Making Sense of Residues on Flaked Stone Artefacts: Learning from Blind Tests

Abstract

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.

Viability of Raman microscopy to identify micro‐residues related to tool‐use and modern contaminants on prehistoric stone artefacts

“…Particles detected included synthetic glass fibre, polyester, proteins, modern cotton fibres, modern dyed fibres, natural plant fibres and starch grains. Similar sources of contamination have been observed by usewear and micro‐residue analysts in optical microscope laboratories …”

“…Indeed, because of their small size and often scattered distributions, micro‐residues are difficult to distinguish from modern contaminants and the effects of post‐depositional processes . To confidently determine that micro‐residues are archaeologically significant, multiple lines of evidence are required, including micro‐residue abundance and meaningful distributions . Identification of a single micro‐residue deposit or micro‐residue class is not sufficient for determining the function of a stone tool, because use‐related micro‐residues are often preserved in relatively high abundance in predictable locations on tool surfaces, based on archaeological and experimental analyses …”

“…[9] To confidently determine that microresidues are archaeologically significant, multiple lines of evidence are required, [10] including micro-residue abundance and meaningful distributions. [11] Identification of a single micro-residue deposit or micro-residue class is not sufficient for determining the function of a stone tool, because use-related micro-residues are often preserved in relatively high abundance in predictable locations on tool surfaces, based on archaeological and experimental analyses. [2,11] Raman microscopy can help relate data from usewear/microresidue and spectroscopic analyses, both of which are minimally destructive and ideally suited for many archaeological applications.…”

Exaggerated expectations in ancient starch research and the need for new taphonomic and authenticity criteria

“…Unfortunately, recent work has also called this link into question (Rots et al 2016), as the location of residues does not necessarily indicate that they are use-related (Xhauflair et al 2017) or contamination distributed along edges (Pedergnana and Ollé 2017). New experimental research (J. Mercader, M. Soto, personal observation, 2018) is focusing on detecting patterns of microbotanical attachment in natural rocks (lying on modern surfaces and in contact with surrounding soils) to build a baseline whereby residue density estimation by geographic information system (GIS) and nearest neighbour heat maps of plant materials adhering to rock surfaces can be compared with residue scatters from stone tools.…”

Blind test evaluation of consistency in macroscopic lithic raw material sorting

“…Blind testing is a highly important method in archaeology, especially when dealing with techniques which might be affected by human biases and subjectivity, allowing the identification of weaknesses within the examined technique (Evans, ). Rots, Pirnay, Pirson, and Baudoux () define blind tests as “an objective means to evaluate the accuracy of information retrieved by a specific method.” Indeed, blind tests are commonly used in microwear and macrowear studies (Bamforth, ; Bamforth, Burns, & Woodman, ; Newcomer, Grace, & Unger‐Hamilton, ; Rots et al, ), residue analysis (Hayes, Cnuts, Lepers, & Rots, ; Lombard & Wadley, ; Rots, Hayes, Cnuts, Lepers, & Fullagar, ; Wadley & Lombard, ; Wadley, Lombard, & Williamson, ), archaeozoological studies (Blumenschine, Marean, & Capaldo, ; Giovas, Lambrides, Fitzpatrick, & Kataoka, ; Gobalet, ; Lloveras, Moreno‐García, Nadal, & Thomas, ; Morin, Ready, Boileau, Beauval, & Coumont, ), micromorphology (Shahack‐Gross, ), and radiocarbon dating (Kim et al, ; Olsen et al, ). However, so far, no such tests have been applied to macroscopic raw material sorting (but see Ferguson & Warren, ; Price, Carr, & Bradbury, ).…”