Imagine a world without toothbrushes, mouthwash and dental floss. That’s an easy one, right? There would be rotten teeth in every mouth, and rich dentists in every town.

The earliest prehistoric human ever found in Africa seemed to confirm as much. In 1921, miners working at Kabwe, or Broken Hill, in what is now Zambia, came across a primitive looking skull.

Look into the mouths of most other early human fossils and you’ll rarely find a dental cavity

It had a sloping forehead, giant brow ridges and cavities in 10 of its teeth. The Broken Hill skull’s original owner, an adult male who belonged to our ancestor species Homo heidelbergensis, may even have died as a consequence of his poor oral health.

But here’s the surprise: the Broken Hill skull is a strange (and still largely unexplained) anomaly. Look into the mouths of most other early human fossils and you’ll rarely find a dental cavity. Strangely, for millions of years of human prehistory our ancestors were blessed with generally good oral health - even though their dental healthcare consisted of little more than the use of simple toothpicks.

In fact, rotten teeth only became a common problem very recently - about 10,000 years ago - at the dawn of the Neolithic period, a time when our ancestors began farming. Relatively sophisticated dentistry emerged soon after. In the last decade or so archaeologists have found evidence from cultures across the world that bad teeth were scraped, scoured, even drilled and filled apparently to remove decayed tissue.

Or, to put it another way, it looks like the dental drill predates writing, civilisation, and even the invention of the wheel by thousands of years.

Tooth decay is not entirely absent from pre-agricultural societies, but it’s very rare. “The frequency of caries among hunter-gatherers is roughly 1-5% and around 6-8% among populations with mixed subsistence strategies,” says Alejandra Ortiz at New York University. “This contrasts with agriculturalists, who show frequencies between 10% and up to 80-85%.”

Carbohydrates, in general, are bad for teeth

The rise of rotten teeth was first recognised in the 1970s, says Marc Oxenham at the Australian National University, and relatively quickly archaeologists decided that it must be explained by the shift to carbohydrate-rich diets that came with farming.

“I guess the increasing clinical awareness - or marketing of the idea at least - that sugars are bad for teeth was also occurring at this time,” he says. “Many archaeologists made the seemingly logical leap that carbohydrates, in general, are bad for teeth.”

The idea does make some sense. Some oral bacteria, such as Streptococcus mutans, convert carbohydrates into enamel-destroying acids - and these species must have thrived in the mouths of early farmers. But Oxenham and some other researchers think that diet alone can’t explain why dental caries became so common worldwide.

“In regions such as Asia, where the dominant farmed crop is rice, the evidence for changes in oral health and the rise of agriculture is very messy,” says Oxenham. “Using a dietary model to explain oral health changes in Asia does not work very well at all.”

Instead, teeth may have suffered because of another change that farming brought: a massive increase in population size. Farmers tended to stay put rather than wander as their hunter-gatherer societies had done before them. They could usually rely on more predictable food supplies than their ancestors.

Women’s oral health was worse than men’s in early farming societies

Both factors contributed to a rise in fertility rates. This was bad news for the oral health of women – for example, hormonal changes during pregnancy has known links to increased inflammation of the gums. It also leads to changes in the pH of saliva that make it less able to neutralise the acids associated with tooth decay

“I do still think that the influence that the Neolithic transition had on women’s health in general is still under-appreciated,” says James Watson at the Arizona State Museum, who has studied the link in the Americas.

There’s plenty of evidence that women’s oral health was worse than men’s in early farming societies, says Oxenham. “Our work has looked at ancient Asian communities and found a correlation between increased fertility and major declines in female oral health,” he says.

We don't know exactly how important these competing factors were in explaining why farming brought such a sudden and dramatic rise in the number of rotten teeth but what's clear is that prehistoric societies didn’t simply put up with the pain. They understandably began exploring ways to soothe sore mouths. And so they invented dentistry.

Whether early dentistry helped relieve the pain from rotting teeth is debatable

At the moment, the earliest potential evidence we have for therapeutic dentistry comes from just before the dawn of farming, at a time when pre-farming communities were already beginning to consume the sorts of carbohydrate-rich grains and starches that would later be farmed.

Last year, Stefano Benazzi at the University of Bologna, Italy, and his colleagues took a closer look at a 14,000-year-old adult male skull that was found on a dig in Italy in the late 1980s. They discovered signs that the biting surface of one rotten tooth in the jaw had been deliberately scoured and scraped with a tool - perhaps in an effort to remove the decayed tissue.

Under a microscope, the scratches on the tooth look similar to those that a finely crafted small flint blade - a “microlith” - might make. This tool technology was relatively new at the time. 

