The first human journey into space would not occur until 1961.
The first human landing on the Moon would follow in 1969.
If the shark had indeed been born around 1620 and survived until the early 21st century, it would have existed through all these milestones without ever witnessing the human world directly.
It might have moved through the North Atlantic while ships crossed the ocean under sail, while industrial fishing developed, and while modern submarines began exploring the deep sea.
It could have lived through enormous changes in human technology while continuing to inhabit an environment that remains largely inaccessible to us.
There is, of course, no evidence that the individual shark encountered any particular historical event. These comparisons simply illustrate the length of time represented by the scientific estimate.
Still, the contrast is difficult to ignore.
Human history often feels long when measured through generations, historical documents, and archaeological discoveries. For a Greenland shark, however, a period spanning several human lifetimes may represent only a portion of its existence.
The ocean has its own timescale, and this animal may be one of its most extraordinary examples.
Why Do Greenland Sharks Live So Long?
Scientists do not yet have a complete explanation for the Greenland shark's exceptional longevity. However, several characteristics of its biology and environment may help explain how it can survive for centuries.
One of the most important factors is temperature.
Greenland sharks inhabit some of the coldest marine environments on Earth. The waters of the Arctic and North Atlantic can remain close to freezing for much of the year, creating conditions very different from those experienced by sharks living in warmer tropical seas.
As cold-blooded animals, Greenland sharks rely on environmental temperatures to influence many aspects of their physiology. Cold conditions generally slow many biological processes, although the relationship between temperature, metabolism, and lifespan is complex.
Their metabolism is believed to be relatively slow, and their movements are often unhurried. These characteristics fit a lifestyle in which energy conservation is important and food may not always be readily available.
But scientists caution against assuming that cold water alone explains a lifespan of several centuries. Longevity is influenced by multiple biological processes, including cellular maintenance, growth, reproduction, and the mechanisms organisms use to cope with damage over time.
Researchers still need more evidence to determine which adaptations allow Greenland sharks to age so slowly and whether those adaptations are unique to this species.
Their slow growth offers another important clue.
According to NOAA, Greenland sharks may grow less than one centimeter per year. Although growth varies among individuals and conditions, this exceptionally slow rate helps explain why the animals can take so long to reach their enormous adult size.
A shark that grows at this pace follows a very different biological schedule from a species that reaches maturity within only a few years.
The Greenland shark's life appears to unfold gradually, with growth, reproduction, and aging occurring over timescales that are difficult for humans to imagine.
That slow pace may be part of what makes the species so remarkable.
A Shark May Spend More Than a Century Growing Up
Perhaps the most surprising finding from the 2016 research concerns reproduction.
The study estimated that Greenland sharks reach sexual maturity at approximately 156 years of age, with an uncertainty of about 22 years around that estimate.
This does not mean scientists have observed every shark waiting precisely 156 years before reproducing. The figure is an estimate derived from the age analysis and information about the animals' size and maturity.