This swirly red flower scrawled on a cave wall some 400 years ago is the first definitive evidence that Native Americans consumed hallucinogenic drugs at rock art sites. 

Discovered in California’s Pinwheel Cave, the cave art is thought to depict a Datura wrightii, a flowering plant that’s part of the nightshade family and known to hold both poisonous and hallucinogenic properties. But the evidence of psychoactive indulgences at this cave goes much further than just a doodle of a flower; archaeologists have now used chemical analysis to show that chewed residue of the hallucinogenic flower can be found in the cracks and crevices of the cave.

Reporting in the journal Proceedings of the National Academy of Sciences, the team argues this serves as "the first clear evidence for the ingestion of hallucinogens at a rock art site." Contrary to previous theories, however, they suspect that the artist was not a shaman under the influence of the mind-altering plant.

It's well established that some Native American cultures, as well as many other cultures across the world, used Datura in spiritual ceremonies and rites of passage. However, this is the first time researchers have discovered physical traces of the drug in a cave alongside rock art. To reach this conclusion, a team of archaeologists, chemists, and forensic experts used liquid chromatography?mass spectrometry to discover the presence of hallucinogenic alkaloids scopolamine and atropine in the chewed lumps of plant material found embedded in the cave walls. Scanning electron microscope analysis was then used to confirm the alkaloids came from a Datura wrightii.

It's also no coincidence, they argue, that the artwork depicts a showy flower-like shape with five elegantly curled petals, just like the flower of many Datura species. 

Their discovery has some important implications for what we know about the creation of rock art and altered states of consciousness. For decades, a dominant theory has posited that many instances of rock art were created by shamans in a trance-like state while they were high on psychedelic drugs. This is often suggested due to the trippy patterns and surreal imagery found in the rock art, yet researchers have never found any clear evidence for the consumption of hallucinogenic substances at any rock art site in the world.

Now, the new study has found this direct evidence of drugs at rock art sites. However, the researchers argue their new discovery challenges the “high shaman” model since they believe the artist was not high when they were creating this illustration, nor was it meant to depict this individual’s personal psychedelic experience. Instead, the art is more likely meant to act like a sign showing individuals that this was a space where this important plant was ingested. Like a stained glass window in a church, the artwork depicts a culturally important image that's relevant to the space and is not meant to show the vivid drug-induced images in the artists’ minds.