Extracting residues from stone tools for optical analysis: towards an experiment-based protocol

The identification of residues is traditionally based on the distinctive morphologies of the residue fragments by means of light microscopy. Most residue fragments are amorphous, in the sense that they lack distinguishing shapes or easily visible structures under reflected light microscopy. Amorphous residues can only be identified by using transmitted light microscopy, which requires the extraction of residues from the tool’s surface. Residues are usually extracted with a pipette or an ultrasonic bath in combination with distilled water. However, a number of researchers avoid residue extraction because it is unclear whether current extraction techniques are representative for the use-related residue that adheres to a flaked stone tool. In this paper, we aim at resolving these methodological uncertainties by critically evaluating current extraction methodologies. Attention is focused on the variation in residue types, their causes of deposition and their adhesion and on the most successful technique for extracting a range of residue types from the stone tool surface. Based on an experimental reference sample in flint, we argue that a stepwise extraction protocol is most successful in providing rep- resentative residue extractions and in preventing damage, destruction or loss of residue.Evohaf

Making sense of residues on flaked stone artefacts: learning from blind tests

Residue analysis has become a frequently applied method for identifying prehistoric stone tool use. Residues adhering to the stone tool with varying frequencies are interpreted as being the result of an intentional contact with the worked material during use. Yet, other processes during the life cycle of a stone tool or after deposition may leave residues and these residues may potentially lead to misinterpretations. We present a blind test that was designed to examine this issue. Results confirm that production, retouch, prehension, hafting, various incidental contacts during use and deposition may lead to residue depositions that significantly affect the accurateness of identifications of tool-use. All currently applied residue approaches are concerned. We therefore argue for a closer interaction with independent wear studies and a step-wise procedure in which a low magnification of wear traces is used as a first step for selecting potentially used flakes in archaeological contexts. In addition, residue concentrations on a tool's edge should be sufficiently dense before linking them with use

Documenting scarce and fragmented residues on stone tools: an experimental approach using optical microscopy and SEM-EDS

Residue analyses are widely applied to studies of stone tool function and can be a powerful method for determining the past tool use(s), especially when combined with other functional investigations such as usewear and technological analysis. Experimental work has shown that optical microscopes and the scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDS) are reliable instruments for identifying intact tool residues. However, little experimental work has aimed to document residues that show various stages of degradation or when abundance is low. We combined traditional optical microscopy and the SEM-EDS to identify the advantages and challenges of each technique when looking at progressively smaller and more fragmented residues following more aggressive stages of cleaning, burial and soaking in a weak acid/base solution. We found that large quantities of intact residues on unwashed stone tools show distinctive morphological features under optical microscopes and the SEM-EDS can be used to document residues under extremely high magnifications and to determine their elemental compositions. After the various stages of washing, we found that residues became highly fragmented and were restricted to common stone features like the micro-cracks/scars along the working edge. These residues were often difficult to characterise using optical microscopes but the SEM-EDS proved highly useful. The weak acid/base solutions caused some residues to become physically altered or modified their elemental composition. Buried tools reduced the abundance of use-residues and introduced additional non-use-related contaminant particles that affected EDS measurements and lead to less reliable residue interpretations

Quartz Knapping Strategies in the Howiesons Poort at Sibudu (KwaZulu-Natal, South Africa)

The variability associated with Sibudu\u27s Howiesons Poort Industry highlights the unpredictable trajectory of technology in the Middle Stone Age. We reach this conclusion through a study of the technology on quartz from one of the Howiesons Poort layers (Grey Sand) from Sibudu rock shelter. Quartz bifacial technology has previously been described at the site, but this new in-depth study of the quartz technology reveals other strategies. First is the recurring employment of bipolar knapping, formerly considered as a defining feature of the Later Stone Age. Secondly, we highlight a laminar technology with emphasis on small quartz bladelets. Bipolar cores are most common, followed by prismatic cores. The knapping strategies in Grey Sand seem to involve systematic recycling and the deliberate production of microliths

The Pleistocene of Rabat (Morocco): Mollusks, Coastal Environments and Human Behavior

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Characterizing the Late Pleistocene MSA Lithic Technology of Sibudu, KwaZulu-Natal, South Africa

Studies of the African Middle Stone Age (MSA) have become central for defining the cultural adaptations that accompanied the evolution of modern humans. While much of recent research in South Africa has focused on the Still Bay and Howiesons Poort (HP), periods following these technocomplexes were often neglected. Here we examine lithic assemblages from Sibudu that post-date the HP to further the understanding of MSA cultural variability during the Late Pleistocene. Sibudu preserves an exceptionally thick, rich, and high-resolution archaeological sequence that dates to ∼58 ka, which has recently been proposed as type assemblage for the “Sibudan”. This study presents a detailed analysis of the six uppermost lithic assemblages from these deposits (BM-BSP) that we excavated from 2011–2013. We define the key elements of the lithic technology and compare our findings to other assemblages post-dating the HP. The six lithic assemblages provide a distinct and robust cultural signal, closely resembling each other in various technological, techno-functional, techno-economic, and typological characteristics. These results refute assertions that modern humans living after the HP possessed an unstructured and unsophisticated MSA lithic technology. While we observed several parallels with other contemporaneous MSA sites, particularly in the eastern part of southern Africa, the lithic assemblages at Sibudu demonstrate a distinct and so far unique combination of techno-typological traits. Our findings support the use of the Sibudan to help structuring this part of the southern African MSA and emphasize the need for further research to identify the spatial and temporal extent of this proposed cultural unit

Integrating Human-Animal Relationships into New Data on Aterian Complexity: a Paradigm Shift for the North African Middle Stone Age

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