Adam Brumm, Carney D Matheson, Fakhri, Melandri Vlok & Roger Papke
Humans have long used mind-altering substances, but surprisingly little is known about how these drugs were first incorporated into daily life. A study we published in Science Advances now uncovers the prehistoric roots of betel nut use in the Asia-Pacific region, pushing its origins back to the Ice Age.
After alcohol, caffeine and nicotine, betel nut is the world’s fourth most widely consumed psychoactive substance. Known to induce mild euphoria and heightened alertness, it is also linked to high rates of oral cancer among habitual users. While written accounts in India and China date back 2,000 years, and the earliest archaeological evidence from Thailand was placed at 3,500 years ago, new findings show the habit began much earlier—perhaps 25,000 years ago.
The discovery stems from archaeological excavations in South Sulawesi, Indonesia, where researchers unearthed skeletal remains of two adult hunter-foragers. One was dated between 25,000 and 16,000 years ago, and the other between 7,600 and 6,300 years ago. Despite living millennia apart, both individuals exhibited unusual, deep rounded grooves in their teeth.
Unlike any documented prehistoric dental wear, the marks pointed to an activity performed repeatedly over extended periods. Researchers concluded the foragers had held a hard, roughly spherical object between their teeth while sucking on it, wearing down the enamel. In one individual, the wear was so severe that the pulp chamber — the living core of the tooth — was fully exposed, a condition that would have caused intense pain.
The notches resembled the "clay pipe facets" seen in colonial-era smokers who clenched abrasive pipe stems. This led researchers to the seeds of the Areca catechu palm, which match the size and shape of the grooves.
Today, betel is consumed as a "quid" — an areca seed mixed with slaked lime and other ingredients. Slaked lime speeds up the absorption of psychoactive compounds and stains teeth red. However, the Sulawesi teeth showed neither red staining nor modern chewing patterns, suggesting that ancient foragers simply sucked intact nuts.
To test if sucking releases brain-altering chemicals, researchers soaked intact betel nuts in artificial saliva and tested the extract on frog egg cells engineered with human brain receptors. The test confirmed that saliva exposure releases arecoline, the principal psychoactive alkaloid. Biomolecular analysis of the ancient teeth subsequently detected traces of arecoline, confirming the foragers habitually sucked betel nuts.
The habit may have been driven by a need for pain relief. Both individuals suffered from chronic dental problems, and arecoline possesses analgesic properties. This creates a cruel irony: while sucking betel nuts offered temporary relief, the physical friction further damaged their teeth, likely compelling them to continue the habit.
Conventional models link the earliest drug traditions to the advent of farming around 12,500 years ago. These findings demonstrate that plant-based drug use has much deeper roots, showing that Ice Age hunter-foragers were already experiencing health trade-offs from long-term substance use long before agriculture emerged.