The general consensus among researchers is that over the last few centuries of increasing human life expectancy most of the early gains were due to reductions in mortality in youth, such as those caused by infectious disease, malnutrition, and the like. Over time the ongoing gains in life expectancy have shifted to occur in later life due to other forms of improvement in medicine and related technologies: present trends are as much in adult life expectancy as in life expectancy at birth. This study takes a novel approach to gain a different confirming perspective from the existing data:
Life expectancy has increased continuously for at least 150 years, due at least in part to improving life conditions for the majority of the population. A substantial part of this historical increase is due to decreases in early life mortality. In this paper we analyse the longevity of four privileged sets of adults, who have avoided childhood mortality and lived a life more similar to the modern middle class. Our analysis is focused on writers and musicians from the 17th through the 21st Centuries. We show that their average age at death increased only slightly between 1600 and 1900, but in the 20th Century increased at around 2 years/decade.
We suggest that this confirms that modern lifespan extension is driven by delay of death in older life rather than avoidance of premature death. We also show that Productive Lifespan, as measured by writing and composition outputs, has increased in parallel with overall lifespan in these groups. Increase in age of death is confirmed in a group of the minor British aristocracy, and in members of the US Congress from 1800 to 2010. We conclude that both lifespan and Productive Lifespan are increasing in the 20th and early 21st Century, and that the modern prolongation of life is the extension of productive life, and is not the addition of years of disabling illness to the end of life.