A compact summary of major trends in human longevity in industrialized countries is presented in Tables 3. Amidst the incredible detail available in historical mortality statistics, we cannot help but discern two major epochs: before 1960 and after 1970. The driving trend in the former period was a rapid decline of mortality due to infectious disease, which had an impact across the age range but certainly a much larger effect at younger ages. The sharp reduction in infant and child mortality led to a rapid increase in average life span and a marked reduction in the variability of age at death. It did not, however, have a major impact on maximum life span, which rose very slowly due to the more gradual improvement in death rates at older ages.
TABLE 3 Summary of Major Trends in Human Longevity in Industrialized Countries
Average life span (life expectancy at birth)
Maximum life span (observed and verified maximum age at death)
Variability of life span (standard deviation, interquartile range, etc.)
Increasing rapidly because most averted deaths are among younger people. Very rapid reduction in infant/ child mortality linked mostly to effective control of infectious diseases
Increasing slowly mostly due to gradual reductions in death rates at older ages. (Size of birth cohorts and improved survival at younger ages matter much less)
Decreasing rapidly due to reductions in mortality at younger ages
Increasing moderately because most averted deaths are among older people. Accelerated reduction in old-age mortality linked mostly to better management of cardiovascular disease Increasing moderately due almost entirely to accelerated reduction in death rates at older ages
Stable because death rates at older ages are decreasing as rapidly as at younger ages
From the mid-1950s to the late 1960s, mortality trends in industrialized countries seemed to stabilize. Then, just before 1970, death rates at older ages suddenly entered a period of unprecedented decline. Compared to the earlier era of rapid reductions in infant and child mortality, these changes yielded a slower increase in life expectancy at birth. On the other hand, the rise of maximum life span accelerated, driven by a more rapid decline in death rates at older ages. The variability of life span tended to stabilize during this period, as the entire distribution of ages at death—now concentrated at older ages— moved upward in parallel fashion. The difference between these two distinct eras is illustrated in Table 4 for the country of Sweden.
Was this article helpful?