The colored speleotopics of the cave of Ardales (Malaga, Spain) have been exploded in recent years.A study published in 2018 concluded that they were painted by Neanderthals over 64,000 years ago. However, some questioned whether they were painted and proposed that they could spontaneously color through physical-chemical processes.
Now, a study published in PNAS confirms that they are painted by Neanderthals and publishes several details. Pigments have been analyzed using different techniques (optical microscopy, scanning electron microscopy, spectroscopy, x-ray diffraction, uranium dating, etc.). And they have shown that they were intentionally installed. According to the researchers, the authors introduced pigments from outside the cave, which would demonstrate a certain organization and planning.
On the other hand, the chronological study of the layers has revealed that the Neanderthals made paintings on those speleotema for thousands of years. Researchers have suggested that they would paint them to highlight the symbolic value of the place, since this activity was transmitted from generation to generation, but they cannot know its meaning and function.