Some thoughts on bone artefact discolouration at archaeological sites

Bradfield, Justin

doi:10.1016/j.jasrep.2017.12.022

Cited by 7 publications

(7 citation statements)

References 64 publications

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“…Therefore, it is important to apply the proposed decision model only to situations in which the (pre-)burning conditions are known or can be deduced from additional information. Discolouration due to staining from organic matter, bacterial or fungal activity or the presence of metals needs to be taken into consideration when dealing with remains that have not been collected within a limited time frame after the fire incident 49–51 . In such cases substantiation of the thermal discolouration is needed.…”

Section: Discussionmentioning

confidence: 99%

Colourimetric analysis of thermally altered human bone samples

Krap

Ruijter

Nota

et al. 2019

Sci Rep

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At this moment, no method is available to objectively estimate the temperature to which skeletal remains have been exposed during a fire. Estimating this temperature can provide crucial information in a legal investigation. Exposure of bone to heat results in observable and measurable changes, including a change in colour. To determine the exposure temperature of experimental bone samples, heat related changes in colour were systemically studied by means of image analysis. In total 1138 samples of fresh human long bone diaphysis and epiphysis, varying in size, were subjected to heat ranging from room temperature to 900 °C for various durations and in different media. The samples were scanned with a calibrated flatbed scanner and photographed with a Digital Single Lens Reflex camera. Red, Green, Blue values and Lightness, A-, and B-coordinates were collected for statistical analysis. Cluster analysis showed that discriminating thresholds for Lightness and B-coordinate could be defined and used to construct a model of decision rules. This model enables the user to differentiate between seven different temperature clusters with relatively high precision and accuracy. The proposed decision model provides an objective, robust and non-destructive method for estimating the exposure temperature of heated bone samples.

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Section: Discussionmentioning

confidence: 99%

Colourimetric analysis of thermally altered human bone samples

Krap

Ruijter

Nota

et al. 2019

Sci Rep

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“…Chemical analysis might be able to reveal if bones have been heat‐exposed under oxidizing or reducing conditions. Metals and other contaminants (including soil) have the capacity to modify bone color , but such contamination is much more likely to happen after rather than during burning. Thus, color contamination will certainly be a problem for color measurements from buried human remains, but perhaps not for fresh forensic cases.…”

Section: Discussionmentioning

confidence: 99%

“…Even though it is generally accepted that bone color changes systematically with the heating temperature, a large number of researchers have concluded that bone color measurements are not useful for accurate temperature estimations . The main argument has been that the bone color after heat exposure is influenced by a multitude of factors, including the burning time , the amount of oxygen and soft tissue present during heating , chemical interactions with soil during or after the fire , and the possible influence of coloring substances (contaminants) such as metals .…”

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confidence: 99%

Estimating the Temperature of Heat‐exposed Bone via Machine Learning Analysis of SCI Color Values: A Pilot Study

Wärmländer

Varul

Koskinen

et al. 2018

Journal of Forensic Sciences

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Determining maximum heating temperatures of burnt bones is a long-standing problem in forensic science and archaeology. In this pilot study, controlled experiments were used to heat 14 fleshed and defleshed pig vertebrae (wet bones) and archaeological human vertebrae (dry bones) to temperatures of 400, 600, 800, and 1000°C. Specular component included (SCI) color values were recorded from the bone surfaces with a Konica-Minolta cm-2600d spectrophotometer. These color values were regressed onto heating temperature, using both a traditional linear model and the k-nearest neighbor (k-NN) machine-learning algorithm. Mean absolute errors (MAE) were computed for 1000 rounds of temperature prediction. With the k-NN approach, the median MAE prediction errors were 41.6°C for the entire sample, and 20.9°C for the subsample of wet bones. These results indicate that spectrophotometric color measurements combined with machine learning methods can be a viable tool for estimating bone heating temperature.

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“…Likewise, at the end of the Late Paleolithic, past populations in North China appear to have specifically selected burnt bones, if not deliberately heated bone fragments in an anaerobic environment to change the color of the whole cortical bone rather than only its surface, to manufacture portable artwork (Li et al, 2020). Although bone discoloration can be achieved through multiple ways (e.g., Bradfield, 2018), a similar process has only been reported for the manufacture of blacken shell beads from Blombos Cave (d 'Errico et al, 2015). Finally, a number of North Chinese sites suggests that the emergence of personal ornaments preceded the first occurrences of formal bone tools in the region by a few millennia.…”

Section: Pleistocene Bone Technology In Chinamentioning

confidence: 99%

Animals for Tools: The Origin and Development of Bone Technologies in China

Doyon

2021

Front. Earth Sci.

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The origin and development of bone technologies in China are reviewed in the light of recent discoveries and compared to trends emerging from the European and African archaeological records. Three categories of osseous tools are targeted: 1) unmodified bone fragments bearing traces of use in technological activities; 2) bone fragments modified to a variable extent with techniques generally used in stone technologies; 3) osseous fragments entirely shaped with techniques fit for the manufacture of formal bone tools. Early evidence of bone technologies in China are sporadically found in contexts dated between 1.8 and 1.0 Ma. By the late MIS6–early MIS5, bone tools are well-integrated in the technological systems of Pleistocene populations and the rules guiding their use appear increasingly standardized. In addition, the first evidence for the use of osseous material in symbolic activities emerges in the archaeological record during this period. Finally, between 40 and 35 ka, new manufacturing techniques and products are introduced in Late Palaeolithic technological systems. It is first apparent in the manufacture of personal ornaments, and followed by the production and diversification of formal bone tools. By that time, population dynamics seem to become materialized in these items of material culture. Despite regional specificities, the cultural trajectories identified for the evolution of bone technologies in China seem entirely comparable to those observed in other regions of the world.

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Some thoughts on bone artefact discolouration at archaeological sites

Cited by 7 publications

References 64 publications

Colourimetric analysis of thermally altered human bone samples

Colourimetric analysis of thermally altered human bone samples

Estimating the Temperature of Heat‐exposed Bone via Machine Learning Analysis of SCI Color Values: A Pilot Study

Animals for Tools: The Origin and Development of Bone Technologies in China

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