For mammals like humans, aging is inevitable. No matter how many vitamins we take, over time the skin becomes sagging, the bones become softer and the joints become stiffer. However, turtles and tortoises are more beautifully aged. Despite their wrinkled skin and toothless gums, the Galapagos giant tortoise-like species seems to have survived the aging catastrophe. Some show some signs of slowing down as they enter their 100s.
To determine what drives these ageless wonders, two teams of researchers tested turtles, turtles and their ectothermic, or cold-blooded brothers in a pair of studies published in the journal Science on Thursday. Previous aging studies have largely revolved around warm-blooded animals such as mammals and birds. However, ectotherms such as fish, reptiles and amphibians dominate longevity record books. For example, salamanders known as olms have been going through underground caves for almost a century. Giant tortoises can live twice as long – earlier this year, a Seychelles tortoise named Jonathan celebrated his 190th birthday.
In a new study, researchers compiled data sets of 77 species of wild reptiles and amphibians, including the Komodo dragon, garter snake and tree frog. The team used decades of observational data to analyze metabolic-like features to determine their effects on aging and longevity.
“We had these great data sets to get aging questions in a way that hasn’t been done before,” Beth Raine, an evolutionary biologist at the University of Northeast Illinois and author of the new study, said. “Only with this broad classification approach can we focus on how aging develops.”
A mild aging curve is needed to survive so long. After most animals reach sexual maturity, most of their energy is devoted to reproduction at the expense of aging tissue repair. This physical deterioration, or aging, often increases the risk of death as older animals become more susceptible to predators or disease. But some cold-blooded animals experience aging at a young age.
One theory is that cold-blooded animals are better equipped to handle the wear and tear of aging because they rely on the environment to calibrate their body temperature rather than the energy-releasing metabolism of endothermic or warm-blooded animals. But what Dr. Rain and his colleagues have found is even more complicated. They discovered that some ectotherms age much faster than endotherms of the same size, others much slower. The aging rates of lizards and snakes were scattered but significantly lower in certain crocodiles, salamanders and mysterious twitters. However, the only groups that were younger were turtles and tortoises.
Another new study has drilled deep into the aging of these timeless turtles. Researchers have studied age-related reductions in 52 species of tortoises and tortoises captured in zoos and aquariums. They found that 75 percent of the species, including the Aldabra giant tortoise and the pancake tortoise, showed low or negligible aging. Some, such as the Greek tortoise and the black marsh tortoise, even display a negative rate of aging, which means that their risk of death decreases as they get older. The aging rate of about 80 percent was slower than that of modern humans.
Turtles are meant to have anti-aging standards considering their lazy metabolism. Researchers have linked their strong shells to longevity. Since herbivorous turtles and tortoises live by eating vegetables (well, most of them), the armored snag suit protects even greased geysers.
This lazy aging rate is amazing considering the tortured lives of captive turtles. But unlike humans, who are older regardless of the fantasy of cryogenic preservation, captive turtles prove that the ideal environment at the zoo can reduce aging because reptiles live at ideal temperatures and enjoy a balanced diet of fruits and vegetables.
“We compared zoo populations with wild populations and found that under preserved conditions they were able to stop aging,” said Rita da Silva, a population biologist at the University of Southern Denmark and author of tortoise research. “For humans, our environment tends to get better and better, but we still haven’t stopped sensing.”
Although long-lived tortoises and turtles were at risk of death for decades, they did not attain eternal youth, according to Caleb Finch, a gerontologist at the University of Southern California who studied aging in humans. Like older humans, the tortoise and tortoise eventually lose their eyesight and heart.
“Some of them get cataracts and don’t need to be fed by hand.” “They won’t survive in the real world, so there’s no question they’re old.”
While these lombing reptiles may not survive death, they can retain insights to prolong longevity and reduce age-related decline.
“If we continue to study the evolution of aging in turtles, at some point we will find a clear connection between turtle and human health and aging,” says Dr. Silva.