TECHNOLOGY

Fire Becomes an Engineer's Tool

~72,000 years ago

Palaeolithic · Middle Stone Age · Last glacial

At Pinnacle Point, on the South African coast, toolmakers discovered that silcrete, a stubborn local stone, flakes far better once it has been cooked. Buried under a fire and brought to temperature, it changes internally and knaps cleanly. The trick appears as early as 164,000 years ago and becomes the dominant way of preparing silcrete by about 72,000 years ago: fire used to transform a material, long before ceramics or metal.

Why it matters

Cooking stone is chemistry in all but name: an invisible transformation, planned in advance, judged only when the knapping begins. How much intelligence it demanded is genuinely debated. The original study read it as evidence of elevated cognition; experiments have since shown that simple surface fires, no hotter than a cooking hearth, already improve the stone significantly. Either way, fire had become a tool for making other tools.

Dating & uncertainty

Bounds follow the archaeological signal: heat-treated silcrete appears by about 164,000 years ago and predominates around 72,000 years ago, the date used here. Recognizing cooked stone is itself a science: gloss, fracture patterns and surface roughness measured under 3D microscopy, with probabilistic models trained on experimentally heated rock.

Sources

  1. Brown et al. (2009), Science · Fire as an engineering tool of early modern humansdoi:10.1126/science.1175028
  2. Pargeter et al. (2020), Journal of Archaeological Science: Reports · 'Simple' surface-fire heat treatment significantly improves silcrete flake quality and flaking efficiencydoi:10.1016/j.jasrep.2020.102203
  3. Murray et al. (2020), Journal of Archaeological Science: Reports · A new approach to identify heat treated silcrete near Pinnacle Point, South Africa using 3D microscopy and Bayesian modelingdoi:10.1016/j.jasrep.2020.102622

Our species’ history as one day

18:30:515 h 29 min before midnight

if the 315,000 years of Homo sapiens were compressed into a single day

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