05 August 2011

Virtue Doesn't Pay (In The Very Long Run)

Virtue is an old fashioned term that used to be applied to morality but that way of thinking now seems mostly confined to issues of personal health. If you virtuously eat right, excerise, don't drink too much, floss, and so on, you will live a long and health life. Right?

Well, maybe not. It turns out that people "who live to 95 or older are no more virtuous than the rest of us in terms of their diet, exercise routine or smoking and drinking habits."

At age 70 the long lived had lifestyles not much different than others at that same time of life.

Overall, people with exceptional longevity did not have healthier habits than the comparison group in terms of BMI, smoking, physical activity, or diet. For example, 27 percent of the elderly women and an equal percentage of women in the general population attempted to eat a low-calorie diet. Among long-living men, 24 percent consumed alcohol daily, compared with 22 percent of the general population. And only 43 percent of male centenarians reported engaging in regular exercise of moderate intensity, compared with 57 percent of men in the comparison group.

Then again, it isn't as if the recommendation for diet and exercise come from nowhere. On average, these things have been demonstrated to help a lot in studies that have extremely large sample sizes and statistical significance, although the habits that have the highest work reward ratios (e.g. low dose asprin regimes and moderate alcohol consumption) are not all those one might naiively expect. Smoking, however, as expected, has a huge impact on life expectency, on average, as do little tips we would expect like not getting exposed to radioactivity above certain doses or to highly toxic chemicals like asbestos at work.

But, genes and luck, rather than diet and exercise, appear to be the key to making it from merely old to very old. And, there appears to be a pretty hard wall beyond which women just don't survive no matter what they do at about 114 to 115 years, and the absolute maximum lifespan of a man seems to be a bit shorter than it is for women.

There are a couple of competing theories as to why there is a maximum. One is that a small number of processes like telomere shorting and senile systemic amyloidosis eventually kill almost everybody that other mishaps didn't kill by that age.

If this is true, a small number of pills or magic bullet treatments might be able to significantly increase maximum human lifespan, although not necessarily average human lifespan. life expectency might increase only modestly (perhaps into the low 80s), but maximum life expectency might increase from 115 years to 130 years or more and a lot more people would live past 110.

An alternative narrative builds on the quip, "I'll bet they'll feel dumb when they get old and are dying of nothing." Maybe the causes of death that get most of us are front loaded, the very old are the people who escape those earlier onset body failures (mostly a few kinds of cancer and cardiovascular system collapses like heart attacks and strokes). Those people who don't die of those causes see more and more body systems that last just a little bit longer start to fail one after the other, until pretty sooner a person has multiple body systems that are all in trouble and one or the other of them catch up with them.

If this is true, comprehensive pre-failure life extension treatments of a large number of body systems would be necessary to meaningfully expand maximum life expectency, but a breakthrough on a small number of conditions might greatly expand average lifespan short of the maximum that is practically possible, which would be followed by multiple body system collapse later in life. Many more people might live to 90 instead of 70, but not many more people would live past 110 than do now.

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