Estimating temperatures of heated Lower Palaeolithic flint artefacts.

Production of stone artefacts using pyro-technology is known from the Middle and Upper Palaeolithic of Europe and the Levant, and the Middle Stone Age in Africa. However, determination of temperatures to which flint artefacts were exposed is impeded by the chemical and structural variability of flint. Here we combine Raman spectroscopy and machine learning to build temperature-estimation models to infer the degree of pyro-technological control effected by inhabitants of the late Lower Palaeolithic (Acheulo-Yabrudian) site of Qesem Cave, Israel. Temperature estimation shows that blades were heated at lower median temperatures (259 °C) compared to flakes (413 °C), whereas heat-induced structural flint damage (for example, pot-lids and microcracks) appears at 447 °C. These results are consistent with a differential behaviour for selective tool production that can be viewed as part of a plethora of innovative and adaptive behaviours of Levantine hominins >300,000 years ago.