longevity secrets – At 194 years old, Jonathan the tortoise is an evolutionary outlier. New research into his DNA offers a rare look at how a creature can defy the typical limits of aging.
On the remote South Atlantic island of Saint Helena. an Aldabra giant tortoise named Jonathan moves through a world he has inhabited for nearly two centuries. In a photograph that captures him fully grown. dated to around 1882. he appears much as he does today—a living relic. At 194 years old. he has lived roughly a century past the usual upper limit for his species. prompting a team of scientists to wonder: what exactly is happening inside his cells?.
To find out, researchers turned to the most direct, if difficult, source. Jonathan’s veterinarian. Joe Hollins. had to perform a delicate maneuver: he pretended to feed the tortoise. wedged his mouth open with a hard glove. and scraped cells from his inner cheek. Stephen Clark, a researcher at the Nashville-based Kallel Foundation, describes the process as both tricky and dangerous. Yet, the genetic material retrieved from that cheek swab provided a unique map of the tortoise’s biological resilience.
The findings. published in Science Advances. identify 287 genes with unique variants in Jonathan’s genome. including several involved in DNA repair. The researchers focused on chemical tags known as methyl groups, which act as switches for genes. In most organisms, these tags become chaotic with age—a process scientists track as entropy. While the overall entropy in Jonathan’s tags was high. consistent with his advanced age. they found a startling exception: in 272 of his genes. particularly those tied to the power-generating mitochondria. the tags remained as orderly as those found in a much younger animal.
This discovery suggests a potential feedback loop. Because maintaining orderly gene expression requires energy. and mitochondria provide that energy. Clark posits that Jonathan may be benefiting from a system where pristine mitochondria create the energy needed to keep the cells themselves in a pristine state. João Pedro de Magalhães. a comparative genomics researcher at the University of Birmingham who was not involved in the study. noted that while the team has identified new candidate genes linked to longevity. the long-term application of this knowledge to human health remains a future possibility.
The path to this discovery was complicated by the nature of the samples. Cheek cells yield genetic material that is often short and contaminated with bacteria. leaving gaps that researchers had to bridge using DNA from a younger tortoise. The resulting sequence is a kind of Frankenstein model—roughly 95 percent Jonathan. Clark admits that if any unique variants were hidden within the borrowed stretches, they would have been missed. While a blood sample might have offered a cleaner genome, officials on Saint Helena barred the procedure.
Joanna Bagniewska, a zoologist at the University of Oxford, defends that caution. Given the tortoise’s status on the island. any injury could have led to public resentment against scientific researchers. she explains. Ultimately. the team acknowledges that they cannot yet claim these specific genetic traits are the definitive cause of Jonathan’s long life. As Clark puts it. they cannot simply plant a flagpole in a gene and declare it the secret to his longevity; the work. he notes. is merely the first step in untangling a very long. very quiet life.
Jonathan the tortoise longevity research Science Advances genetics aging Aldabra giant tortoise Saint Helena