There is no confirmed single “secret” behind Greenland sharks’ extraordinary longevity. A chromosome-level genome study published in PNAS in 2026 identified several candidate clues—including DNA repair, immune function, cancer resistance and changes to a chromatin-associated protein—but these are genomic findings and hypotheses, not proof of what causes the sharks to live so long. Even the often-cited age of 392 years is an estimate with substantial uncertainty, not a verified lifespan record.
What did the Greenland shark genome reveal about longevity?
The 2026 study, “The Greenland shark genome: Insights into lifespan extremes and population dynamics,” reports a 5.9-gigabase chromosome-level genome assembly with 96.7% completeness. The researchers examined it for features that might help explain the species’ exceptional lifespan and identified several possible leads.
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- DNA repair: The analyses point to DNA-repair mechanisms associated with longevity. Maintaining and repairing DNA is relevant to aging, but the genomic findings do not establish how much these mechanisms affect a shark’s lifespan.
- Immune function and cancer resistance: The study identifies immune enhancement and cancer resistance among candidate longevity-related features. These are proposed explanations, not demonstrations that a particular immune or cancer-protection mechanism is responsible.
- Linker histone H1.0: The researchers report unique amino-acid substitutions in the globular domain of this protein. They predict that the substitutions may enhance chromatin stability—the organization of DNA with proteins in cells—but that predicted effect is not the same as a proven cause of longevity.
- Ferroptosis: The paper raises a possible relationship between the shark’s gene repertoire, ferroptosis and longevity. It presents this as a hypothesis for further investigation, not an established mechanism.
The authors describe their findings as potential mechanisms that “may enable this species to exceed conventional lifespan limits.” The distinction matters: a genome can reveal promising biological clues, but identifying a feature in DNA does not by itself show that it extends lifespan.
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Source: PNAS, May 19, 2026.
How certain is the claim that Greenland sharks can live for centuries?
The estimate comes from radiocarbon measurements in eye-lens nuclei, not from counting growth rings or observing sharks from birth to death. Canada’s 2025 COSEWIC assessment describes the underlying aging study as involving 28 female sharks, 81–502 cm long, caught off Greenland. For the largest animal, the reported age estimate was 392 years, with a 95.4% probability range of ±120 years. The same work estimated age at sexual maturity at 156 ±22 years.
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Those figures should be read as estimates, not exact ages or a confirmed maximum lifespan. COSEWIC says the results have not been validated by an alternative aging method; it also notes that uncertainty about radiocarbon dynamics in the deep ocean makes birth dates difficult to determine. The evidence supports the view that Greenland sharks are among the longest-lived vertebrates, while leaving considerable uncertainty about any individual shark’s age.
Source: Environment and Climate Change Canada / COSEWIC, 2025.
How does the 2026 genome study compare with earlier findings?
A University of Copenhagen account of an earlier genome project, published in 2024, reported a genome of 6.5 billion base pairs and said transposable elements made up more than 70% of it. That account also discussed gene duplications involving DNA repair and the gene p53, as well as speculation about how the shark might counter harmful effects of transposable elements. Its researchers cautioned that more work was needed to determine how much the observed genetic changes contribute to longevity.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problems| Study or report | Reported genomic finding | What it supports—and what it does not |
|---|---|---|
| University of Copenhagen account, 2024 | 6.5 billion base pairs; transposable elements reported to make up over 70% of the genome | Earlier genomic observations and proposed explanations involving DNA repair and transposable elements; the account says their contribution to longevity needs further study. |
| PNAS study, 2026 | 5.9-gigabase chromosome-level assembly; 96.7% completeness | A newer assembly and analyses identifying candidate longevity-related features; these do not establish a causal mechanism. |
The reported genome sizes refer to different projects and should not be treated as competing measurements of the same assembly. Neither study, on its own, proves why Greenland sharks live so long.
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Sources: University of Copenhagen, September 11, 2024; PNAS, May 19, 2026.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.So, has the secret been uncovered?
No single cause has been uncovered. The strongest conclusion is that researchers now have a better genomic resource and several plausible avenues to investigate, including DNA repair, immune function, cancer resistance, chromatin stability and a possible link involving ferroptosis. Whether any of these features materially explains the shark’s longevity remains unresolved. The age evidence is also indirect and uncertain, so the genome findings should not be presented as a settled explanation for a precisely known lifespan.
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