Ancient people created cave art while hallucinating
Stone Age people may have deliberately ventured into oxygen-depleted caves to paint while having out-of-body experiences. In the 19th century, researchers discovered a series of decorated caves that date back between 14,000 and 40,000 years to the Upper Paleolithic era, or Late Stone Age, across Western Europe. Found mainly in Spain and France, they were filled with paintings, many of them in areas that could be accessed only through narrow passageways. The depictions were painted in black and red and primarily showed animals, with some hand stencils, handprints and geometric abstract signs.
But why would people go through the trouble of walking through narrow cave passages to make art? To answer this question, a group of researchers at Tel Aviv University focused on a characteristic of such deep, narrow caves, especially those that require artificial light to navigate: low levels of oxygen. The researchers ran computer simulations of model caves with different passageway lengths that lead to slightly larger ‘hall’ areas where paintings may be found, analysing the changes in oxygen concentration if a person was to stand in the different parts of the cave burning a torch.
They found that oxygen concentration depended on the height of the passageways, with the shorter passageways having less oxygen. Such low levels of oxygen can induce hypoxia in the body, a condition that can cause headaches, shortness of breath, confusion and restlessness. But hypoxia also increases the hormone dopamine, which can lead to hallucinations and out-of-body experiences. For caves with low ceilings or small halls, the oxygen concentration dipped as low as 11 per cent, which would cause the more severe symptoms.
The researchers hypothesise that ancient people crawled into these deep, dark spaces to induce altered states of consciousness. “Hypoxia might well be a plausible explanation for many of the depiction locations, which are far from the cave mouth and require passing through low, narrow passages,” researchers wrote. “We contend that entering these deep, dark caves was a conscious choice, motivated by an understanding of the transformative nature of an underground, oxygen-depleted space.”
Caves had a special significance for these ancient civilisations. They were seen as “portals that connect to the underworld,”says Yafit Kedar, a doctoral candidate in the department of archaeology and near-eastern cultures at Tel Aviv University. The findings suggest that the ancient people sought altered states of consciousness and created cave depictions as “a way to maintain their connection with the entities” of the underworld.