The World's Oldest Drug Habit: Ancient Teeth Might Push Psychoactive Use Back 25,000 Years

Betel nuts, I had heard of them before but never quite knew what they were. In fact, until this article, I had never seen the word either; I had assumed it was a “beetle nut” because of its shape, but apparently not.

But what is it? Betel nut, or rather betel nut chewing, is a common habit practised by around 10% of the world’s population. The nut is supposedly very, very bitter and just generally unpleasant, but why chew it then? 

Well, it is valued for its stimulant effect, which produces a short-term feeling of euphoria and energy achieved through a chemical called arecoline.

Today, many people chew processed nuts, staining their teeth red. But recently, a new study of the teeth of ancient humans from Sulawesi found two unusual cases. Two ancient foragers died between 6,300–7,600 and 16,000–25,000 years ago, respectively. What made them unusual was that their teeth were not stained red; rather, they had an unusual pattern of wear, one likened to pipe smokers.

But what caused this odd wear? Did they grind their teeth against stones in their food, or habitually chew on sticks? No, the researchers argue the culprit was betel nuts, not chewed but sucked on so often and for so long they literally began carving away at their teeth.

The discovery may push back the history of betel nut use, but more so fills in a gap in our understanding of when humans first began using mind-altering drugs.

Mind-Altering Drugs and Bitter Betel Nuts

Humans across the planet have used mind-altering substances, from alcohol to mushrooms. Some are stimulants, others hallucinogens and others narcotics. Yet despite their widespread and well-documented use, we know surprisingly little about when the habit began.

The oldest evidence we have of deliberate plant-based drug use isn’t even that old. They include evidence of beer (~13,000 years old, from Israel), certain cacti and seeds in Peru and Texas (~10,400 years old), coca in Peru (~8,000 years old) and psychedelic mushrooms from the Sahara (~8,000 years old). Some people believe drug use only began after humans began farming and settling. But that doesn’t make sense either, as hunter-gatherers are known to use mind-altering substances and are known for their deep understanding of the effects of plants in their environment.

And anyway, if you’ve ever watched a documentary or googled a fun fact about animals, you may have also known that chimpanzees and elephants will sometimes purposefully eat rotting (fermenting) fruit to get a little drunk, and reindeer in the Arctic eat certain mushrooms to get high. While I doubt this was intentional, my grandpa told me a fun story about local chickens drinking the excess beer poured into the street in Mayen in the early 1900s, resulting in a drunken cacophony of fowl.

So odds are humans and pre-modern humans have been using these substances for a very long time. The problem is, we have no evidence to prove it.

Betel nut is one of these substances, often called one of the world’s oldest drugs. It comes from the fruit of the areca palm tree and is known by many names depending on the region, from betel to areca to supari and pinang.

Although it isn’t as well known in the West, it is reputedly the fourth most popular psychoactive drug in the world, behind alcohol, caffeine, and nicotine.

Its use is also rather widespread from the Pacific Islands to East Africa, into India and Southeast Asia, and parts of China. In many of these cultures, it is also an important social ritual and part of weddings, greetings and community gatherings.

Traditionally, the ‘quid’, which is a mixture of processed betel nut, slaked lime, and a leaf from the betel pepper plant, is tucked into the cheek and chewed. This is so it can quickly be absorbed into the bloodstream, but it also raises the risk of mouth cancer. Lime is a key ingredient because it converts the nut’s alkaloids into a free base form the body can absorb far more easily; arecoline then acts on the brain’s acetylcholine receptors, giving you a mild high.

To date, the oldest securely dated evidence of betel nut chewing comes from Bronze Age Thailand, where chemical traces were found on an individual between 3,000 and 3,500 years old. Thus, the common theory holds that the practice began in the Indo-Malay region before spreading via Austronesian farmers around 4,000 years ago. But what if it has a much older precedent?

Two Puzzling Sets of Teeth

While examining the remains of two adult hunter-gatherers in Sulawesi, Indonesia, researchers noted previously undocumented tooth damage. The teeth of these individuals carried smooth, hollowed-out grooves.

It suggested they had repeatedly held or sucked on something hard, similar to people who smoked clay pipes.

By themselves, these two individuals were already ancient: one individual, CPL-R2a, was 7,600–6,300 years old, while the other, Maros-LBB-1a, was a whopping 25,000–16,000 years old. Such ancient human remains are incredibly rare in hot, humid climates, where fungus, bacteria, and moisture destroy organic remains quickly. CPL-R2a was also, strangely, the only securely provenanced adult burial at a site where the other individuals were children and infants.

So finding odd dental wear only made them more special. But what caused it? The researchers wondered whether holding an unprocessed betel nut and sucking on it could have caused the patterns they were seeing.

But they weren’t certain if the betel nut would release its stimulant compounds when sucked, or if chewing was strictly necessary, so they made betel nut broth.

Betel Nut Broth

Okay, this was more complicated than just making betel nut broth, but in essence, to figure out whether whole betel nuts could release their active drug compounds just by sucking, the researchers broke, sliced, and soaked broken and intact nuts in a saline solution. They then applied the resulting liquid to frog egg cells engineered to carry the human receptors that arecoline and other brain-altering chemicals act on.

Broken nuts triggered a response, and interestingly so did the intact nuts, suggesting that even if the nut was completely intact, simply sucking on it long enough could eventually release arecoline in quantities large enough to have an effect.

But other components such as GABA and the larger molecules linked to betel’s more toxic effects were not released by whole dried nuts, though fresh nuts may release some of them.

Great, but just because it is possible doesn’t mean these two individuals were sucking on betel nuts. So how do you test it?

One of the researchers bravely sacrificed himself and has been sucking on a betel nut for 20 whole years… Okay, no, I’ll be serious.

The researchers conducted chemical tests on the teeth and found both individuals had compounds consistent with betel nut consumption, arecoline included. Tellingly, the compounds that only form when slaked lime is added to a quid were absent, exactly what you’d expect if the nuts were sucked plain.

Maybe they just ate the betel nuts for nutrition or because they liked the taste? Unlikely; betel nuts have nearly no nutritional value, and as for the taste, they are apparently horribly bitter, so food seemed out of the question.

Psychoactive side effects? A more likely motivator.

Though whether it was recreational or medicinal, that cannot be said. The nuts do cause heavy salivation, which could have helped digest starchy foods or even prevent tooth decay (i.e. cavities). The study’s authors also suspect the nuts were used as painkillers, since arecoline has mild analgesic properties.

But the habit came at a cost; both individuals had signs of severe gum disease, while CPL-R2a had worn their teeth down so much that the nerves had become exposed, likely causing chronic pain and infection.

So, what do we learn? One, betel nut chewing may have evolved from a much earlier form of betel nut sucking. Two, the findings would push back the oldest evidence of psychoactive drug use from the beginning of farming 12,500 years ago to as early as 25,000 to 16,000 years ago. And three, humanity has possibly been grappling with substance abuse for a very long time. 

That said, the evidence rests on just two sets of teeth, a limitation the authors are upfront about, though preagricultural remains from Sulawesi are so that even these two individuals are remarkable enough.

I am sure we humans, and our ancestors from Homo erectus to Australopithecus, probably used some psychoactive drugs, but the evidence is simply not there. I also wonder: if it left no physical or chemical trace, can we ever prove it happened?

Are you surprised simply sucking betel nut could cause such damage, and how far back do you think our use of psychoactive drugs actually goes?

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Reference

Adam Brumm et al., Betel nut sucking is the earliest recorded evidence for the habitual use of a neuroactive plant drug.Sci. Adv.12,eaei1901(2026).DOI:10.1126/sciadv.aei1901