People and other animals age at a far faster pace than do turtles, tuatara, and some species of salamanders. But they are not eternal.
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| [A turtle] |
It is often believed that turtles have very lengthy lifespans. However, there are very few accurate numbers available about this topic at this time. Both a large research group from Northeastern Illinois University in Chicago led by Beth Reinke and a smaller team from the University of Southern Denmark in Odense led by Rita da Silva and Fernando Colchero are now providing data in two independent studies that support this idea and have been published in the journal Science.
For instance, the Danish group that studied the lives of individual animals in zoos, animal parks, and aquariums analyzed data on the lives of individual animals. Three halves of these animals either aged very slowly or so slowly that it was nearly undetectable. Nearly eighty percent of these animals had a slower rate of aging than humans, who are regarded to have a relatively lengthy lifespan in comparison to many other mammals. Alexander Scheuerlein, a biologist and age researcher from the University of Greifswald who was not involved in either of the Science investigations, says that aging in the scientific community implies that the mortality rate continues to climb over the course of a lifetime.
Eight to ten year olds have the lowest mortality
Mortality rates begin to drop shortly after a human baby is born, and they reach their lowest point in children aged eight to 10 years old. In this age range, the average number of deaths per year is twenty out of every one hundred thousand, and over half of these deaths are the result of accidents. After then, mortality rates continue to climb, with illness gradually taking over as the leading cause of death over the course of time. For instance, there are an average of 800 deaths per year among adults in their 50s and 60s due to cardiovascular disease, stroke, cancer, and other disorders for every 100,000 persons in that age group.
But why do tortoise species, on average, age twenty times more slowly than creatures like birds and mammals, which have a relatively high and consistent body temperature?
Armor protects against danger
There is a possibility that the solution lies inside the turtle's shell, which serves as an effective defense mechanism against external threats such as falling rocks and adversaries. It has been known for a long time that a similar connection exists in mammals. According to age researcher Alexander Scheuerlein, "Small animals like mice are much more at risk from such natural hazards or enemies like the not too big cats than large elephants, which hardly any other animal attacks." This is in contrast to large elephants, which are rarely attacked by other animals. Because of this, mice are forced to run away from predators and other threats a great deal more often than elephants. The production of additional chemicals that are toxic to the body contributes to a rise in death rates.
Because of this, a turtle that is protected by its shell is able to maintain a metabolism that is far slower than it otherwise would be. The average human has a resting heart rate of around 70 beats per minute, however a Galapagos giant tortoise only has six beats per minute in their hearts. As a matter of fact, one of these enormous tortoises is the current holder of the age record. "Harriet," who lived her whole life in an Australian zoo, passed away from cardiac death in 2006 at the age of 170.
On the other hand, animals that are kept in zoos are housed in artificial environments, so many of the dangers that they would normally face in their natural habitats have been eliminated or at least mitigated. The team led by Beth Reinke investigated the age distributions of animals that are found in their natural environments. In addition to 14 different types of turtles, amphibians, snakes, crocodiles, and the primitive tuataras were also investigated. However, only one species of these animals now exists in New Zealand, and that is the tuatara. The death rate of turtles, as well as that of some species of salamanders and tuataras, was especially low in their natural environment.
Tuatara live up to 137 years
Alexander Scheuerlein provides an explanation that "this outcome is not too unexpected." Bear in mind that they are cold-blooded species, meaning that their internal temperature is maintained at a far lower level than that of mammals and birds. Because of their greater body temperatures, they acquire more harm over time than animals that have a cool blood temperature. Species that inhabit warmer climates have accelerated aging. On the other hand, in the case of frogs, salamanders, and other amphibians and reptiles of a similar kind, the species that inhabit warm tropical climates live far longer than the creatures that inhabit colder locations.
The tuatara tuataras were taken aback by the event. Tuataras have an aging rate that is 90 percent slower than that of tortoises, but humans age at a pace that is twice as fast as that of tortoises. Their average lifespan is somewhere around 137 years. The length of the reptiles ranges from fifty centimeters to seventy-five centimeters, and their weight is just around one kilogram. The tuataras not only have a very low metabolic rate, but they also move extremely slowly, and they are nevertheless active while having a body temperature of eleven degrees Celsius. These are all possible causes for the low death rate of the tuataras.
On the other hand, all of these different species have one thing in common with the creatures that have a greater mortality rate: they will all perish at some point.