[The evolutionary threshhold of age from old age: comparative approaches in France and Sweden].

The major criticism to be made concerning studies of ageing populations is that the threshold chosen as the entry into old age has remained fixed. However, in recent years, the realities of the age at which one becomes elderly have changed so much that persons in the category "over 60", for example, no longer occupy the same place in the succession of generations, the same economic and social roles as their not so distant forefathers. In particular, they no longer have the same life expectancy or the same state of health. Therefore, how are we to understand and interpret the growing proportion of older persons in our populations? To get out of this impasse, this article presents one possibility for determining an evolutionary threshold--it is one of the conditions of the comparison-- for entry into old age. It depends on the state of health of the persons concerned at each stage. This synthetic indicator has been applied in the French and Swedish populations since the mid-nineteenth century. The results underline the extent of the changes that have occurred, especially in the twentieth century, the closeness of the thresholds between the two countries at the beginning and end of the period, as well as the differences in the progress of masculine life expectancy. Although the proposed indicator can certainly be improved, it emerges strengthened by this comparative approach.