With many turtle species, the chance that the animals die each year does not or hardly increase.

He would be about 190 years old: the turtle Jonathan, who must have hatched in the Seychelles around 1832 and who has resided on the island of Saint Helena since the end of the nineteenth century. For example, there are more known cases of ancient tortoises – but not much scientific research has been done into aging in these animals.

Two groups of researchers are now changing that, with publications in the scientific journal science† And this shows: both in the wild and in the zoo, many turtle species age hardly or not at all. As in: they are obviously not immortal, but the chance that they will die in a year does not increase as they get older.

To put some numbers into that, a woman in the US has a 1 in 2,500 chance of dying when she’s 10, but by the time she’s 80, that chance has increased to 1 in 24. If an animal doesn’t age on the other hand, if you have a 1 in 100 chance of dying at the age of 10, that chance at the age of 80 is still 1 in 100.

Complicated Consequences

In front of their studies watched Rita da Silva and colleagues from the South Danish University on 52 species of turtles in captivity. About three quarters of those species were found not to age. 80 percent of species aged less quickly than modern humans.

What that says about turtles in general is just not entirely clear. “The implications of captivity on animals’ aging and longevity are complex,” says biologist Luke Hoekstra from Oklahoma State University, not involved in either study.

Generations of research

It is more interesting than watching turtles in the wild – but also a lot more difficult. “You can’t ask an animal about its age,” says Hoekstra. “To make sure you know them well, you should start tracking animals when they are very young and then catch them as often as possible.” If these are animals with a lifespan comparable to that of humans, the biologist continues, then you are talking about research that “comprises several generations of scientific careers”.

However, biologist Beth Reinke from the American Northeastern Illinois University, along with a huge international team of scientists, that kind of research for 77 species of reptiles and amphibians. This also showed that a number of turtle species do not or hardly age.

Protective shield

What’s in it for him? One theory is that cold-blooded animals — animals that produce no body heat themselves — age more slowly and live longer than warm-blooded animals. But that idea does not rhyme with what Reinke and colleagues found. Although their research shows that there are cold-blooded animals that age slowly, there are also cold-blooded species that age more quickly than warm-blooded animals.

The research does support the idea that, at least among reptiles and amphibians, physical protection is associated with slower aging. And of course physical protection is obvious to a turtle with its shell.

‘Very satisfactory result’

How earth-shattering is this research? According to the headline above the article by Da Silva and colleagues, “it challenges existing evolutionary theories about aging”. Hoekstra thinks that is going too far. He does say that both studies offer “new and interesting additions to the field of aging biology.”

As far as Hoekstra is concerned, the interesting insight comes from the study of wild reptiles and amphibians. This supports the theory that a species that reproduces faster or is more fertile, generally lives shorter. “The study by Reinke and colleagues shows that these species also age more quickly. And the species that reproduce more slowly live longer and age more slowly. That may seem obvious, but it is a very satisfying result!”

Blind and odorless

In the meantime, it is good to know that old age, even in a species that does not or barely age, comes with defects. Turtle Jonathan may have a good chance to touch the two centuries later, but he is now blind, can no longer smell, and has to be fed by hand.