Giant Tortoise Genomes and Longevity: Research Review 2026

Giant tortoises are one of the longest-lived groups of vertebrates. Several species routinely live beyond 100 years, and Jonathan, the famous Aldabra giant tortoise on Saint Helena, was estimated in 2025 to be around 192 years old. Because they combine slow ageing with large body size — a pairing that usually increases cancer risk in mammals — they make an unusual and valuable model for longevity biology.

This post reviews three milestone publications:

1. Quesada et al., 2018 — the genome of Lonesome George, last of the Pinta Island tortoise, and an Aldabra giant tortoise, compared with shorter-lived relatives.
2. Çilingir et al., 2022 — a chromosome-level reference genome for the Aldabra giant tortoise and its use for conservation genetics.
3. Vaisvil et al., 2025 (preprint) — the genome and epigenome of Jonathan, the oldest known living land animal.

I explain what each study found, how the findings connect to the Hallmarks of Ageing, and why readers should be cautious about anyone selling a "tortoise longevity" supplement.

1. Quesada et al., 2018: Lonesome George and the First Giant Tortoise Genomes

Citation: Quesada V et al. "Giant tortoise genomes provide insights into longevity and age-related disease." Nature Ecology & Evolution, 2018. doi: 10.1038/s41559-018-0733-x

This study sequenced the genome of Lonesome George, the last known member of Chelonoidis abingdonii, plus an Aldabra giant tortoise (Aldabrachelys gigantea). The researchers then compared these genomes with those of shorter-lived turtles and other vertebrates.

Key findings

• Expanded exosome-related gene families. Giant tortoises carried duplications and expansions in genes linked to exosome formation — cellular packages used to clear waste, exchange molecules and regulate inflammation. These expansions were also seen in another long-lived tortoise, Gopherus agassizii.
• Positive selection in ageing-related pathways. The team identified 43 genes showing signs of positive selection, including TUBE1, TUBG1 (tubulin cytoskeleton), VPS35 (intracellular trafficking), AHSG and FGF19. The latter two have been linked to metabolic regulation and successful ageing in humans.
• Variants in DNA repair, inflammation and cancer genes. Lineage-specific variants affected DNA repair genes, inflammatory mediators and genes related to cancer development. The authors suggested these changes may help giant tortoises maintain genome integrity and suppress tumours over very long lives.
• Low historical diversity. Demographic modelling showed that giant tortoise populations were already small and low-diversity long before human arrival, which may have made them vulnerable to extinction.

What it means for readers

The 2018 paper is important because it connected tortoise longevity to specific biological systems: DNA repair, inflammation control, intracellular trafficking and exosome biology. It also hinted that giant tortoises may have evolved better protection against cancer than expected for their body size — a phenomenon sometimes called Peto's paradox.

2. Çilingir et al., 2022: A Chromosome-Level Aldabra Giant Tortoise Genome

Citation: Çilingir FG et al. "Chromosome-level genome assembly for the Aldabra giant tortoise enables insights into the genetic health of a threatened population." GigaScience, 2022. doi: 10.1093/gigascience/giac090

While the 2018 study assembled the Lonesome George genome from short reads into scaffolds, the 2022 study produced a much higher-quality, chromosome-level reference genome for Aldabrachelys gigantea. The reference individual was a female called Hermania at Zurich Zoo.

Key findings

• Chromosome-level contiguity. The assembly resolved chromosomes, making it far easier to compare gene order, structural variation and runs of homozygosity across individuals.
• Conservation genomics in practice. By comparing Hermania's genome with 30 wild tortoises from the Aldabra Atoll, researchers could identify genetic differences between populations, trace Hermania's likely island of origin and spot potentially harmful mutations.
• A tool for future longevity research. The authors noted that a high-quality reference genome will help future studies on the genetic basis of the species' long lifespan, including efforts to estimate age from DNA.

Why this matters

Good reference genomes are the foundation of almost all modern genetics. The 2022 assembly made it possible to ask finer questions about how Aldabra tortoises age, how inbred different island populations are, and whether specific gene variants are associated with lifespan. It also supports conservation breeding by helping zoos preserve the wild genetic diversity.

