Paper short abstract:

Jomon people of Japan had high caries rates, unparalleled by any other hunters and gathers in the world. The reasons are thought to be (1) their high-carbohydrate, plant-based diet and (2) rapid aging due to excessive physical stress. Thus, they developed periodontal disease in their early middle age, resulting in multiple root caries.

Paper long abstract:

The Japanese Neolithic period lasted 10,000 years until the Jomon period ended 2700 years ago. My study determined that the caries rates in Jomon people were much higher than other hunters and gathers in the world. The high caries rates in the Jomon people were strongly dependent on high-starch, plant-based diet. In addition, they aged rapidly due to their difficult living environment, i.e., severe environmental stress. Their carious lesion did not develop on the occlusal surfaces where many carious lesions in modern people are located. Jomon people had marked attrition, causing flat occlusal surfaces. This condition was speculated to decrease susceptibility to occlusal caries. They developed periodontal disease in their early middle age, resulting in the exposure of roots to the oral environment. Roots are covered cementum which is softer than enamel. Thus, multiple root caries was thought to have occurred in the Jomon people. Root caries is a type of caries often seen in the modern elderly. The high rate of root caries suggests rapid aging in the Jomon people and that individuals in that society had a short life span.