Exactly when and where humans gained control over fire has been an archaeological dispute for years. What is undisputed is how profound of an impact this discovery had on human evolution, influencing everything about how people lived. It provided protection and warmth, allowed for cooking, and likely changed social structures as a whole. Determining when this milestone was reached, and thus how exactly it impacted our past, requires a way to discern if fires were started incidentally, or opportunistically controlled. This can be done by examining the tools that would have been used to make the fires: strike-a-lights, or pieces of flint which have been hit against a sulfuric iron core to produce sparks. We created a series of strike-a-lights and examined them microscopically for use-wear and residue traces. Findings showed a distinctive trace remained from use as a strike-a- light as compared to contact with other minerals.
Deryck, Sean and Hardy, Bruce, "Rocks and Residues: Rekindling the Past Microscopy of Flint Flakes" (2015). Kenyon Summer Science Scholars Program. Paper 1.