There are three ways to die: from injuries, illness or old age. Over time, people have become better at avoiding the first two, but as we get older, old age – the gradual deterioration of bodily functions with age – is inevitable. However, some species seem to do better than others: Take the hydra, a small freshwater creature that some scientists have considered potentially immortal. Last year, a naked mole rat made headlines to fill 39, five times the typical lifespan of rodents of the same size. And just a few months ago, a giant Aldabra turtle named Jonathan celebrated what was thought to be his 190th birthdaymaking him the world’s oldest living land animal.
Cases like these raise the question: Is it possible to escape aging?
The authors of a examination published in Science last month say yes. Well, if you’re a turtle. With a comprehensive analysis of 52 species of turtles (a term that includes both aquatic and terrestrial turtles), the team of four scientists found that the majority of them showed unusually slow – and in some cases insignificant – aging while in captivity. . It does not make them immortal; turtles can still die from disease or injury. However, unlike birds and mammals, their overall risk of death does not increase with age. “We confirmed something that was suspected a long time ago, but never proven,” says Fernando Colchero, a biodemographer at the University of Southern Denmark.
The aging rate is a measure of how the risk of death increases among a population of organisms as they age. For birds and mammals, this risk is thought to grow exponentially with age. But for most of the turtle species in the study, this rate was almost flat, no matter how old they got.
Colchero and his colleagues also found that the environment in which the animals lived played a role. “Turtles and tortoises, based on comparing our results with those of animals in the wild, can actually change their aging rate dramatically as conditions improve,” he says, referring to factors such as predator protection, a controlled climate and unlimited access to food and shelter. It is separated from previous work with primate data there were reported increases in life expectancy due to better living conditions, but no significant reduction in mortality due to slower aging.
What gives? Some evolutionary theories suggest that old age is the result of an energy balance. Most mammals and birds stop growing when they reach sexual maturity, Colchero says, at which point their energy is prioritized for reproduction rather than cellular repair. Without adequate maintenance to counteract wear and tear, the body becomes more vulnerable to chronic age-related conditions, as well as injuries or infections. “But a lot of reptiles don’t. They keep growing, which means they seem to be really effective at repairing damage and keeping bodily functions going,” he says.
According to Rita da Silva, a biologist who led the study with Colchero, animals of this quality are the best candidates to avoid old age. It is an idea that has existed since the 1990s, and to prove it, the researchers collected demographic information from the Zoological Information Management System, a database of records from zoos and aquariums maintained by the non-profit organization Species 360. The selected species that had data for at least 110 animals and focused only on turtles living in freshwater or on land.