But their presence in passages that would otherwise be completely dark indicates something straightforward: whoever made them needed artificial light to see, and they had it.

Charcoal was also recovered from clay surfaces in the cave — small deposits of burned organic material consistent with the use of torches or other fire-based lighting.

This charcoal is the kind of material that can, under good conditions, be radiocarbon dated.

The association of charcoal with the passages leading toward the remains provided additional evidence that someone with fire had been in those passages before the modern cavers arrived.

The smudge marks and the charcoal do not, by themselves, prove that all of this evidence was made by the same individual whose bones lay at the end of the traverse.