Browsing by Author "Schunk, Lisa"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- An experimental approach on dynamic occlusal fingerprint analysis to simulate use-wear localisation and development on stone toolsPublication . Rausch, Hannah; Marreiros, Joao; Kullmer, Ottmar; Schunk, Lisa; Gneisinger, Walter; Calandra, IvanInformation about the use of stone tools in the past is encoded in the wear patterns left on their surface; however, post-depositional processes can modify and obstruct these traces. One aim in the field of lithic functional analysis is to develop methods to detect and quantify these traces on stone tools. The occlusal fingerprint analysis (OFA) is a well-established method in dental wear studies to virtually simulate dental occlusal (contact between teeth) stroke movements and thus locate and quantify the sequential contact between opposing tooth crowns. Reaching across disciplines, we conducted controlled experiments to test the applicability of the OFA method on stone tools to address the challenge of use-wear quantification and localisation, and therefore the identification of post-depositional wear. Our findings reveal a clear overlap between zones of experimentally produced use-wear and OFA-calculated contact areas. We demonstrate OFA as a potential method to generate models of multiscale use-wear that can be used as references on experimental tools to identify post-depositional surface modifications on stone tool artefacts.
- Back to the edge: relative coordinate system for use-wear analysisPublication . Calandra, Ivan; Schunk, Lisa; Rodriguez, Alice; Gneisinger, Walter; Pedergnana, Antonella; Paixao, Eduardo; Pereira, Telmo; Iovita, Radu; Marreiros, JoaoUse-wear studies rely heavily on experiments and reference collections to infer the function of archeological artifacts. Sequential experiments, in particular, are necessary to understand how use-wear develops. Consequently, it is crucial to analyze the same location on the tool's surface during the course of an experiment. Being able to relocate the area of interest on a sample is also essential for reproducibility in use-wear studies. However, visual relocation has limited applicability and there is currently no easy and efficient alternative. Here we propose a simple protocol to create a coordinate system directly on the sample. Three ceramic beads that serve as reference markers are adhered onto the sample, either with epoxy resin or acrylic polymer. The former is easier to work with but the latter is reversible so it can be applied to archeological samples too. The microscope's software then relocates the position(s) of interest. We demonstrate the feasibility of this approach and measure its repeatability by imaging the same position on an experimental flint blade 10 times with two confocal microscopes. Our results show that the position can be relocated automatically with a horizontal positional repeatability of approximately 14% of the field of view. Quantitative surface texture measurements according to ISO 25178 vary due to this positional inaccuracy, but it is still unknown whether this variation would mask functional differences. Although still perfectible, we argue that this protocol represents an important step toward repeatability and reproducibility in experimental archeology, especially in use-wear studies.
- Evaluating the microscopic effect of brushing stone tools as a cleaning procedurePublication . Pedergnana, Antonella; Calandra, Ivan; Bob, Konstantin; Gneisinger, Walter; Paixão, Eduardo; Schunk, Lisa; Hildebrandt, Andreas; Marreiros, JoaoCleaning stone tool surfaces is a common procedure in lithic studies. The first step widely applied at any archeological site (and/or at field laboratories) is the gross removal of sediment from the surfaces of artifacts. Lithic surface alterations due to mechanical action applied in wet or dry cleaning regimes have never been examined at a microscopic scale. This could have important implications in traceology, as any modern surface modifications inflicted on archeological artifacts might compromise their functional interpretations. The current trend toward quantification of use-wear traces makes the testing even more important, as even slight, apparently invisible surface alterations might be measured. In order to evaluate the impact of common cleaning procedures, we undertook a controlled experiment. The main aim of this experiment was to assess the effects that brushing actions applied for removing sediment particles have on flint and quartzite surfaces. All surfaces were analyzed with confocal microscopy before and after having been brushed to quantify possible changes in the micro-topography. Surface roughness parameters (ISO 25178-2 among others) were applied. Nine parameters changed significantly when mechanical actions were applied to lithic surfaces, meaning that some changes in the surface micro-topography were detected. Therefore, archeologists need to be cautious when applying prolonged mechanical actions for cleaning archeological stone tools.
- Past human decision-making based on stone tool performance: Experiments to test the influence of raw material variability and edge angle design on tool functionPublication . Schunk, Lisa; Calandra, Ivan; Cramer, Anja; Gneisinger, Walter; Marreiros, João; Marreiros, JoaoOne of the main interests in the interpretation of the archaeological record and its variability within and through time and space is the production and use of past human stone tool technologies. Tool design and function are inevitably intertwined and strongly related to tool use. Understanding tool design provides information about early human technological adaptations and reflects human behaviour in the sense of conscious or unconscious decision-making. Nevertheless, the reason for major changes (including novelties, innovations, and loss) in past human stone tool technology is still poorly understood. A comprehensive approach focusing on tool function (What was the tool meant for?) and use (What was the tool used for?) can help to overcome this gap. While tool function (including performance) can be investigated experimentally, tool use can be addressed with use-wear analyses. These questions can be best investigated on technological systems showing little tool variability but strong evidence of maintenance and long-term use, such as Middle Palaeolithic industries. The Late Middle Palaeolithic record of Central and Eastern Europe is marked by the emergence of an asymmetric tool-type called Keilmesser (bifacial backed knives). Due to their sophisticated morphology, Keilmesser as a case study offer the potential to address aspects of raw material selection, tool production, maintenance, and reworking. This paper presents the results of an experiment designed to study the tool performance of Keilmesser from three archaeological sites, namely Balver Hohle, the Upper site of Buhlen and Grotte de Ramioul by testing raw material, edge angle and movement as independent variables. A highly controlled, sequential experiment was conducted using a mechanical device performing unidirectional cutting and carving movements on hard contact material. Results demonstrate the possibility to perform the mentioned task with 35 degrees and 45 degrees edge angles, maintaining function, albeit at differing levels of efficiency. The data has a direct impact on the interpretation of the archaeological assemblages regarding aspects such as stone tool morphology and resharpening. At the same time, the study highlights the importance of raw material analysis to understand the variability in the archaeological record and the implications on past human decision-making strategies.
