Somatic Mutations Unravel the Mystery of Aging
As mammals and humans grow older, the cells experience genetic mutations called “somatic mutations.” It's the most common cause of cancer.
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After researchers had sequenced the genomes of 16 species, the Welcome Sanger Institute discovered an unexpected pattern in how normal animal cells mutate. It could be the secret to the research into longevity.
Aging and Somatic Mutations
As mammals and humans grow older, the cells experience genetic mutations called “somatic mutations.” As these changes are the most common cause of cancer, most of the mutations are harmless, and it is impossible to pass down to their children.
Scientists have assumed a link between aging and somatic mutations since the early 1950s. Unfortunately, studying this link is very difficult. But thanks to the technological advances in DNA sequencing, it is no longer the case.
Genome Sequencing Study
Sanger researchers for their study sequenced the genomes of 48 creatures from 16 mammalian species: human, cat, dog, cow, horse, rabbit, rat, ferret, giraffe, black-and-white colobus monkey, harbour porpoise, mouse, naked mole-rat, lion, tiger, and a ring-tailed lemur.
When the researchers observed the somatic mutations in the cells of the animals, they discovered that the longer the species lived, the more minor modifications its cells needed each year. Every species had a lifetime maximum of 3,200 mutations.
Peto’s Paradox for Somatic Mutations
The researchers hoped their study could shed some light on Peto’s paradox, an observation made by the epidemiologist Richard Peto in 1977.
Peto wrote, in theory, that bigger or longer-living species could have a higher cancer risk than smaller or shorter-lived ones. This is because they have way more cells available that can mutate and more time for them to mutate.
Sadly, this mystery remains. The researchers found no critical association between the species’ rate of somatic mutations and how much they weighed after accounting for their lifespan.
The Future of Aging
Aging is a complicated process that somatic mutations alone are not easily explainable.
Although the link between these lifespans and mutation is fascinating for longevity research, maybe by slowing down a person’s mutation rate, they might be able to slow the aging process.
The Sanger research team now has plans to explore the rates of somatic mutations in non-mammalian species, including the Greenland shark, which has been shown to live more than 400 years. They want to see if the lifetime mutation limit goes beyond mammals.