High-Carb Diet Caused Dental Disease In Prehistoric Hunter-Gatherers

British scientists have discovered some of the earliest evidence of tooth decay in the skeletal remains of Stone-Age hunter-gatherers who lived in Africa more than 13,700 years ago. The researchers attribute the dental disease to a high-carbohydrate diet of starchy plants and nutty foods that wreaked havoc on the teeth of these ancient humans. The fermented carbohydrates in the nuts caused cavities, tooth decay and bad breath, the researchers said in a paper about the findings published Monday in the journal Proceedings of the National Academy of Sciences (PNAS).

Dental disease was long thought to have originated with the introduction of farming and changes in food processing about 10,000 years ago, when humans began eating processed foods on a wide scale. Toothaches were presumed rare among hunter-gatherers, but the current study suggests tooth decay may have been more prevalent in prehistoric societies than previously believed, the researchers said.

The findings were based on an analysis of 52 adult dentitions from African hunter-gatherer skeletons found in Morocco’s Taforalt Cave dating from between 15,000 and 13,700 years ago. The remains were uncovered in the 1950s as well as during more recent excavations that began in 2003.

Evidence of decay was found in more than half of the teeth that were intact, with only three skeletons showing no sign of cavities. That is far higher than the rate of tooth decay typically seen in other hunter-gatherers, which has ranged from zero to 14 percent, the study’s authors said.

This “exceptionally high prevalence of caries” is comparable to “modern industrialized populations with a diet high in refined sugars and processed cereals,” the researchers said.

Furthermore, the poor condition of the hunter-gatherers’ teeth suggests these ancient humans were often in pain.

“At a certain point, the tooth nerve dies but up until that moment, the pain is very bad and if you get an abscess the pain is excruciating because of the pressure on the jaw,” explained the study’s lead author, Dr. Louise Humphrey from London’s Natural History Museum, in an interview with BBC News. “Then, of course, the bone eventually perforates and the abscess drains away, and we see this in a lot of the jaw remains that we studied.”

The scientists used accelerator mass spectrometry to date the remains and powerful microscopes to identify the fossils of plant material that included acorns, pine nuts, juniper berries, pistachios and wild oats. The remnants of acorns were so numerous that researchers concluded the nuts must have been harvested and stored for eating as a staple food all year long.

With little oral hygiene, this diet would have facilitated the growth of mouth bacteria which produce an acid that rots tooth enamel.

“Sweet acorns are neat, easily storable packages of carbohydrate. We think they were cooking them, and that would have made them sticky. The cooking process would have already started to break down the carbohydrates, but the stickiness of the food would then have got into the gaps in the teeth and literally stuck around. And if you’ve already got cavities, it becomes a bit of a vicious circle,” Dr. Humphrey said.

Long esparto grasses were also identified in the excavation, and were likely used to weave baskets for carrying nuts, storing them and even cooking them, the researchers said.

“This is the first time we have documented this set of behaviors in the Iberomaurusian,” a distant culture that thrived in the Maghreb, Dr. Humphrey told the AFP. The Iberomaurusians are described as complex hunter-gatherers that inhabited Taforalt between 13,000 and 15,000 years ago.

Dr. Humphrey said the study also provides “the earliest documented evidence of systematic exploitation of wild plant resources in hunter-gatherers from Africa.”

The study’s authors concluded that this “increased reliance on wild plants rich in fermentable carbohydrates and changes in food processing caused an early shift toward a disease-associated oral microbiota in this population.”