Experimental and archaeological assessment of use-wear persistence on burnt flint from Tinshemet Cave.

Fire plays a central role in human evolution and site formation, yet its impact on the preservation of microscopic use-wear remains poorly understood. Because heating can modify flint's surface structure, burnt artefacts are often excluded from functional studies, limiting behavioral interpretations at fire-rich sites such as Tinshemet Cave (Israel), where nearly 40% of the lithic assemblage shows thermal alteration. This study evaluates how heating affects surface roughness on flint and whether functional traces can still be identified on burnt artefacts. Experimental flakes used on bone, wood, meat, and ochre were heated under controlled fire conditions. Surface textures were measured before and after burning using 3D confocal profilometry and analyzed through paired statistics and mixed-effects models. Burnt flakes from Tinshemet Cave were compared to the experimental reference dataset. Burning significantly increased vertical roughness (Sv, Sz) and altered shape parameters (Ssk, Sku), while spatial parameters (Str, Sdr, Sal) remained largely stable. The results of this study indicate that thermal alteration transforms but does not obliterate use-wear, suggesting that quantitative functional analysis of heateed flints is feasible when parameter-specific effects are considered. Additionally, in experimental fires, flakes deliberately buried at varying depths showed no macroscopic or microscopic damage, whereas only surface-exposed flakes displayed thermal alteration, indicating that even thin sediment layers can protect flints.