Geometric Morphometrics

The study of form may be descriptive merely, or it may become analytical. We begin by describing the shape of an object in the simple words of common speech: we end by defining it in the precise language of mathematics; and the one method tends to follow the other in strict scientific order and historical continuity.  — D’Arcy Wentworth Thompson (1915)

My work with geometric morphometrics (GM) is currently focused upon the morphological variation of lithics and ceramics, where those attributes associated with shape, size, allometry, and asymmetry for specific types (designs) are being further scrutinized. The goal of this work is to identify and expound upon the morphological traits, while also working to identify potential morphological transitions.

R Graphics Output
A sample of Caddo bottle shapes from the Webb collection; the five ceramic types are denoted by different colors.

While I plan to couch the ceramic results in terms of practice theory, other theoretical approaches also have utility here. Evolutionary theory is a favorite of GM practitioners in archaeology, but craft specialization also provides a useful means of explaining how the results articulate with current (and new) interpretations. Additionally, there are some art-historical approaches that are useful. One example is the work of George Kubler (The Shape of Time), where the designs (types) and shapes (forms) of ceramics might be explored as two discrete components (adherent and autogenous signals) of design.

In addition to my work with ceramics, I am also exploring fluctuations in lithic (stone tool) morphology. My current project is focused upon the morphological variability that occurs in Gahagan bifaces. While more work is needed to expound upon these results, those bifaces from the Mounds Plantation site differ significantly in morphology, flaking technique, and–potentially–raw material.

Comparison of mean consensus configurations between (a) Mounds Plantation and Gahagan Mound, (b) Mounds Plantation and George C. Davis, and (c) Gahagan and George C. Davis.

Should it prove possible to identify a morphological transition, 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 communities of practice, craft specialization, 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 design, and by adding related qualitative measures to our results we might just have the potential to bolster evidence for human behaviors associated with the design, production, and use of artifacts.

Initially a development in the biological sciences, the study of geometric morphometrics in archaeology will no doubt include some interesting discussions regarding the various analytical and theoretical underpinnings 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 upon the preliminary results, the capacity for geometric morphometrics to inform upon issues related to material culture and cultural systems could be enormous.


robert z selden jr, archaeology, archeology, geometric morphometric, ceramic, analysis, mathematics, statistics, 3d, 3d scan

Geometric Morphometrics – Ceramics

My most recent work, and latest obsession, has focused upon the geometric morphometric analysis of Caddo bottles. The vagaries associated with the analysis of ceramic vessel shapes have long consumed analysts, and rigorous statistical analyses of Caddo vessel shapes have been a topic of considerable interest for some time.

Geometric Morphometrics – Lithics

Similar to our efforts with ceramics, we are hoping to capitalize on both 2D and 3D data from across the East Texas region (prior to synthesizing these data in a larger network analysis), since there is a veritable wealth of readily accessible data available in the published–and gray–literature.

robert z selden jr, archaeology, archeology, geometric morphometric, ceramic, analysis, mathematics, statistics, 3d, 3d scan

Geometric Morphometrics–Citation Networks

Literature and material culture represent the primary sources employed in archaeological inquiry. Our goal in constructing the citation network for geometric morphometric studies in archaeology has been both exploratory and epistemological. The analysis is ongoing; however, we are making the initial iteration of the citation network available below as a means of soliciting additional input and sources from our colleagues.