Biologists reveal secrets of the longevity of turtles and amphibians

Published:

Jun 27, 2022 04:34 GMT

An international study analyzed the reasons for the longevity of cold-blooded animals and refuted the idea that they live on average longer than warm-blooded animals.

It is generally assumed that cold-blooded animals age more slowly than warm-blooded animals. However, an analysis of the aging and longevity of dozens of amphibian and reptile species found that this is not always the case.

The researchers found that some of the species studied age more slowly and live longer than birds and mammals, while the opposite is true for others.

The long investigation of an international team of 114 biologists who studied 107 wild populations, covering 77 different species, has found new reasons for the longevity of cold-blooded animals, details a release signed by several universities in the USA and Australia.

The scientists found that in every group of amphibians and reptiles sampled — which included frogs, salamanders, lizards, crocodiles and turtles — there is at least one species with “negligible senescence,” a term coined in the 1990s to describe organisms showing no signs of aging.

In this case, this means that in these species mortality does not increase and fertility does not decrease with age.

The popular ‘thermoregulatory mode hypothesis’ suggests that ectotherms (cold-blooded animals), because they require external heat to regulate their body temperatures and thus often have slower metabolisms, age more slowly than humans. endotherms (animals that use internally generated heat), which have faster metabolisms.

However, contrary to traditional belief, the authors found no evidence that cold-blooded animals, on average, age more slowly and live longer than warm-blooded ones.

“We found no evidence to support the idea that a lower metabolic rate means that ectotherms age more slowly,” said one of the study’s authors, associate professor David Miller, an expert in wildlife population ecology at State University. from Pennsylvania.

“That relationship is only true for tortoises, suggesting that tortoises are unique among ectotherms,” ​​he added.

The team also determined that the rate of aging in cold-blooded animals depends on environmental temperature: reptiles age faster at high temperatures, while amphibians age more slowly.

Another finding of the study was the existence of a link between the physical or chemical characteristics that protect some species, such as hard shells, spines or the poison of some frogs, with slower aging and greater longevity.

The authors pointed out as the factors that most influence the rate of aging and lifespan at room temperature, the presence of protection devices, the age at which reproduction begins and fecundity.

The study was published in Science magazine.