Humans, by most estimates, discovered fire over a million years ago, but when did we really begin to control fire and use it for our daily needs is still hotly debated.
A team of Israeli scientists discovered the earliest evidence - dating to around 300,000 years ago - of unequivocal repeated fire building over a continuous period in the Qesem Cave, an archaeological site near present-day Rosh Ha'ayin.
These findings hint that those prehistoric humans already had a highly advanced social structure and intellectual capacity, researchers said.
Using infrared spectroscopy, she and her colleagues were able to determine that mixed in with the ash were bits of bone and soil that had been heated to very high temperatures.
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This was conclusive proof that the area had been the site of a large hearth.
Shahack-Gross tested the micro-morphology of the ash. To do this, she extracted a cubic chunk of sediment from the hearth and hardened it in the lab.
Then she sliced it into extremely thin slices - so thin they could be placed under a microscope to observe the exact composition of the materials in the deposit and reveal how they were formed.
Around the hearth area, as well as inside it, the archaeologists found large numbers of flint tools that were clearly used for cutting meat.
In contrast, the flint tools found just a few meters away had a different shape, designed for other activities. Also in and around the area were large numbers of burnt animal bones - further evidence for repeated fire use for cooking meat.
The team has shown that this organisation of various "household" activities into different parts of the cave points to an organisation of space - and a thus kind of social order - that is typical of modern humans.
"These findings help us to fix an important turning point in the development of human culture - that in which humans first began to regularly use fire both for cooking meat and as a focal point - a sort of campfire - for social gatherings," she said.
The findings were published in the Journal of Archaeological Science.