Many of the worlds longest-lived people became the world's longest-lived people despite a history of what are considered to be poor lifestyle choices from the perspective of long term health. Amongst their number are smokers, the overweight, and the sedentary - all items shown to cause great harm to health in the long term. Studies have shown that each of these considered in isolation can shave as much as a decade from your life expectancy, and that's quite aside from what they will do to your quality of life via an increased risk of suffering chronic and debilitating medical conditions.

So how is it that we see a fair proportion of extremely old people with such a poor track record for basic good health choices over the course of their lives? So far it looks like that can be attributed to fortunate genes:

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 ... 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.

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In previous studies of our centenarians, we've identified gene variants that exert particular physiology effects, such as causing significantly elevated levels of HDL or 'good' cholesterol. This study suggests that centenarians may possess additional longevity genes that help to buffer them against the harmful effects of an unhealthy lifestyle. ... Although this study demonstrates that centenarians can be obese, smoke and avoid exercise, those lifestyle habits are not good choices for most of us who do not have a family history of longevity. We should watch our weight, avoid smoking and be sure to exercise, since these activities have been shown to have great health benefits for the general population, including a longer lifespan.

Why rely on having a genetic buffer against subtle forms of self-harm when the odds are good that you have no such thing? The only reliable ways to ensure that you live for a long, long time in good health will come from progress in medical technology aimed at engineering greater human longevity: repair biotechnologies capable of reversing the known forms of cellular and molecular damage that cause aging. That progress in turn depends on the degree to which we choose to support and advocate rejuvenation research today.