World's oldest land animal at 194 has DNA that looks like a youngster's

This image is not directly related to the article. [Getty Images Bank]

Tortoises have long been symbols of longevity, and none more so than Jonathan, an Aldabra giant tortoise living on the South Atlantic island of Saint Helena. Estimated to be 194 years old, Jonathan is recognized as the oldest known living land animal on Earth. The average life expectancy for his species is about 80 years — 94 at most — meaning Jonathan has outlived his peers by roughly a century.

Now, an analysis of Jonathan's DNA has found that the epigenetic regulatory system, which typically grows more disordered with age, remained remarkably stable in certain genes — comparable to the levels seen in a 5-year-old tortoise.

The findings were published in volume 12, issue 41 of the international journal Science Advances by Benjamin Vaisvil and Steven Clark of the Caliel Foundation in the United States, who sequenced Jonathan's genome and compared it with those of four other Aldabra giant tortoises.

Unusual mutations found in aging-related genes

Saint Helena authorities refused to allow a blood draw, citing infection risks, so the research team collected Jonathan's DNA by swabbing the inside of his mouth. They then completed his genome by cross-referencing the sample against the sequenced genome of a 36-year-old Aldabra giant tortoise kept in captivity.

The analysis revealed changes across multiple aging-related genes in Jonathan's genome, including those involved in DNA damage repair, insulin regulation, cellular energy production, and the maintenance of telomeres — the protective caps at the ends of chromosomes.

The team also compared Jonathan's genome with that of Lonesome George, the last known Pinta Island tortoise, who lived in the Galápagos Islands. Lonesome George died in 2012, making his subspecies extinct.

Earlier research had identified longevity-related genetic variants in Lonesome George's genome as well.

By comparing Jonathan against Lonesome George, other Aldabra giant tortoises, and humans, the researchers identified genetic variants unique to Jonathan across 287 genes.

Jonathan carried 10 copies of the gene encoding perforin, a protein used by immune cells to attack aged or cancerous cells. Lonesome George had seven.

The research team suggested that having more perforin genes could help immune cells more effectively identify and eliminate senescent or cancerous cells.

This image is not directly related to the article. [AP]

Some genes in 194-year-old tortoise show patterns of a 5-year-old

DNA carries chemical tags called methyl groups at various points along its sequence, and where those tags attach determines whether genes are switched on or off. In youth, the tags follow a consistent pattern, but that pattern grows increasingly disordered with age.

The research team compared the DNA methylation patterns of Jonathan with those of younger tortoises aged 5 and 12, as well as two older tortoises.

Older animals showed greater disruption to their methylation patterns overall, and Jonathan's genome was the most disordered of all. Yet in certain genes, the 194-year-old's patterns were comparable to those of the 5- and 12-year-old tortoises.

When the team examined 272 genes displaying this youthful stability, a significant portion were involved in energy production in the mitochondria — the cell's power plant — as well as genes that help translate genetic information into proteins and genes responsible for repairing DNA damage.

Jonathan's case resonates with human longevity research as well.

A 2024 study analyzing long-lived elderly people in China found a similar pattern: while overall DNA methylation became more disordered with age, centenarians showed less disruption to their genetic "DNA switches" — the regulatory mechanisms that control gene activity — compared with ordinary older adults.

Other research has linked mitochondria to longevity. Longer-lived animals tend to produce fewer reactive oxygen species — cell-damaging byproducts of energy metabolism — than shorter-lived ones.

A recent study of a woman who lived to 117 found that her mitochondria functioned with notably greater efficiency than those of other people her age.

The research team suggested that Jonathan's ability to maintain youthful patterns in genes related to energy production and genetic information processing may have offered him some degree of protection against aging.

However, the team acknowledged that because they could not draw Jonathan's blood, they were unable to confirm how actively those genes are actually functioning. The oral swab DNA allowed analysis of only about 10 percent of the genome's regulatory regions, and the researchers said the results alone were not sufficient to establish a definitive cause-and-effect relationship.

Reference

DOI: 10.1126/sciadv.adw8887

Benjamin Vaisvil et al., "Epigenetic insights into extreme longevity in the world's oldest terrestrial animal, Jonathan." Sci. Adv. 12, eadw8887 (2026).

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