Molar crenulation trait definition and variation in modern human populations

Area of Science:

• Biological anthropology
• Human evolution
• Dental morphology

Background:

• Molar crenulations are utilized in biological anthropology but lack formal definition and population frequency data.
• Understanding trait variation is crucial for anthropological studies.

Purpose of the Study:

• To formally define molar crenulations.
• To outline population frequencies of molar crenulations in a large, diverse sample.
• To analyze statistical differences and correlations of this trait across populations.

Main Methods:

• Formal definition and creation of a rank-scale for molar crenulations.
• Data collection on maxillary and mandibular molars from 750 individuals across South African, Hispanic, Japanese, American White, and American Black populations.
• Statistical analyses including chi-squared tests, correspondence analysis, and trait correlations.

Main Results:

• Significant population-level differences in molar crenulation frequencies were observed across all molars.
• American White and Japanese samples exhibited lower frequencies, while American Black and South African samples showed higher frequencies; Hispanic samples were intermediate.
• Correspondence analysis indicated distinct clustering of populations based on crenulation grades, with minimal sexual dimorphism.

Conclusions:

• Population-specific differences in molar crenulations exist, likely influenced by evolutionary factors.
• Molar crenulations can be incorporated as a valuable trait for studying human population variation.
• The formal definition and frequency data provide a foundation for future anthropological research.