Sequencing of 194-year-old Jonathan the tortoise turns up 287 gene changes unique to him
Kallel-led researchers found 287 gene changes unique to Jonathan, the 194-year-old Aldabra tortoise, touching DNA repair, inflammation, insulin and cancer. Because the baseline was just four other tortoises, the 287 are candidates to explain his slow ageing.
The Scientist · Science desk
What happened
- Of the 287, 41 are thought to be functionally significant, and 12 also appear in ageing databases built from other long-lived species.
- St Helena authorities refused to let researchers draw Jonathan's blood, citing his fame and infection risk, so his genome came from saliva and cheek swabs.
- In the first epigenome study of a giant tortoise, switches on Jonathan's DNA repair and metabolism genes closely matched those of younger tortoises.
- Senior author Stephen Clark said regions of the genome tied to mitochondrial function look as young as those of a 5-year-old Aldabra tortoise.
Why it matters
- What it limits constraint Any of the 287 could be ordinary individual variation until more Aldabra tortoises are sequenced the same way, so none can yet be ranked as a longevity factor.
- What doesn't add up contradiction Phys.org's account says the 287 variants reduce the effects of ageing, yet only about 14% are thought functionally significant, a far narrower claim than the headline count.
- What's now possible capability A first giant-tortoise epigenome gives later studies a reference for testing whether stable gene switches track long life in other old tortoises.
- Who has to decide decision Backing Kallel's push toward human treatments means accepting Clark's view that ageing mechanisms carry across species, supported here by database matches and resemblance to supercentenarians.
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The 287 is a count of differences from a small comparison group. "We found 287 genes that had changes in them that were unique to him," Clark told New Scientist, describing a comparison of Jonathan's genome with those of four other Aldabra tortoises [6][23]. Kousuke Hashimoto of the University of Osaka called the work "fascinating" [25]. He also noted, according to New Scientist, that the comparison animals were few and may have unique genetic changes of their own [25]. The coverage does not report how many unique changes each of those four tortoises showed against the others.
The researchers attribute Jonathan's long life less to good genes alone than to a lack of genetic wear and tear [26]. Phys.org's account of the Science Advances paper says the variants reduce the usual effects of aging and sit in DNA repair, inflammation control, insulin regulation and cancer suppression [2][22]. A spread across that many pathways fits the wear-and-tear description. The filtered numbers are much smaller. The 41 functional candidates are about 14% of the 287, and the dozen database matches are about 4% [17][20][21]. On the evidence published so far, the 287 are a list of candidates.
Working from saliva had costs. Without blood, the team could not isolate the large pieces of DNA that blood keeps stable; saliva DNA is more prone to bacterial contamination, and gaps in the assembly were filled with DNA from another Aldabra tortoise [9]. New Scientist calls this a major limitation [9].
"We found that the gene regulators involved in energy production and DNA repair have remained incredibly stable in Jonathan over almost two centuries," said Justin Gerlach of the University of Cambridge, a co-author [5]. The thing this doesn't tell you is which causes which. Young-looking switches in a 194-year-old animal [1] fit the idea that stable regulation helped him last. They fit just as well if stable regulation is simply what a body that stayed healthy looks like, and one tortoise cannot separate the two.
Clark links the young-looking mitochondrial regions to DNA repair. "This, in turn, has helped him manage the effects of ageing by giving the DNA repair systems more energy from the mitochondria to fight off the effects of ageing," he said [24]. The hypothesis came before the tortoise data. Manel Esteller's study of a 117-year-old woman found exceptionally efficient mitochondria, and that led Clark's team to suspect Jonathan's were similar [13].
Jonathan's age is itself an estimate. He reached St Helena in 1882 as an adult already thought to be about 50 [10]; add 144 years on the island and the total is about 194 [12][18]. The researchers put the species' average lifespan at around 80 years, so he has lived roughly 2.4 times as long [14][19].
Clark, who founded Kallel, the US nonprofit that led the work, is the study's senior author [3]. "Our goal is to take these evolutionary insights and immediately translate them into practical, affordable treatments for everyday people," he said [11]. His case for moving from tortoise to human rests on overlap, since some of Jonathan's changes resemble those found in supercentenarians [15]. "This study adds to the body of evidence that the mechanisms of ageing may be conserved across species," he said [16].
What to watch
- Whether the team sequences a larger panel of Aldabra tortoises, showing how many private changes an ordinary animal carries against four relatives.
- Whether St Helena authorities permit a blood sample, allowing a genome for Jonathan without gaps filled from another tortoise.
- Whether Kallel names any of the 41 functionally significant genes as a target for human treatment work.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence58
- Adoption
- Not scored
- Hype gap+35
- Incentives45
- Confidence62
Perspective Coverage
10 publishers- Builder
- Builder 61%
- Operator
- Operator 19%
- Investor
- Investor 20%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Jonathan, an Aldabra giant tortoise (Aldabrachelys gigantea), is estimated to be 194 years old, making him the oldest living giant tortoise and the oldest land animal in the world today.
