Greenland shark's ageless eyes reveal anti-aging secrets for human vision

The Greenland shark is a creature that seems built for decline. It moves through the ocean at a crawl, its skin mottled and scarred, its eyes clouded and often infested with parasitic crustaceans that hook into the cornea like tiny white tassels. Yet this animal, which can live for roughly 400 years in the frigid waters of the North Atlantic and Arctic, harbors a secret that scientists are only now beginning to understand: its eyes barely age at all.

Researchers examining the eyes of ten dead Greenland sharks, each between 100 and 134 years old, found something remarkable. The retinal tissue—the light-sensing layer at the back of the eye—showed almost no signs of deterioration. "The structure of the eye looks beautiful," said Dorota Skowronska-Krawczyk, a senior author of the study published in Nature Communications. "It's basically pristine." This finding matters because human eyes, by contrast, accumulate damage over decades. The rod cells that allow us to see in dim light gradually fail. In millions of people worldwide, this process accelerates into blindness.

To understand how the shark maintains such youthful eyes across centuries, the research team looked closely at the organ's cellular machinery. Greenland sharks, unlike humans, possess only rod cells—the light receptors designed for darkness. They lack cone cells entirely, meaning they see their world in shades of gray, without color or fine detail. This adaptation makes sense for an animal that spends most of its life in pitch-black waters three kilometers deep. Yet even with this simplified visual system, the sharks' eyes remain functional. The parasites that colonize their corneas reduce image clarity, but the underlying retina and its neural pathways stay intact and responsive to light.

The breakthrough lies in the genes. The researchers identified unusually high expression of two DNA repair genes—ERCC1 and ERCC4—in the shark's retinal tissue. These genes are the cellular equivalent of a repair crew, constantly fixing damage to DNA before it accumulates into permanent harm. Humans possess these same genes, but we do not activate them with the same vigor. When these genes malfunction in people, the results are severe: premature aging and accelerated vision loss. The implication is striking: the shark has solved a problem that has plagued human medicine for decades.

For the more than 200 million people worldwide living with age-related vision loss—conditions like macular degeneration and retinitis pigmentosa—this discovery opens a door. Patricia Jusuf, a visual neuroscientist at the University of Melbourne, noted that rod cells are often the first casualties in these human diseases. "Being able to manipulate DNA repair pathways to slow down or halt degeneration of these rod photoreceptors in humans holds great benefits," she said. The path forward involves genetic and molecular therapies designed to boost the same repair mechanisms the shark has perfected over evolutionary time.

Yet the researchers emphasize that this knowledge emerged not from hunting for a cure, but from simple curiosity about how an animal could live so long. Skowronska-Krawczyk stressed the importance of funding basic science—research driven by questions rather than predetermined outcomes. "It's only through the curiosity of researchers that the long life-span of the Greenland shark was discovered," she said. "And only then could we start working and thinking about applications."

The work also hints at untapped potential closer to home. Two relatives of the Greenland shark—the southern sleeper shark and the Pacific sleeper shark—inhabit waters around Australia and New Zealand. Little is known about their biology or their eyes. They may carry their own genetic secrets, waiting for researchers willing to look.