Some Applications of Geometric Morphometrics to Archaeology (original) (raw)
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We present here a newly developed software package named Artifact GeoMorph Toolbox 3-D (AGMT3-D). It is intended to provide archaeologists with a simple and easy-to-use tool for performing 3-D landmarks-based geometric morphometric shape analysis on 3-D digital models of archaeological artifacts. It requires no prior knowledge of programming or proficiency in statistics. AGMT3-D consists of a data-acquisition procedure for automatically positioning 3-D models in space and fitting them with grids of 3-D semi-landmarks. It also provides a number of analytical tools and procedures that allow the processing and statistical analysis of the data, including generalized Procrustes analysis, principal component analysis, a warp tool, automatic calculation of shape variabilities and statistical tests. It provides an output of quantitative, objective and reproducible results in numerical, textual and graphic formats. These can be used to answer archaeologically significant questions relating to morphologies and morphological variabilities in artifact assemblages. Following the presentation of the software and its functions, we apply it to a case study addressing the effects of different types of raw material on the morphologies and morphological variabilities present in an experimentally produced Acheulian handaxe assemblage. The results show that there are statistically significant differences between the mean shapes and shape variabilities of handaxes produced on flint and those produced on basalt. With AGMT3-D, users can analyze artifact assemblages and address questions that are deducible from the morphologies and morphological variabilities of material culture assemblages. These questions can relate to issues of, among others, relative chronology, cultural affinities, tool function and production technology. AGMT3-D is aimed at making 3-D landmarks-based geometric morphometric shape analysis more accessible to archaeologists, in the hope that this method will become a tool commonly used by archaeologists.
Curvature-Based Method for Morphometric Analysis of Archaeological Shapes
This contribution will look at a particularly effective method of curvature-based analysis of two-dimensional outlines. See Kampel and Zambanini (Chapter 5, this volume), who introduce the general idea of curvature-based analysis. I apply this method to examine global and localized differences in the endocranial outline of a small sample of fossil hominins and modern humans. Other archaeological applications of this curvature-based method include the shape analysis and classification of artifacts with smooth outlines, such as groundstone and shell preciosities. For example, the curvature of points along two-dimensional outlines of artifacts could be used as a multivariate raw data set for a classification analysis based on shape, which I will present in a future paper. Please note that I should have mentioned in this chapter that Dr. Dwight Read (UCLA) directed me to the transformation of the elliptical Fourier function to a curvature function, which he had discussed in his 1997 book chapter, please see: Read, D.W. 1997. Growth and form revisited. pp. 45–73. In: P.E. Lestrel (ed.). Fourier Descriptors and their Applications in Biology. Cambridge University Press, New York, New York.
Evaluating morphological variability in lithic assemblages using 3D models of stone artifacts
Technological and morphological variability in lithic artifacts is commonly used to identify taxonomic entities in Paleolithic research contexts. Assemblages are mainly studied using either linear distance measurements or qualitative assessments of morphologies. Here, we present a method to quantify morphological variability in lithic artifacts using 3D models of stone artifacts. Our study on the sequence of the Upper Paleolithic layers VeI from the site Yabroud II in western Syria, demonstrates that utilizing 3D models provides a new insight into the variability of lithic technologies. We use quantitative data on convexities, twist and scar patterns on cores and blades, attributes previously not readily quantifiable, to trace technological change through the archaeological sequence. We are able to identify differences and translate these findings into a grouping of the layers. While layers VIeII are characterized by technological continuity and were grouped together, layers V and I can be separated from this group and represent technologically different groups chronologically before and after. Our results demonstrate the potential of 3D models for studying morphological variability in lithic assemblages.
Journal of Archaeological Method and Theory, 2024
One of the main objectives of Palaeolithic art researchers is to study and systema- tise the form of artistic representations. Some methodologies include the analysis of qualitative variables, linear measurements or the use of geometric morphometry with landmarks. However, these techniques depend to a large extent on the subjec- tivity of the researcher, which often leads to biased results. To overcome this issue, we present an application of geometric morphometry using Elliptic Fourier Analysis (EFA), together with multivariate statistics and hypothesis testing, for the first time to the study of form in prehistoric art. In order to explain its use, the “duck-bill” convention of pre-Magdalenian horses, often used as a chronological and geographi- cal marker, has been used as a case study. This formalism is described disparately in the literature, so the main objective is to use EFA to determine whether it is pos- sible to characterise this type of convention according to the definitions given by certain authors. The results indicate a possible classification of the heads of these animals. Through this taxonomic proposal, it has been possible to verify the great diversity of forms in which the authors classify the duck-bill horses and, therefore, to demonstrate that this peculiar form can be considered neither a conventionalism nor a chronological/regional marker. In conclusion, the methodology based on EFA combined with multivariate statistics for the objective study of form in prehistoric art is effective and opens a new avenue of analysis in the art of prehistoric societies.
Curvature-Based Method for the Morphometric Analysis of Archaeological Shapes
This contribution will look at a particularly effective method of curvature-based analysis of two-dimensional outlines. See Kampel and Zambanini (Chapter 5, this volume), who introduce the general idea of curvature-based analysis. I apply this method to examine global and localized differences in the endocranial outline of a small sample of fossil hominins and modern humans. A previous morphometric study (Bookstein et al. 1999), which used procrustes analysis of semi-landmarks, compared the endocranial outlines of 21 fossil hominins and modern humans provided a surprising result. Specifically, that the shape of the mid-sagittal endocranial frontal bone profile of the fossil and modern humans was very similar. The fossil hominin sample used in the Bookstein et al. study consisted of three Homo heidelbergensis (Bodo, Kabwe, and Petralona), the Spanish Atapuerca SH5 cranium (possibly proto-Neanderthal), and a “classic” Homo neanderthalensis skull, Guattari I.
