It is not a guarantee, and its influence is far from absolute, but the long and powerful hand of genetics, filled with nucleotides, also plays a role in human longevity.
There is a general consensus that life expectancy has a low heritability. In the past, it was considered to have a heritability of 20-25%, although recent studies suggest that this figure may be even lower.
However, this refers to overall life expectancy. Could it be that, in the most exceptional cases, individuals with extreme longevity have a higher heritability?
Life Expectancy and Extreme Longevity
Scientific studies have proven that surviving to advanced ages is not a random occurrence but rather seems to be inherited within families.
This fact appears to be reinforced in families with individuals belonging to the top 10% of their cohort—the 10% longest-living people in their group, so to speak.
People with close relatives within that group have a 31% chance of living longer than their peers, even if those long-lived relatives were not their direct parents.
Additionally, this heritability appears to be quantitative: the more long-lived relatives a person has, the greater their chances of living many years.
This inherited longevity does not distinguish between men and women. There are no differences in its transmission between sexes. However, we must not forget that, on average, women live longer than men.
In 2021, the global difference in life expectancy between the two sexes was approximately five years.
If we compare human longevity records:
- The longest-living woman in history was Jeanne Calment from France, who lived 122 years.
- The longest-living man in history was Jiroemon Kimura from Japan, who reached 116 years.
Therefore, we find that life expectancy has low heritability, but in extreme longevity, genetic variants transmitted within families have a greater impact.
One of the biggest challenges in making these measurements is assessing the impact of environmental factors.
It is evident that, as members of the same family, the surrounding environmental conditions will be similar.
People from the same family environment often develop similar lifestyles and behaviors. If these environmental factors are positive (or negative) for extending life expectancy, they would have the same effect on all members subjected to them.
A Harvard study, conducted over 85 years, focused on identifying the most influential environmental factor in longevity.
The result? Strong social connections.
More than diet, exercise, or money, those who had a positive social life, with strong community and interpersonal bonds, lived longer and with better quality of life.
This largely explains why certain countries have higher life expectancy.
Countries like Japan or those in the Mediterranean region place a high value on family and friendships, which significantly contributes to their longevity.
Genes Associated with Longevity
In the genetic field, there is a general lack of consistency among studies focused on this area. Believe us, there is a lot of research on longevity.
On one hand, longevity is a highly heterogeneous trait, both genetically and environmentally.
Moreover, there is no clear consensus on the definition of longevity.
Genes whose correlation with life expectancy and longevity has been confirmed have been identified. Analyses have focused on those related to DNA repair, cellular senescence and apoptosis, the immune system and inflammation, metabolism, and telomerase.
Perhaps the two most notable ones are the APOE and FOXO3A genes.
The APOE gene encodes an apolipoprotein, whose main function is the transport of lipids within the body. It is an important component of chylomicrons, VLDLs, and HDLs.
However, its popularity is due to the various correlations of its alleles. The 𝜀2 allele is more common in people who have reached 100 years of age, compared to the rest of the population. Unfortunately, it is the least common allele, which has made research on it quite challenging.
On the other hand, the 𝜀4 allele has been associated with an increased risk of Alzheimer’s disease and cardiovascular diseases. Ironically, within the same gene, we have one allele correlated with low life expectancy and another possibly related to longevity.
There is also a third allele, 𝜀3, which simply wants to do its job and be left alone.
The FOXO3 gene has a more varied function. It encodes a transcriptional activator that recognizes and binds to the DNA sequence 5′-[AG]TAAA[TC]A-3′, regulating various processes such as autophagy and apoptosis.
This activity is crucial. In fact, various projects have been developed to optimize its functions and capabilities with the aim of increasing life expectancy and reducing aging-related diseases.
It is a cellular switch that you want to keep turned on for as long as possible.
Other Genetic Factors in Longevity
Maintaining or not maintaining the activity of a gene is another aspect: epigenetics.
Epigenetics refers to changes that occur in the genome, modifying gene expression without altering the DNA sequence.
MicroRNAs, histones, acetylation, and methylation, among others, are examples of epigenetics, as they modify gene activity without changing the DNA sequence.
Except in rare cases, epigenetics is not inheritable and is highly influenced by environmental factors. The impact of epigenetics, not only on aging but on all biological functions, is immense and would require an entire article to explain.
Another detail linking the genome with longevity is telomeres.
Telomeres are regions at the ends of chromosomes that contain repetitive DNA sequences. These sequences lack genetic information. Their function is to prevent degradation of these regions and prevent chromosome fusion with others.
When eukaryotic DNA replicates (creates copies), the ends cannot be fully copied. This causes telomeres to shorten with each replication until they reach a critical length.
Telomere length is one of the main causes of the Hayflick limit. This limit determines the number of times a eukaryotic cell can divide before entering senescence (cellular death).
Obviously, if your cells are dying at an accelerated rate, your life expectancy is also being shortened at a significant pace.
For this reason, telomeres are considered one of the best indicators of longevity.
The tellmeGen genetic analysis can help you plan your life, but it cannot predict the exact moment of your death. For now, foreseeing death remains within the realm of science fiction.
