Multiple systems work in concert to prevent the diseases of aging
In the cold depths of the Arctic, a slow-moving shark has quietly outlived empires, and scientists are only now beginning to understand why. Researchers at the University of Tokyo have decoded nearly the entire genome of the Greenland shark — Earth's longest-lived vertebrate, capable of surviving four centuries — uncovering a layered biological architecture of DNA stability, immune resilience, and iron regulation that together resist the erosion of time. The findings, published in the Proceedings of the National Academy of Sciences, do not yet offer a formula for human immortality, but they suggest that longevity is not a single gift bestowed by nature, but a negotiated treaty between many systems working in concert. In studying a creature that was alive before the Industrial Revolution, science finds itself asking older questions anew: what does it mean to age, and what would it take not to?
- A shark that reaches sexual maturity at 150 and lives to 400 has forced biologists to confront the outer limits of vertebrate life — and ask what cellular machinery makes such a timeline possible.
- The sequencing of 96.7% of the Greenland shark's genome revealed not one longevity mechanism but many: altered histone proteins stabilizing DNA, expanded immune and repair gene families, and tightly regulated iron metabolism that suppresses oxidative damage and cell death.
- Iron, essential yet corrosive, emerges as a key battleground — the shark's expanded ferritin genes appear to keep it in check, potentially preventing both cancer and a form of programmed cellular self-destruction called ferroptosis.
- Independent scientists caution that the genome is a map, not proof — functional experiments must still confirm whether these genetic features directly cause the observed longevity, or merely correlate with it.
- Even the shark's celebrated 400-year age estimate carries uncertainty, as deep-ocean isotope mixing may have skewed radiocarbon dating — though researchers agree the animal is at minimum 200 years old, still a biological category unto itself.
- The research opens a corridor toward human applications in longevity and cancer prevention, but the path runs through decades of further study, with the shark itself as a living, ancient guide.
Deep in the North Atlantic and Arctic Ocean, the Greenland shark moves through cold darkness at crushing depths — not built for speed, but for time. Scientists have now sequenced nearly its entire genome, and what they found suggests this animal has evolved a remarkable answer to aging.
Led by fisheries chemist Shigeharu Kinoshita of the University of Tokyo, the team decoded 96.7% of the shark's genetic blueprint, published in May in the Proceedings of the National Academy of Sciences. The shark lives roughly 400 years and does not reach sexual maturity until around age 150 — figures confirmed not by guesswork but by radiocarbon isotopes embedded in the shark's eye lenses, remnants of Cold War nuclear testing that act as a biological clock stretching back centuries.
Within the shark's cells, the researchers found a genetic architecture that appears purpose-built for survival. Alterations in histone proteins stabilize the DNA-protein complexes that make up chromosomes, slowing the accumulation of cellular damage across an extraordinarily long life. The team also identified expansions in gene families governing immune response and DNA repair — overlapping systems that detect and correct genetic damage before it becomes dangerous.
Perhaps most striking were the expanded ferritin genes, which regulate iron storage. Iron is vital to life but also a driver of oxidative stress and DNA damage. By managing iron more tightly, the shark appears to suppress both cancer risk and ferroptosis, a form of iron-dependent cell death. Kinoshita stressed that no single gene explains the shark's longevity — it emerges from integrated changes across the entire genome, each system reinforcing the others.
Not everyone is ready to declare the mystery solved. Physiologist Dorota Skowronska-Krawczyk of UC Irvine called the findings compelling but noted that functional studies — experiments directly testing whether these genes cause longevity — are still needed. The genome, she suggested, is a map; the proof lies in following it. Biologist Aaron MacNeil of Dalhousie University also raised questions about the 400-year estimate, noting that slow deep-ocean mixing could have delayed isotope arrival and inflated the figure. Even so, he conceded, these sharks are certainly at least 200 years old — a lifespan that already places them in a class of their own, and a living archive of what biology can achieve across timescales that dwarf human history.
Deep in the cold waters of the North Atlantic and Arctic Ocean, a creature moves through the darkness at depths that would crush most life. The Greenland shark is not built for speed or aggression. It is built for time. Scientists have now sequenced nearly all of its genetic code, and what they found suggests that this animal has solved a problem that has haunted every living thing: how to stay alive, and stay healthy, for an impossibly long time.
