The average life expectancy in many developed countries is around 80 years old. Some individuals have famously lived for for much longer – the oldest one that ever lived was 122 years old!
Whilst death is inevitable, longevity varies drastically between individuals. what’s the secret key to live longer life? Is our longevity already encoded in our DNA or is it determined by our lifestyle?
We asked 11 experts in ageing, cell biology & genetics: “Is longevity primarily determined by genetics?”. Here’s what we found out.
Longevity as compared to what?
Experts had 2 different interpretations of the question:
1) ‘Is the longevity of humans as compared to other species primarily determined genetics?’
2) ‘Is the longevity of some individual humans as compared to other humans primarily determined by genetics?’
Genetics determines cross-species lifespans
Different animal species have very different lifespans. The Greenland shark able to live to be 400 years old, whilst some species of mayfly only live for five minutes. the cause for these differences is genetics.
Professor David Gems, an expert in ageing from University College London, says “the question could mean: are the upper limits of longevity in humans as a species primarily determined by genetics, in which case the solution is ‘near certain’. for instance , the utmost lifespan of human-beings is approximately twice that of our closest relatives among the high primates, like chimpanzees and gorillas.”
Lifestyle more important than genes across humans
Dr Gems says “If one takes [the question] to mean: are the differences in lifespan between individual people primarily determined by genetics, then the solution is ‘extremely unlikely’.” Most of the experts agreed with Dr Gems. Whilst genetics plays a task in longevity, it’s not the first determining factor.
Professor Dame Janet Thornton, an expert in anti-ageing and cell biology and former director of the European Bioinformatics Institute says that “genetics accounts for fewer than 30% of the effect – but it’s true that longevity tends to run in families – i.e. some families have many very old people”.
It may be often difficult to find out if the existence of families with many very old people is thanks to genetics or environment, as often family members adopt similar diets & lifestyles. Studying the DNA of those long-lived people could tell us more.
Professor Ken Parkinson, an expert in anti-aging and oncology from Queen Mary University London says “many groups try to know this by sequencing the DNA of centenarians and supercentenarians and performing genome-wide analysis.”
The lifestyle effect on longevity is clearly apparent once we check out how average life spans have increased over many hundreds of years thanks to increased accessibility of unpolluted water, food and medical aid .
Counter-intuitively, it’s been shown that restricting calorie intake might be linked to longevity in humans. Another lifestyle factor is exercise. Even light exercise for quarter-hour each day has been shown to increase life span by around 3 years.
Individual longevity between humans is suffering from genetics, but not primarily. Professor Lorna Harries, an expert in genetics and cell biology from Exeter University summarizes that “genetics can set you up for an longer life span, but you then got to do the proper things to understand that.”
Differences in longevity between humans isn’t primarily determined by genetics. Regular exercise and a healthy diet could also be the ‘secret’ to longevity.
Article based on 11 expert answers to this question: Is longevity primarily determined by genetics?