Researchers have recently suggested that Paleolithic cave paintings may have been painted by cave dwellers who were on drugs.
Due to the cave paintings' geometric patterns that are commonly seen while high on certain hallucinogens, the researchers believe the painters may have been consuming these drugs before letting out their creative side.
They also believe the painters deliberately went out and sought these drugs, likely in plant form, to heighten their artistic ability.
Paleolithic art seen in caves is similar across the world, giving rise to the conclusion that the artists everywhere may have been taking the same drugs to produce the same inspiration.
This hints that cave paintings included a mix of rituals which induced altered states of perception for its participants.
"The prevalence of certain geometric patterns in the symbolic material culture of many prehistoric cultures, starting shortly after the emergence of our biological species and continuing in some indigenous cultures until today, is explained in terms of the characteristic contents of biologically determined hallucinatory experience," the researchers said.
The reason painters were drawn to the same kinds of shapes might be due to some hallucinations inducing the brain to see "neural" patterns, or the structure of brain cells.
"Researchers also generally gleam that the geometric hallucinations experienced by the subject are mental representations of these neural patterns," the wrote. "However, while these neural models are capable of reproducing some of the geometric patterns that are found in prehistoric art and non-ordinary visual experiences, their range remains severely limited."
"We speculate that the self-sustaining dynamics may account for why these geometric hallucinations were experienced as more significant than other phenomena, and that at the same time their underlying neural dynamics may have served to mediate and facilitate a form of imaginary sense-making that is not bound to immediate surroundings."