Ancient teeth suggest humans were using psychoactive betel nuts 25,000 years ago, pushing the history of habitual drug use deep into the Ice Age.
Archaeologists from Griffith University have found evidence suggesting that humans were using mind-altering substances far earlier than previously believed.
The research team, led by Professor Adam Brumm of Griffith’s Australian Research Centre for Human Evolution (ARCHE), combined archaeological discoveries with biochemical evidence to investigate the deep history of betel nut use. ARCHE researchers Associate Professors Carney Matheson and Michelle Langley also contributed to the work.
Betel nut is one of the most widely used addictive stimulants in the world and has a long history across the Asia-Pacific region. Working with archaeologists from Makassar’s University of Hasanuddin and Indonesia’s National Research and Innovation Agency (BRIN), the researchers found evidence that some communities in Indonesia may have been using it as a drug as far back as 25,000 years ago.
That pushes the practice far beyond earlier estimates that placed its origins in the Neolithic or Bronze Age (~3500 years ago).
Rethinking the Origins of Human Drug Use
One influential view of early psychoactive drug use holds that such traditions became established after the rise of farming during the Neolithic period. Fermented alcoholic drinks, including barley beer made about 13,000 years ago in Israel, have often been cited among the earliest examples.
“However, this theory fails to account for the possibility that very ancient drug-taking lies at the roots of our most commonly used psychoactive substances,” Professor Brumm said.
Brumm and his colleagues focused on betel nut because its use remains widespread today. Hundreds of millions of people between India and the South Pacific consume it (about one in 10 of the modern global population).
Betel nut can produce mild euphoria and increased alertness, along with other effects.
“Although poorly known in Western societies, it is the world’s fourth most widely used psychoactive substance, after alcohol, caffeine and nicotine,” Professor Brumm said.
Today, people typically prepare the drug using a processed seed from the Areca catechu palm (the betel “nut”). The seed is mixed with slaked lime – commonly made by grinding burnt shells into a fine powder – and other ingredients to make a “quid,” which is then chewed to get high.
“Slaked lime is an essential ingredient because it causes a chemical reaction that releases the nut’s psychoactive compounds into the bloodstream more rapidly,” Professor Brumm said.
Until now, tracing the practice deep into prehistory has been difficult because areca seeds rarely survive at archaeological sites.
Ancient Teeth Reveal a Prehistoric Habit
In the new study, published in Science Advances, the researchers examined exceptionally rare remains belonging to two early human foragers from Sulawesi, Indonesia.
One individual lived between 25,000 and 16,000 years ago, while the other dates to 7600-6300 years ago.
Both hunter-gatherers had an unusual pattern of tooth damage consisting of deep, rounded tooth grooves. The researchers identified this wear pattern as a new bioarchaeological marker linked to a previously unknown way of consuming the drug: repeatedly sucking whole betel nuts.
Earlier research had generally suggested that the nut’s main neuroactive chemical, arecoline, becomes especially potent when processed betel nut is chewed with slaked lime. The lime converts arecoline into a free base form, increasing its bioavailability.
“But our team conducted experiments in which we soaked betel nuts in artificial saliva and tested the resultant broths against a panel of cloned human receptors expressed in frog egg cells, including specialized proteins that act as molecular switches, regulating neural activity,” Professor Brumm said.
“This showed that just sucking on intact betel nuts will release arecoline in sufficient amounts to have a physiological effect, altering brain function.”
The evidence did not stop with the unusual wear on the teeth. Biochemical testing led by Associate Professor Carney Matheson detected arecoline inside the dental tissues of the ancient foragers.
That chemical signature provided strong evidence that the individuals had actually consumed betel nut.
Together, the dental wear and biochemical evidence indicate that early people on Sulawesi may have repeatedly sucked whole betel nuts over long periods, leaving dramatic marks on their teeth.
A Painkiller With Painful Consequences
The effects of sucking whole betel nuts may have been weaker than those produced by modern quid chewing, but the researchers believe the habit still had serious consequences for dental health.
Ancient foragers on the island generally had poor teeth, while arecoline itself has natural analgesic (“painkiller”) properties. The researchers therefore suspect that some people may initially have sucked the nuts to reduce tooth pain.
The relief may have come at a steep cost.
“Over time, however, sucking these hard, abrasive seeds wore down the foragers’ teeth so badly that in some cases the inner pulp chamber became completely exposed – this would have been extremely painful, caused difficulty eating, and greatly increased the rate of chronic tooth infection,” Professor Brumm said.
“So while this habit may have been a remedy for toothache, years of prolonged nut-sucking eventually caused much worse dental health problems, creating a cycle of continued habitual use.”
In other words, a practice that may have started as a way to relieve discomfort could eventually have caused even more pain and damage, potentially encouraging further use.
Drug Use May Reach Back to the Ice Age
The discovery could significantly change how researchers think about the history of human psychoactive drug use.
Rather than emerging only after the rise of agriculture, habitual betel nut use may already have existed during the Late Pleistocene.
“Emerging by up to 25,000 years ago in Sulawesi, thus long preceding the onset of agriculture, betel nut-sucking may be the earliest evidence for drug use anywhere in the world,” Professor Brumm said.
“By identifying the ancient practice underlying betel-nut chewing as we know it, the study implies that some modern drug-taking behaviors are deeply rooted in forager traditions.”
The results suggest that regular psychoactive substance use, along with some of its health consequences, may already have been part of hunter-gatherer life tens of thousands of years before farming began.
Reference: “Betel nut sucking is the earliest recorded evidence for the habitual use of a neuroactive plant drug” by Adam Brumm, Fakhri, Melandri Vlok, Roger L. Papke, Carney D. Matheson, Budianto Hakim, Clare Stokes, Basran Burhan, Suryatman, Andi Muhammad Saiful, Michelle C. Langley, Pratiwi Yuwono, Delta Bayu Murti, Sofwan Noerwidi and Marlon N. R. Ririmasse, 9 September 2026, Science Advances.
DOI: 10.1126/sciadv.aei1901
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