The secret to a long life lies, above all, in your genes

When supercentenarians are asked what their secret to a long life is, some claim it's having a life purpose, the famous ikigai of the Japanese; while others, more pragmatic, maintain that the recipe for longevity involves a daily yogurt. Until now, the science of aging had indicated that, to reach centenarian status, it was necessary to follow a healthy lifestyle: healthy food, no smoking or alcohol, exercise, rest, and stress under control. But now a new work published in Science It puts another factor ahead of all this: our genetic inheritance.

After scrutinizing data from more than 16,000 siblings, the study concludes that life expectancy, at least in Western countries, depends 55% on the genes we inherit from our parents, and the rest, yes, on our environment and lifestyle. This percentage is much higher than previously thought, which was around 25%, and is in line with what has been observed in other animal species.

In other words, whether we reach 90 has a lot to do with whether our parents and grandparents reached that age and, of course, also with whether we have taken care of ourselves and the environment in which we have lived. The study's conclusions, to some extent, dismantle the idea that, until now, leading a healthy lifestyle was our guarantee of longevity. And, as this new study concludes, no matter how healthy our lifestyle is, if our parents died of natural causes in their 80s, we won't reach 100.

To reach this conclusion, researchers analyzed a database of Swedish twins born between 1900 and 1935. Although these individuals lived through two world wars, the Great Depression, and the flu pandemic, they also lived in an era of significant improvements in sanitation and healthcare. To isolate the influence of genetics, the researchers attempted to exclude extrinsic mortality factors—those not linked to genes—such as death from infectious diseases, accidents, toxicities, homicide, and other causes. This type of extrinsic mortality had not been considered in previous studies, which largely explains the discrepancy in the results regarding the heritability of longevity. Furthermore, the new study suggests that this type of death increased with age, as people became more frail.

Next, they analyzed another database, this time of Danish twins born between 1870 and 1900, a time when many premature deaths occurred due to infectious diseases such as diphtheria and cholera. They wanted to test their results with another American database containing data on more than 2,000 siblings.

The results of the study suggest that longevity, as with most other complex human traits, is hereditary, and this is consistent with what has been observed in studies conducted with other animal species, notes Daniela Bakula, a researcher at the University of Denmark, in an opinion piece accompanying the study. "In all other organisms studied, life expectancy is closely linked to genetics," she writes.

Dementia, the most inherited

Heritability is a biological concept that establishes the proportion in which a certain trait or characteristic, such as height, weight, or longevity, in a population can be attributed to genetics and not to environmental factors. To measure the heritability of life expectancy, the authors of this study created a mathematical model that took into account extrinsic mortality and the impact of biological aging. They calibrated the model using Scandinavian and American sibling databases. In the study, they also analyzed the role of genetic heritability in different diseases. Thus, in the case of cancer, they found it to be independent of age and around 30%. In contrast, for cardiovascular conditions, heritability was higher, reaching 50% at younger ages. Deaths from dementia had the highest heritability, at 70% by age 80.

The fact that life expectancy depends more than 50% on family inheritance does not imply, the authors of the study point out, that lead a healthy life It's not important; in fact, it's very important for quality of life. Nor is it deterministic. Heritability is ultimately a population statistic, applied to a specific population in a given environment and at a specific time. This doesn't imply that lifespan is fixed for an individual.

"The most important and lasting advances in longevity have historically come from population-level measures in living conditions, education, public health and social protection, as well as from medical innovations when they are widely and equitably disseminated," recalls Ikerbasque demographer and researcher Tim Riffe, from the University of the Basque Country. Science Media Center Spain.

According to this expert, these interventions raise overall living standards and lead to longer, healthier, and more fulfilling lives, while reducing inequalities in survival between social groups.