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Thermal engineering of stone increased prehistoric toolmaking skill.

ABSTRACT: Intentional heat treating of toolstone has been documented to have begun at least by 70?K BP; however, the advantages of such treatment have been debated for decades. There are two schools of thought with regard to its purpose. One, is that it merely reduces the force required for flake propagation. A second is that it also alters flake morphological properties. We systematically tested these hypotheses by generating flakes from cores exposed to three different temperatures (ambient, 300?°C, and 350?°C) using automated propagation procedures that bypassed any human agency. While the force propagation magnitude is altered by heat treatment, the flakes were not. We examined these flakes according to nine measures of morphology. None differed significantly or systematically within the three categories. While our results confirm that heat treatment does reduce the force needed for flake propagation, they also demonstrate that such treatment has no significant effect on major morphological aspects of flake form.

SUBMITTER: Mraz V

PROVIDER: S-EPMC6787202 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Thermal engineering of stone increased prehistoric toolmaking skill.

Mraz Veronica V Fisch Mike M Eren Metin I MI Lovejoy C Owen CO Buchanan Briggs B

Scientific reports 20191010 1

Intentional heat treating of toolstone has been documented to have begun at least by 70 K BP; however, the advantages of such treatment have been debated for decades. There are two schools of thought with regard to its purpose. One, is that it merely reduces the force required for flake propagation. A second is that it also alters flake morphological properties. We systematically tested these hypotheses by generating flakes from cores exposed to three different temperatures (ambient, 300 °C, and ...[more]

PMID: 31601931

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Project description:IntroductionStudies suggest that the width of the acoustic shadow on ultrasound (US) more accurately reflects true stone size than the stone width in US images. We evaluated the need for training in the adoption of the acoustic shadow sizing technique by clinical providers.MethodsProviders without shadow sizing experience were recruited and assigned in a stratified, alternating manner to receive a training tutorial ("trained") or no intervention ("control"). Each conducted a baseline assessment of 24 clinical US images; where present, shadow width was measured using custom calipers. The trained group subsequently completed a standardized training module on shadow sizing. All subjects repeated measurements after ?1 week. Group demographics were compared using Fisher's exact test. Measurements were compared to clinically reported stone sizes on corresponding CT and US using mixed-effects models. One millimeter concordance between shadow and CT size was compared using a generalized linear mixed-effects model.ResultsTwenty-six subjects were included. There was no significant difference between groups in demographics, clinical role, or US experience. Mean reported CT and US stone sizes were 6.8?±?4.0?mm and 10.3?±?4.1?mm, respectively. At baseline, there was no difference in shadow size measurements between groups (p?=?0.18), and shadow size was no more accurate than US stone size (p?=?0.28 trained; p?=?0.81 control), compared to CT. After training, overestimation bias of shadow size in the trained group decreased to 1.6?±?0.5?mm (p?<?0.01), relative to CT. This was not significantly associated with clinical rank, US experience, or stone-measuring experience. One millimeter concordance with CT size significantly increased from 23% to 35% of stones after training (p?=?0.01). No significant improvement occurred in the control group.ConclusionAcoustic shadow sizing was readily adopted by inexperienced providers, but was not more accurate than reported US stone sizes without training. Education on shadow sizing may be warranted before clinical adoption.

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Thermal engineering of stone increased prehistoric toolmaking skill.

Publications

Thermal engineering of stone increased prehistoric toolmaking skill.

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