How old is old? Revising the definition based on life table criteria.

"Sixty-five has long been thought of as the point of entry into ¿old age'. We propose a number of life table criteria for answering the following questions: If 65 was considered appropriate four decades ago, what is the corresponding age today? If 65 was (implicitly) a male-oriented definition four decades ago, as we believe it was, what would have been the appropriate definition for women at that time, and what is it today? We address these questions by applying our criteria to Canada, using 1951 and 1991 life tables, but the criteria could be applied equally well to other countries. For other developed countries we would expect broadly similar results." (EXCERPT)