25,000-year-old teeth yield earliest evidence of drug use

Ancient teeth from the Indonesian island of Sulawesi have yielded the oldest known evidence of habitual drug use, suggesting hunter-gatherers were sucking on psychoactive betel nuts as far back as 25,000 years ago — thousands of years before humans began farming.

The study, published September 9 in the journal Science Advances, was led by Professor Adam Brumm of Griffith University's Australian Research Centre for Human Evolution, working with Indonesian archaeologists from the University of Hasanuddin and Indonesia's National Research and Innovation Agency.sciencedaily+1

Ancient Grooves Tell a Story

The researchers examined the skeletal remains of two adult hunter-foragers unearthed at separate cave sites in South Sulawesi. One individual, a man who died between the ages of 40 and 50, lived between 25,000 and 16,000 years ago during the coldest phase of the last ice age. The second, whose sex could not be determined, lived between 7,600 and 6,300 years ago.bbc+1

Despite being separated by at least 10,000 years, both individuals shared a striking trait: deep, rounded grooves worn into their teeth, unlike any previously documented form of prehistoric dental wear. The grooves were consistent with repeatedly holding and sucking a hard, roughly spherical object — matching the size and shape of a whole betel nut.theconversation+1

"I was thinking, what the hell were these people doing? It's like someone had a drill head shaped like a gobstopper and wore away the inner part of the tooth," Brumm told The Guardian.zmescience

Chemical Confirmation

Chemical analysis of the ancient teeth detected arecoline, the main psychoactive alkaloid in betel nuts, while finding none of the compounds that appear when betel nut is mixed with slaked lime — confirming these individuals were sucking intact nuts rather than preparing them in the modern fashion. To test whether this method could produce a drug effect, the team soaked whole betel nuts in artificial saliva and applied the resulting solution to frog egg cells engineered with human brain receptors. The experiments confirmed that sucking alone releases enough arecoline to alter brain function.abc+3

The researchers believe the practice may have started as pain relief. Both individuals suffered from chronic dental problems, and arecoline has analgesic properties. But the habit created what Brumm described as a "vicious cycle": prolonged nut-sucking wore grooves so deep that, in one individual, the tooth's inner pulp cavity was fully exposed.livescience+1

Rewriting the Timeline

Previously, the oldest documented evidence of drug use was fermented beer brewed roughly 13,000 years ago in what is now Israel. The Sulawesi discovery pushes that timeline back by at least 3,000 years and potentially as many as 12,000 years.archaeologymag+2

"Although poorly known in western societies, it is the world's fourth most widely used psychoactive substance, after alcohol, caffeine and nicotine," Brumm said. Today, an estimated 600 million people chew betel nut mixed with slaked lime across South and Southeast Asia and the Pacific. The study suggests this modern custom evolved from the simpler, older practice of sucking the raw nut, with the addition of slaked lime arriving around 4,000 years ago.bbc+2

Sofia Samper Carro, an archaeologist at the Australian National University who was not involved in the research, called the evidence compelling. "I'm convinced that even earlier hominids, such as Neanderthals, would have used natural remedies to fight pain and infection," she said.abc