Many tortoise and tortoise species have found a way to slow or even eliminate the aging process, a new study has found.
While all living organisms age and die, not all creatures follow the same pattern of debilitation and deterioration leading to old age and death, the experts suggest.
Among other things, the researchers documented for the first time that turtles, crocodiles and salamanders have particularly low aging rates and longer lifespans for their size.
At 190 years old, Jonathan, the Seychelles giant tortoise, is believed to be the world’s oldest living land animal.
It sounds dramatic to say that they don’t age at all, but basically their likelihood of dying doesn’t change with age once they’re past reproduction
Beth Reinke, Northeastern Illinois University
They also found that protective traits like the hard shell of most turtle species contribute to slower aging, and in some cases even what is called negligible aging — or the lack of biological aging.
Beth Reinke, first author and assistant professor of biology at Northeastern Illinois University, said: “These various protective mechanisms can reduce the mortality rate of animals because they are not eaten by other animals.
“As a result, they tend to live longer, and that puts pressure on them to age more slowly. We found the greatest support for the protective phenotype hypothesis in turtles.
“This shows again that turtles are unique as a group.”
The results suggest that senescence – the process of deterioration – is not inevitable for all organisms, said biologist Rita da Silva, who was at the University of Southern Denmark at the time of the work.
Studying turtles and tortoises living in zoos and aquariums, the researchers found that 75% of 52 species show extremely slow aging, while 80% of them show aging slower than modern humans.
David Miller, senior author and associate professor of wildlife population ecology at Penn State University in America, said: “There is anecdotal evidence that some reptiles and amphibians age slowly and have long lifespans, but up until now nobody has actually done this widely studied across numerous species in the wild.
“If we can understand what causes some animals to age more slowly, we can better understand aging in humans, and we can also inform conservation strategies for reptiles and amphibians, many of which are threatened or endangered.”
Some of these species may even reduce their rate of aging in response to improved living conditions in zoos and aquariums compared to the wild, the study suggests.
Contrary to many theories, the results suggest that how an animal regulates its temperature — cold-blooded or warm-blooded — isn’t necessarily indicative of its aging rate or lifespan.
The team observed negligible aging in at least one species in each of the ectothermic groups, including frogs and toads, crocodiles and turtles.
“It sounds dramatic to say that they don’t age at all, but basically their likelihood of dying doesn’t change with age once they’re past reproduction,” said Prof. Reinke.
However, the researchers say that the fact that some of the animals show negligible aging does not mean they are immortal.
It just means that their risk of dying doesn’t increase with age, but is still greater than zero.
All of them will eventually die due to unavoidable causes of death like sickness.
The results are published in the Science Journal.