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Integrative Approaches to Dental Wear: Non-Masticatory Tooth-Use Across the Mesolithic-Neolithic Transition Among Iberian Foraging and Farming Societies

Periodic Reporting for period 1 - IDENTITIES (Integrative Approaches to Dental Wear: Non-Masticatory Tooth-Use Across the Mesolithic-Neolithic Transition Among Iberian Foraging and Farming Societies)

Reporting period: 2017-10-01 to 2019-09-30

During the IDENTITIES project, our research team investigated human dental wear related to the habitual use of teeth for non-dietary behaviors – what is often referred to as using the “teeth-as-tools” – among prehistoric peoples from the Iberian Peninsula. A lifetime of using one’s teeth for manipulative tasks leaves distinct wear traces on their surfaces, and these distinct patterns of wear can be used to interpret what types of behaviors prehistoric peoples engaged in. The information on behavior that is interpreted through dental wear informs us about the social identities of the individuals we studied when we consider additional factors like sex, age, occupation, or status of individuals. The archaeological human remains studied in the IDENTITIES Project were from sites located in the Iberian Peninsula. The chronological coverage included Mesolithic hunting and gathering peoples, Neolithic food producing peoples that relied on domesticated plants and animals, and later Chalcolithic and Bronze Age peoples that exhibit archaeological evidence for greater specialization in craftwork and food production. The wide range of social, economic, and technological practices these groups engaged in provided ideal case studies for examining variation in tooth-using behaviors and social identities in the prehistoric peoples of the Iberian Peninsula.

While a primary objective of the project was to use dental wear as a proxy for exploring the habitual behaviors and social identities of prehistoric peoples from the Iberian Peninsula, another objective was to advance the methodologies used to study dental wear. To accomplish this, we took an interdisciplinary approach that brought together experts in microscopy, experimental methods, bioarchaeology, prehistoric archaeology, and paleoanthropology. We used a variety of methodologies that allowed us to examine dental wear from macroscopic and microscopic perspectives as well as in two- and three-dimensions. Our integrative methodology allowed us to refine interpretations of dental wear signals obtained using specific technology, but also allowed us to suggest alternative methods when specific technologies are not available to all researchers. Thus, the IDENTITIES Project not only provided new insights into prehistoric human behavior that are of general interest to the public, but also provided specific suggestions for how meaningful results can be obtained when specific equipment is unavailable.
Numerous datasets were collected and analyzed to address our research objectives. We created 3D models with surface scanners and employed confocal microscopy for dental microwear texture analysis. However, we also used more traditional methods like macrophotography, optical light microscopy, and scanning electron microscopy to assess dental wear patterns.

One reason for applying such a diverse array of methodologies, is that a single method may not provide conclusive results, or the application of more than one method could provide a more detailed interpretation of prehistoric human behaviors (Lozano et al, in review; Willman et al, in review). Another reason to use “traditional” methods alongside “state-of the-art” 3D scanning and confocal microscopy is because the equipment and software associated with these latter methodologies is prohibitively expensive for many researchers and institutions. Thus, using multiple methodologies on the same dataset not only refines interpretations, but also allows one to see what information is potentially lost, gained, or complimentary between studies using different methodologies.

We also explored the utility of Gigapixel-like images for didactic and training purposes. These images are created by focus-stacking and merging of adjacent images into a larger photomosaic. The result of the method is a high-resolution image that observers can “pan and zoom” across to view detailed surfaces.

Our detailed, integrative analyses also revealed interesting findings in our samples. For instance, Chalcolithic human teeth from El Mirador Cave presented cases of dental erosion – chemically-induced wear – which is rarely documented in prehistoric populations, and largely thought to be a contemporary oral health concern. In another case, we found a female-specific pattern of dental wear in a Bronze Age population from southeastern Spain that revealed new insights into divisions of labor related to craft work in this Bronze Age context.

IDENTITIES Project research was presented at several conferences (Willman et al, 2018; Lozano et al, 2019a, b), and two articles are currently in review (Lozano et al, in review; Willman et al, in review). The project has also been promoted through social media, personal and institutional websites, public outreach events, and European Researcher’s Night.

References:
Lozano M, Jiménez-Brobeil S, Willman JC, Sánchez-Barba, LP, Molina D, Rubio A. (in review) Argaric craftswomen: sex-based division of labor in the Bronze Age southeastern Iberia.

Lozano M, Willman JC, Gamarra B, Ceperuelo D, Hernando R. (2019a) Novedades en el estudio de los restos dentales de El Mirador. Pastores y Agricultores de la Prehistoria. Una Mirada Transdisciplinar al Registro Arqueológico de El Mirador (Atapuerca, Burgos). Reunión Científica. IPHES, Tarragona, Spain.

Lozano M, Willman JC, Hernando R, Ceperuelo D. (2019b) Microscopic and virtual approaches to oral pathology: a case study from El Mirador Cave (Sierra de Atapuerca, Spain). 25th Annual Meeting of the European Association of Archaeologists, Bern, Switzerland.

Willman JC, Romero A, Subirà MaE, Lozano M. (2018) Non-alimentary tooth use in European Prehistory. XVIIe Congrès Mondial UISPP – Paris, France.

Willman JC, Lozano M, Hernando R, Vergès JM. (in review) Gigapixel-like imaging strategies for dental anthropology: Applications for scientific communication and training in digital image analysis.
Our initial findings show that an integrative approach to the study of non-dietary dental wear can yield more conclusive results for the reconstruction of prehistoric human behaviors than single-method approaches. Indeed, in some cases – such as identifying prehistoric dental erosion – the combination of optical light microscopy and scanning electron (or confocal) microscopy provides a more conclusive interpretation of specific features. The interdisciplinary aspects of the IDENTITIES Project were key factors contributing to this conclusion, since our collaborators have developed similar integrative methodologies to assess material surface modification in other archaeological materials (e.g. bone, shell, lithics). Therefore, this project shows the strength of interdisciplinary communication and collaboration for the analysis of both the human remains and the artifacts recovered from archaeological contexts.

Our public outreach initiatives were successful in part through the public’s inherent fascination with archaeology and our portrayal of detailed reconstructions of prehistoric social lives. The careful analysis of human remains can yield an astonishing level of detail about the social identities of past peoples, but the results are often best communicated through images. The imaging techniques explored in the IDENTITIES Project highlight the utility of many of these approaches for the communication of scientific results to both academic and public audiences.
"An example of a gigapixel-like image. Note the large groove caused by using the ""teeth-as-tools"""