Living Forever is Hard, part 2: Adult Longevity

by gwern 8y9th Sep 201111 comments

13


Following Fight Aging's "A Primer on Compression of Morbidity" today to Fries's 2011 review article "Compression of Morbidity 1980–2011: A Focused Review of Paradigms and Progress" (Fries, incidentally, introduced the concept of "compression of morbidity" in 1980), I found some interesting details in it.

From section 3:

Mortality changes can be tracked with acceptable accuracy using the Vital Statistics of the United States or other sources [16]. Figure 2 summarizes the US data since 1900, which is generally similar to that of other developed nations. All measures of longevity increase monotonically for almost all years, providing periodic headlines and prophecies of impending crises. The real message, however, is that longevity gains from age 65 and above are quite slow and probably getting slower.

...Table 1 shows the average number of years of life remaining from 1900 to 2007 from various ages, combining both sexes and ethnic groups. From birth, life expectancy increased from 49.2 years (previously estimated at 47.3 years in these same sources) in 1900 to 77.9 in 2007, a gain of life expectancy of nearly 29 years and a prodigious accomplishment. The increase was largely due to declines in perinatal mortality and reduction in infectious diseases which affected mainly younger persons. Over this period, developed nations moved from an era of acute infectious disease to one dominated by chronic illness. As a result, life extension from age 65 was increased only 6 years over the entire 20th century; from age 75 gains were only 4.2 years, from age 85 only 2.3 years and from age 100 a single year. From age 65 over the most recent 20 years, the gain has been about a year [16].

Much confusion in longevity predictions comes from using projections of life expectancy at birth to estimate future population longevity [18]. For example, “If the pace of increase in life expectancy (from birth) for developed countries over the past two centuries continues through the 21st century, most babies born since 2000 will celebrate their 100th birthdays” [29]. Note from the 100-year line of Table 1 that life expectancies for centenarians would be projected to rise only one year in the 21st century, as in the 20th. Such attention-grabbing statements follow from projecting from birth rather than age 65, thus including infant and early life events to project “senior” aging, using data from women rather than both genders combined, cherry-picking the best data for each year, neglecting to compute effects of in-migration and out-migration, and others.
...Over the 107-year base period, the increase in life expectancy from birth over that from age 65 is approximately fourfold; over the 27-year base, it is less than twofold, documenting a flattening of the rate of increase in more recent periods (in the US). The “Point of Paradox” is the point at which the converging lines would cross. With the 107-year base, the Point of Paradox occurs in 2035 at an average age of 85.4.
...Since 1980 [1], we have performed similar calculations using data from many nations and many baseline periods and from different ages, with congruent results. The maximal average age ranges from 85 to about 93 years, with later base periods tending to be higher, and Japan and several other countries higher than the US We estimated the US maximum average life expectancy at 85 years in 1980, and now at 90 years. US White females currently project to 90.1 years. Thus, given generally stable trends, the maximal attainable mean life expectancy appears to be greater than 90 years and is almost certainly less than 100, far less than the 150 to 200 years still projected by some enthusiasts [29]

Related material is in Mike Darwin's ongoing series, "Interventive Gerontology":

  1. The Basics
  2. Diet,  Part 1
  3. Diet,  Part 2
  4. Diet,  Part 3

13