Abstract
After the end of the glacial period, the temperate and subtropical zone appeared in the North American Continent due to the change of climate. In particular, California in the north-west of the Continent and in contact with the Pacific Ocean changed to an area with a mild climate and fertile soil. The forest producing acorns grew and many animals inhabited the area. In addition, the coasts, rivers and lakes changed to harbor many fish. The ancestors of aborigines moved into the area as many groups of tribal units for getting foodstuff, and established their territories as they settled down in the area. The acorn was the staple food for these people for the last five thousand years. Further, they made a unique culture and science around the acorn, and the acorn was the most important food for them until the beginning of the 20th century. Therefore, both California and Korea are the centers concerning the culture and science of the acorn in the world.
