The world’s oldest paintings have been found deep inside ancient caves leaving researchers to wonder why they were never found at cave entrances.
But a new study by scholars from the Tel Aviv University has found that cavemen in the Upper Paleolithic Age (the late Stone Age)—approximately 40,000 to 14,000 years ago—were deliberately starving themselves of oxygen while making art deep inside caves. This led to hallucinations and out-of-body experiences, allowing “early humans to maintain their connectedness with the cosmos,” says the study, published in the journal Time and Mind: The Journal of Archaeology, Consciousness and Culture on March 31.
Oxygen levels vary through the length of the cave: the deeper and narrower the cave gets, the more the oxygen level falls.
To study the levels of oxygen concentration, the researchers ran computer simulations of model caves with different passageway lengths that lead to slightly larger “hall” areas where paintings may be found. Then, they analysed the changes in oxygen concentrations keeping in mind if a person was to stand in the different areas of the cave with a burning torch. Inside a closed environment like in this case, fire can cause levels of oxygen to rapidly deplete.
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Researchers found that oxygen concentration depended on the height of the passageways, with the shorter passageways having less oxygen. In most of the simulations, oxygen concentrations dropped from the natural atmosphere level of 21 percent to 18 percent after being inside the caves for only about 15 minutes. The study recorded that for a passage height of one metre, the oxygen concentration decreased to 11 percent after two hours.
Ran Barkai, the co-author of the study told CNN that using fires to light the caves would have reduced oxygen levels and led to a state of hypoxia which releases dopamine in the brain and can cause out-of-body experiences. The study reports that this was possibly deliberate since cavemen didn’t use the deeper areas of the cave for everyday activities and chores. “It appears that Upper Paleolithic people barely used the interior of deep caves for daily, domestic activities. Such activities were mostly performed at open-air sites, rockshelters, or cave entrances,” reads the study. Researchers found that children too were taken deep inside the cave but no one knows why.
So what makes people deep inside caves to start hallucinating? The study recorded that the dark cave environment and extended isolation from the world results in altered state of consciousness.
Speleologists, or people who study caves, have reported experiencing hallucinations while exploring deep underground caves. “It is tempting to slip away from this by switching off the light, and entering a state of peaceful nothingness that normally is not reached by living persons without the use of strong mind altering drugs,” wrote researcher Hein B. Bjerck in his 2012 study on cave paintings in Norway. “It is like being dead or unborn.”
But why were cavemen going deep inside caves with little oxygen levels to make art? Why couldn’t they take the easier route and make the paintings at the cave entrances? “It was not the decoration that rendered the caves significant but the opposite: The significance of the chosen caves was the reason for their decoration,” the study reports. Researchers argue that caves played a significant role in the belief systems of the Upper Paleolithic Age and the paintings were representations of them. According to Barkai, cavemen used these paintings to interact with the cosmos. “It was used to get connected with things. We don’t call it cave art, it’s not a museum.” he added.
This is not the first time researchers have found cave art that was most likely created while early humans hallucinated. A study from 2020 found that Native Californians were getting high on Datura or jimson weed to make cave paintings. In 2013, researchers found that cavemen were painting while high on hallucinogens. In 2011, a 6,000 year old cave mural from Spain became popular because it suggested Europeans may have used magic mushrooms back in the day.
