Long before humans planted the first crops, hunter-gatherers on the Indonesian island of Sulawesi were already chewing a mind-altering nut heavily enough to permanently reshape their teeth. A study published this month in the journal Science Advances identifies grooves and chemical residue in prehistoric teeth as the oldest known physical evidence of habitual drug use anywhere in the world, pushing the record back roughly 25,000 years.
Grooves That Puzzled Researchers at Leang Bulu Bettue
The find began with a set of molars and a jaw fragment recovered from a cave called Leang Bulu Bettue in southern Sulawesi, belonging to an individual who lived between 16,000 and 25,000 years ago. The teeth carried deep, rounded grooves unlike any dental wear pattern researchers had documented before, according to the team led by archaeologist Adam Brumm of Griffith University in Australia. A second set of teeth from a different individual who lived between 6,300 and 7,600 years ago, found at another site on the island, showed the same distinctive grooves, this time severe enough to expose the tooth pulp and raise the risk of infection.
Chemical Traces Confirm the Betel Nut
To identify what caused the wear, the researchers tested the size and shape of the grooves against objects the foragers might have handled repeatedly, and settled on the seed of the areca palm, commonly known as the betel or areca nut. Laboratory analysis of the dental tissue then turned up traces of arecoline, the psychoactive compound in the nut, in both sets of remains, a finding the study published in Science Advances describes as close to definitive proof. To confirm the compound could actually be released through sucking rather than chewing, the team soaked betel nuts in artificial saliva and applied the resulting liquid to frog egg cells engineered to carry human brain receptors, demonstrating that arecoline transferred out of the nut even without it being crushed. Brumm has described the arecoline traces as close to a smoking-gun proof, since dental wear alone could theoretically have other explanations, but combined chemical and physical evidence from two individuals separated by thousands of years leaves little room for an alternative reading.
A Habit That Likely Began as Pain Relief
Betel nuts numb the mouth, and the researchers suspect the practice started as an attempt to dull the pain of a toothache rather than for recreation. The nuts’ numbing effect appears to have set off a damaging cycle: the more the prehistoric individuals sucked on the nuts, the more their teeth deteriorated, which likely increased the pain that drove them back to the nuts in the first place. Modern betel nut users typically grind the nut and mix it with slaked lime to intensify the psychoactive effect, a method the study’s authors believe emerged later than the simpler sucking behavior documented in the Sulawesi remains, meaning the ice-age foragers likely experienced weaker effects than today’s users.
Older Than the Previous Record by Thousands of Years
Before this discovery, the oldest confirmed evidence of drug use came from residue of a wheat-and-barley beer found in Israel’s Raqefet Cave, dated to around 13,000 years ago and associated with ritual feasting. The Sulawesi teeth predate that beer evidence by more than 10,000 years and predate the emergence of agriculture on the island entirely, suggesting that people were already managing pain and altering their mental states with plant compounds well before farming, pottery or permanent settlements existed. Independent archaeologists who reviewed the study, including Elisa Guerra-Doce of Spain’s University of Valladolid, called the dental-wear marker a genuine new tool for detecting drug use in remains too old to preserve organic residue any other way. Sofia Samper Carro, an archaeologist at the Australian National University who was not involved in the study, said the findings may push other researchers to look for even earlier evidence, suggesting that Neanderthals and other early hominids likely relied on natural remedies to manage pain and infection long before modern humans developed the specific habit documented on Sulawesi.
A Practice That Continues Among Hundreds of Millions Today
Areca nut chewing remains widespread in the present day, with an estimated 600 million people worldwide continuing the habit, most of them combining the nut with slaked lime or tobacco in a way the Sulawesi foragers apparently did not. Public health researchers now link the modern version of the habit to oral cancer, cardiovascular disease and the same kind of dental damage first documented in these prehistoric remains, giving the ancient discovery an unusually direct line to a health issue still affecting a large share of the world’s population, largely across South and Southeast Asia and the Pacific. Both sets of prehistoric teeth came from limestone caves in the same general region of Sulawesi that has separately produced some of the oldest known figurative rock art anywhere in the world, part of a broader pattern in which the island’s caves keep pushing back the timeline for milestones in human behavior once assumed to have emerged only in Europe or the Middle East.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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