A new method to pair-match metacarpals using bilateral asymmetry and shape analysis

Area of Science:

• Forensic Anthropology
• Bioarchaeology
• Geometric Morphometrics

Background:

• Accurate skeletal element pairing is crucial for re-associating individuals from commingled remains.
• Traditional methods rely on size measurements, which can be insufficient for precise identification.
• Understanding individual shape variation is key to improving skeletal analysis.

Purpose of the Study:

• To develop and test a novel method for pairing skeletal elements using both size and shape data.
• To evaluate the hypothesis that intra-individual shape asymmetry is less than inter-individual shape variation.
• To assess the efficacy of geometric morphometrics in forensic anthropology for bone identification.

Main Methods:

• Collected anthropometric size measurements (maximum length) of 111 metacarpals.
• Quantified absolute mean asymmetry between right and left metacarpals.
• Utilized 2D landmark data from digital images, analyzed with generalized Procrustes analysis and multivariate statistics.

Main Results:

• The combined method of size and shape analysis achieved 100% accuracy in pair-matching metacarpals.
• Shape analysis via geometric morphometrics proved effective in differentiating individual skeletal elements.
• Intra-individual asymmetry was found to be smaller than inter-individual shape differences.

Conclusions:

• Integrating geometric morphometrics with traditional measurements significantly enhances the accuracy of skeletal element pairing.
• This combined approach offers a powerful tool for forensic anthropology and bioarchaeological research.
• The method demonstrates high utility for assessing shape similarities and differences between individuals.