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  • Scientists identified 287 unique genetic variants in Jonathan’s DNA associated with inflammation reduction, insulin management, and DNA damage repair.
  • Epigenetic analysis showed that while overall genomic entropy matched his advanced age, specific regions related to mitochondria and DNA repair resembled those of a juvenile tortoise.
  • The study relied on cheek swab samples combined with data from younger tortoises due to infection risks, resulting in a genome that is approximately 95 percent derived from Jonathan.

Researchers have published new findings regarding the genetic makeup of Jonathan, an Aldabra giant tortoise widely recognized as the oldest living land animal. The study, released in Science Advances, offers potential insights into the biological mechanisms that allow certain organisms to withstand the degradation typically associated with aging. By examining DNA collected from Jonathan, who resides on the British island territory of Saint Helena, scientists aim to understand how his cells maintain integrity over what is estimated to be nearly two centuries.

Jonathan’s exact age remains uncertain, though historical records provide a baseline for estimation. A photograph from 1882 depicts him as a fully grown adult, a stage reached by Aldabra giant tortoises at approximately fifty years of age. This suggests he is currently around 194 years old, significantly exceeding the species’ average life expectancy of eighty years. His veterinarian has previously indicated that Jonathan may be even older, but definitive proof remains elusive. Regardless of the precise number, his survival through world wars, pandemics, and multiple centuries marks him as an exceptional outlier in longevity.

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To gather genetic data without subjecting the animal to invasive procedures, researchers used a cheek swab to collect saliva and cells. This method was chosen because drawing blood posed too high a risk of infection for the elderly tortoise. However, the sample yielded incomplete DNA sequences. To compensate, the team integrated Jonathan’s genetic material with that of a younger tortoise, creating a composite genome that is roughly 95 percent derived from Jonathan. This limitation means some unique variants specific to his biology may have been excluded from the final analysis.

Despite these sampling constraints, the sequencing process identified 287 genetic variants unique to Jonathan. Many of these variations are associated with critical cellular functions, including the repair of DNA damage, the reduction of inflammation, and the regulation of insulin. The researchers also noted similarities between Jonathan’s aging-related genes and those found in other long-lived species, such as naked mole-rats, which are known for their resistance to cancer. These findings suggest that evolutionary adaptations for longevity may share common genetic pathways across different animal classes.

The study also examined Jonathan’s epigenome, referring to the chemical tags on DNA that regulate gene expression. As organisms age, these tags often become erratic, leading to unpredictable gene activity and increased genomic entropy. When compared to four younger tortoises, Jonathan’s overall epigenetic profile showed the level of chaos expected for his advanced age. However, in specific regions linked to mitochondria—the energy-producing centers of cells—and DNA repair, his chemical tags appeared remarkably youthful.

In these targeted areas, Jonathan’s epigenome resembled that of a five-year-old juvenile tortoise rather than an animal approaching two centuries old. This preservation of youthful markers in critical cellular functions may explain how he has avoided the chronic diseases that typically afflict aging organisms. The results align with previous research on human supercentenarians, individuals who have lived past 110 years, suggesting that certain biological mechanisms for longevity are conserved across species.

Experts caution that these findings do not prove causation. Jonathan represents a single data point, making it difficult to generalize the results to other tortoises or humans. The comparison group consisted of only a few younger individuals, which may have overlooked unique variants present in those subjects as well. Nevertheless, independent researchers describe the work as fascinating and consistent with the broader understanding of longevity biology. The study highlights how evolutionary insights might eventually inform medical treatments for age-related diseases.

Before any practical applications can be developed, further research is required to validate these genetic markers. The incomplete nature of the current genome data necessitates additional studies to confirm which variants are truly unique to Jonathan and which were artifacts of the composite sequencing method. Scientists hope that translating these evolutionary insights into affordable treatments could help address aging as a primary risk factor for chronic illness. For now, Jonathan continues his slow life on Saint Helena, serving as a living archive of biological endurance.

The research follows a period of public confusion earlier this year when false reports of Jonathan’s death circulated online. A hoax post on social media, designed to solicit cryptocurrency donations, claimed the tortoise had passed away. The incident underscored the public fascination with his survival and the importance of accurate information regarding his health. As scientific inquiry continues, Jonathan remains a unique subject for understanding the limits of life and the potential for extending healthy aging in other species.

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Go to the original reporting

  • Smithsonian Magazine↗Scientists Took a Cheek Swab From the World's Oldest Tortoise. His DNA Could Reveal Hints to Longevity