Artificial cranial deformation among Native American population according to metric and 2D coordinate data

This study examines the shape variability of artificially deformed crania using standard craniometric protocol and 2D coordinate data, and compares the effectiveness of these approaches. The analysis encompasses samples representing Native American populations, comprised of fronto-occipitally deformed crania. Procrustes coordinates were subjected to principal component analysis (PCA) and canonical discriminant analysis (CDA); metric data were subjected to the latter only, with the sample reduction to the three most numerous series: Peru, Cuba, and the Southwestern United States. The results of PCA demonstrated that the cranial shape in the lateral norm in the pooled sample exhibits variation from fronto-occipital erect (tabular erecta, predominantly in the US sample) to fronto-occipital oblique (tabular oblicua, predominantly in the Cuban sample). Crania from Peru and Florida occupy an intermediate position along this gradient. The degree of parietal flattening differs between groups regardless of the type of deformation. The CDA of the coordinate data revealed that the centroids of the Cuban and the US samples are the most distant from each other and exhibit the most pronounced differences in the frontal and occipital regions. In contrast, the Peruvian sample displays a greater variability with some individuals exhibiting shapes more similar to those observed in the Cuban or US variants. The metric data, despite the reduction in accuracy at the posterior classification of cases, enable the effective delineation of groups through the application of a mere two indices: the height-length index and the frontal bone curvature index. The suitability of an approach depends on the specific objectives of the study and the available data.