Centennial turtles may set the standard in anti-aging

For mammals like humans, aging is inevitable. No matter how many vitamins we take, skin sags over time, bones soften, and joints become stiff. Turtles and tortoises, however, age more gracefully. Despite wrinkled skin and toothless gums, species such as Galapagos giant tortoises appear unscathed from the ravages of aging. Some show little sign of slowing down as they reach their 100s.

To determine what drives these ageless wonders, two teams of researchers studied turtles, tortoises and their ectothermic or cold-blooded counterparts in a pair of studies published Thursday in the journal Science. Previous research on aging has mostly revolved around warm-blooded animals such as mammals and birds. But exotherms love fish, reptiles and amphibians dominate the longevity record books. For example, salamanders are called olms glide through underground caverns for nearly a century. Giant tortoises can live twice as long – earlier this year, a Seychelles tortoise named Jonathan celebrated its 190th anniversary.

AT one of the new researchThe researchers collected data sets on 77 species of wild reptiles and amphibians, including Komodo dragons, garter snakes and tree frogs. The team used decades of monitoring data to analyze traits such as metabolism to determine their impact on aging and lifespan.

“We had these amazing datasets to answer the questions of aging in ways that have never been done before,” said Beth Reinke, an evolutionary biologist at Northeastern Illinois University and author of the new study. “Getting to the heart of the question of how aging develops is only possible with this broad taxonomic approach.”

Living that long requires a smooth aging curve. After most animals reach puberty, most of their energy is spent on reproduction by repairing aging tissues. This physical deterioration or aging often causes a spike in mortality risk as older animals become susceptible to predators or disease. But some cold-blooded animals practically do not age as they age.

One theory is that cold-blooded animals are better adapted to aging because they rely on their environment to calibrate their body temperature, rather than the energy-draining metabolism of endothermic or warm-blooded animals. But what dr. Reinke and her colleagues found that it was more difficult. They found that some exotherms age much faster than similarly sized endotherms, while others age much more slowly. The aging rates of lizards and snakes have been scattered, but have been surprisingly slow in some crocodiles, salamanders and other animals. mysterious tuatara. However, the only group that barely aged were the tortoises and tortoises.

another new study delved into the aging of these timeless turtles. The researchers studied the age-related decline in the population of 52 species of tortoises and tortoises kept in captivity in zoos and aquariums. They found that 75% of species, including Aldabra giant tortoises and pancake tortoises, showed little or no aging. Some, such as Greek tortoises and black bog turtles, even showed negative aging rates, meaning their risk of mortality declined with age. About 80% of them age more slowly than modern people.

Turtles, the benchmark for rejuvenation, make sense given their sluggish metabolism. Researchers have also linked their tough carapace to longer life spans. How herbivorous turtles and tortoises spend their lives chewing vegetables (well, basically), comfortable suits or armor provide protection even for gray-haired old people.

This sluggish rate of aging is not surprising given the pampered life of captive turtles. But unlike humans, who age regardless of the fantasy of cryopreservation, captive turtles are proving that ideal zoo conditions can slow aging because reptiles rest at ideal temperatures and enjoy a balanced diet of fruits and greens.

“We compared populations in zoos with wild populations and found that those in protected conditions are able to stop aging,” said Rita da Silva, a population biologist at the University of Southern Denmark and author of the turtle study. “For humans, our environment keeps getting better and better, but we’re still not able to turn off aging.”

Although the mortality risk of long-lived turtles and tortoises has remained the same for decades, according to Caleb Finch, a gerontologist at the University of Southern California who studies aging in humans, they have not reached eternal youth. Like the elderly, turtles lose their eyesight and heart over time.

“Some of them get cataracts and are so weak that they have to be hand-fed,” the doctor said. Finch, who was not involved in the new research. “They wouldn’t survive in the real world, so there’s no doubt they’re getting old.”

While these clumsy reptiles can’t outrun death, they may have ideas for extending life and reducing age-related decline.

“If we continue to study the evolution of aging in turtles, at some point we will find a clear link between turtles and human health and aging,” says the doctor. da Silva said.