Ancient Teeth Found in Indonesia Reveal Earliest Known Evidence of Drug Use, Study Finds

Thousands of years before humans discovered fermented beer or cultivated crops, hunter-gatherers on the Indonesian island of Sulawesi were apparently sucking on betel nuts — and a striking set of ancient teeth is the evidence. A new study led by researchers at Griffith University has found what scientists are calling the earliest known evidence of habitual psychoactive substance use, pushing humanity's relationship with mind-altering plants back by tens of thousands of years.

What the Ancient Teeth Revealed

The study, led by Professor Adam Brumm at Griffith University, examined the teeth of two skeletons unearthed on Sulawesi. One set of remains dated to between 16,000 and 25,000 years ago; the other to between 6,300 and 7,600 years ago. Both sets of teeth displayed an unusual pattern: deep, rounded grooves that couldn't be explained by ordinary chewing or diet.

After careful analysis, researchers concluded these distinctive grooves were caused by a previously unrecognised behaviour — the habitual sucking of betel nuts over extended periods. The repeated contact of the hard palm seed against the teeth wore them down in a characteristic way that archaeologists had not previously associated with drug use.

The betel, or areca, nut is a seed from a palm tree native to Southeast Asia and is currently the fourth most widely used psychoactive substance in the world, ranking behind only alcohol, caffeine and nicotine. Today it is typically mixed with slaked lime powder and chewed, a combination that boosts its stimulant properties and can induce mild euphoria and heightened alertness.

A Drug Habit That Predates Modern Chewing Practices

The critical distinction in this discovery is that the ancient hunter-gatherers were not chewing betel nut in the modern sense. The addition of slaked lime — which dramatically amplifies the psychoactive effect — came much later. Instead, researchers believe these early humans were simply sucking on the raw nut, most likely for pain relief rather than to get high.

"We think this was a longstanding cultural tradition of drug use that predated the invention of betel nut chewing as we know it today," Professor Brumm said. "We think this is how humans discovered the mind-altering properties of this particular type of drug."

While the researchers could not entirely rule out some psychoactive effect from sucking the raw nut, Brumm was clear about the likely motivation: "We can't exclude that they were getting a psychoactive hit but … we don't think they were getting high on sucking betel nut."

In fact, the study points to a self-reinforcing cycle of use that may be startlingly familiar to modern eyes. Continuous sucking of the betel nut gradually wore down the teeth of ancient users, leading to cavities and intense dental pain. That pain, in turn, likely prompted greater use of the nut for its analgesic properties — a loop of dependency that researchers describe as an addictive cycle driven by the very damage the behaviour was causing.

Rewriting the Timeline of Human Drug Use

Before this discovery, the prevailing view among researchers was that the world's first traditions of deliberate psychoactive substance use emerged after the Neolithic agricultural revolution. The earliest previously known example was fermented barley beer, with evidence dating back roughly 13,000 years from the region now known as Israel — a product of settled, farming societies.

The Sulawesi findings shatter that timeline. They suggest that habitual psychoactive substance use was already embedded in human behaviour among hunter-gatherers, potentially tens of thousands of years before agriculture existed. Professor Brumm described the find as the earliest known evidence both of the deliberate consumption of a psychoactive plant product and of habitual drug use in the archaeological record.

The implications extend beyond curiosity about ancient habits. Brumm noted that the health costs associated with habitual drug use — the dental destruction documented in these ancient individuals being a stark example — were present in human populations long before the structures of farming or settled civilisation emerged. This reframes our understanding of how deeply entwined psychoactive plant use is with the human story.

Over generations, it is thought, ancient peoples eventually discovered that combining betel nut with slaked lime produced a far more powerful stimulant effect, driving the evolution of the chewing practice that remains common across parts of Asia and the Pacific today. That transition from passive sucking to active, chemically enhanced chewing represents one of humanity's earliest experiments in refining a drug for greater potency.

What This Means for Our Understanding of Human Behaviour

The study adds significant weight to the idea that the human impulse to seek out and habitually use mind-altering substances is ancient and deeply rooted — not a by-product of civilisation, but a feature of our species long before cities, farms or written language. The grooves in two sets of ancient teeth on a remote Indonesian island have quietly redrawn one of the more provocative chapters in the story of what it means to be human.

For Australians interested in the science of health, behaviour and what researchers are learning about substances that alter the body and brain, this discovery serves as a reminder that our relationship with psychoactive compounds is far older — and more complex — than previously imagined.