3. Vaisvil et al., 2025: Jonathan the Tortoise — Epigenomic Insights into Extreme Longevity

Citation: Vaisvil B et al. "Epigenomic insights into extreme longevity in the world's oldest terrestrial animal, Jonathan." bioRxiv, 2025. doi: 10.1101/2025.02.05.636284

Jonathan is an Aldabra giant tortoise living on Saint Helena, estimated to have hatched around 1832. In early 2025 a team reported his whole-genome sequence and DNA methylome, comparing them with a 5-year-old Aldabra tortoise.

Key findings

• Age-related DNA methylation changes. Jonathan showed clear differences in DNA methylation compared with the young tortoise, consistent with an "epigenetic clock" ticking even in very long-lived animals.
• Gene variants in DNA repair and telomere regulation. Relative to other giant tortoises, Jonathan carried variants in pathways linked to ageing, including DNA repair and telomere maintenance.
• Low methylation entropy near energy genes. The most intriguing finding was that regions of low methylation entropy in Jonathan's genome were enriched for genes involved in the electron transport chain — the mitochondrial machinery that produces ATP. The authors proposed that preserving high-fidelity transcription of these energy genes may be important for extreme longevity.
• A model linking mitochondria and epigenome. The authors suggested a speculative model: efficient mitochondrial energy production, combined with a stable nuclear epigenome, could be a signature of extreme longevity.

What to make of it

This preprint is exciting because it looks at an individual of verified extreme age, rather than comparing species. However, it is a single animal, and the study has not yet passed peer review. Correlation is not causation: showing that Jonathan's methylation pattern differs from a young tortoise does not prove those differences caused his long life. Some may be consequences of age, chance, environment or population-specific variation.

4. Connecting the Studies to the Hallmarks of Ageing

The Hallmarks of Ageing provide a useful map. The tortoise research touches several:

• Genomic instability — DNA repair gene variants and exosome biology may help tortoises manage DNA damage.
• Telomere attrition — the Jonathan preprint flagged telomere-related variants.
• Epigenetic alterations — methylation clocks and entropy differences were central to the 2025 study.
• Loss of proteostasis / mitochondrial dysfunction — low methylation entropy around electron transport chain genes hints at preserved mitochondrial gene regulation.
• Altered intercellular communication and chronic inflammation — inflammatory mediator variants and exosome-related gene expansions point to better immune and signalling control.

None of this means giant tortoises have "solved" ageing. They still age, can develop disease and eventually die. But they appear to age more slowly than mammals of similar size, and the genomic clues are helping researchers build testable hypotheses.

5. Can Readers Act on This?

Honestly? Not directly. There is no supplement that reproduces a tortoise's DNA repair system or epigenome. The most useful takeaway is that longevity is partly about protecting information: genome integrity, epigenetic clocks fidelity, mitochondrial efficiency and controlled inflammation. The behaviours with the strongest human evidence remain the boring but powerful ones:

• Regular physical activity, especially resistance training.
• Enough high-quality sleep.
• A diet rich in plants, legumes, whole grains, oily fish and fermented foods.
• Not smoking and limiting alcohol.
• Social connection and purpose.

For readers interested in supplements, our Supplement Guides Hub reviews the evidence on compounds like omega-3, vitamin D3 + K2, magnesium glycinate guide-sleep-muscle-ageing-uk-evidence.html">magnesium and NAD+ precursors. None are proven to extend lifespan, but some have reasonable evidence for specific health outcomes.

6. Bottom Line

Giant tortoise genomics has moved from a single draft assembly in 2018 to a chromosome-level reference in 2022 and now to the epigenome of the oldest known land animal in 2025. The emerging picture points to better DNA repair, tighter inflammation and immune regulation, and possibly preserved mitochondrial gene expression over many decades. These are clues, not cures. The real value is in understanding the biology of ageing better — and in protecting the species that make such research possible.

References

• Quesada V et al. Giant tortoise genomes provide insights into longevity and age-related disease. Nat Ecol Evol. 2018. doi: 10.1038/s41559-018-0733-x
• Çilingir FG et al. Chromosome-level genome assembly for the Aldabra giant tortoise enables insights into the genetic health of a threatened population. GigaScience. 2022. doi: 10.1093/gigascience/giac090
• Vaisvil B et al. Epigenomic insights into extreme longevity in the world's oldest terrestrial animal, Jonathan. bioRxiv. 2025. doi: 10.1101/2025.02.05.636284

Related LongevityTortoise Guides