Semester of Graduation
Master of Arts (MA)
Department of Geography & Anthropology
Certain cranial morphologies referred to here as “cranial predictor features” are known to allometrically scale with body mass at statistically significant levels. Brain size likewise is known to scale with body mass, with brain-to-body-mass ratio being expressed numerically via the encephalization quotient. The study at hand aims to demonstrate whether brain size via its skeletal proxy of cranial capacity also scales with cranial predictor features. Correlation analysis was employed on two samples of contemporary male and female modern humans, respectively, in order to determine the statistical significance and degree of association between cranial predictor features and cranial capacity, as well between cranial predictor features and those cranial vault dimensions used to biometrically estimate cranial capacity. Supplementary statistical testing with respect to the significances of sexually dimorphic differences between cranial predictor features was also conducted. The results indicate a general lack of significant scaling relationships with respect to estimated cranial capacity as well as cranial vault dimensions for the majority of cranial predictor features. Those cranial predictor features that exhibited a significant scaling relationship with cranial capacity did so at weak to moderate levels only. The association between cranial capacity and the cranial vault dimensions from which it is estimated is inferred to have contributed to the nature of scaling relationships between cranial predictor features and cranial capacity, with additional non-allometric evolutionary selective pressures also having played a role. The suitability of certain cranial predictor features to accurately estimate brain size – and by inference, intelligence – therefore cannot be established with strong confidence.
Jesch, Jacob, "Scaling Relationships Between Cranial Morphological Features and Cranial Capacity in Modern Humans" (2017). LSU Master's Theses. 4356.