At 194 years old, Jonathan is one of the oldest living land animals in the world. Scientists are trying to determine what genetic characteristics might be helping this giant tortoise maintain his unusually long lifespan.
Jonathan hatched in the Seychelles around 1832. In 1882, he was presented as a gift to the Governor of Saint Helena, an island in the South Atlantic Ocean. Since then, the tortoise has lived on the grounds of Plantation House, the Governor’s official residence.
The international research team included representatives from the US-based organization Kallēl and the Vanderbilt University Medical Center. They collected a DNA sample from the mucosal lining of Jonathan’s oral cavity and examined both his genome—the complete set of genetic information—and his epigenome, which regulates gene activity.
To understand what might drive Jonathan’s longevity, scientists compared his epigenetic data to that of four other tortoises of the same species. They focused on DNA methylation, an epigenetic process involved in regulating gene activity that acts like an “on/off switch.” As individuals age, DNA methylation patterns change, which can affect gene function. In Jonathan’s case, low methylation entropy was revealed in the regulatory regions of genes related to mitochondrial function and RNA metabolism.
In general, entropy measures the degree of chaos and disorganization within a system, whereas in this context, methylation entropy describes the variability of DNA methylation patterns. Accordingly, low entropy indicates that the methylation profile in these specific regions of Jonathan’s cells remained relatively stable and less variable despite his advancing age (although the study also identified other significant age-related changes across his entire genome). Researchers hypothesize that proper RNA processing and stable mitochondrial function may be linked to longevity, as RNA processing contributes to the accuracy of cellular instructions and mitochondria participate in maintaining cellular energy stability—though a direct cause-and-effect impact of these mechanisms on Jonathan’s long life has not been proven.
Further research is needed to determine the precise role these genetic features play in Jonathan’s lifespan.
In addition, scientists discovered 287 unique genetic variants in Jonathan’s genome. Some of these were found in genes involved in biological processes related to aging, such as DNA damage repair, regulation of telomere length (the protective caps of chromosomes), inflammation control, insulin regulation, and tumor suppression. Furthermore, the study revealed 10 copies of the perforin gene (a protein used by immune cells to destroy damaged and potentially cancerous cells); however, the abundance of gene copies does not automatically prove that Jonathan possesses a more effective immune defense.
The study’s authors note that these findings do not represent the discovery of a ready-made anti-aging treatment. Nevertheless, studying Jonathan’s genome and epigenome helps scientists better understand the biological mechanisms that may be involved in sustaining long life. Additional research is necessary to ascertain whether these mechanisms can be applied to extend healthy lifespan in humans.
