The red ochre stains were assumed to be natural but one reporting team disagrees:
The team members analysed samples of red residues collected from the flowstone surface and compared them with iron oxide-rich deposits in the cave. They concluded that the ochre-based pigment was intentionally applied, i.e. painted — by Neanderthals, as modern humans had yet to make their appearance on the European continent — and that, importantly, it had probably been brought to the cave from an external source.
Furthermore, variations in pigment composition between samples were detected, corresponding to different dates of application, sometimes many thousands of years apart. Thus, it seems that many generations of Neanderthals visited this cave and coloured the draperies of the great flowstone formation with red ochre. This behaviour indicates a motivation to return to the cave and symbolically mark the site, and it bears witness to the transmission of a tradition down through the generations.
CNRS, “Neanderthals indeed painted Andalusia’s Cueva de Ardales” at ScienceDaily
The paper is closed access. It’s title is intriguing: The symbolic role of the underground world among Middle Paleolithic Neanderthals.
If this is correct, the Neanderthals didn’t live in Andalusia’s Cueva de Arales; they seem to have been using it as a ceremonial site.
See also: Neanderthal Man: The long-lost relative turns up again, this time with documents
and
A deep and abiding need for Neanderthals to be stupid. Why?