Humans harnessed fire to improve their tools much earlier than we’d thought, according to a new report in Science (doi:10.1126/science.1175028).

Though our forebears cooked with fire some 800,000 years ago, the consensus so far was that people hadn’t used fire to heat-treat materials until around 25,000 years ago. The new finding pushes that back at least 45,000 years.

“Our illumination of the heat treatment process shows that these early modern humans commanded fire in a nuanced and sophisticated manner," says the lead author Kyle Brown, from the University of Cape Town in South Africa. [Press release from Arizona State University, Brown’s other affiliation]. “We’ve shown that, at least 72,000 years ago and perhaps much earlier, modern humans had an understanding of how fire and heat could transform the materials around them to suit their needs.” [Science News].

Researchers spent six years looking for the same type of silcrete rock that they found in tools at Pinnacle Point, a Middle Stone Age site on the South African coast. It wasn’t until they happened across such a piece of silcrete embedded in ash that they realised that they could get the deep red, glossy and brittle silcrete such as the one found in tools by putting regular silcrete in fire. They estimate that stones were heated to around 300 degrees Celsius, probably by cooking them under fire in a process that could last for up to 40 hours. This resulted in stones that were easier to shape into tools by using other rocks, and that could be used as knives, hunting weapons or for exchange for other goods.

“I think heating stones is the dawn of human engineering. One of the things that makes us uniquely human is that we can take the things in our landscape and adapt them. We can engineer them to fit our needs.” Brown told the BBC.

Posted for Mico Tatalovic

Image: Kyle Brown/South African Coast Paleoclimate, Paleoenvironment, Paleoecology, Paleoanthropology Project