Structural effects of variation in the human clavicle
Résumé
Objectives: Purported evolutionary shifts in shoulder structure have been linked to changes in
hominin behavior and adaptation. Researchers use clavicle morphology to infer these shifts.
However, there is a lack of empirical data underlying such predictive relationships. This study
investigates how clavicle morphology affects articulated shoulder girdle and upper thorax configuration
in humans.
Materials and Methods: Landmarks and scalar measurements on the clavicle, scapula, and ribs
1–3 were collected from three-dimensional computed tomographic scans of living humans.
Covariation between disarticulated and articulated morphology was assessed using partial least
squares and regression analyses.
Results: We found support for hypotheses linking combined dimensions of the clavicle, ribs, and
scapula to resting protraction. Individuals with relatively short clavicles tend to exhibit protracted
and elevated resting positions of the scapula. It is more difficult to predict superoinferior
configuration, which is only minimally affected by clavicle curvature. Instead, the superoinferior
position of the scapula on the thorax is governed equally by clavicle orientation and rib declination.
Shoulder breadth is determined primarily by clavicle length, but orientation has a comparable
effect. Therefore, reliable reconstructions of shoulder breadth can be established using
clavicle length, together with consideration of orientation. Relationships between clavicle and
thorax morphology are weaker.
Discussion: Understanding the determinants of variation in human shoulder structure informs
interpretation of skeletal remains. Our investigations describe how important aspects of shoulder
structure can be inferred from disarticulated clavicles and we provide the attendant predictive
equations. Future work on interspecific variation will improve skeletal reconstruction for
more ancient hominins.
Domaines
Anthropologie biologique
Origine : Fichiers produits par l'(les) auteur(s)