Okinawa: an exception to the social gradient of life expectancy in Japan.

This paper examines why the social gradient of life expectancy does not apply in Japan when Okinawa is considered. The social gradient thesis links differences in longevity to social rank, with people and populations in higher status hierarchical positions having lower mortality and longer life expectancies than those beneath them in the social scale. Japan has been cited as a major example of this thesis in that Japanese life expectancy improved dramatically as Japan rose to the top echelon of nations in economic rank in the late 20th century. Thus it follows that Japan's most affluent and leading prefectures should be the major catalysts behind the nation's rise in life expectancy as well to the number one position in the world. However, this is not the case as life expectancy in Okinawa, Japan's poorest prefecture, exceeds that of Japan as a whole. We find that the social gradient of life expectancy does not apply at the prefectural level and question its validity for geographical areas. We suggest that healthy lifestyles, especially diet and the social support of family and friends, are more important than sense of hierarchy for longevity in Okinawa.