The improvement in tools like this could have spurred their use for rudimentary dental treatment, says Benazzi. The research team even experimented with modern teeth and similar sorts of microliths to confirm that these fine tools could have made such marks.

Whether this early dentistry really helped relieve the pain from rotting teeth is debatable - in the case of the 14,000-year-old Italian patient, the surgical procedure managed to remove only part of the decayed tissue. More effective treatment would only come a few thousand years later with the invention of better technology: the first dental drill.

We don’t know for sure where it was first invented, but some researchers believe it was being put to use in what is now Pakistan, between about 9,000 and 7,500 years ago. There, in a Neolithic graveyard, scientists discovered evidence that at least nine different individuals had gone under the drill. All of them had molars with precise holes - each just 1 to 3mm in diameter - bored into the biting surfaces. One individual had actually undergone the procedure three times on different teeth.

Under a microscope the researchers found concentric ridges on the internal walls of some of the holes. They say these holes were not simply made by careful scraping but as a result of drilling.

It might seem remarkable that such ancient people could fashion a dental drill with basic materials, but it's a technology that still exists.

It took under a minute to drill holes of the kind seen in the 9,000-year-old teeth

Some indigenous societies today carve holes in objects using a tool called a bow-drill. This consists of a few sticks of wood, a sharp stone, and a length of cord. The cord is tied to either end of one flexible stick, making it look like a small version of an archer’s bow.

The cord is then wrapped tightly around a second stick held perpendicular to the “bow”. By simply moving the bow back and forth, this second stick will rotate just as a drill does. Attaching a sharp stone to the end of this drill increases its cutting power. 

To get an idea of whether a stone-tipped bow-drill could function in dentistry, the research team working in Pakistan constructed a bow-drill and attempted to drill holes in human enamel. The results were surprising; it took under a minute to drill holes of the kind seen in the 9,000-year-old teeth.

Inevitably, though, there are still those who doubt that such early societies had the wherewithal to drill teeth. “There is still debate about whether bow-drilling was used in the Late Upper Paleolithic or [whether] holes were produce by percussion [hammering or scraping],” says Benazzi.

A prehistoric dentist might even have given his patients local anaesthetics

What might help to convince sceptics is more evidence of similar sorts of dentistry in early farming societies. Last year Ortiz and her colleagues found exactly that - almost half the world away from Pakistan in the pre-Hispanic societies of Peru. They examined the remains of two individuals who lived about 550 and 650 years ago. Both teeth contained the same tiny round holes as seen in the 9,000-year-old teeth from Pakistan.

“It appears to me that the way the drilling was done included two different tools,” says Ortiz. “A rotary drilling followed by some sort of micro-tool for scraping.”

What’s more, she says there is emerging evidence of drilling in a different Peruvian culture - the Yschma – a society which dates back more than 1,000 years.

There, a prehistoric dentist might even have given his patients local anaesthetics, such as coca leaves, to mask the pain of the operation. “They are generally used as painkillers, so it is likely that either coca leaves (or any other medicinal plant) were used as anaesthetics,” says Ortiz. “Especially considering the great knowledge of traditional medicine that pre-Hispanic peoples appear to have had.”

As good as dental drilling is at removing decayed tissue, there is one more skill a dentist needs: the ability to fill the tooth after treatment. Remarkably, there is some evidence that fillings have prehistoric roots too.

In 2012, Claudio Tuniz at the International Centre for Theoretical Physics in Trieste, Italy, and colleagues were testing new state-of-the-art 3D imaging technology. One specimen they examined was a 6,500-year-old human jaw (below). It was found about 100 years earlier in a cave near the village of Lonche in what is now Slovenia. The researchers noticed something unusual attached to one tooth. It turned out to be a cap of beeswax, as old as the tooth. It had been applied to fill a hole in the enamel.

Beeswax would actually have made a reasonably good filling material. That's because it is soft and easy to work when warmed but becomes solid at human body temperature. It also has the added benefit of antibacterial and anti-inflammatory properties. 

The idea of dental drilling still scares many of us today

“It seems that the canine of our Lonche Man remains the earliest dental filling that has been discovered so far,” says Tuniz. “I was recently contacted by Guinness World Records since our discovery exceeds their current record. They are still evaluating our case.”

The Trieste Natural History Museum, where the specimen is housed, is already convinced of its importance. “Until 2012 the mandible [jawbone] was in a small corner of the museum, while now it is the star of the museum and has its own special room, enriched with images from our analyses,” says Tuniz. It's already “a big attraction for school kids”. 

And you can imagine why. Despite our rapidly advanced dental technology, the idea of dental drilling still scares many of us today. Now imagine your teeth being drilled by Neolithic tools and our ancestors suddenly appear a great deal braver than us. They must have known the true fear of a trip to the dentist. 

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