Why This Matters to Us
As longevity enthusiasts, learning from the natural world can shed light on pathways to extending human life. The Greenland shark, boasting an extraordinary lifespan of hundreds of years, offers tantalising insights into how biology can defy ageing through genetic and environmental adaptations. By understanding the unique traits of these deep-sea giants, we may be able to discover lessons applicable to human longevity. This study reminds us of the interconnectedness of life and the potential for groundbreaking discoveries that nature holds.
The Detail
The Greenland shark (Somniosus microcephalus), native to the cold depths of the Arctic and North Atlantic, is a living marvel of nature. Scientists estimate its lifespan to be at least 250 years, but some individuals may live over 500 years, making it the longest-living vertebrate on Earth. But what is the secret to this shark’s unbelievable lifespan?
One major clue lies in its growth rate. Greenland sharks grow incredibly slowly – less than 1 cm per year – and may take over 100 years just to reach sexual maturity. They are estimated to grow up to 6 metres in length and weigh more than 1,000 kilograms. This slow growth reflects an extremely low metabolic rate, which is believed to have evolved as an adaptation to frigid Arctic waters. These sharks have been observed as deep as 2,200 metres beneath the ocean's surface. Their metabolism likely contributes not only to their longevity but also to their sluggish movements, with a top swimming speed of under 2.9 kilometres per hour.
For decades, scientists struggled to pinpoint the age of Greenland sharks, as traditional methods like counting growth rings—used for other fish species—don’t work. Their soft vertebrae lack the firm structure needed to record age-related growth bands. However, a breakthrough came when researchers turned to carbon dating. They focused on proteins in the lenses of the shark’s eyes that are formed before birth and remain unchanged throughout life. By carbon-dating these eye proteins in captured sharks, scientists determined that a 5-metre-long female shark was likely between 272 and 512 years old. Even conservative estimates make the Greenland shark the oldest vertebrate known to science.
Recent genetic studies add another layer to the story. Researchers have begun to map the Greenland shark’s genome to uncover possible molecular explanations for its extreme longevity. Early findings suggest these sharks possess unique genetic traits that promote DNA repair, reduce inflammation, and regulate cellular damage. Specifically, the sharks show variations in genes tied to the process of NF-κB signalling. This pathway plays a major role in maintaining healthy cells by controlling inflammation, cellular repair, and immune function. Differences within these genetic instructions may reduce the risk of diseases like cancer and autoimmune disorders, which typically increase with age.
It’s not just the shark’s genetic code that has scientists excited – its life history highlights its vulnerability and importance to the marine ecosystem. With such a slow growth rate and a late age of sexual maturity (potentially over 150 years), losing just one Greenland shark can disrupt population balance for decades. Historically, these sharks were hunted for their oil-rich livers, but today, the main threat is bycatch – accidental capture by fishing vessels. Their long lifespans mean that even a small reduction in numbers could have a profound impact on the species’ survival. Protecting this ancient creature is therefore not just an ecological responsibility but also a window into understanding a marvel of natural ageing and cellular preservation.
Beyond purely biological implications, studying the Greenland shark offers a broader perspective on longevity research that may be relevant to humans. Its unique ability to repair DNA, avoid cancer, and maintain immune function over centuries is a source of inspiration for scientists exploring how to extend human lifespan and improve healthy ageing. Future investigations into the shark’s genome could reveal further insights into maintaining cellular integrity and combating the effects of ageing over time.
At the same time, the extreme environments these sharks inhabit demonstrate how environmental factors like temperature and metabolism interact with genetic traits to create biological resilience. Understanding these deep-sea survivors may challenge and expand our current understanding of physiology and ageing, offering lessons on how to achieve longevity under harsh conditions.
Read more about the Greenland shark on NOAA’s website.
Summary: The Greenland shark’s remarkable lifespan of up to 500 years continues to fascinate scientists. Recent advances in carbon dating and genomic research reveal that its longevity is due to a combination of slow metabolism, unique genetic traits, and resistance to age-related diseases. As the oldest vertebrate, it serves as a natural role model for longevity research, with lessons potentially relevant to human health and ageing. However, the Greenland shark’s survival is under threat due to bycatch and environmental pressures, making conservation critical to understanding this extraordinary species. Exploring its