Prehistoric Humans Knew the Secret of Healthy Teeth, Say Scientists

Archaeologists analyzing dental plaque in Sudan found a 7,000-year history of eating a bitter root that killed cavity-producing bacteria.

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This uncovered herbivore jaw illustrates the principle: Crud found on the teeth can tell tales about diet (illustration).
This uncovered herbivore jaw illustrates the principle: Crud found on the teeth can tell tales about diet (illustration).Credit:
Ruth Schuster
Ruth Schuster

Prehistoric humans in Sudan cooked and ate plants - and at least one of them was to stay healthy, surmise archaeologists based on analysis of the plaque on teeth found at a site called Al Khiday.

The analysis concludes that through millennia, these individuals consistently ate the root of a perennial weed called sedge, that tasted absolutely terrible but that provided a rich source of carbs – and killed the bacteria causing cavities, note the researchers in a paper published earlier this month in Plos One.

Evidence of the ingestion of sedge was found in all the plaque samples tested, spanning some 7,000 years from pre-agrarian to farming society. Since the weed tastes bitter, the scientists wondered why people continued to eat it after starting to cultivate tastier plants, and postulate: Perhaps the people realized the added value of the tuber. They certainly don't today - latter-day farmers are mainly concerned with getting the awful weed off their fields.

It is difficult to analyze the vegetable diet of prehistoric man; evidence is often circumstantial. But once the remains of a plant – chemical compounds or signature micro-fossils – are found in plaque, one may conclude that the person in question had the plant in his mouth.

The plaque also presented soot deposition from smoke, which doesn’t mean these individuals had prehistoric cigarettes, rather, that they cooked their food on open fires. Evidence from starch granules found in the plaque shows these ancient peoples both roasted and boiled their food, according to the researchers.

Read here: Neanderthals ate their veggies too

The Al Khiday study, led by the University of York and the University of Barcelona, spans a complex of five prehistoric sites 25 kilometers south of Omdurman, down the White Nile River in Central Sudan. One of the sites was used for burials over a period of thousands of years, stretching from a pre-agricultural, fisher-hunter-gatherer era to the early agricultural era in the early Neolithic period, to the more developed farming culture characteristic of the Meroitic era.

It is there that the mystery of the missing cavities arose.

Make no mistake. The people whose remains were found at the site had plenty of dental woes, including worn-down enamel and caries. What baffled archaeologists was that the specific samples from the Meroitic farming period had plenty of plaque – but very few cavities.

Normally the transition to a farming lifestyle is associated with an increase in carbohydrates in the diet and hence an increase in cavities. The more sugars you eat, the more likely you are to have happy bacterial films and, therefore, plaque. Indeed the farming folk at the site had the most evidence of plaque – but they didn’t have more cavities. If anything they had less.

The results were based on positive findings of seven samples – seven others did not produce enough organic material to allow a proper analysis.

Plaque is created when bacterial films build up on the teeth and mineralize. It is found on teeth dating from all periods. Your dog has it, too, by the way.

Interestingly, the scientists found heavier hydrocarbon "char" markers – soot deposition on teeth from consuming food cooked over fire – in the Neolithic samples. Analysis of starch granules found in the plaque dating to that era reveal that these individuals cooked the roots more than later peoples did, but the area in which they'd settled was also becoming drier and hotter, which could point to a lesser need for fire for warmth, leading to less cooking, the researchers postulate.

Another intriguing find was that the protein intake of the individuals studied varied greatly.

The plaque found in the remains at Al Khiday also show that the people also chewed raw plants not to in order to eat them, but to process them for raw materials.

The climatic conditions back then were different, the scientists explain. Today the area in question is desert. In the Stone Age, it was savannah characterized by heavy rainfall, though it began to dry out during the Neolithic and Meroitic periods, they note. In any case the ancient peoples there ate sedge throughout the 7,000-year period, even after they began cultivating other plants – which may testify to the fact that they were indeed aware of the vile root’s beneficial properties. It is possible that their ancient insight was passed onto subsequent civilizations: The ancient Greeks and Egyptians wrote of using sedge in perfume and medicine.

You know this weed. It sticks to your legs. But ancient peoples in the Sudan ate its roots, possibly to keep their teeth healthy.Credit: Wikimedia Commons

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