Will 90 Become The New 60?

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As our lifespans have increased, so too have our active years. Can that go on?

Immortality: Trust us, you wouldn’t like it.

It’s a comforting message, in a sour-grapes sort of way. It sounds wise and mature, suggesting that we put aside childish dreams and accept once and for all that there can be no vital Veg-O-Matic that slices mortality and dices infirmity. Gerontologists like it, being particularly eager to put on a respectable front and escape the whiff of snake oil that clings to the field of life extension.

In 1946 the newly founded Gerontological Society of America cited, in the first article of the first issue of its Journal of Gerontology, the need to concern ourselves to add “not more years to life, but more life to years.” The dictum was famously sharpened 15 years later by Robert Kennedy when he told the delegates at the first White House Conference on Aging “We have added years to life; it is time to think about how we add life to years.” Political theorist and futurist Francis Fukuyama was particularly eloquent but hardly alone when he warned two decades ago that if we maintain our obsession with extending life at all costs, society may “increasingly come to resemble a giant nursing home.”

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Robert Holland / Getty Images

Around the same time noted aging researchers S. Jay Olshansky and Bruce Carnes wrote in ominous tones that we were treading into the realm of “manufactured survival time,” warning that “this success has been accompanied by a rise in frailty and disability in the general population.1 This is a consequence that neither the medical community nor society was prepared for.” A celebrated article by epidemiologist E.M. Gruenberg in 1977 bemoaned the “failures of success”: “at the same time that persons suffering from chronic diseases are getting an extension of life, they are also getting an extension of disease and disability.”

This message is particularly dire if lifespans rise over extended periods of time—which they have done. In 1936 Louis Dublin, the chief actuary of Metropolitan Life teamed up with the esteemed mathematical demographer Alfred Lotka, to calculate the maximum life expectancy theoretically possible. They came up with a limit of 69.93 years. This limit was exceeded by women in Iceland five years later, by American women in 1949, and by American men in 1979. Life expectancies have been increasing at a steady rate of 3 months per year for the past 175 years, and on average, expert calculations of the maximum possible human lifespan have been exceeded an average of five years after being made. In some cases, they had already been overtaken by events somewhere in the world at the time they were issued.

But what if long lifespans don’t necessarily mean more years of disability? At the turn of the present century George C. Williams, celebrated evolutionary theorist of aging, attacked what he termed the “Tithonus error.” Tithonus, son of a nymph, lover of a goddess, was granted the boon of eternal life. But the further gift of eternal youth was unattainable. Frail, bent, and suffering he shriveled at last into a cricket. Williams’ argument was almost a trivial one, from the perspective of evolutionary biology: The very aged are rare, hence there is unlikely to have been any evolutionary pressure to shape the timing of the end of life, in the way that the timing of early development has been shaped. What we see as the “natural lifespan” is simply a balance between the wear of daily life and the limited ability of repair mechanisms to undo it fully. Shifting the balance, either by increasing the rate or efficiency of repair, or by reducing the rate of damage, must surely stretch out the whole process. Actually, it should do even better than that: The end stage, where most of our suffering is found, ought to be the least susceptible to extension, since it requires maintaining the function of an organism that is failing on multiple levels. This is consistent with the observation that, while mortality rates have been falling at all ages, the pace of progress has been slowest at advanced ages. Youth, according to this argument, should take up a greater portion of our lifespan over time. In 1980 the medical researcher James Fries called this process “compression of morbidity.”

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http://nautil.us/issue/46/balance/will-90-become-the-new-60-rp

WIKK WEB GURU
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