The 25,000-Year-Old Evidence of Drug Use

What if humans were deliberately using mind-altering plants thousands of years before farming, permanent settlements or the first known alcoholic drinks?

A new archaeological discovery from the Indonesian island of Sulawesi suggests that humans may have been using a psychoactive plant as far back as 25,000 years ago.

The evidence comes not from a written record, a ceremonial object or a preserved stash of plants.

It comes from human teeth.

A strange pattern in ancient teeth

Researchers examining the remains of two prehistoric individuals from Sulawesi noticed something unusual.

Their teeth contained deep, rounded grooves and extensive wear that could not easily be explained by ordinary eating.

The older individual lived sometime between approximately 25,000 and 16,000 years ago, during the last Ice Age. The second individual lived thousands of years later, approximately 7,600–6,300 years ago.

Despite the enormous gap between them, both showed remarkably similar patterns of dental damage.

The researchers proposed that the damage resulted from repeatedly holding and sucking hard, abrasive objects in the mouth.

One possibility stood out. Betel nuts.

The betel nut

Despite its name, the betel nut isn't actually a nut. It is the seed of the Areca catechu palm.

Today, areca nuts are commonly consumed throughout parts of South and Southeast Asia and the Pacific. They are often prepared with betel leaf and slaked lime, producing a psychoactive chew known as a betel quid.

The active compound of particular interest is arecoline, which affects the nervous system and can produce stimulation, increased alertness and other psychoactive effects.

But the ancient Sulawesi practice may have been considerably simpler.

Rather than preparing a modern-style quid, the researchers believe people may have simply sucked on whole betel nuts.

Could simply sucking a nut really have an effect?

The researchers tested the idea. They soaked betel nuts in artificial saliva and analysed what was released from them. The resulting solution contained arecoline.

They then tested the solution against cells carrying human receptors to investigate whether the compound could produce a physiological effect.

The results suggested that sucking an intact betel nut could release enough arecoline to affect human neurological pathways — although the effect would have been weaker than modern betel chewing with slaked lime.

That makes the unusual tooth wear considerably more interesting.

It wasn't simply evidence of someone putting an object in their mouth. There was a plausible psychoactive substance capable of being released through the behaviour.

Medicine, pleasure — or both?

But why were Ice Age people doing it? This is where the evidence becomes much harder to interpret. The researchers suggest that toothache relief may have been one reason.

Betel nut can produce a numbing sensation in the mouth. Someone suffering from painful teeth could have discovered that sucking the nut temporarily reduced the pain.

But there is an unfortunate twist.

The same behaviour could gradually cause severe wear to the teeth.

That creates a potential vicious cycle: tooth pain → betel nut → temporary relief → repeated use → dental damage → more pain → more betel nut

The ancient individuals had such extensive dental wear that the researchers believe the habit may have been extremely prolonged.

Of course, pain relief may not have been the only motivation. The psychoactive effects could themselves have been desirable.

There may have been cultural, social or ritual reasons for using the plant that have simply disappeared from the archaeological record.

Before farming

Perhaps the most significant aspect of the discovery is when it happened. 

The oldest individual lived during the Ice Age, long before agriculture had transformed human societies.

For a long time, discussions about the origins of psychoactive substance use have focused on much later periods.

One commonly cited early example is fermented barley beer from the Levant, dating to roughly 13,000 years ago.

The Sulawesi evidence potentially moves the known history of habitual psychoactive plant use back by another 12,000 years.

These weren't farmers cultivating specialised drug crops. They were prehistoric foragers living in a world of forests, animals, stone tools and constantly changing environments.

Yet they appear to have recognised that a particular plant could alter how they felt.

How old is the human search for altered states?

This raises a much bigger question. Humans have probably been experimenting with plants for as long as humans have been capable of observing the effects of plants.

Some plants relieve pain. Others cause illness. Some alter perception. Others stimulate, sedate or produce unusual sensations. A curious hunter-gatherer didn't need modern chemistry to discover that eating or sucking a particular plant could produce an unusual effect. They simply needed to notice what happened.

The Sulawesi discovery therefore doesn't necessarily represent the first time humans ever used a psychoactive substance.

It represents something more important archaeologically: the oldest evidence currently identified for habitual human drug use.

There may have been much earlier examples that simply left no surviving evidence.

A habit that survived thousands of years

Modern betel use gives the discovery another fascinating dimension. The practice hasn't disappeared.

Hundreds of millions of people across Asia and the Pacific still consume areca products today, although modern preparation is considerably more elaborate.

That means a tradition that may have roots stretching back into the Ice Age could have persisted, changed and spread across generations for thousands of years.

We don't know whether today's practice descends directly from the behaviour represented by the ancient Sulawesi teeth.

But the possibility is striking.

The evidence in our mouths

Archaeologists often search for ancient drugs in pottery, pipes, seeds, residues and burial objects.

Here, the evidence was hiding somewhere much more personal. Inside the teeth of people who died thousands of years ago. Their damaged enamel may be recording a behaviour that would otherwise have vanished completely.

And it raises a provocative possibility.

Perhaps the human relationship with psychoactive plants isn't a relatively recent development associated with civilisation.

Perhaps it is something much older. Something that began with hunter-gatherers, long before cities, agriculture and written history — when people were still discovering, one plant at a time, what the natural world could do to the human mind.