🧪 Echoes from the lab
Greenland Shark Eye Dating Revealed Centuries-Long Lifespans
- What: Scientists estimated that Greenland sharks can live for centuries by radiocarbon-dating tissue from the centers of their eye lenses.
- Where: Greenland waters and the North Atlantic and Arctic waters.
- When: The study was published in 2016, using radiocarbon markers shaped by 20th-century nuclear bomb testing.
Greenland sharks can live for centuries, and scientists figured that out by dating tissue from the center of their eyes. The finding, published in 2016, made the Greenland shark one of the longest-lived vertebrates ever measured.
Eye Lens Age Dating
The key idea is unusual but simple. Most of a shark’s body keeps changing over time, which makes age hard to pin down. But the nucleus of the eye lens forms early in life and then stays largely unchanged. That means it can preserve a chemical timestamp from when the animal was young.
Researchers used radiocarbon dating on those eye-lens nuclei from 28 female Greenland sharks. Radiocarbon levels in living things shifted dramatically during the 20th century because of nuclear bomb testing, creating a useful marker. By comparing the carbon signal in the eye tissue with known atmospheric changes, the team could estimate when each shark was born.
Radiocarbon Results in Greenland Sharks
The smallest sharks in the study appeared to have been born after the mid-20th-century bomb pulse. The biggest animal, about 5 meters long, was estimated to be roughly 392 years old, with a wide uncertainty range. Even with that uncertainty, the evidence pointed in one direction: these sharks were living far longer than scientists had expected for a vertebrate.
That scale is the striking part. A shark swimming in Greenland waters today could have been alive before the United States existed as a country. Not because of legend or exaggeration, but because a dating method built from the shark’s own eye tissue gave researchers a way to measure age in an animal that had resisted ordinary methods.
Centuries-Long Shark Lifespan
Greenland sharks grow slowly, mature late, and move through cold North Atlantic and Arctic waters at a pace that matches their biology. The radiocarbon work did not turn them into a mystery story. It established a hard fact: at least some Greenland sharks live for several centuries, placing them among the longest-lived vertebrates known.
Did You Know?
Greenland sharks are among the slowest-growing sharks known, which helps explain why they can take so long to reach maturity.