- Rethinking use-wear analysis and experimentation as applied to the study of past hominin tool usePublication . Marreiros, Joao; Calandra, Ivan; Gneisinger, Walter; Paixão, Eduardo; Pedergnana, Antonella; Schunk, LisaIn prehistoric human populations, technologies played a fundamental role in the acquisition of different resources and are represented in the main daily living activities, such as with bone, wooden, and stone-tipped spears for hunting, and chipped-stone tools for butchering. Considering that paleoanthropologists and archeologists are focused on the study of different processes involved in the evolution of human behavior, investigating how hominins acted in the past through the study of evidence on archeological artifacts is crucial. Thus, investigat ing tool use is of major importance for a comprehensive understanding of all processes that characterize human choices of raw materials, techniques, and tool types. Many functional assumptions of tool use have been based on tool design and morphology according to archeologists’ interpretations and ethnographic observations. Such assumptions are used as baselines when inferring human behavior and have driven an improvement in the methods and techniques employed in functional studies over the past few decades. Here, while arguing that use-wear analysis is a key discipline to assess past hominin tool use and to interpret the organization and variability of artifact types in the archeological record, we aim to review and discuss the current state-of-the-art methods, protocols, and their limitations. In doing so, our discussion focuses on three main topics: (1) the need for fundamental improvements by adopting established methods and techniques from similar research fields, (2) the need to implement and combine different levels of experimentation, and (3) the crucial need to establish standards and protocols in order to improve data quality, standard ization, repeatability, and reproducibility. By adopting this perspective, we believe that studies will increase the reliability and applicability of use-wear methods on tool function. The need for a holistic approach that combines not only use-wear traces but also tool technology, design, curation, durability, and efficiency is also debated and revised. Such a revision is a crucial step if archeologists want to build major inferences on human decision making behavior and biocultural evolution processes.
- The effect of numerical aperture on quantitative use-wear studies and its implication on reproducibilityPublication . Calandra, Ivan; Schunk, Lisa; Bob, Konstantin; Gneisinger, Walter; Pedergnana, Antonella; Paixão, Eduardo; Hildebrandt, Andreas; Marreiros, JoaoMany archeologists are skeptical about the capabilities of use-wear analysis to infer on the function of archeological tools, mainly because the method is seen as subjective, not standardized and not reproducible. Quantitative methods in particular have been developed and applied to address these issues. However, the importance of equipment, acquisition and analysis settings remains underestimated. One of those settings, the numerical aperture of the objective, has the potential to be one of the major factors leading to reproducibility issues. Here, experimental flint and quartzite tools were imaged using laser-scanning confocal microscopy with two objectives having the same magnification but different numerical apertures. The results demonstrate that 3D surface texture ISO 25178 parameters differ significantly when the same surface is measured with objectives having different numerical apertures. It is, however, unknown whether this property would blur or mask information related to use of the tools. Other acquisition and analyses settings are also discussed. We argue that to move use-wear analysis toward standardization, repeatability and reproducibility, the first step is to report all acquisition and analysis settings. This will allow the reproduction of use-wear studies, as well as tracing the differences between studies to given settings.
- The role of artificial contact materials in experimental use-wear studies: A controlled proxy to understand use-wear polish formationPublication . Schunk, Lisa; Gneisinger, Walter; Calandra, Ivan; Marreiros, JoaoTraceological studies aim at the recognition and the identification of use-wear traces on artefacts to gain a functional interpretation of past human technologies. However, the development of use-wear traces is known to be dependent on different mechanics involved, such as those related to the contact materials, but also to the tool raw material and morphology, the use intensity and the performed task. Therefore, an understanding of the fundamental mechanics affecting wear formation is necessary to build reliable interpretations based on causation. The cause-effect relationship between individual variables and the formation of use-wear can only be inves-tigated by conducting controlled, second-generation experiments. To test individual variables, others have to be standardised. This applies, for instance, to the contact material. The here presented sequential second-generation experiment tested for differences between soft and hard contact materials. Simultaneously, this experiment aimed to validate the comparability of artificial and natural contact material as a standardised substitute, but also as an ethically more acceptable choice. Combined with qualitative and quantitative use-wear analyses, the data generated throughout the experiment did not only provide insights into the development of use-wear, but also into abrasion processes within the experimental setup. Concerning these aspects, no significant difference between the natural and artificial contact materials could be observed. Consequently, while not used as direct proxies to interpret wear on archaeological artefacts, the use of standardised contact materials can be an advantageous choice in controlled experimental setups. Moreover, the experiment highlights the relevance of use intensity and duration in the context of wear formation.