Why humans can live 80 years while turtles more than 100 years?
Chitetsu Watanabe of Niigata, Japan, was once the world’s oldest living person, 112 years old – Photo: AFP
Why each animal species has a different lifespan has been a mystery that has puzzled scientists for years.
Many previous scientific studies have shown that size and nutrition do not determine the lifespan of a species. For example, the average human life expectancy is about 70-80 years old, giraffes (very tall) can only live 24 years, moles (small) also live up to 25 years, even turtles can live. more than 100 years.
To help unravel this mystery, researchers from the Wellcome Sanger Institute of Genetics and Genetics (UK) compared the genomes of 16 different sized mammals, including humans, mice and lions. , giraffe, tiger.
They found that species with slower rates of gene change – known as somatic mutations – had longer lifespans.
Somatic mutations occur spontaneously in all cells throughout an animal’s life. Most somatic mutations are harmless, but some can impair cell function or produce a cancerous cell.
Species with slower somatic mutation rates have longer lifespans – Photo: Shutterstock
In this study, the team found that somatic mutations are caused by a similar mechanism in all species, including humans. They also accumulate linearly over time, species with higher mutation rates have shorter lifespans.
For example, giraffes, which can grow to more than 3m, have been found to have a rate of about 99 mutations per year and a lifespan of about 24 years. Meanwhile, mole rats are very small in size, found to have a very giraffe-like mutation rate of 93 mutations per year and a similar lifespan of about 25 years. The average human has about 20-50 mutations per year, with a lifespan of about 70-80 years.
Dr Alex Cagan, who led the study, said it was surprising to find a similar pattern of gene changes in animals of different sizes. The most interesting aspect of this study was the finding that species lifespan was inversely proportional to the rate of somatic mutation.
To put it simply, the less somatic mutations occur in a species, the longer it will live. This suggests that somatic mutations may play some role in aging.
“Over the next few years, extending these studies to even more diverse species, such as insects or plants, will yield even more exciting findings,” said Dr Alex Cagan.
With recent advances in DNA sequencing technology, science can finally figure out the role of somatic mutations in aging and many other diseases – Photo: Shutterstock
Still unable to decipher the “Peto’s paradox”
One of the questions that has puzzled scientists for a long time is “Peto’s paradox”. The question is why larger animals don’t have a higher risk of cancer, despite having more cells.
After calculating the lifespans of the species in this study, the Wellcome Sanger Institute for Genetics and Genetics team did not find any significant association between the rate of somatic mutations and body mass.
This shows that there are clearly other factors associated with the cancer risk of large animals that science has not yet discovered.
“Differences in somatic mutation rates between species are related to lifespan, but not body size, suggesting that adjusting mutation rates is not necessarily a way for large species to grow. control cancer incidence,” said study co-author Dr Adrian Baez-Ortega.
Chances are that every time a species evolves to be larger than its ancestors, such as giraffes, elephants and whales, natural evolution may offer a different solution to the problem. . And scientists still need time to study these species in more detail to find the answer to Peto’s paradox.
In many studies from the 50s of the last century, scientists have mentioned the role of somatic mutations in the aging process. But to this day, even with new scientific and technological advances, observing them in reality is still difficult.
Even so, the researchers hope the findings will help unravel the mystery of exactly what causes aging. It’s a complex process that results from many forms of molecular damage in our cells and tissues.
at Blogtuan.info – Source: tuoitre.vn – Read the original article here