Analytical potential of 2D shape analysis to study Epigravettian lithic assemblages
Proceedings of the 2022 IMEKO TC4 International Conference on Metrology for Archaeology and Cultural Heritage
In this paper we apply for the first time a 2D shape analysis to a sample of Epigravettian lithic artefacts with the aim of evaluating the potential of such approach. The lithic sample comes from layer 9c2 (Evolved Epigravettian, Upper Palaeolithic) of Grotta Paglicci (Apulia, southern Italy). After extracting the outline coordinates from highresolution images using the software DiaOutline, we conduct Elliptic Fourier Analysis, Principal Component Analysis, and Linear Discriminant Analysis in the R package Momocs to investigate the internal variability of the sample. The results of the analysis are extremely promising and highlight significant separation between common tools, laminar blanks, and backed tools. Furthermore, this analysis can be useful to evaluate the technical investment in the retouching of the blanks to manufacture backed points.
Advances in Morphometrics in Archaeobotany
Environmental Archaeology
Morphometric analysis offers an alternative or augmentation to traditional archaeobotanical methods to address differences within and between plant species and their remains, refining and enhancing taxonomic resolution. Morphometrics, the measurement of size and shape, and the multivariate statistical analysis of generated quantitative variables, have long played a major role in biological research, including plant taxonomy and systematics, although its application in archaeobotany is relatively recent. Over the last few decades there has been an increasing interest in the use of morphometrics for analysing a varied range of archaeological plant materials (mainly seeds, pollen, phytoliths, and starch grains). In particular, morphometrics have contributed to the study of the domestication and spread of many cereals worldwide , as well as that of other taxa including legumes, underground storage organs (USO), and fruits (such as olives, grapes, and dates). This paper reviews current methodologies, recent applications, and advances in the use of morphometrics in archaeobotanical research, discusses its role in exploring major research questions, and suggests possible future directions for its use.
Journal of archaeological science: Reports, 2024
In Uruguay, Geometric morphometrics (GM) studies in archeology have been exclusively applied to “Fishtail” projectile points. The variability observed in this morphotype is attributed to the modifications due to diverse events such as resharpening or reworked during the history life. In this work, we aim to expand the recognition of the morphological variability of the archaeological lithic projectile point with stem from Uruguay, advance on the functional aspects of these projectiles, and discuss their link with the weapons systems that were used by the indigenous populations of the region. Through optical magnification and non-parametric statistical analysis, we characterize the allometric variation of n = 84 lithic projectile points. To gain independence from the ontogenetic changes, we selected 36 basic designs and analyzed their morphological variation GM. Based on their weight, we were allowed to assign them to the arrow, dart, and spear categories. The principal components analysis and partial least squares showed that shape changes are associated with the blade-stem relationship, which is proportionality 1:1 and 2:1 in negative values and > 2.5:1 and > 3:1 in the positive values. Arrows and darts share the 1:1 and 2:1 relationship morphospaces of this structure. Darts and spears share the one defined by the ratio > 2,5:1 and, finally, the morphospace defined by the ratio > 3:1 was exclusively integrated for spears. The standardization of proportionalities found in this contribution crosses morphological variability and allows us to discuss the versatility of designs and the complementarity between weapon systems.
GLIMR: A GIS-BASED METHOD FOR THE GEOMETRIC MORPHOMETRIC ANALYSIS OF ARTIFACTS
Lithic Technology, 2015
Archaeology's participation in the digital renaissance of the twenty-first century requires adequate operationalization of technological methods, such as three-dimensional scanning. Here, we describe and demonstrate a geographic information systems-based lithic morphometric research (GLiMR) software approach. GLiMR accurately and rapidly handles a sequence of ArcGIS procedures to extract geometric morphometric data from D and D scan files that are impractical to record by hand, opening new doors to the analysis of lithic artifacts. GLiMR generates three main types of geometric properties: shape data, topographic data, and domain aggregate data. These data can be extracted in ways that support other analyses of artifact form, including generalized Procrustes analysis, principal components analysis, and cluster analyses. We illustrate the use of GLiMR by presenting a basic case study that compares the geometric morphometry of Western Stemmed Tradition projectile points found in two cache features at Idaho's Cooper's Ferry site and from other sites in the Columbia River Plateau region of the Pacific Northwest. Cluster analyses of the generalized Procrustes analysis of D landmarks from Cooper's Ferry cache points fail to separate the two caches from one another on the basis of their geometric morphometric attributes. We interpret these results to suggest that these stemmed projectile points were probably created by persons who shared a specific set of technological production guidelines for the manufacture of Western Stemmed Tradition projectile points. Cluster analyses indicate that Cooper's Ferry Western Stemmed Tradition projectile points can be morphometrically separated from stemmed points found at other regional sites; however, significant overlaps were seen among stemmed projectile points from the Pilcher Creek site, which may suggest the existence of contemporaneous information sharing networks or macroband territorial movements.