Exploring artificial cranial deformation using elliptic Fourier analysis of procrustes aligned outlines

Abstract

The anatomical effects of artificial cranial deformation on the face and the base have been subject to various metric approaches, including standard linear as well as finite element techniques, and have produced controversial results (Antón [1989] Am. J. Phys. Anthropol. 79:253-267; Kohn et al. [1993] Am. J. Phys. Anthropol. 90:147-158). It can be argued that diverging observations partly result from methodological constraints. The present study compares samples of intentionally deformed and undeformed human crania, using elliptic Fourier analysis (EFA), a morphometric approach which has been shown to be particularly appropriate for characterizing the shape of two-dimensional outlines and associated shape changes. We improve the standard EFA approach by adding a preliminary orientation of the outlines following the rotation parameters of a Procrustes superimposition, using multiple homologous landmarks called control points. The results confirm that circumferentially deformed skulls exhibit modifications of the basioccipital region, together with increased anterior and inferior facial projection. However, the degree to which basioccipital flattening is modified in circumferentially deformed Peruvians was found to be less marked than changes observed in the face. Some of the modifications observed here can be related to morphological trends existing in the population from which our sample was taken. The observation of other modifications may be subject to methodological constraints of standard morphometric approaches.

Identifying artificially deformed crania

“…Based on previous work (cf. Friess & Baylac, 2003), it was expected that variation between deformed and undeformed crania would be continuous and gradual. Therefore, in order to assist in categorisation, the sample was physically seriated on a two-dimensional grid that had been laid out upon several large laboratory tables.…”

Deformaciones artificiales de la bóveda del cráneo en el delta del Paraná y cauce inferior del río Uruguay

“…doi:10.17139/raab.2018.0020.02.04 La deformación artificial de la bóveda del cráneo es un fenómeno de dispersión mundial y que, particularmente en América, se ha encontrado en frecuencias muy altas durante la prehistoria, transformándose en objeto de interés por parte de la antropología biológica desde sus orígenes (Dembo e Imbelloni, 1938;Imbelloni, 1933;Moreno, 1882). Esta práctica es entendida como la alteración deliberada de la forma de cráneo, mediante el uso de fuerzas mecánicas externas, que influyen en el normal crecimiento y desarrollo de los huesos craneales durante la infancia (Buikstra y Ubelaker, 1994;Dembo y Imbelloni, 1938;Ubelaker, 1984 Desde fines del siglo XIX el estudio de las modificaciones artificiales de la bóveda del crá-neo, ha sido abordado para desarrollar diferentes aspectos tales como, el reconocimiento de la influencia de este fenómeno en la variación fenotípica craneofacial Cocilovo, Varela y O'Brien, 2010;Del Papa y Perez, 2007;Dembo y Imbelloni, 1938;Imbelloni, 1924Imbelloni, -1925Perez, 2006), el estudio de los efectos de la deformación craneal de la bóveda sobre el crecimiento y desarrollo craneofacial (Frieß y Baylac, 2003;Richtsmeier, Cheverud y Buikstra, 1984), como así también los estudios referidos a la clasificación de las deformaciones craneales (Broca, 1879;Dembo y Imbelloni, 1938;Imbelloni, 1924Imbelloni, -1925Virchow, 1892).…”

Novelty and “Homology-free” Morphometrics: What’s in a Name?

“…If only a reduced number of harmonics are included to achieve a smoothing of the contour, this relationship is no longer a simple identity, although it remains as a background in the analysis (the smoothing does not alter the fundamental nature of the data). Assumptions about correspondence also ''creep in'' through the standardization for the size and orientation of the outline using the bestfitting ellipse (Ferson et al 1985) or through alignment by specific landmarks (e.g., Frieß and Baylac 2003). Analyses of three-dimensional surfaces by methods related to Fourier analysis (McPeek et al 2008) or by entirely different methods (Plyusnin et al 2008) also include steps for alignment and standardization that make implicit assumptions about homologies of the structure.…”