The historical progress of health and medicine and life-extension can be demonstrated most effectively by comparative "survival curves". By sequencing through these curves over the last 100 years and projecting forward, one gains some startling and profound observations. To the left, you may select the specific links for each decade; but it is much better to sequence chronologically by using the NEXT link.

The survival curve is a graphic representation of the percentage of a population, surviving according to age categories. In the case here, it is calibrated to numbers of survivors within a population of 100,000. Initially, at age 0, there is 100% survival, and then that percentage decreases with age as different causes of mortality take their toll. Important points of demarcation are the 50% or median survival of the group, the 0-25% or fourth quartile, and the maximum survival, with the latter reflecting the genetic potential of the specie. Improvements in those parameters and a bowing of the curve to the right demonstrate improved survival and therefore improved living conditions and medical technology. Although people talk about the "quality"of life in preference to the "length" of life, the fact remains that length is still the most objective and quantifiable criterion of quality.

Keep in mind that clinical medicine (i.e., that medicine where a doctor treats an individual's particular medical problem) did not have any impact on the improvement of population survival until after 1950, when antibiotics came into use.