When interacting with people who have lived to 100, or even 110 years or more, we often pose rather clichéd and mundane questions like: “What have you done to live so long?”
Surely, some interesting and surprising answers will emerge, catching our attention. For instance, the regular consumption of fish and chips every Friday. Or drinking a strong alcoholic beverage daily. Eating bacon at every breakfast. Or continuously indulging in wine and chocolate.
While reporting on centenarians often attracts a large readership, asking such questions is relatively meaningless and does not help us understand why some people live so long. In an article for CNN, author Brady Elliot from Westminster University in the UK argues why seeking the “secret” to longevity from long-lived individuals is futile.
The survivor bias may lead us to an inaccurate view of how a person achieves a long life. (Source: CNN).
He points out that during World War II, Allied statisticians attempted to apply their skills to minimize the number of bombers shot down by enemy fire. By studying the damage patterns of returning bombers after each mission, they mapped out the parts of the planes that were most frequently damaged and recommended adding expensive armor to these areas.
Sounds like a simple solution, right? However, that was when another statistician named Abraham Wald entered the scene. He presented a completely opposite viewpoint, noting that the planes under study had all survived their missions, despite sustaining heavy damage. But what about the planes that did not return?
Wald argued that armor should be added to the areas that were undamaged on all the planes that returned safely. According to him, any plane that was hit in these undamaged areas might have crashed and could not return to base for analysis.
Survivor Bias
The phenomenon that Wald highlighted is known as survivor bias, or cognitive and statistical bias, created by only considering the factors that are present while ignoring those that have “not survived.”
Try applying survivor bias to the study of longevity secrets, and you will quickly see the absurdity. Imagine a group of 100 people, all of whom have smoked their entire lives.
As a group, regular smokers are likely to die earlier due to cancer, lung disease, or heart disease. But within this group, there will still be one or two individuals who defy the odds and live to 100.
Now imagine journalists surrounding these lucky individuals on their 100th birthday, asking the classic question we all know: “What do you attribute your longevity to?”
“Smoking a pack a day,” would surely be the response of the centenarian.
It sounds absurd, but survivor bias exists everywhere in society. We have all likely heard stories about a famous actor or entrepreneur who has succeeded against the odds. They work hard, believe in their goals, and succeed. Yet, we rarely, if ever, hear the other stories of those who have tried, given their all, but ultimately did not find success.
To be honest, writing or telling stories about failures is not a popular media topic. But this contributes to the survivor bias: we mainly hear success stories, while failure stories remain unheard.
This bias applies and shapes our perceptions in various fields, from architecture (most of us only know about great buildings from a specific period) to finance (we often hear examples of individuals who have succeeded by making risky investments, while those who fail do not publish books or self-help courses) and career planning (you may have heard successful individuals recount how they dropped out of school and became wealthy, but are unaware of the many others who did the same and failed).
Brady Elliot shares that he has worked with many elderly individuals, including some who are exceptionally old. He and his colleagues at the university are researching those over 65 who maintain an unusually high level of exercise in old age and enjoy excellent health.
They are remarkable examples of elderly individuals who are still faster and healthier than Elliot, even though they are nearly twice his age. However, while it is known that lifelong exercise is associated with the good health of these individuals in old age, Elliot’s team has yet to draw a specific conclusion about which factor leads to which. It could be that regular exercise protects centenarians from serious diseases such as cancer, diabetes, and heart disease. But it could also be that these individuals continue to exercise and maintain good health in their old age because they never experienced cancer, diabetes, or heart disease earlier in life.
There may also be some unidentified third factors that scientists still need to uncover to understand the mechanisms that allow many individuals not only to live long but also to maintain their ability to exercise for good health.
Correlation does not always imply causation. This point is often emphasized to students conducting scientific research. Our brains tend to see similar patterns between two variables and assume they are related in some way. But often, much like survivor bias, we do not examine enough input data and will “discover” correlations where, in reality, there are none.
