Structural Causes of Increasing Life Expectancy

As I'm sure you're all aware by now, human life expectancy for both young and old in the most developed regions of the world is slowly increasing, and this has been the case for some time. As medical technology advances and our wealth grows, we benefit in ways that lead to less biochemical damage to the complex machinery of our body accumulated over the course of a lifetime - and thus a greater likelihood of living longer.

That the medical and research establishments have achieved this ongoing benefit even in advance of any structured, deliberate, large-scale efforts to slow or (more preferably) repair the consequences of aging bodes well for the future. The scientific community should be able to achieve far more impressive results when they are actually trying to directly tackle aging.

I noticed an open access paper today (PDF version included) that applies some mathematical wizardry so as to break out the most important structural contributions to increasing longevity. I think you'll find it interesting:

The ongoing increase in life expectancy in developed countries is associated with changes in the shape of the survival curve. These changes can be characterized by two main, distinct components: (i) the decline in premature mortality, i.e., the concentration of deaths around some high value of the mean age at death, also termed rectangularization of the survival curve; and (ii) the increase of this mean age at death, i.e., longevity, which directly reflects the reduction of mortality at advanced ages. Several recent observations suggest that both mechanisms are simultaneously taking place.


We illustrate the method with the evolution of the Swiss mortality data between 1876 and 2006. Using our approach, we are able to say that the increase in longevity and rectangularization explain each about 50% of the secular increase of life expectancy.

There's more of the same in a past PDF format paper by one of the same authors. A further good resource is chapter 3 of Between Zeus and the Salmon: The Biodemography of Longevity - a good read if you have the time. The book is available for free online and that chapter contains some visual examples of what is meant by rectangularization of the survival curve.

ResearchBlogging.orgRousson, V., & Paccaud, F. (2010). A set of indicators for decomposing the secular increase of life expectancy Population Health Metrics, 8 (1) DOI: 10.1186/1478-7954-8-18



Posted by: ABU BASHEER at July 18th, 2010 4:56 AM

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