Integrating whole-bone and regional analyses to understand human scapular growth

Area of Science:

• Human anatomy and developmental biology
• Bioarchaeology and paleoanthropology
• Biomechanics and morphology

Background:

• Understanding human scapular morphology development is crucial for fields like forensics and clinical studies.
• Previous research often focused on global shape changes, potentially overlooking regional developmental differences.

Purpose of the Study:

• To investigate ontogenetic changes in human scapular morphology using 3D geometric morphometrics.
• To determine if the scapula follows a regular developmental pattern and if its components (scapular spine and glenoid fossa) show divergent growth.
• To explore the influence of size, biomechanics, and ossification timing on scapular development.

Main Methods:

• Analysis of 3D surface scans from 127 human scapulae across seven ontogenetic groups.
• Application of Generalized Procrustes Analysis and Principal Component Analysis on whole-bone and region-specific landmark data.
• Examination of shape and form variation in the entire scapula, scapular spine, and glenoid fossa.

Main Results:

• Principal Component 1 captured the primary axis of ontogenetic variation, separating age groups effectively.
• Whole-scapula analysis indicated a gradual developmental pattern, while regional analyses revealed distinct growth trajectories.
• The scapular spine showed progressive curvature and torsion, whereas the glenoid fossa had more constrained changes.

Conclusions:

• Scapular growth appears modular, with distinct regions responding to intrinsic and extrinsic factors like biomechanics and ossification timing.
• Integrating regional and whole-bone analyses reveals developmental plasticity missed by global approaches.
• Findings have implications for forensic, clinical, paleoanthropological, and bioarchaeological research.