A new analysis of 300,000-year-old stone tools discovered in a cave in Israel suggests that hominins in the Levantine region used fire at controlled temperatures to make tools, according to a paper published in Nature Human Behaviour.
The use of fire to treat raw materials was an important discovery made by early hominins. Previous research reported evidence of systematic flint tool production by hominins in the Levant during the Late Lower Palaeolithic (420,000 to 200,000 years ago), and the presence of burned flint artefacts indicated that tools were exposed to fire in some way. However, it was unknown whether the exposure to fire was random or the inhabitants had control over the fire to create specific tools.
The Qesem Cave in central Israel is a key Levantine site during the Late Lower Palaeolithic era and has yielded many significant finds, including the extensive and habitual use of fire and intensive blade production. Aviad Agam, Filipe Natalio and colleagues examined two types of flint tools with evidence of fire exposure found in this cave. They used a combination of spectroscopy and machine learning to estimate the temperature at which the artefacts were burned. They found that blades were heated to a lower temperature (259°C) than flakes (413°C), and that pot lids from the same cave were exposed to an even higher temperature (447°C). The authors then performed an experiment to replicate similar heat conditions and found that controlling the heat levels of flint can improve blade production.
The authors conclude that Levantine hominins may have purposefully heated materials to different temperatures in order to enhance the production of tools.
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