Ancient cultures and peoples have always been preoccupied with creating the "elixir of immortality" or the "nectar of the gods" that gave the drinker eternal life.

While these cultures did not succeed in finding such a substance to extend life, some cold-blooded animals were able to live longer than their peers of about the same size.

Longer-lived animals

Therefore, the latter fact attracted the curiosity of scientists, and made them question the reasons why cold-blooded animals live longer.

Recently, a study that included 114 scientists searched for the causes of this phenomenon in 107 groups of wild creatures, representing 77 different species, and the study was published in the journal "Science" on June 23.

This is the first study that focuses on understanding the phenomenon of longevity and aging in this detail. The study relied on collecting and analyzing decades-old data related to how the animal's body regulates temperature, environmental temperature data, the distinctive characteristics of organisms and the pace of life.

Reptiles and amphibians rely on environmental heat sources rather than their low endogenous temperature (Pixabay)

Of the 30 species of vertebrates known to have survived for more than 100 years, only 26 were "ectotherms", meaning that these organisms - such as reptiles and amphibians - depend on environmental heat sources because their internal physiological sources of heat are few. Relatively, therefore, scientists were interested in knowing how these organisms in particular avoid death for long periods.

slow aging

The results revealed that a number of factors are linked to slow aging, such as physical or chemical traits that protect the species, such as hard armor, spines, shells or venomous bites.

"These various protective mechanisms reduce animal mortality," says Beth Rink, an evolutionary biologist at Northeastern Illinois University and the study's first investigator. These animals can then live longer, and this may be selected for over successive generations of animals, leading to the development of a slow-aging phenotype.”

Various protective mechanisms such as hard armor reduce animal mortality rates (Pixabi)

"It's interesting to say that some species don't age at all, but the possibility of them dying remains as they age," Rink adds.

To simplify the matter, if the probability of an animal dying was one for every 100 individuals at the age of ten, and this percentage remained when he was at the age of 90, then this is a negligible old age.

To compare it with humans, the probability of a female death in the United States is one in 2500 when they are 20 years old, and this percentage becomes one in 24 when they are 80 years old.

Scientists have observed this slow aging in at least one of each group of exothermic organisms, including frogs, salamanders, lizards, crocodiles and turtles.

Contrasted with previous hypotheses

However, the study did not support the other hypothesis that longevity is due to these animals adopting lower metabolisms and relying on external sources of heat to regulate their internal body temperature (as cold-blooded animals do).

The study also found that exothermic animals may live much longer or shorter than their warm-blooded counterparts of similar size, and therefore this discrepancy in rates of aging and longevity is much greater than in birds and mammals.

Therefore, previous studies have been limited to wild turtles, which age slowly and in which a low metabolic rate is associated with longevity.

Previous studies were limited to land turtles that age slowly and have a low metabolic rate (Pixabe).

Ann Bronikowski, an evolutionary biologist at Michigan State University and co-author of the study, notes that the modified phenotype of hard shells "likely provides protection for animals that contribute to the evolution of their lifestyle, and may have led to the onset of this aging." slow and exceptional longevity.

Hence, this study indicates that the animal's morphological, physical and chemical characteristics are a major player in determining longevity and slow aging, in contrast to what has long been assumed that the low metabolic rate and dependence on heat from outside the body are the reason for this.

This finding will help to understand the mechanisms of aging in humans in the future.

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