A diet rich in starchy foods may have led to high rates of tooth decay in ancient hunter-gatherers, said a new study published in the Proceedings of the National Academy of Sciences.

The research led by a team from Oxford University and the Natural History Museum challenges the long-held view that dental disease was linked to the advent of farming. Their research shows widespread tooth decay occurred in a hunter-gathering society in Morocco several thousand years before the dawn of agriculture.

The researchers analysed 52 sets of adult teeth from hunter-gatherer skeletons found in Taforalt in Morocco, dating between 15,000 and 13,700 years ago. Unexpectedly, they found evidence of decay in more than half of the surviving teeth.

Archaeological deposits at Taforalt include a deep ashy layer with exceptionally well preserved charred plant remains. Excavations revealed evidence of the systematic harvesting and processing of wild foods, including sweet acorns, pine nuts and land snails.

"A reliance on edible acorns as a staple food could account for the high prevalence of cavities in the teeth found at Taforalt, since eating fermentable carbohydrates is a key factor in the initiation and progression of this disease." Lead researcher Louise Humphrey at the Natural History Museum said.

The researchers also added that, the acorns may have been boiled or ground to make flour; cooking the acorns would have added to their stickiness, and abrasive particles from grindstones contributed to rapid tooth wear so that caries started to form on the roots of the teeth.