SULAWESI, Indonesia — Humans may have been deliberately using mind-altering plants thousands of years earlier than scientists once believed — and the evidence was hiding in prehistoric teeth.
Researchers examining the remains of two hunter-gatherers from the Indonesian island of Sulawesi say they have uncovered what may be the earliest known evidence of habitual human use of a neuroactive plant drug.
The substance was not alcohol, cannabis or an exotic hallucinogen.
It was areca nut, commonly known as betel nut — a stimulant still consumed by hundreds of millions of people across Asia and the Pacific today.
But what stunned researchers was not simply what these ancient people were using.
It was how long ago they were doing it.
One individual may have lived 25,000 years ago
The study, published in Science Advances, examined rare skeletal remains of two pre-agricultural foragers found at separate archaeological sites in South Sulawesi.
The older individual lived sometime between roughly 16,000 and 25,000 years ago. The second dates to approximately 6,300 to 7,600 years ago.
Both displayed remarkably similar damage to their teeth despite being separated by thousands of years.
Deep, rounded grooves had been worn into their teeth — in some cases penetrating so deeply that the sensitive dental pulp would likely have been exposed.
Study leader Professor Adam Brumm of Griffith University said the unusual wear initially left researchers struggling for an explanation.
The shape suggested something small, hard and rounded had repeatedly been held and moved inside the mouth over long periods.
The prime suspect eventually became the seed of the Areca catechu palm.
Then scientists found the chemical evidence
Dental wear alone would not have been enough to prove betel nut use.
So researchers looked for chemical traces.
Their biomolecular analysis detected arecoline, the principal neuroactive alkaloid found in areca nut, in the ancient dental material — evidence consistent with repeated exposure to the plant.
Researchers also tested whether simply sucking an intact nut could release enough arecoline to affect the nervous system.
They soaked areca nuts in artificial saliva and then tested the resulting solution using laboratory cells engineered with human neurological receptors.
The experiments indicated that prolonged sucking could release biologically active arecoline even without the preparation methods widely used today.
That finding matters because modern areca-nut users typically chew processed nut together with ingredients such as slaked lime, which increases the availability and intensity of its active compounds.
The Sulawesi hunter-gatherers may have been practicing a far more primitive version of the same habit: holding and sucking whole nuts inside the mouth for extended periods.
Were they getting high — or treating pain?
That is where the discovery becomes even more intriguing.
Arecoline has stimulant and psychoactive effects and can produce heightened alertness and mild euphoria.
But researchers believe pleasure may not have been the only reason prehistoric people used the nut.
Brumm suggested its numbing properties could have made it an early form of toothache relief.
Sucking the nut can make the mouth feel numb, potentially easing existing dental pain.
There was just one devastating problem.
Repeatedly holding the hard, abrasive nut against the teeth appears to have gradually worn them away.
That means the substance that may initially have relieved pain could eventually have created even more pain.
Some grooves were severe enough to expose the dental pulp, potentially causing chronic toothache and infection.
Researchers therefore raised the possibility of a self-reinforcing cycle: a person uses the nut to relieve discomfort, the habit damages the teeth further, and worsening pain encourages continued use.
That explanation remains a hypothesis rather than a proven motive. Archaeologists cannot know precisely what prehistoric individuals were thinking or why they adopted the habit.
The discovery pushes drug history deep into the Ice Age
For years, much discussion of early human psychoactive-substance use focused on societies that appeared after the development of agriculture.
Evidence from Israel, for example, has suggested people were producing fermented beverages roughly 13,000 years ago.
The Sulawesi discovery pushes evidence of habitual psychoactive plant use several thousand years further back — potentially into the Late Pleistocene, or Ice Age.
Independent archaeologist Sofia Samper Carro of the Australian National University, who was not involved in the research, told ABC that the evidence predates previously published examples of drug consumption by thousands of years.
Dr. Elisa Guerra-Doce of Spain’s University of Valladolid similarly told The Guardian that the work provides direct evidence of the deep antiquity of psychoactive plant use.
Researchers nevertheless emphasize that this does not mean humans first discovered mind-altering substances 25,000 years ago.
Earlier humans — and perhaps other hominins — could have experimented with psychoactive or medicinal plants much earlier.
Organic plant material simply survives poorly in tropical archaeological environments, making direct evidence extraordinarily difficult to preserve.
Betel nut is still used on a massive scale
The discovery also connects prehistoric behavior to a practice that remains widespread.
Areca nut is still consumed across South Asia, Southeast Asia and Pacific communities and is often combined with betel leaf, slaked lime and sometimes tobacco to create what is commonly called betel quid.
The Science Advances paper describes modern betel-nut chewing as a habit practiced by roughly one in 10 people worldwide.
That makes the Sulawesi discovery particularly significant: rather than uncovering an extinct prehistoric custom, researchers may have identified an ancestral form of a practice that survived for thousands of years.
But modern medicine carries a stark warning
The archaeological finding should not be interpreted as evidence that areca nut is safe because humans have used it for millennia.
The opposite is true.
The International Agency for Research on Cancer, part of the World Health Organization, classifies areca nut as carcinogenic to humans.
IARC says betel quid without tobacco can cause oral cancer, while areca-nut consumption is also associated with oral submucous fibrosis, a potentially precancerous condition.
Arecoline itself — the principal active chemical detected by researchers — has been classified by IARC as possibly carcinogenic to humans.
In other words, the painful consequences visible in Ice Age teeth may represent an ancient version of health problems that continue today.
Why the discovery matters
The most important implication goes beyond betel nut.
For much of human history, hunter-gatherers have sometimes been portrayed primarily as people focused on survival — finding food, avoiding predators and coping with harsh environments.
But discoveries like this suggest their relationship with plants was far more sophisticated.
They were apparently experimenting not only with what plants could feed them, but also with what plants could change pain, mood, alertness and consciousness.
That behavior may have eventually contributed to medicinal traditions, ritual practices and recreational drug use across human societies.
And because the Sulawesi skeleton is merely the oldest evidence scientists have found so far, the true story could stretch much deeper into prehistory.
Twenty-five thousand years ago may not mark the beginning of humanity’s relationship with psychoactive drugs. It may simply be the oldest chapter that archaeology has managed to preserve.
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