Research press release


Nature Human Behaviour

Archaeology: Evidence of controlled heating of tools 300,000 years ago

イスラエルの洞窟で発見された30万年前の石器の新たな解析から、レバント地方のヒト族が、異なる道具を作る際に、火を異なる温度に制御していた可能性があることを明らかにした論文が、Nature Human Behaviour に掲載される。


イスラエル中央部に位置するケセム洞窟は、前期旧石器時代後期の重要なレバント遺跡であり、火の広範かつ習慣的な使用や、石刃の集約的な製作など、数多くの重要な発見がなされている。Aviad Agam、Filipe Natalioたちの研究チームは今回、2つのタイプのフリント石器の調査を行い、この洞窟内で火にさらされていた証拠を得た。Agamたちは、分光法と機械学習を組み合わせることで、遺物が焼かれた温度を推定した。その結果、石刃の加熱温度(摂氏259度)は薄片の加熱温度(摂氏413度)よりも低く、また同じ洞窟で見つかった壺の蓋の加熱温度はさらに高かった(摂氏447度)ことが判明した。また、Agamたちは同様の加熱条件を再現する実験を行い、フリント石器の加熱レベルの制御によって、石刃の製作を改善できることを明らかにした。


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.

doi: 10.1038/s41562-020-00955-z


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