To shed light on the issue, a study published in Scientific reports that they analyzed the findings of blocks of manganese dioxide at the excavations of Pech-de-l’Azé I, in southwestern France. Where excavations, which are dating back to 50,000 years ago, are showing traces of Neanderthal. So far the best hypothesis about the discovery of these blocks of manganese dioxide was that it was used by Homo neanderthalensis as a kind of trick, or rather as a pigment to decorate the body.
What might suggest that Neanderthals were able to start the fire, from scratch, using nothing less than some chemistry is some archaeological evidence about the presence of powder of manganese dioxide in hearths. Also considering that to decorate their body, the coal fire was more available and easily accessible than manganese dioxide, which is preferred to other manganese oxides.
The researchers notes that “the combustion and thermogravimetric measurements show that the manganese dioxide reduces the self-ignition temperature of the wood, and substantially increases the coal combustion capability, suggesting that the most appropriate use of this substance was inn fact to produce fire”.
Practically, the Neanderthals could have treated the wood with this substance to start the fire, because it was easier. The more we know them, the more the stereotype of rough and undeveloped Neanderthals appear to be wrong.