A most interesting experience is that of the people of Iceland. The island was settled in the ninth century by colonists from Scandinavia and Ireland. The colonists took with them cattle and sheep, but no poultry. The latter were not introduced until about a century ago. Their diet was practically carnivorous in character for several hundred years. Since agriculture did not prove profitable, they subsisted on milk, mutton, fish, and in some parts of the island during the summer, eggs were added to the fare. Very little vegetable food was eaten. The health conditions on this regimen were good and dental caries were unknown until after about 1850. Stefansson exhumed 96 skulls from a cemetery dating from the ninth to the thirteenth centuries and presented them to the Peabody Museum of Harvard University. These have been described by Hooton (6), who found that there were no evidences of caries in any of them. There were but three or four defective teeth in the entire series, and these had suffered mechanical injury. During the last half century the incidence of caries has steadily increased in Iceland, and apparently because of changes in the character of the diet. Everywhere in Europe and America during the last century the use of degerminated cereal products such as bolted wheat flour, degerminated corn-meal and polished rice has steadily increased, owing to the extension of commerce and the changed conditions with respect to the relative numbers of urban and rural population. Not only has the amount of cereal products consumed greatly increased, but the modern milling methods have greatly reduced their quality by removing the germ and the bran layer.

It is very suggestive that such diets as we are discussing as in use in recent years are so poor as to produce faulty teeth in experimental animals, and that the teeth of mankind have deteriorated so rapidly within the last century.