The Mega Foundation
Gerontocracies 2 - Discussion
12/2/2002

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Longevity Index

    As someone who lived through 70 years of the above 100-year increase in life span from 47 in 1900 to 77 in 2000, I should, perhaps, comment on the changes that people actually observed over that time of transition.
There were long-lived individuals in the 1900's
    First, most people had relatives who lived at least into their 70's, and many of us had relatives who died in their 90's. Much of the limitation in life span must have occurred during the early years, in the form of infant and child mortality caused by infectious diseases. I grew up expecting to, hopefully, live into my 90's.
    Second, there were centenarians then as well as now. My grandparents had a friend who was as spry as a monkey at 93. He died at the age of 106.
The greater part of the increase in life expectancy took place between 1900 and 1950
    Infant and childhood mortality must have dropped dramatically after the introduction of antibiotics in the 1940's.
    Life expectancy tables reveal that U. S. life expectancy at birth was 47.3 years in 1900, 68.2 years in 1970, and 76.9 years in 2000, so 70% of the change took place between 1900 and 1950.
    Average life spans have continued to increase since then. The list of numbers below shows the fraction of the U. S. population living past 85 from 1950 through 2000. There about 4.44 times as many people living into their 80's today as there were in 1950. 

1950:  1 in 2,612
1960:  1 in 1,930
1970:  1 in 1,345
1980:  1 in 1,011
1990:  1 in    760 .
2000:  1 in    588
But the average life expectancy for a 75-year-old male has only increased 7 months between 1900 and 2000
    In 1900, the life expectancy for a 75-year-old male, (http://www.lifeexpectancy.com/le_birth.pdf ), was 85.4 years, and in 1999, it was 86.2 years. In other words, all the improvements of the last 100 years have only contrived to raise the life span of a 75-year-old by about 7 months. Clearly, the benefits of modern medicine and dietary interventions are primarily benefiting people who are younger than 75, allowing more of them to reach the age of 75.
    For me, this is very disappointing news, and is certainly not what I wanted or expected to find.
    There has been virtually no increase in the average life spans of people who have survived into old age.
However...
    There's another interesting twist to this life expectancy forecasting that's embodied in the three  personal-life-expectancy calculators listed below. These calculators attempt to take into account your health habits in estimating your life expectancy. They lead to predictions that are far above the average life expectancies. This should come as no surprise, since the practice of harmful health habits must surely shorten one's potential life span.   


Microsoft's Life Expectancy Calculator


  The "Living to 100" calculator is the product of Dr. Thomas Perls, the Harvard researcher who has specialized in centenarians. (See Discovery of 'Methuselah gene' unlocks secret of long life, Does chromosome 4 hold the secret to human longevity?, Long-life gene secrets, and Does chromosome 4 hold the secret to human longevity?.)

Living To 100 Life Expectancy Calculator


Of particular interest to me is the Northwestern Mutual life expectancy calculator, since, presumably, it must be what this insurance uses to estimate life expectancies.

Northwestern Mutual Game


I like their forecast for me....
    All three of these calculators agree when I give them certain parameters for myself. They lead to a convergent forecast for me, given what I've input, of an age of death of 101 or 102. (It's worth noting that the fact that many of my relatives lived to their mid-90's doesn't really enter into the above life expectancy calculations. Clearly, environment is more important than heredity.)
How can these calculators' numbers be so much higher than the average life expectancies?
    It might be asked: how can such longer life spans be possible through good health habits if age-75 life expectancies have changed so little between 1900 and 1999? Wouldn't people have profited from all that's been learned about health maintenance and longevity over the past 100 years? If life expectancies are largely environmentally determined, wouldn't the life expectancies of a 75-year-old have increased more than seven months?
    One answer to that might be that what we've learned, and what people have changed is what has permitted more of us to survive to reach 75. But when it comes to average life expectancy looking forward from age-75, perhaps the general public... and especially men... haven't adopted the best health practices as much as we might expect over the past century. Exercise has boomed over the past 50 years, but perhaps dietary discretion has been less in evidence. Many high-rollers probably don't make it to 75, and among those who do, the life expectancy must be shorter than it is for those who pay homage to health care. And of course, we're dealing with averages here.
A rift within the lute
    Clearly, you can see daylight between the 1999 life expectancies for 75-year-olds and the actuarially- projected life expectancies of a 75-year-old who does everything right. 
Overseas and historic life expectancy tables
    A current (1999) table of personal life expectancies for different ages is given here.
    Two other life expectancy tables are listed below.
Life expectancies around the world
Life expectancies in ancient Rome
World Life Expectancy Chart
  

If you want to live well for a long time....

    For those rare individuals who would want to live to 120 or beyond, Dr. Roy Walford has some advice:
Beyond the 120 Year Diet - Dr. Walford

The Future of Human Longevity
    The Social Security Administration projects an average life expectancy of 80.2 years in 2050, and 81.6 years by 2070. The above document forecasts an average life span of 84.3 years by 2050, approaching the assumed 85-year life expectancy of model 1 in Gerontocracies 1 - Four Scenarios, but 50 years earlier.