3D Morphometrics of Caddo NAGPRA Vessels from the Washington Square Mound Site

Using our revised approach to the analysis of morphometrics outlined here, and employing the geomorph package in R, the collection of intact/reconstructed Caddo NAGPRA vessels from the Washington Square Mound (41NA49) site is being reanalyzed.

The Washington Square Mound vessels were used in our first attempts to discern whether it was possible to demarcate between the various vessel shapes. Having progressed substantially since that initial effort, and since we plan to include all of our 3D scans for Caddo burial vessels in the upcoming morphometric analysis of the Turner Collection, each previously analyzed collection is being reprocessed and populated with a new LM/sLM configuration.

RefGeometry_Blog

Working with a number of colleagues from Australia and Europe to further refine my methods, a configuration for a single landmark (central base), and 300 semilandmarks populated across 12 splines (see above) was defined. Once populated in Geomagic Design X, all point data were exported to a .csv file. The .csv files from all of the vessels were then imported into R, where we used the geomorph package to create sliding vectors for the semilandmarks prior to a Procrustes superimposition (GPA) (below) and an analysis of principal components.

SSP_2015_WSMProcrustesSuperimposition


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Results of Procrustes superimposition (GPA) in R.

A variety of approaches were explored with regard to sliding vectors, and we found that vectors along the splines were more true to vessel shape than surface vectors. Preliminary results of the PCA (below) highlight the variation for all intact/reconstructed vessels from the Washington Square Mound site, and further illustrate the potential for a study of ceramic morphology to discriminate between discrete vessel shapes.

WSM_PC1-2_FINAL

While the goal of the combined analysis is to–eventually–posit a hierarchically-nested method for defining a taxonomy of Caddo vessel shape/form that can easily evolve based upon the addition and incorporation of new data, it is not meant as a replacement for the current taxonomic definitions associated with decorative elements. In fact, we plan to use relative dates (see those here) associated with decorative elements to assist in parsing out some of the temporal dynamics related to Caddo vessel shape and form.

Taking this one step further, these 3D data are being modeled (at or below a 0.01mm tolerance with the 3D scan data), where each element (i.e., base, body, neck, rim, etc.) can be segregated and analyzed independently of the whole. This allows us to look at additional manufacturing and design trends concerned with specific elements in aggregate (i.e., how did bottle neck [or base, or body, or rim…] shape and form evolve through time?). The shape and form of ceramic vessels are assumed to be products of the same social parameters and craft traditions that influenced decorative elements. To what extent the attributes of ceramic shape and form may or may not correlate with elements of decoration and design is a question that was previously out of reach, but might now be considered using this systematic, and replicable, method.

Additionally, should it prove possible to identify something akin to a transitional species, that could point to several interesting social possibilities including, but not limited to, (1) identifying the locus of a specific innovation, (2) the spatial and temporal dynamics of morphological variation for specific elements (neck, body, base, etc.) of ceramic design, (3) identifying or refining social networks used by specific Caddo polities/groups during temporal periods previously defined—primarily—through design-based seriations, (4) intra/inter-polity/group variation of shape and form for ceramic design, (5) potential trade relationships based upon the presence of a specific shape/form of vessel outside of known (assumed) social boundaries, and (6) the power or influence that shifted among and between polities through time. These considerations could theoretically be couched in discussions of craft specialization, ceramic technological organization, politics, religion, and—possibly—inter/intra-polity disputes/warfare. Furthermore, this research design has the capacity to inform greatly upon the evolution of ceramic design as it relates to the shape and form of ceramic vessels, and by adding related qualitative measures to our results we might just have the potential to bolster evidence for human behaviors associated with ceramic production and use within the ancestral Caddo territory.

Initially a development in the biological sciences, the study of 3D morphometrics in archaeology will no doubt include some interesting discussions regarding the various analytical and theoretical elements that are most appropriate for a cultural system versus a biological system. There remains plenty of thinking left to do on this subject, but based on the preliminary results, the capacity for 3D geometric morphometrics to inform upon issues related to material culture and cultural systems could be enormous.

Written by zselden

Selden (PhD, Texas A&M University, 2013) is a husband, father, US Marine Corps veteran, cyclist, kayaker, backpacker, hiker, climber, fisherman and general all-around outdoor enthusiast. His research is focused at the confluence of archaeological methods and digital technology, and he is particularly interested in the application of 3D technologies to archaeological problems, geometric morphometrics, network analyses, predictive modeling, archaeological theory, and archaeological science.