A metric study of three types of artificial cranial modification from north‐central Peru

Abstract

Artificial cranial modification (ACM) involves the alteration of cranial vault shape by cultural means, and is performed during infancy while the cranial bones remain soft and malleable. The direction of normal cranial growth is altered through the application of external forces. In this study, three types of ACM from north-central Peru (posterior flattening, bilobed and circumferential) were analysed using standard craniometric techniques. The aim was to determine the effects of these forms of ACM on craniofacial morphology, and the extent to which different types of ACM could be distinguished from one another and unmodified crania on the basis of these measurements. Significant differences between artificially modified and unmodified crania, and between different types of ACM, were demonstrated in cranial vault shape for all types. Significant differences in facial morphology were found only in the bilobed group compared with the unmodified crania. Canonical variates analysis (discriminant analysis) confirmed that major differences between modification types and unmodified crania were in measurements and angles of the cranial vault. While the results show some similarities to previous studies, they add to the variability in the patterns and extent of differences documented to date. It is suggested, based on these results and visual observations, that interpopulation variation in ACM within major modification categories may explain some of the variability in results between studies, an explanation which has previously received insufficient recognition but which remains to be tested since varied methodology between studies may also be a contributory factor. While previous studies have often sought to generalise about the effects of ACM, the examination of the differences between populations even within major ACM categories may offer new insight into cultural variation in modification techniques between populations and the nature of craniofacial development.

Estimation of stature and body mass from the skeleton among coastal and mid‐altitude andean populations

“…ACM was classified based on modification technique and vault angle as: unmodified; tabular erect; tabular oblique; or circumferential; following Dembo and Imbelloni (1938). Although masking some variation in vault form (Pomeroy et al, 2010;Torres-Rouff, 2008), this scheme is useful and widely applied in the Andes for documenting the predominant characteristics of modified crania.…”

“…An additional problem encountered in applying the revised Fully method to Andean samples is the widespread practice of artificial cranial modification (ACM) in the past (e.g., Dembo and Imbelloni, 1938;Hoshower et al, 1995;Perez, 2007;Pomeroy et al, 2010;Torres-Rouff, 2008;Weiss, 1961). If ACM increases cranial vault height, this would inflate stature estimates using the revised Fully method relative to predicted statures from regression-based methods, as the latter may not sufficiently account for outlying individuals who have modified crania.…”

“…If ACM increases cranial vault height, this would inflate stature estimates using the revised Fully method relative to predicted statures from regression-based methods, as the latter may not sufficiently account for outlying individuals who have modified crania. Previous studies have indicated that ACM can affect cranial vault and facial dimensions (Antón, 1989;Blackwood and Danby, 1955;Brown, 1981;Cheverud et al, 1992;Cocilovo et al, 2011;Kohn et al, 1993;Perez, 2007;Pomeroy et al, 2010;Rhode and Arriaza, 2006) so a preliminary evaluation of the effect of ACM on BBH was necessary.…”

The Bioarchaeology of Artificial Cranial Modifications

“…To this end, cranial landmarks are commonly recorded and now digitalized prior to statistic processing (Barrientos and L'Heureux 2009; Béguelin et al 2006;Clark et al 2007;Gómez-Valdés et al 2007;Manríquez et al 1884;Pomeroy et al 2010;. Most of these measurements, which are recorded using 3D digitizers, craniophores and/or callipers, are designed to distinguish presence from absence of cultural flattening and to differentiate general head types.…”

“…Recent approaches have also successfully used multivariate calculations of cranial landmarks and distance measurements to evaluate either continuous change in skull form or to examine and compare the morphological features of previously assigned modeling types in subscribed areas in Mesoamerica and South America (Gómez-Valdés et al 2007;Pomeroy et al 2010;. Also on a more general level the sophisticated digital measure meuts of coordinates, angles and cords, aligned according to the culturally flattened areas of the cranium, offer useful objective tools to distinguish the vault's shifts, bulges and reductions, reclination and heightening (see Fig.…”