Scientists now believe they have unearthed the earliest evidence of human use of psychoactive drugs, tracing it back 25,000 years to foragers inhabiting what is now Indonesia.
Two skeletons, discovered on the island of Sulawesi, exhibit distinct signs that their owners habitually sucked on betel nuts. This substance is still consumed today in various parts of the world as a recreational drug.
These rare skeletal remains belonged to pre-agricultural foragers found at two separate archaeological sites. One individual lived approximately 7,000 years ago, while the other dates back between 16,000 and 25,000 years. This places their use of betel nuts significantly earlier than the first known human consumption of alcohol or other psychoactive substances.
Both skeletons displayed unusually deep, rounded grooves in their teeth, with the wear pattern exposing the dental pulp. Furthermore, traces of arecoline, the psychoactive compound inherent in betel nuts, were detected within the teeth.
Writing in Science Advances, a team led by Adam Brumm from the Australian Research Centre for Human Evolution, Griffith University, Brisbane, suggested that this distinctive dental wear was likely caused by the repetitive sucking of the nuts. Brumm stated, "With the earliest forager dating to 25 to 16 thousand years ago, our findings suggest the use of betel nut as a drug has more ancient origins than previously supposed."
The researchers noted that, in contrast to modern users who chew processed nuts, these ancient ancestors would have sucked the nuts whole. This practice was still effective in releasing the psychoactive compounds contained within the betel nuts.
The contemporary custom of chewing betel nuts is practiced by roughly one in ten people globally. Today, the seeds of the Areca catechu palm (commonly known as betel nuts) are typically combined with slaked lime—a substance made by grinding burnt shells or other calcium-rich materials—to create a chewable mixture known as a "quid." They are traditionally wrapped in leaves of the betel vine before consumption, hence the common name.
The researchers theorised that people might have consumed betel nuts in a simpler form before discovering that the addition of slaked lime enhanced the release of the psychoactive compound, thereby producing a stronger effect. To test this hypothesis, they immersed betel nuts in artificial saliva. The liquid rapidly accumulated sufficient arecoline to induce a psychoactive effect, although the researchers conceded that this effect would have been weaker than that achieved by chewing processed nuts.
Subsequent analysis of the ancient teeth confirmed the presence of arecoline within the dental tissues. These findings could potentially push back the documented history of deliberate drug use by several millennia. While it is probable that humans experimented with mind-altering plants far back into prehistory, the oldest previously known instances of psychoactive substance use have been linked to fermented drinks, dating back approximately 13,000 years with early forms of beer. The discoveries in Sulawesi indicate that the pursuit of altered states of consciousness may have commenced much earlier, among hunter-gatherer communities who experimented with naturally occurring plants long before the advent of agriculture facilitated the cultivation and easier processing of such plants.