What may be the earliest known evidence of human drug use suggests that it occurred 25,000 years ago, according to findings by archaeologists that push back on earlier estimates by over 10,000 years.
In a recent paper published in Science Advances, an international team of researchers led by Professor Adam Brumm from Griffith University’s Australian Research Center for Human Evolution (ARCHE) discovered betel nut residue on ancient teeth in Indonesia.
Betel nuts are an addictive stimulant popular throughout the Asia-Pacific region, which researchers previously believed only came into use about 3,500 years ago. Globally, archaeologists had believed psychoactive drugs had been tied to the rise of agriculture.
Betel Nuts: the First Drugs
Archaeologists typically point to Israel’s brewing of fermented alcoholic drinks, such as those made of barley, as the earliest use of psychoactive drugs, roughly 13,000 years ago.
“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.
Betel nuts are only regionally popular in India and the South Pacific, but their use is almost ubiquitous among the 10% of the world’s population that lives there. The psychoactive effects of the stimulant include enhanced alertness and mild euphoria.
The betel nut is the seed of the Areca catechu palm. Locals burn its shell, then grind it into a fine powder and mix it with slaked lime, another powder made from quicklime and water. They mix these powders with other minor ingredients, wrap them in a betel leaf, and chew them to produce a mild altered state.
Research on the drug suggests that this processing releases Arecoline, the neuroactive alkaloid present in the betel nut, in a more bioavailable form. Modern usage is linked to cancer, gum disease, and tooth decay, making it a significant public health problem in regions where it is used.
A Prehistory of Betel Nut Usage Uncovered
The seeds were rarely preserved in archeological sites, creating a great deal of uncertainty about the drug’s early history.
Human remains used in the study came from Sulawesi, one of the islands that make up Indonesia. There, archeologists uncovered two hunter-gatherer skeletons: one dating to 7,600 to 6,300 years old and the other 25,000 to 16,000 years old.
These skeletons carried an unusual signal, which the team interpreted as related to ancient drug use. Their teeth had deep, rounded grooves that the researchers believe developed from the habit of sucking on whole betel nuts. Biochemical analysis further supported this interpretation by identifying Arecoline in the remains’ dental tissues.
“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,” said lead author Professor Adam Brumm. “This showed that just sucking on intact betel nuts will release Arecoline in sufficient amounts to have a physiological effect, altering brain function.”
Rethinking Prehistory
This crude attempt to use the betel nuts as a drug likely produced a milder high, while also promoting periodontal disease. Given the poor state of the teeth in human remains previously found on the island, the team believes the betel nuts may have initially been used as a toothache remedy, though it was a poor choice for that purpose.
“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.”
Pushing back the use of these psychoactive substances so far significantly rewrites our understanding of human drug history.
“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 concluded. “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 paper, “Betel Nut Sucking is the Earliest Recorded Evidence for the Habitual Use of a Neuroactive Plant Drug,” appeared in Science Advances on September 9, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.