Scientists might have solved the complex problem surrounding the human life span by comparing it to other mammals in the animal kingdom.
Animals with a large difference in lifespan and size end their natural lives with a similar number of genetic changes, researchers have discovered. The first study to compare the accumulation of mutations across many animal species has shed new light on decades-old questions about the role of these genetic changes in aging and cancer.
The findings come from a study by the Wellcome Sanger Institute which analyzed genomes from 16 species of mammals to understand the role genetic changes play in aging and the development of cancer.
Researchers found that despite huge variations in lifespan and size, different animal species end their natural life with similar numbers of genetic changes. The results of whole-genome sequencing across 16 different mammalian species confirmed that the longer the species lifespan, the slower the rate at which mutations occur. This lends support to the long-standing theory that somatic mutations play a role in aging.
The authors write “Giraffe and naked mole-rat, for instance, have similar somatic mutation rates (99 and 93 substitutions per year, respectively), in line with their similar lifespans (80th percentiles: 24 and 25 years, respectively), despite a difference of around 23,000-fold in adult body mass.”
The authors go on to say “Similarly, cows, giraffes and horses weigh much more than an average human, and yet have somatic mutation rates that are several fold higher, in line with expectation from their lifespan but not their body mass.”
More details of this breakthrough research from AWM:
This new research supports how a five-inch naked mole rat can live for twenty-five years – it has an inherent ability to minimize the amount of damage its cells are accumulating over the years and therefore has a very long lifespan for such a small mammal. The naked mole-rat actually has a longer lifespan than the average giraffe, which lives an average of twenty-four years. Scientists examined the number of gene mutations these two species have and found them to be very similar. Giraffes suffer an average of ninety-nine gene mutations per year, while naked mole rats have about ninety-three.
Meanwhile, mice, which only live about 3.7 years, have about 796 gene mutations per year. Humans, on the other hand, which lead an average life of about eighty-three years, have far fewer annual gene mutations at a rate of around forty-seven.
As a note, many gene mutations are harmless. However, some can lead to cell damage and develop into cancers and other conditions that impair normal functioning and reduce the creature’s survival rate.
Dr. Alex Cagan, the first author of the study, said: “To find a similar pattern of genetic changes in animals as different from one another as a mouse and a tiger was surprising. But the most exciting aspect of the study has to be finding that lifespan is inversely proportional to the somatic mutation rate. This suggests that somatic mutations may play a role in aging.”
Dr. Inigo Martincorena, senior author of the study from the Wellcome Sanger Institute, said:
“Aging is a complex process, the result of multiple forms of molecular damage in our cells and tissues. Somatic mutations have been speculated to contribute to aging since the 1950s, but studying them had remained difficult. With the recent advances in DNA sequencing technologies, we can finally investigate the roles that somatic mutations play in aging and in multiple diseases. That this diverse range of mammals end their lives with a similar number of mutations in their cells is an exciting and intriguing discovery.”
Source: AWM
