Aging is central to human experience. As we grow up, we acquire language, and as we grow old, our language adjusts to changing requirements. In the process of being passed on from one generation to the next languages change. This is a well-known fact, true of every language. However, little is known about the actual process and velocity of linguistic change, whether some languages change faster than others, and, if so, why. Are a speech community's average age and life expectancy significant variables in this regard? The effects of demographic changes on language are largely unexplored.

Greying Japan now has the world's oldest population. How can the effects of the aging society on the Japanese language be observed, described and explained? Average life expectancy since Meiji has almost doubled. What is the impact of social aging on intergenerational communication, and how does it affect the extent of linguistic differences between co-existing age cohorts? These are questions of considerable theoretical interest. However, in the context of the all-encompassing transformation Japan is undergoing at the present time the effects on language constitute no more than a minor facet of a large picture. Yet, they highlight the pervasiveness of the ongoing changes that leave nigh on no arenas of social, economic, political and cultural life unaffected. The present transformation of Japan is driven by recent demographic trends: the democratisation of longevity and declining fertility. These trends are themselves the outcome of a complex interplay of social, economic, political and technological developments. The investigation of language change in aging Japan is just one small piece to a big jigsaw puzzle. The deeper currents of the big transformation we are witnessing today we can only understand by carefully looking at the pieces and trying to assemble them to yield the larger picture. In this sense I hope to contribute to DIJ's research focus, "Challenges of Japan's demographic change."

Japan's population has the highest average age and the highest life expectancy of the world. The resultant “demographic time bomb” is the greatest challenge Japan faces today. Many problems arising from this situation have been identified, but only few solutions. What will be the consequences of the demographic development? Will depopulation occur to the extent of current projections? What kind of redistribution measures will be necessary as a result? How can social, economic and educational policies be co-ordinated to do justice to the changing age structure of the population? Will immigration policies come under pressure? How will the needs of an ageing population affect the relationship of state and society? How do markets adjust to satisfy these needs? How will the democratisation of longevity influence intergenerational and gender relations? What will be the impact of the growing proportion of the old and the very old on elections, political power relations and cultural production? How will declining fertility affect the social behaviour of coming generations? These are questions that are confronting several advanced industrial nations with increasing urgency. Japan is one of them. Where will it pursue its own solutions, where will it be forced to yield to structural constraints and reveal tendencies to conform or converge with other capitalist democracies? By means of individual projects and interdisciplinary co-operation the DIJ research focus, “Challenges of Demographic Change”, seeks answers to these questions, trying thereby to contribute to the German-Japanese dialogue about problems of common concern.