The longest-lived woman on Earth is French: Jeanne Calment, a supercentenarian who died in 1997 at the age of 122 years and 164 days. Just behind her, Kane Tanaka, a Japanese woman who died in 2022 at 119 years and 107 days. Tomiko Itooka (116 years old) has been the dean of humanity since August 19, 2024. The number of people reaching the age of 100 continues to increase in industrialized countries. If the environment and healthy lifestyle play an undeniable role, scientists demonstrate that our genes hold part of the key to this exceptional longevity.
At the dawn of the 20th century, only one person in 100,000 became centenarians in the United States. Today, this ratio increased to one in 10,000. This spectacular increase of 8% per year – well above the average population growth of 1% – has intrigued researchers around the world.
The DNA of longevity: a family affair
The work carried out by Dr. Thomas Perls and his team at Boston University (The Genetics of Exceptional Human Longevity) have put their finger on a striking reality: longevity is passed down within families. In The analysis of 444 families of centenarians, including 2,092 brothers and sisters, reveals eloquent statistics. Women in these families have a 3.6 times greater probability of survival after age 65, while men see their chances multiplied by 3.4, compared to the 1900 birth cohort studied in this research.
In other words, if you had a centenarian sibling, your chances of living a long life would be about 3.5 times higher than those of someone not related to a centenarian. This significant difference therefore suggests a strong genetic component in the ability to reach very old age, since siblings share approximately 50% of their genes.
Even more striking, the researchers identified “ family clusters ” Or longevity manifests itself in extraordinary ways. In one of these families, no less than 23 people out of 46 members of the same generation are over 90 years old, some even reaching 106 years old.
The molecular guardians of time
Researchers have identified a particularly interesting genetic element: apolipoprotein E. This protein exists in different forms in the population. One of them, called ε4, is associated with an increased risk of developing Alzheimer’s disease and cardiac pathologies. Scientists have observed that this unfavorable variant is becoming increasingly rare as the age of the subjects studied increases. At the same time, another form of this protein, the ε2 allele, is found more frequently in elderly people of Caucasian origin, suggesting a protective role in aging.
This discovery is accompanied by other observations. Dr. Nir Barzilai and his team in this same study, by focusing their analysis specifically on the community of Ashkenazi Jewish centenarians, highlighted another factor: these exceptionally elderly people naturally present lipid profiles (fat levels in the blood ) associated with lower cardiovascular risk.
A healthier old age
Exceptional longevity is accompanied by a quite remarkable reduction in morbidity (the state of being ill, the frequency of an illness in a given population). The data collected shows that at age 92, 88% of women and 100% of centenarian men retained their autonomy. Even more impressive, at age 97, 45% of women and 75% of men maintained their independence and lived in good conditions.
These observations confirm the hypothesis of James Fries, an American rheumatologist. Formulated in the 1970s, it suggests that the maximum length of human life is fixed and that medical progress does not allow this limit to be increased, but rather to reduce the period of morbidity.
The environment: an essential partner
Genetics only tell part of the story of exceptional longevity. A study carried out on Scandinavian twins in the 1990s made it possible to precisely quantify the influence of genes on our lifespan. The results show that only 20 to 30% of our life expectancy is determined by our genetic heritage.
These discoveries have led scientists to an optimistic conclusion: the average human being has a potential genetic capital allowing him to live up to 85 years while maintaining good health. This encouraging message, however, comes with a warning: our individual behaviors can considerably reduce this potential written in our genes.
In the United States in particular, researchers observe that average life expectancy is around ten years lower than it could be, mainly due to poor lifestyle habits. Today, more than 42% of American men suffer from obesity compared to 17% in 1990. For women, this rate has increased from 21 to 44%.
Today, researchers continue their investigations to identify other additional genes which could explain these unusual life expectancies. Some avenues are emerging: the FOXO3A gene (involved in the stress response and DNA repair) or SIRT6 (protection against oxidative stress). A very complex job that could be compared to finding several needles in a huge haystack: longevity is influenced by numerous genes and each has a relatively small effect on them. However, better understanding the mechanisms underlying this phenomenon will perhaps ultimately allow us to develop strategies for healthier aging.
- Families of centenarians have much higher chances of survival, indicating a strong hereditary component.
- About 20-30% of longevity is determined by genes, the rest depends on lifestyle and hygiene.
- Centenarians live longer and in better health, with reduced morbidity and preserved autonomy at advanced ages.
