A single protein, formed before birth and unchanged for centuries, unlocked one of the most remarkable biological findings in recent marine science. Scientists used radiocarbon dating on crystalline proteins inside a Greenland shark‘s eye lens to estimate the animal’s age at approximately 392 years, making it the oldest known vertebrate on the planet.
The shark was not caught for research. It was among 28 female Greenland sharks accidentally taken as bycatch by fishermen working in the North Atlantic. Researchers examined those specimens to test a dating method never before applied to this species at scale, and the results pushed the known limits of vertebrate longevity further than any previous study.
The animal’s estimated age places its birth sometime around the early seventeenth century, before the industrial revolution and before the United States existed as a country. It makes the Greenland shark feel less like a fish and more like a living record of deep time.
The Answer Was Frozen Inside the Shark’s Eye
Ageing a Greenland shark (Somniosus microcephalus) is not straightforward. These sharks have no fin spines, and their vertebrae are too soft to produce the growth rings scientists typically count to estimate age. For decades, researchers could only guess at lifespan based on known growth rates of under one centimeter per year and the large sizes these animals can reach, sometimes exceeding six meters.
The solution came from the eye. Inside a shark’s eye lens sit proteins that form during embryonic development and are never replaced or degraded over the animal’s lifetime. Because those proteins incorporate carbon from the environment at the moment they form, and because atmospheric carbon-14 levels have shifted in documented ways over time, scientists can date when those proteins were first laid down.
As NOAA Fisheries explains, researchers extract the innermost layer of the lens, isolate the original proteins, and submit them for radiocarbon analysis. That innermost material is the oldest, giving scientists a biological timestamp that no other tissue in the animal’s body can provide.
In the landmark study, the largest shark, measuring approximately five meters, returned an estimated age of between 272 and 512 years, with the central estimate near 392 years. As detailed in the original research published inScience, carbon dating produces ranges rather than exact figures, and the researchers presented those uncertainty bounds alongside their central estimate. Even the lower end, 272 years, would be enough to make the Greenland shark the longest-lived vertebrate confirmed by science.
It Takes a Century Just to Become an Adult
One biological detail from the research carries significant weight for conservation. Greenland sharks are not thought to reach sexual maturity until they are more than 100 years old, a figure that follows directly from the species’ documented growth rate and the body sizes at which reproduction is believed to begin.
Any mature shark removed from the ocean represents a loss the population cannot quickly absorb. A species requiring a century to produce breeding adults cannot recover on human timescales if adults are regularly removed. A shark killed at 80 years old has not yet contributed a single offspring to the next generation.
Though Greenland sharks were historically harvested for their liver oil, the National Oceanic and Atmospheric Administration notes that most caught today are taken accidentally as bycatch, making bycatch reduction a central conservation concern for the species.
These sharks inhabit some of the coldest and deepest marine environments on Earth, recorded at depths of 2,200 meters and the only shark species known to remain in Arctic Ocean waters year-round. Scientists believe their extremely slow metabolism, an adaptation to cold, low-oxygen deep water, underlies both their sluggish movement and their slow biological aging. Each biological process runs at a pace that appears to reduce the cellular wear that accumulates in faster-living animals.
A Genome Twice the Size of Ours May Help Explain Its Extreme Lifespan
In September 2024, an international team published the first complete genome sequence of the Greenland shark. The University of Copenhagen published a full account of the sequencing project, which involved scientists from the Fritz Lipmann Institute on Aging in Jena, Ruhr University Bochum, the Scuola Normale Superiore in Pisa, and other institutions.
At approximately 6.5 billion base pairs, the genome is twice the size of the human genome and the largest shark genome sequenced to date. Assembling a sequence of that scale required specialized computational tools, placing it alongside only a handful of animal genomes of comparable size.
The early findings point toward the shark’s DNA repair mechanisms as a likely contributor to its extreme longevity. The team reported that the genetic toolkit the Greenland shark uses to fix damage in its own DNA appears unusually robust compared to shorter-lived species. Computational biologist Steve Hoffmann described the genome as a foundational step for understanding the molecular basis of aging, with the sequence made publicly accessible for further study.
Slow and Ancient Does Not Mean Passive
Despite a reputation for sluggishness, Greenland sharks are not passive feeders. Research published in Frontiers in Marine Science examined feeding ecology across sharks ranging from 81 centimeters to 474 centimeters using stomach content analysis and stable isotope measurements from muscle tissue.
Smaller sharks fed predominantly on squid and lower trophic-level prey, while larger individuals shifted toward seals, large benthic fish, and fast-swimming species. Stable isotope data confirmed that trophic position increased with shark size, pointing to a species that actively adjusts its predatory strategy as it grows.
The researchers concluded that larger individuals are capable of active predation on fast-swimming seals and large fish. As detailed in the University of Copenhagen‘s researchprofile on the eye lens study, the genome sequence remains publicly accessible, and the team has indicated that further analysis is ongoing.
Enjoyed this article? Subscribe to our free newsletter for engaging stories, exclusive content, and the latest news.