The 400-Year-Old Shark: How the Greenland Shark Outlives Every Mammal on Earth

Picture this: a shark swimming in the icy North Atlantic today that may have been alive when Shakespeare’s plays were still new. That’s not a myth. It’s the Greenland shark (Somniosus microcephalus), now recognized as the longest-living vertebrate ever recorded.

These massive, slow-moving sharks inhabit the freezing waters of the Arctic and North Atlantic Oceans. They glide through darkness hundreds — sometimes thousands — of meters below the surface. For decades, fishermen caught them accidentally, but no one realized just how old they might be.

Then science stepped in, and the results stunned everyone.


The Study That Changed Everything

In 2016, marine biologist Julius Nielsen and colleagues at the University of Copenhagen published a groundbreaking study in the journal Science. Because Greenland sharks lack the typical growth rings found in other fish, researchers couldn’t simply “count” their years.

Instead, the team used radiocarbon dating on proteins extracted from the sharks’ eyes. These proteins form before birth and remain unchanged throughout life, essentially preserving a chemical record of when the shark was born.

By analyzing 28 female sharks accidentally caught as bycatch, researchers estimated that the largest individuals were about 392 years old. Statistical models suggested possible lifespans ranging from about 272 to over 500 years.

That makes the Greenland shark older than any known mammal. Even the bowhead whale, long considered the champion of longevity, reaches just over 200 years.

Life in Slow Motion

So how does a vertebrate live for centuries?

One of the strongest explanations lies in temperature. Greenland sharks spend their lives in near-freezing water, often between several hundred and more than 2,000 meters deep. In such cold environments, metabolism slows dramatically.

A slower metabolism means the body burns energy more gradually. Cellular processes move more slowly. Over time, this may slow the buildup of damage that contributes to aging.

In simple terms, everything about this shark runs slowly — and that may be the secret.

Growing Just One Centimeter a Year

Their growth rate is almost hard to believe. Scientists estimate that Greenland sharks grow only about one centimeter per year. That’s slower than most plants in a backyard garden.

Because of this, they don’t reach sexual maturity until around 150 years of age. Imagine an animal that spends more than a century just growing up.

This slow development is tied closely to their longevity. Species that grow slowly and reproduce later often invest more biological energy in maintenance and survival. The Greenland shark appears to be a powerful example of that pattern.

But there’s a downside. Because they mature so late, their populations are extremely vulnerable. Losing adult sharks to fishing or environmental disruption can have effects that last for generations.

What Their DNA Might Be Telling Us

Scientists are also looking at the Greenland shark’s genetic makeup. Early genomic research suggests the possibility of unique adaptations related to DNA repair and inflammation control — two key processes associated with aging in many animals.

In most species, DNA damage accumulates over time, and chronic inflammation contributes to age-related decline. If Greenland sharks have enhanced systems for managing these processes, it could help explain how they maintain stability over centuries.

Research in this area is ongoing, but it opens the door to broader questions about aging in vertebrates.

Still Full of Questions

Despite what we now know, the Greenland shark remains mysterious.

Radiocarbon dating provides strong evidence, but estimating age across centuries always involves some uncertainty. Scientists continue refining their methods to ensure accuracy.

Even reproduction remains largely unknown. No confirmed pregnant female has been documented in modern scientific research, leaving major gaps in understanding how these animals sustain their populations.

Behavior is another evolving story. Once considered sluggish scavengers, newer studies suggest they may be more capable hunters than previously believed.

Studying them isn’t simple. They live in deep, dark, frigid waters — places that challenge even the most advanced research equipment.

Redefining the Limits of Life

The Greenland shark quietly reshapes what we thought was possible for vertebrate lifespan. While humans measure time in decades, this shark measures it in centuries.

Some individuals swimming today may have been alive before the United States was founded. They have outlived empires, industrial revolutions, and modern technology — all while moving slowly through Arctic waters.

The Greenland shark isn’t just an ocean curiosity. It is living proof that evolution can stretch the boundaries of aging far beyond what we once believed.