The process of ageing is unavoidable for animals like humans. No matter how many vitamins we take, our skin will eventually droop, our bones will crumble, and our joints will get stiffer as we age. Tortoises and turtles, on the other hand, seem to age more gracefully. Species such as the Galápagos giant tortoises seem to be unaffected by the ravages of ageing, despite the fact that they have wrinkled skin and toothless mouths. As they make their way into their 100s, some people are showing no symptoms of slowing down at all.
In a pair of studies that were published on Thursday in the journal Science, two teams of researchers looked at turtles, tortoises, and other members of their ectothermic, or cold-blooded, family. Their goal was to figure out what motivates these time-tested marvels. Previous studies on ageing have concentrated almost exclusively on warm-blooded creatures like mammals and birds. However, ectotherms such as fish, reptiles, and amphibians take the cake when it comes to living the longest. For example, salamanders known as olms have been known to crawl through underground tunnels for about a century. The average lifespan of a giant tortoise is twice as long as that of a regular tortoise; a Seychelles tortoise by the name of Jonathan just celebrated his 190th birthday.
One of the recent studies included the collection of data sets on 77 different species of wild reptiles and amphibians. These animals include tree frogs, Komodo dragons, and garter snakes. In order to evaluate the role that characteristics such as metabolism play in the ageing process and lifespan, the research team examined data spanning decades.
A slow and steady decline in health is required for such a lengthy life. When most animals reach sexual maturity, a significant portion of their energy is channelled towards reproduction; as a result, the process of repairing damaged, aged tissue is neglected. This physical degeneration, also known as senescence, often causes an increase in the risk of death, since older animals become more vulnerable to illness and to the attacks of predators. On the other hand, certain cold-blooded creatures don’t show much sign of ageing as they become older.
There is a theory that suggests that cold-blooded animals are better equipped to deal with the wear and tear of ageing than warm-blooded animals because cold-blooded animals rely on the environment to calibrate their body temperatures rather than endothermic, or warm-blooded, animals’ energy-draining metabolisms. However, Dr. Reinke and her colleagues discovered something far more complicated. They made the discovery that certain ectotherms aged much quicker than endotherms of comparable size, while others aged considerably more slowly. The rates of ageing for lizards and snakes were all over the place, but the rates of ageing for some crocodiles, salamanders, and the mysterious tuatara were astonishingly low. Tortoises and turtles, on the other hand, were the only group that showed signs of ageing very slowly.
The second recently published research delved even farther into the topic of these ageless turtles. The researchers looked at the effects of ageing on 52 different kinds of turtles and tortoises that were kept as captives in zoos and aquariums. They discovered that 75% of the species, which included Aldabra giant tortoises and pancake tortoises, had mild or insignificant signs of senescence. A few of them, such as Greek tortoises and black marsh turtles, even demonstrated negative rates of senescence, which means that their risk of death dropped as they became older. Approximately 80 percent have much slower rates of ageing compared to contemporary people.
It makes perfect sense that turtles would be used as a model for anti-aging treatments given their slow metabolisms. The robustness of their shells has also been linked by researchers to longer lifespans. Even though herbivorous turtles and tortoises spend their whole lives eating vegetables (well, primarily vegetables), their shells are like tight suits of armour that protect them from predators.
When one considers the luxurious existence that captive turtles enjoy, their sluggish ageing rates should not come as a surprise. Captive turtles, on the other hand, provide evidence that ideal environments in zoos can slow the ageing process. This is because the reptiles enjoy lounging in ideal temperatures and eating a balanced diet of fruits and greens, in contrast to humans, who continue to age regardless of the fantasy of cryogenic preservation.
According to Rita da Silva, a population biologist at the University of Southern Denmark and an author of the tortoise research, “We compared the populations in zoos to the populations in the wild and discovered that the ones under protected settings were able to turn off senescence.”
According to Caleb Finch, a gerontologist at the University of Southern California who studies ageing in people, even if the risk of death in long-living turtles and tortoises has stayed the same throughout the decades, this does not mean that they have achieved perpetual youth. Turtles and tortoises, like old people, ultimately experience a decline in their vision and the strength of their hearts.
Although these ponderous reptiles cannot outrun death, they may provide insights that may be used to extend the human lifespan and reduce the deterioration associated with ageing.