The biology of aging is shaking things up! A study in geriatrics reveals that 50% of our longevity depends on a genetic factor. Here’s how to live to 100 years.
Why do some people reach the age of 90 or 100 in good health, while others see their health decline much earlier? We have always been told that the secret of centenarians lies in a balanced diet, for example, with fish containing omega-3 which preserves cognitive abilities, regular physical activity, and sound sleep. But in reality, the biology of aging is more complex. While geriatrics has long focused on lifestyle, a major meta-analysis has just shattered this taboo: our habits may not be everything. Another factor, linked to our biological heritage, would weigh much more heavily than expected in the mechanism of human longevity.
Originally, researchers wanted to “understand human longevity and ways to improve it” by studying the data of three groups of twin subjects, over a century of scientific analysis. They compared twins raised together to those who grew up separately, allowing them to more finely isolate the possible influence of genes from that of the family environment. “For many years, life expectancy was mainly attributed to non-genetic factors, fueling skepticism about the genetic determinants of longevity,” the scientists point out. Indeed, until now, science estimated that genetics accounted for only 10 to 25% of a person’s life expectancy, with some studies even suggesting even lower numbers.
The problem with previous studies is that they did not clearly distinguish age-related declines caused by biological aging from those caused by external factors. This is what researchers call “extrinsic mortality”: these are declines caused by external factors such as accidents, violence, or infections. By using new mathematical models and simulations to correct this bias, they managed to isolate intrinsic mortality (linked to aging and associated diseases) and revealed in the journal Science that “the heritability of intrinsic human life expectancy exceeds 50%”. In other words, this means that an individual’s life expectancy depends on 50% of the DNA passed down from generation to generation. A figure much higher than previously thought.
This genetic influence changes the perspective for future medicine. As Ben Shenhar, one of the study’s authors, points out, “this encourages the search for genetic variants that extend life expectancy, in order to understand the biology of aging and, potentially, develop treatments.” By identifying the genes associated with people who reach an advanced age in good health, science hopes to better understand the biological mechanisms capable of protecting humans against cellular decline. But there’s no question of giving up under the pretext that “everything is written” in our genes. They weigh more heavily than expected on the scale but do not make decisions alone.
While about 50% of our longevity is inherited, our fate is not immutable. Our lifestyle – diet, physical activity, sleep, exposure to stress or pollution – does not directly alter our DNA, but influences how it is expressed. This is what scientists call epigenetics. In other words, some genes related to aging or diseases can be activated or inhibited depending on our lifestyle. Knowing that “your genes are much more important than previously thought” mainly allows us to anticipate our weaknesses to act on them before they manifest. Because while we do not choose our genetic heritage, we still have control over how it is expressed.