- [2]
The study is Benjamin Vaisvil et al, 'Epigenetic insights into extreme longevity in the world's oldest terrestrial animal, Jonathan', Science Advances (2026).
- [3]
The study was led by researchers at the longevity research nonprofit Kallel in the US; Stephen Clark is Kallel's founder and the study's senior author.
- [4]
The team compared Jonathan's epigenome with those of younger tortoises of the same species and found the switches controlling his DNA repair and metabolism genes were very similar; this is the first time the epigenome of a giant tortoise has been investigated.
- [5]
"We found that the gene regulators involved in energy production and DNA repair have remained incredibly stable in Jonathan over almost two centuries."
- [6]
"We found 287 genes that had changes in them that were unique to him."
- [7]
Parts of Jonathan's genome to do with mitochondrial function were as young as those of a 5-year-old Aldabra tortoise, according to Clark.
- [8]
St Helena authorities refused requests to draw Jonathan's blood, given his fame and the risk of infection, so researchers studied his genome via saliva samples and cheek swabs.
- [9]
Without blood the researchers could not isolate large pieces of DNA, which are more stable in blood; they assembled fragments from saliva, where DNA is more prone to bacterial contamination, and filled gaps using DNA from another Aldabra tortoise. New Scientist describes this as a major limitation.
- [10]
Jonathan is thought to have been shipped to St Helena, possibly from Aldabra Atoll, in 1882, arriving as a fully grown adult thought to be already about half a century old.
- [11]
"Our goal is to take these evolutionary insights and immediately translate them into practical, affordable treatments for everyday people."
- [12]
Jonathan arrived on St Helena from the Seychelles 144 years ago, already fully grown.
- [13]
Manel Esteller's team, studying a 117-year-old woman once the world's oldest person, found exceptionally efficient mitochondrial function, which led Clark and colleagues to suspect Jonathan similarly had very efficient and young mitochondria.
- [14]
The researchers calculated that Aldabra tortoises have an average lifespan of around 80 years.
- [15]
Some of Jonathan's genetic changes seem similar to those of supercentenarians.
- [16]
"This study adds to the body of evidence that the mechanisms of ageing may be conserved across species."
- [17]
Of the 287 genes, 41 are thought to be functionally significant, and a dozen were also found in ageing databases of the genes of other long-lived animal species.
- [18]
Jonathan's estimated age of about 194 comes from about 50 years at arrival plus 144 years on St Helena.
- [19]
Jonathan has lived roughly 2.4 times the species' average lifespan.
- [20]
The 41 genes thought functionally significant are about 14% of the 287.
- [21]
The dozen genes also found in ageing databases are about 4% of the 287.
- [22]
Scientists pinpointed 287 unique gene variants in Jonathan that reduce the usual effects of aging; these control key processes including repairing DNA damage, reducing inflammation, regulating insulin and suppressing cancer.
- [23]
After assembling a composite of Jonathan's genome, the researchers compared it to the DNA of four other Aldabra tortoises.
- [24]
"This, in turn, has helped him manage the effects of ageing by giving the DNA repair systems more energy from the mitochondria to fight off the effects of ageing."
- [25]
Kousuke Hashimoto at the University of Osaka says the work is "fascinating" but notes that Jonathan's genome was compared against that of only a few other tortoises, which may have unique genetic changes themselves.
- [26]
Researchers studying Jonathan say it is not just good genes but a lack of genetic wear and tear that has kept him going for nearly two centuries.
Sources
10 independent publishers whose own reporting we read for this story.
- 404media.co‘Jonathan’ Is the Oldest Land Animal on Earth. He Could Hold the Secrets to Defying Death
1 article · October 7, 2026
- channelnewsasia.comA 194-year-old tortoise, world's oldest land animal, may hold clues to longer life
1 article · October 7, 2026
- discovermagazine.comAt 194, a 450-Pound Tortoise Is the Oldest Living Land Animal, and its DNA May Help Explain Why
1 article · October 7, 2026
- genengnews.comSecrets of Oldest Land Animal’s 194-Year Lifespan Revealed with Epigenetics
1 article · October 7, 2026
- livescience.comScientists discover the genetic secrets that may have helped Jonathan the tortoise live to 194 years old
1 article · October 7, 2026
- newscientist.com194-year-old tortoise has exceptional DNA repair systems that fight off ageing
1 article · October 7, 2026
- phys.org194-year-old tortoise reveals stable gene switches that may help resist aging
1 article · October 7, 2026
- popsci.comJonathan the tortoise is 194 years old and thriving. His genes help explain why.
1 article · October 7, 2026
- scientificamerican.comScientists unlock the longevity secrets of 194-year-old Jonathan the giant tortoise
1 article · October 7, 2026
- theguardian.comJonathan the giant tortoise, 194, offers up insight into secrets of longevity
1 article · October 7, 2026
Topics and entities
Entities
- Aldabra giant tortoise
- Benjamin Vaisvil
- Science Advances
- Kallel Foundation