The genome sequencing, published in May in the Proceedings of the National Academy of Sciences, was led by Shigeharu Kinoshita, a fisheries chemist at the University of Tokyo, and his colleagues. They decoded 96.7 percent of the Greenland shark's genetic blueprint, revealing patterns that may explain how a vertebrate can live roughly 400 years and not reach sexual maturity until around age 150. These are not estimates pulled from thin air. Researchers have used radiocarbon isotopes trapped in the shark's eye lenses—remnants of Cold War nuclear testing—to establish a timeline. As the lens grows in layers over decades, the position of the isotope marks when that layer formed, creating a biological clock that stretches back centuries.
The shark itself is an unassuming animal by most measures. It grows to between 13 and 16 feet long and inhabits waters so deep and cold that observation is nearly impossible. Yet within its cells lies a genetic architecture that appears purpose-built for survival across centuries. The researchers identified alterations in histone proteins, the molecular structures that wrap and compact DNA into chromosomes. These changes involve unique amino acid substitutions that appear to stabilize chromatin, the complex of DNA and proteins that makes up chromosomes. This stability matters because it may slow the accumulation of DNA damage over an exceptionally long life. In an organism that lives for 400 years, limiting cellular wear is not a luxury—it is a biological necessity.
Beyond DNA stability, the team found expansions in gene families tied to immune response and DNA repair. These are not minor variations. They suggest that the Greenland shark has evolved multiple, overlapping systems to detect and fix genetic damage before it becomes dangerous. The research also revealed expanded ferritin genes, which regulate iron storage and metabolism. Iron is essential to life, but it is also a source of oxidative stress—a chemical process that damages DNA and can lead to cancer. By controlling iron more tightly, the shark appears to reduce this cellular damage. The expanded ferritin genes may also limit ferroptosis, a form of programmed cell death that depends on iron. Together, these genetic features paint a picture of an organism where multiple biological systems work in concert to prevent the diseases of aging.
Kinoshita emphasized to reporters that the shark's longevity does not stem from a single gene or mechanism. Instead, it emerges from integrated changes across the genome—shifts in how DNA is stabilized, how the immune system functions, how iron is managed, and how cellular stress is handled. Each piece alone might offer modest protection. Together, they create a biological fortress against time.
Yet the work remains incomplete. Dorota Skowronska-Krawczyk, a physiologist and biophysicist at the University of California, Irvine, who did not participate in the study, acknowledged that the findings are compelling. She has previously shown how DNA repair genes in the shark's retina help preserve its vision. But she stressed that functional studies—experiments that directly test whether these genetic features actually cause the observed longevity and cancer resistance—are still needed. The genome sequence is a map; the proof lies in testing whether the map leads where scientists believe it does.
Aaron MacNeil, a biologist at Dalhousie University in Nova Scotia, offered a note of caution about the 400-year estimate itself. The radiocarbon dating method relies on the assumption that isotopes reach the shark's environment at a predictable rate. But the deep ocean mixes slowly, and cold water moves even more slowly. The delay in isotope arrival could have inflated the age estimate. Still, MacNeil conceded, these sharks are certainly at least 200 years old—a lifespan that already places them in a category of their own. As researchers move forward with functional studies, the Greenland shark remains a living archive of how life can persist, and thrive, across timescales that dwarf human history.
Citas Notables
The shark's longevity does not stem from a single gene or mechanism, but from integrated changes across the genome working in concert— Shigeharu Kinoshita, University of Tokyo
Functional studies will be necessary to test directly whether these genetic features actually cause the observed longevity and cancer resistance— Dorota Skowronska-Krawczyk, University of California, Irvine
La Conversación del Hearth Otra perspectiva de la historia
Why does a shark that lives in the deep ocean matter to us? It's not like we're going to become Greenland sharks.
No, but the mechanisms are universal. DNA damage, cancer, aging—these are problems every animal faces. This shark has solved them in ways we haven't. Understanding how could reshape how we think about human longevity and disease.
So the genome tells us the shark is built differently. But does that mean the differences actually cause the longevity?
That's exactly what Skowronska-Krawczyk is saying. The genome is a hypothesis. You can see the expanded genes, the altered proteins, but you have to test them in cells and organisms to know they're doing what you think.
What about the 400-year estimate? MacNeil seemed skeptical.
He's right to be. The radiocarbon method is clever but depends on assumptions about how fast isotopes move through cold water. Even if it's 200 years instead of 400, that's still extraordinary. The shark is still the longest-lived vertebrate we know.
If we could understand this, what would we actually do with it?
That's the open question. You might develop drugs that mimic what the shark's genes do—enhance DNA repair, boost immune function, control iron metabolism. But we're years away from knowing if that's even possible in humans.
So this is a beginning, not an answer.
Exactly. It's a beginning with real substance. We now know what to look for.