Some reptiles have just revealed to us a secret that we have been searching for millennia: eternal youth

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Jonathan turns 190 years old in 2022. Maybe even more. When he was born in Spain he still ruled Ferdinand VII, Otto von Bismarck Y Charles Darwin they were two youngsters and they lacked a good handful of decades to the historic flight of the wrights. Of all this the indolent Jonathan can tell us rather little. The reason: he is a huge seychelles giant tortoise housed in the Saint Helena Island… And the longest living land animal on record.

Jonathan’s is an exceptional case, but surely you’ve spent half your life listening to how long-lived turtles can be. So much so that it is not strange —as is the case with the famous quelonid on the island of Santa Elena— that they outlive their human owners. But… What is the reason?

Researchers from the universities of the South of Denmarkthe Northwestern Illinois Y Penn State have thoroughly investigated how they age turtles and other reptiles.

The result of his work are two studies published in Science that unravel some theories that help us understand a little better what the secret of his longevity is and how natural “miracles” are possible —those that have a lot of science and no magic— such as that of the Jhony bicentennial.

What the turtles hide

Jonathan The Tortoise 1900

The turtle Jonathan, in Santa Elena, in a photograph taken around 1900.

one of the teamsmade up of 144 scientists led by Northwestern Illinois University and Penn State, set about analyzing data from ectotherms —“cold-blooded” animals, such as turtles— from 107 populations spread around the world of 77 different species of reptiles and amphibians. His goal was to clarify with empirical and large-scale data the truth of the observations that suggest that these animals can enjoy exceptionally long lives.

One of his first conclusions is that turtles, crocodiles and salamanders enjoy particularly low rates of aging and – even more curious – that the phenotypes protectors, such as shells, spines or poison, facilitate slower aging or “insignificant”.

“It could be that their altered morphology with hard shells provides them with protection and has contributed to the evolution of their life histories, including insignificant aging and exceptional longevity,” explains Anne Bronikowski, co-author of the study. published study in Science.

The logic is relatively simple.

What details Beth Reinkeanother of the authors, animals with shells or armor are harder to eat and that makes it easier for them to live longer. “It puts pressure to age more slowly,” he adds. We found the strongest support for the hypothesis in turtles.”

It is not the only aspect in which the congeners of the ancient Jonathan stand out.

One of the questions they wanted to clarify is to what extent the “thermoregulatory mode hypothesis” is accurate, the idea that by needing external temperatures to regulate their body, ectotherms – “cold-blooded” animals – have metabolic shorter and age more slowly than endotherms (“hot blood”), which generate their own heat.

“People tend to think, for example, that mice age fast because they have a high metabolismwhile turtles age slowly because they have a low metabolism,” says David Miller, a professor in Pennsylvania and also responsible for the study.

Their analysis shows, however, that aging rates and lifespans of “cold-blooded” animals vary widely and can be either higher or lower than other “warm-blooded” animals of similar size. “We found no support for the idea that a lower metabolic rate means that ectotherms age more slowly,” add the teacher: “That relationship was only true for turtles, suggesting that they are unique among ectotherms.”

The Spaniards who search the DNA of turtles for the secret of longevity

The observations show that each group of ectotherms analyzed has at least one species with “an insignificant level of aging”. That includes everything from turtles to toads, frogs and crocodiles. “It sounds dramatic to say that they don’t age at all, but their probability of dying does not change with age once they no longer reproduce”, Professor Beth Reinke abounds.

What does that mean? Basically, that the percentages of staying on the road work in their favor.

“Negligible aging means that if the probability of an animal dying in one year is 1% at ten years, if it is alive at 100 its probability of dying is still 1%. In adult females in the US, the risk of dying in a year is about one in 2,500 at 10 years and one in 24 at 80. When a species sees negligible senescence, aging simply does not occur.” clarifies Miller.

That their senescence is “insignificant”, of course, does not mean that these animals are immortal. Your risk of dying may not increase with age to the same extent as it does for us, but it exists. Sooner or later an illness or any other unavoidable cause will take them away. If Jonathan is, after all, a celebrity, it is precisely because he is exceptional.

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The researchers of the University of Southern Denmarkwho have published the second studio in Science after analyzing tortoises and freshwater turtles in zoos and aquariums. Collecting and comparing data, the experts found that around 75% of the 52 species studied showed “extremely slow” senescence. In 80% of the cases, in fact, it was less than what modern humans present.

“We found that some of these species can reduce its rate of senescence in response to better living conditions in zoos and aquariums, compared to nature”, says Professor Dalia Conde. “We show that many species of tortoises have found a way to slow down or turn off senescence,” Rita da Silva abounds.

How is that possible? Some theories hold that once sexual maturity is reached, individuals stop growing and begin to experience senescence, a gradual deterioration of their bodies that causes them to age. It simply changes your investment of energies. There is an exchange between the one dedicated to repairing damage to cells and tissues and the one focused on reproduction.

Scientists have verified that such “compensation” is unavoidable in certain species, particularly mammals and birds; but it might not be the same for all creatures.

Is eternal life possible?

“Organisms that continue to grow after sexual maturity, such as tortoises, are thought to have the potential to continue to invest in repairing cellular damage and are therefore considered ideal candidates for reducing and even avoiding the deleterious effects of senescence”.

Beyond the curious thing that it turns out to better understand cases like Jonathan’s, revealing the secret of the longevity of certain reptiles can help us shed light about our own life.

“If we can understand what allows some animals to age more slowly, we can better understand aging in humans and develop conservation strategies for reptiles and amphibians, many of which are threatened or endangered,” concludes Miller.

Pictures | Deb Dowd (Unsplash), Wikipedia Y Giorgio Nicodemus (Flickr)

Jonathan turns 190 years old in 2022. Maybe even more. When he was born in Spain he still ruled Ferdinand…

Jonathan turns 190 years old in 2022. Maybe even more. When he was born in Spain he still ruled Ferdinand…

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