Using advanced AI techniques, researchers from the Weizmann Institute of Science, Israel, uncovered evidence for the use of fire dating back at least 800,000 years, according to a study published in the journal PNAS. This is one of the earlier known pieces of evidence for the use of fire. This new method also pushed archeology towards a more data-driven methodology, and the authors believe it could help us understand the origins of human history and traditions.
The use of fire under controlled conditions is believed to date back at least a million years to the time when Homo habilis started transitioning into Homo erectus. The “cooking hypothesis” defends that the use of fire at this time was key to our evolution, allowing us to stay warm, create advanced tools, keep predators away and cook our food. Cooking has two advantages: not only does it eliminate pathogens in the food, but it also improves the digestion of protein, paving the way for brain growth.
However, this is just a theory with no data to back it up. Until now, evidence of the use of fire relied on archeological evidence from finding burnt objects. These traditional methods have only managed to go as far back as 200,000 years. There is some limited evidence for the use of fire about 500,000 years ago, but it only comes from five locations around the world and is not very reliable.
To cover this gap, Dr. Filipe Natalio from Weizmann’s Plant and Environmental Sciences Department and Dr. Ido Azuri from Weizmann’s Life Core Facilities Department used pioneering AI and spectroscopy technology to find evidence for using fire on the Evron Quarry in Israel. “When we started this project,” says Natalio, “the archaeologists who’ve been analyzing the findings from Evron Quarry told us we wouldn’t find anything. We should have made a bet.”
The quarry, located in western Galilee, is an open archaeological site discovered in the 70s, where researchers have found several animal fossils and tools dating back to between 800,000 and 1 million years ago, making it one of the oldest archeological sites in Israel.
None of these finds really shows visual evidence of heat. This is not surprising given that ash and charcoal degrade over time, eliminating the chances of finding any evidence. But the team was determined to continue the search.
To do this, they turned to an advanced AI model they had previously used in other samples. “We tested a variety of methods, among them traditional data analysis methods, machine learning modeling, and more advanced deep learning models,” said Azuri. “The deep learning models that prevailed had a specific architecture that outperformed the others and successfully gave us the confidence we needed to further use this tool in an archaeological context having no visual signs of fire use.” They settled on AI because it can find hidden patterns across a multitude of scenarios.
By analysing the chemical composition of different materials, the AI system can estimate the temperature to which the stone tools were heated, providing valuable information about if and how humans used fire almost a million years ago. For the study, the team analysed the heat signature of 26 flint tools found at the quarry site. The results showed that the tools had been heated to different temperatures, some more than 600°C. In addition, an analysis of 87 animal remains found that some of them had also been exposed to high temperatures.
“Our approach highlights the possibility of extracting “hidden” information on pyrotechnology-related activities from artifacts beyond the classical visual initial assessment,” concluded the authors. “We propose reexamining artifacts unearthed from other sites, including those located in the Levant may broaden our understanding of the relationship between early hominins and fire.”
Stepka Z, Azuri I, Horwitz L, Chazan M and Natalio F (2022) Hidden signatures of early fire at Evron Quarry (1.0 to 0.8 Mya). PNAS, 119 (25) e2123439119, https://doi.org/10.1073/pnas.2123439119