Enamel thickness variation is influenced by molar position, tooth type, and section plane.
• Lumping diverse molar types exaggerates variability, hindering taxonomic discrimination.
• Accurate analysis requires considering tooth type and section plane for reliable enamel thickness studies.