Limits to aging and longevity
The rise in human longevity is one of humanity’s crowning achievements. Although advances in public health beginning in the 19th century initiated the rise in life expectancy, recent gains have been achieved by reducing death rates at middle and older ages. A debate about the future course of life expectancy has been ongoing for the last quarter-century.
Some suggest that historical trends in longevity will continue and radical life extension is either visible on the near horizon or has already arrived. Others propose that there are biologically based limits to the duration of life, and those limits are being approached now. A growing compilation of research is starting to point towards there being limits to human longevity. Observed mortality trends in the United States since 1990 indicate definitively that the rate of improvement in life expectancy in the United States has decelerated dramatically.
So, predictions of radical life extension just by boosting lifespan independent of healthspan are unlikely to be forthcoming. That suggests that there may be a greater benefit to aging and longevity if the primary goal of medicine and public health is to focus on healthspan extension instead of thinking purely of lifespan extension. Promoting advances in aging biology may allow humanity to break through biological barriers that influence both healthspan and lifespan, allowing for a welcome extension of the period of healthy life, a compression of morbidity, but only a marginal further increase in life expectancy.