If you measure age simply as time already lived, things are pretty darn simple for population statisticians. Yet, if age is adjusted to take into account the time left to live, well, the status quo flies out the window and things begin to get interesting. Faster increases in life expectancy do not produce faster population aging, say researchers who developed new measures of aging and applied them to projections of residential lifespans in Europe.
“If you don't consider people old just because they reached age 65 but instead take into account how long they have left to live,” Sergei Scherbov, a researcher at International Institute for Applied Systems Analysis, stated in a press release, “then the faster the increase in life expectancy, the less aging is actually going on.”
Today, most everyone over the age of 50 is arguing (rather loudly) that traditional measures of age no longer work. Age is not a number and what once was considered middle-aged is still young. (You heard me!) And though people in their 20’s might disagree — at least they do for now — it is pretty clear to everyone, no matter where they find themselves along the time-on-earth continuum, that people vary a lot in terms of health and ability at every age. Exercising regularly, eating nutritious foods, protecting your skin against sun damage, remaining present, as the yogis say, in your life, you can look and feel awfully good well into and beyond middle-age.
So how do we measure our precious lives? Sure we all know your ages and generally conform to the Western calendar, but, existentially speaking, don’t we think of our lives in terms other than years passing? We remember moments of love, we remember early sorrows, we remember the feeling of spring breezes at the back of our knees. No matter how many email reminders pop up — no matter how often we glance at the clock — it isn’t the minutes we count but experiences to tell us where we are, where we can be found, within this one most precious life.
And so we return to calculations of population aging. The researchers looked at the proportion of the population categorized as old using conventional measures that assume age 65 is old and compared that to the proportion of the population considered old based on their new measure of age, which incorporates changes in life expectancy. Next, the study examined three scenarios for future population aging in Europe. In one scenario, for example, they used an increase in life expectancy of about 1.4 years per decade, the level projected by the Wittgenstein Center's European Demographic Datasheet.
As expected, a faster increase in life expectancy led to faster population aging when people are simply categorized as old at age 65. However, when the researchers used new measures of age, faster increases in life expectancy led to slower population aging.
“Older people in the future will have levels of many characteristics exhibited by younger people today,” wrote the authors in their published study. Going forward, they hope to redefine age by developing a new model that includes comprehensive measures of health and disability.
Source: Sanderson WC, Scherbov S. The Characteristics Approach to the Measurement of Population Aging. Population and Development Review. 2013.