Teeth from 52 skeletons dating back between 13,700 and 15,000 years showed evidence of widespread decay, with only three individuals showing no sign of cavities.
The hunter gatherers pre-dated the rise of farming, which has previously been blamed for a big increase in dental problems linked to carbohydrate-rich foods.
Scientists believe the cause of their molar misery was a diet largely dependent on wild acorns and pine nuts.
Both contain high levels of fermentable carbohydrates that are especially destructive when they lodge in teeth because of the oral bacteria they attract.
Relying on harvesting abundant wild nuts may also have led the hunter gatherers to live a more sedentary lifestyle than was previously thought.
"These people's mouths were often affected by both cavities in the teeth and abscesses, and they would have suffered from frequent toothache," said researcher Isabelle De Groote, from London's Natural History Museum, who studied the teeth.
The skeletons were recovered from Grotte des Pigeons, a cave system at Taforalt, Morocco containing a plethora of preserved Stone Age remains.
Scientists have found charred remains of foods that would have been cooked and eaten by the cave residents. "We use the charred fragments to identify plants that were carried back to the cave including foods items, such as acorns and pine nuts, and grasses that were used to make baskets," said palaeobotanist Dr Jacob Morales.