Prehistoric humans sought psychedelic experiences in deep and narrow caves, a team of Israeli scholars claimed in a paper published in The Journal of Archaeology, Consciousness and Culture last week.
“People have always been fascinated by caves. Underground cavities and hollows in mountains played a special role in the ontology and cosmology of indigenous societies, past and present,” Yafit Kedar, a PhD candidate in the Department of Archaeology and Near Eastern Studies at Tel Aviv University explained.
Kedar’s research focuses on understanding the implications of smoke dispersal and air circulation on humans at Paleolithic caves and rock shelters.
“A few years ago, as I was visiting some decorated caves in France, I started to notice that most images are found deep in very narrow caves,” she told The Jerusalem Post. “I began to wonder why they chose to work this way, as opposed to paint at the entrance of wider caves, where they could have also enjoyed some natural light.”
Over 400 decorated caves whose drawings date back to the Upper Paleolithic period – between 40,000 and 11,000 years ago – have been found in Western Europe.
The researchers began contemplating the possibility that for prehistoric humans, penetrating several hundred meters deep into the caverns represented a conscious choice that allowed them to connect with their cosmos, with the low concentration of oxygen found in those environments acting as a drug.
“The natural oxygen concentration in the atmosphere is 21%,” Kedar explained. “A lower concentration of oxygen creates a condition known as hypoxia.”
Hypoxia officially occurs when the oxygen concentration is below 18%.
Its symptoms, the researcher pointed out, include dizziness and headaches but also euphoria and an increase in the release of dopamine – which can lead to hallucinations and out-of-the-body experiences, especially if the level of oxygen drops below 14.5%.
The team, which included independent researcher Gil Kedar and TAU Professor of Prehistoric Archaeology Ran Barkai, simulated the use of artificial light in various closed spaces inside caves in order to analyze the conditions in such contexts in Upper Paleolithic caves.
The combination of limited air circulation and the use of torches and oil lamps resulted in a decrease of oxygen concentration below 18% in 15 minutes, with the percentage dropping as low as 11%. Humans can survive in an environment as long as the rate is above 9%.
According to the researchers, the altered state of mind caused by hypoxia also affected the practice of drawing in the caves.
“We suggest that the depictions themselves should be viewed as one component of human connectedness and interactions with the cosmos, and not as the sole and ultimate objective of the humans who created them in the innermost depths of the cave,” they wrote in the paper.
“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.”
The next step for the team will be to understand more about how many people those caves could accommodate at the same time in terms of oxygen level, as well as the number of torches.
“After running the simulation on computers, I would like to measure the oxygen levels in real caves,” Kedar concluded.