Centenarians' alleged longevity secrets: An examination of whether their advice remains valid
Some fascinating and unexpected habits are under the spotlight. Fast food and alcohol every week. Bacon each dawn. Wine and chocolate daily.
Although this issue frequently headlines the news, it fails to offer insights into why some individuals live long lives. Let me try to clarify this, using architectural wonders, aeronautics, and statistics.
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During World War II, Allied analysts were utilizing their skills to minimize the number of aircraft being hit by enemy fire. By examining the damages incurred by returning planes from combat, maps could be created highlighting the most often damaged sections of aircraft, so additional heavy armor could be added to these targeted areas.
Straightforward enough, right? Then, along steps statistician Abraham Wald who advocates for the exact and contrary approach. The aircraft being studied are those that managed to return from combat with significant damage, but what about those that didn't return?
Wald argues that armor should be added to those areas that are undamaged on all the surviving planes, as any plane hit in these undamaged areas was likely destroyed, never making it back for inspection.
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Survivorship Bias
This occurrence is known as survivorship bias, or the cognitive and statistical preference for counting only those still present, while disregarding those that didn't "survive."
You can take these examples to the extreme. Imagine a group of 100 individuals, all lifelong smokers. As a whole, the smokers would likely die younger due to cancer, lung disease, or heart issues, but one or two might beat the odds and reach 100 years of age. Now envision the determined journalist interviewing the lucky centenarian on their 100th birthday, posing the classic question: "What do you credit your exceptional longevity to?"
"Smoking a pack a day," explains the newly minted centenarian.
It seems obvious, but survivorship bias is rampant in society. We can all think of that one celebrated actor or business magnate who succeeded despite adversity, worked tirelessly, and eventually made it. However, we seldom hear about or learn about the countless attempts by others who never quite managed to make it.
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That's not a catchy headline. But this creates a bias, as we primarily hear about the successes, while failing to recognize the failures. This bias manifests in our perceptions of architecture, finance, and career decisions, as we predominantly hear about the wonderful buildings from a given period ("surviving"), risky investments that have paid off ("survivors"), and inspiring success stories of those who achieved their dreams by dropping out of college ("survivors").
I collaborate with a variety of elderly individuals and often include extreme outliers who have lived to exceptional ages. We're currently studying over 65-year-olds who have maintained unusually high levels of exercise into their later years and have maintained excellent health.
These remarkable senior citizens, many of whom are faster, fitter, and stronger than me, despite being nearly twice my age, based on the measures we perform in the lab, are phenomenal examples of human longevity.
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Although we recognize that their lifelong exercise is associated with their exceptional health in their later years, we cannot definitively state that one factor causes the other. It could be that individuals with consistently high physical activity levels are shielded from chronic diseases like cancer, diabetes, and heart disease. But it also might be that these people remain active as they haven't been affected by these diseases earlier in their lives.
Conversely, a third, still unknown factor might be at play, affecting both their health and their continued exercise.
For clarity, there are things that scientists like me will say in carefully nuanced, scientific language that can potentially help you live longer. Regular and intense physical activity, not overeating, and avoiding smoking are all on the list, along with maintaining a positive outlook in life and, of course, inherited good genes.
Correlation does not imply causation. This notion is drilled into students in science programs repeatedly. It's human nature to see a pattern between two variables and assume they're linked in some way. However, often, like survivorship bias, we're not examining all the data, which can lead us to find relationships where none actually exist.
