Mandibular ramus flexure and gonial eversion as morphologic indicators of sex

Area of Science:

• Forensic Anthropology
• Human Osteology
• Bioarchaeology

Background:

• Mandibular traits, specifically ramus flexure and gonial eversion, are increasingly utilized for sex estimation in forensic and archaeological contexts.
• Previous studies suggest these traits hold potential as independent indicators of biological sex.

Purpose of the Study:

• To evaluate the reliability and repeatability of ramus flexure and gonial eversion as sole sex indicators.
• To investigate the influence of confounding factors such as age and post-tooth loss remodeling on the accuracy of these traits.

Main Methods:

• Analysis of two distinct skeletal samples: a forensic (N=153) and an archaeological (N=80) collection.
• Forensic sample assessed by one observer; archaeological sample scored by three independent observers.
• Assessment of intra- and inter-observer error and accuracy rates for each trait.

Main Results:

• Accuracy for ramus flexure was 66% (males) and 32% (females), with an overall accuracy of 59%.
• Gonial eversion showed 75.4% accuracy for males and 45.2% for females, with 69.3% overall.
• Both traits demonstrated significant reductions in accuracy with increasing age and after tooth loss, alongside notable observer bias.

Conclusions:

• Ramus flexure and gonial eversion accuracy is significantly compromised by age and tooth loss, questioning their universal applicability.
• The scoring system may introduce male bias, and both traits are susceptible to observer variability.
• While possessing some utility, these mandibular traits require cautious application due to their adaptive and functional plasticity.