Scientists have come one step closer to unraveling the age-defying secrets of the world's longest-living vertebrate: the Greenland shark. Understanding the biological mechanisms that facilitate this longevity may offer new insights into extending our own life spans and treating age-related diseases.
Greenland sharks can live up to 400 years and possibly even longer. As their name suggests, these animals are found in the cold waters of the North Atlantic and Antarctic oceans. To survive in these freezing waters, the sharks have extremely slow metabolisms, with top swimming speeds of less than 1.8 miles per hour, and grow less than 0.4 inches a year. These metabolic adaptations may also be the secret to their remarkable longevity.
"In most shorter-lived species, including humans, we would anticipate seeing variation in metabolic enzyme activity with age," Ewan Camplisson, a Ph.D. student at the U.K.'s University of Manchester, told Newsweek. "This won't necessarily happen in all enzymes, but we would expect to see some have a reduction in activity while others will increase to compensate and keep energy production high."
Enzymes are important parts of cellular machinery that facilitate chemical reactions within cells. After studying five different enzymes involved in chemical reactions in the muscles of Greenland sharks, Camplisson and his colleagues found that these animals do not appear to conform to the changes in enzymatic activity we expect to see with age.
"We don't see any variations with increasing age in the five enzymes we tested in the Greenland sharks' red muscle," he said. "This suggests that they aren't showing this traditional sign of aging which we would expect to see in most animals. This gives us some insight into their longevity, and with further research we may be able to determine if their metabolism is a significant factor in their long life span."
Of course, one of the most important muscles in our bodies is our heart, which is one of the leading causes of mortality in humans. "Anatomically, [human and shark hearts] differ quite significantly," Camplisson said. "For example, sharks' hearts have two chambers while human hearts have four. However, at a cellular level they have more similarities.
He went on: "If we can understand what adaptations allow the Greenland sharks to live so long while seemingly not being seriously afflicted by cardiovascular disease, we can hopefully incorporate some of these adaptations into humans to allow improved cardiac health. This may could lead to a higher quality of life in the elderly population which are most afflicted by cardiovascular conditions."
There is still a lot that we don't know about the age-defying adaptations of these animals. But Camplisson is hoping that studies like these provide a step in the right direction.
"I believe that once we fully understand how the shark can live so long and what specific adaptations it has, we can try to incorporate these into treatments that will reduce the risk of some age-related conditions, such as cardiovascular disease, which is seen most significantly in the elderly population."
As exciting as these developments are for our own longevity, improving our understanding of these sharks is also essential for species conservation.
"All information we can gain about a species helps in its protection," Camplisson said. "The work we have done has shown that the Greenland sharks' metabolism would be significantly altered with increasing temperature, and therefore, as we previously predicted, warming oceans are likely to cause big issues for the species. This will most likely result in the Greenland shark being forced into an ever-shrinking geographic range where they can stay in their cold waters.
The ever-warming oceans are a massive problem for all marine life, according to Camplisson.
"There may be many other species similar to the Greenland shark, which could offer interesting research which would be beneficial to humans," he said. "However, if we continue to destroy the environment, we may never have the chance to study them, which would be both a disaster for those species and for humanity."
Camplisson will present these findings in Prague on Wednesday at the Society for Experimental Biology's annual conference.
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