ポスト人口転換社会における緩和策と適応策

Abstract

During the 20th century, Japanese society experienced dramatic demographic changes accompanied by shifts in the epidemiological and health-related domains. During this demographic transition, mortality rates have declined, life expectancy has increased, and fertility rates have declined. Since 2008, the population has decreased and is expected to continue decreasing, with a higher average age. These changes are associated with shifts in the distribution of employment opportunities ; in the composition of households ; and in the balance between rural and urban populations, in favor of the latter, with jobs moving from the agricultural sector to manufacturing and service industries. Lifestyles have changed, social bonds have weakened, and the economic gap between generations and genders has increased. These changes have challenged society's ability to provide adequate and financially sustainable medical and nursing services while also reducing the potential environmental burden on future generations. The close relationship between demographic and social changes underlying this transition renders it difficult to mitigate the effects of future aging and shrinking of the Japanese population. Indeed, to develop strategies for the post-transition reality, various scenarios related to the population dynamics of the future must be examined. To this end, we suggest replacing the concept of chronological age with one of biological and societal age. Biological age can be represented by life-expectancy-equivalent age or by healthy life-expectancy-equivalent age, and societal age can be represented by age-structure-equivalent age. A healthy aging population should be promoted by developing sound relations between health and the natural, man-made, and societal environment.