Longevity has taken the world by storm recently as everyone scrambles for just the right thrill to slap on their face as they wildly swim their way to eternal life – but can we learn the secrets of longevity from nature? And if so, what does the world’s longest-lived vertebrate say about it all?
A new experimental study on the subject has found that metabolic activity may be the key to the incredibly long lives of Greenland sharks. This increased understanding could help us conserve them on a warming planet, while also likely informing interventions for human cardiovascular health.
Greenland sharks – known to science as Somniosus microcephalus – have a life expectancy of at least 270 years, but can live over 500 in the most remarkable cases (which, strangely, we know thanks to nuclear weapons). It has long been suggested that the cold environment they inhabit, combined with the minimal effort they make to move, may be the key – but a team including Ewan Camlison, a PhD student at the University of Manchester, UK, decided to take a closer look. up close.
In pursuit of the adaptations that allow bowhead sharks to live so long, the team conducted enzyme analyzes on preserved muscle tissue samples. Such samples are a rare opportunity to study these animals, which are the focus of the University of Copenhagen’s Old And Cold project.
Greenland shark tissue collection.
Image credit: Ewan Camplisson
“While on an expedition, a key focus is to catch sharks to tag them with both electronic and physical tags so that we can release them and then either monitor where they swim (via electronic tag) or we record how much they grow if they are recaptured and we can identify them by their physical tag,” Camplison explained to IFLScience.
“Sometimes during this process a shark is injured and may not survive to be released. To avoid unnecessary suffering for the shark, we may decide not to release it back into the water, but instead ethically euthanize it. In this case, we collect samples for future work so that the animal is not lost in any way and can still be used for science. All shark remains are also donated to local fishermen or hunters who feed the shark meat to their dogs so that none of the animal is wasted.
The team used samples of red muscle in the repository to measure the metabolic enzyme activity of the sharks with a spectrophotometer, looking at a range of different shark ages and environmental temperatures. Surprisingly, they observed no significant change in muscle metabolic activity in sharks, indicating that their metabolism does not decline with age – as we see in other animals – and may be a crucial contributor to their extraordinary longevity.
“To us, this is important because most animals that show traditional signs of aging would show decreases in some enzyme activities and compensatory increases in others as they age,” Camclison said. “It’s all part of natural metabolism, as aging causes it to fail and change over time. The fact that we don’t see this in the Greenland shark suggests that they don’t show this traditional sign of aging.
The results show variations in ambient temperatures, indicating that metabolic enzymes are significantly more active where it is warmer. According to Camplisson, this suggests that muscle metabolism is not adapted to the polar environment, as otherwise there would be less difference in temperature-related activity.
The team’s work continues in the hope that a better understanding of bowhead sharks can inform how they may respond to the planet’s rapidly changing climate, while possibly revealing insights that can be applied to the study of human cardiovascular health with advancing age.
“I have other projects, all focused on studying the aging of the Greenland shark,” Camclison said. “Looking at changes in metabolism is just one of those projects. However, as part of this small project, I plan to look at some other tissues in the Greenland shark that may show different metabolic profiles, as well as look at some more enzymes that will give even more insight into metabolism in this amazing species.
The study was presented at the Society for Experimental Biology annual conference in Prague on July 2-5, 2024.
