This analysis is not an attempt to estimate a biological limit of human longevity beyond which no human being can live but rather, in a much more pragmatic and modest fashion, to measure the life expectancy at birth of a population enjoying the lowest age- and cause-specific death rates in the world at a given time. By repeating the same calculations for different periods, we can also see how this life expectancy changes over time. This was done systematically for each year from 1950.
We have reached two major conclusions. First, the ideal life expectancy that emerges from such calculations has not stopped increasing for the past 50 years, and has risen at a sustained pace, similar to that of the best life expectancy actually observed. In addition, the suspicions of implausibility that such an indicator may initially arouse prove unfounded when we realize that the ideal level reflecting the conditions of a given year is reached, and even largely exceeded at times, by almost all advanced countries 25 years on, among women at least.