Life-Span Extension

Demography is the science that deals with human longevity, among other things. Demographers have learned to be very careful about accepting claims of extraordinary longevity, because there is a very human tendency to exaggerate one's age after a certain point. A combination of good documentation and continual historical verification of identity help to rule out those who are making untruthful claims.

Demographers who work on human longevity have documented that the human life expectancy is going up rapidly, and has been doing so since about 1850. Overall mortality rate (the probability of death per year) has shown a consistent decline during the same period. Most of the increase in longevity in the nineteenth and early twentieth centuries resulted from better nutrition and from public health and sanitation measures used to prevent the spread of disease (e.g., inoculations to prevent early childhood diseases). These seemingly simple interventions have almost eliminated early causes of death and are responsible for the increased longevity and decreased early-life mortality seen throughout the twentieth century.

Since 1950, the increase in life expectancy has continued. In this period, the decline in mortality rate in developed countries has occurred largely in the older populations. Indeed, the population of adults age eighty-five and older showed the fastest rate of decline in mortality between 1950 and 2001. There is considerable debate about whether or not there is an upper limit to life span, but since mortality in the oldest cohorts is dropping most rapidly it seems unlikely that there are built-in limits to human longevity.