Neanderthals used manganese dioxide to facilitate fires, not facepaint
Some day in the future, archaeologists may look back at artifacts from our life and assume that we use matches as hair pins. It seems odd, but it appears we’ve been making a similar mistake with Neanderthals and chunks of manganese dioxide (MnO2). This may not seem terribly obvious since this compound is most often found today in the production of dry cell batteries and thus out of our daily routines, but varying lines of evidence suggest that Neanderthals regularly made use of it to start fires.
Rocks for rubbing?
Manganese dioxide can be found as mineral deposits, usually resembling dark, nondescript rocks. Like other forms of manganese oxides, they can leave a black stain on the skin, and so when quantities of the these rocks were found around Neanderthal dig sites, the first assumption was that they were used for personal adornment, or possibly for some kind of ritual markings. However, researchers from Leiden University excavating at the Pech-de-l’Azé I site in southwestern France noted that while all manganese oxides could mark the skin, Neanderthals seemed to be selective about the dioxide variation specifically. What’s more, with fire pits at the site, it would have been easier to blacken the skin with soot or charcoal, indicating that these rocks were gathered for another purpose.
Rocks for roasting
Their hypothesis is that the rocks were gathered for their chemical, not cosmetic, uses. When ground into a powder, manganese dioxide can act a bit like stone-age lighter fluid. The powder, sprinkled amongst dry wood shavings, lowered the ignition temperature of the wood from 350° to 250° Celsius. Considering that Neanderthals were likely starting their fires with sparks from striking flint, this 100° difference would have made their life a lot easier. While the shavings and MnO2 would have been dry and small, once lit larger and possibly greener twigs and leaves could have been built into a larger fire.
To further confirm this alternate model for Neanderthals’ interest in manganese dioxide, the research team actually built a few fires using the powered compound. After confirming this experimental data, they also looked to the original archaeological evidence, and found scratches and scrapes on the collected manganese rocks themselves. These scratches were a good match for scraping out shavings, indicting that at the very least, they hadn’t just been rubbed on their skin.
My first grader asked: You can start a fire by rubbing sticks together or hitting rocks? I won’t ever do that! Not here at home!
While Neanderthals probably became quite practiced at these techniques, it’s easy to see that starting a fire with friction isn’t simple enough to be done by accident. Even when people use magnesium and flint to start a fire today, they’re usually using tools (and a different starter) not available 50,000 years ago.