The secret of the turtles to reach the hundred years without aging

judith de george

Madrid

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All living organisms age and die. There is no way to escape death, but senescence, as biological aging is known, may not be an inescapable fate after all. Two studies published Thursday in the prestigious journal Science show that many tortoises that live exceptionally long lives – some of them exceeding 100 years – have found a way to slow down or even turn off age decline altogether. Researchers have discovered that these animals can stay young longer if their environmental conditions improve, something impossible for humans.

A team from the University of Southern Denmark studied 52 species of tortoises and tortoises that live in zoos and aquariums around the world.

To do this, they used the database of the Species360 organization, which manages the data of more than 1,300 zoos and aquariums. In this way, they found that their pattern of aging it does not resemble that of humans or other animals. In fact, most of them age extremely slowly – 80% do so more slowly than humans – and, incredible as it may seem, in some cases their senescence is insignificant. They include the Greek tortoise (testudo graeca) and Hermann’s (T. hermanni), whose aging rates are indistinguishable from zero.

sexual maturity

Some evolutionary theories predict that senescence appears after sexual maturity as an exchange between the energy that an individual invests in repairing damage to their cells and tissues, and the energy that they invest in reproduction, so that their genes pass on to the next cells. generations.

This compensation implies, among other things, that, after reaching sexual maturity, individuals stop growing and begin to experience a gradual deterioration of bodily functions with age. This prediction has been confirmed for several species, particularly mammals and birds.

However, organisms that continue to grow after sexual maturity, such as turtles, are thought to have the potential to continue to invest in repair cell damage and thus reduce and even prevent the harmful effects of senescence.

they are not immortal

The researchers also discovered that some of these species may reduce their aging in response to better living conditions in zoos and aquariums, compared to nature.

For us it is different. In the last century, human longevity has increased unprecedentedly. However, in primates, the improvement of living conditions does not greatly modify the rate of aging. Among these species, including humans, environmental changes mainly affect infant and juvenile mortality, as well as causes of death independent of age, such as predation or extreme conditions. “We cannot avoid senescence,” emphasizes Fernando Colchero, Professor of Mathematics and Computer Science at the University of Southern Denmark.

Of course, the fact that the turtles hardly age ¬ędoes not mean that they are immortal; Rather, your risk of death does not increase with age, but is still greater than zero. In short, everyone will eventually die due to unavoidable causes, such as disease, “says Colchero.

calmly

In a second study, Beth Reinke and colleagues at Northeastern Illinois University in Chicago compared aging rates and lifespans for 77 species from 107 wild populations, including turtles, amphibians, snakes, and crocodiles. Ectotherm longevity (estimated as the number of years after first breeding when 95% of adults have died) ranged from 1 to 137 years. For comparison, primate longevity ranges from 4 to 84 years. The authors also found little evidence of aging in multiple species of turtles, in some salamanders, and in the tuatara (a reptile endemic to the islands off New Zealand). For these researchers, protective adaptations like shells and the relatively slow pace of life, in the case of turtles, help explain their insignificant aging.

Interestingly, and contrary to what happens with humans, males outlive females. However, when the females are larger than them, they have a longer life expectancy.

Can we learn something from turtles to slow down human aging? Colchero does not believe it, at least directly. “But we can improve on theories of the evolution of aging, which have been studied in mammals and birds, but not in species with life strategies as different as turtles,” he says.

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