Unexpected Insights on Longevity from the Planet’s Oldest Creatures

As I embarked on this story, I pondered whether my subject should be included in my research. I envisioned a striking introduction: “Meet the longest-living animal on Earth. And yes, it’s edible.”

The creature in question is a type of shellfish, namely the ocean quahog, best known for its role in dishes like spaghetti alle vongole. While they are quite tasty, considering the moral implications of harvesting and consuming our fellow beings, as well as the harmful impact on marine ecosystems, I came to realize it raises deeper issues. This extraordinary mollusk can live for over 500 years. Killing it for food seems unjust. Thus, I must alter my introduction: This is the world’s longest-living animal, and my objective is to unravel its mysteries.

If the ocean quahog, also referred to as the Icelandic cyprin, is unfamiliar to you, don’t fret; it isn’t exactly a household name. This sizable bivalve is found buried in sandy beaches all around the North Atlantic, from the warm coasts of Florida and Cadiz, Spain, to the frigid waters of Canada and Norway. If you’ve ever tasted clam chowder in the USA, you’ve likely encountered this species. Its shell showcases fine lines akin to a tree’s annual growth rings, allowing one to determine its age by counting them.

The oldest known specimen, named Hafrun—an Icelandic term that translates to “mystery of the sea”—was born in 1499. It led an unremarkable life, living modestly on a diet scavenged from the shores of Iceland, just as its ancestors had done for generations. Its long life, however, was anything but ordinary. Sadly, Hafrun’s existence came to an abrupt end in 2006 when a team from the University of Exeter, UK, retrieved it from the ocean for research on aging by chronologist Paul Butler. The study aimed to analyze bivalve shells to devise a timeline of the surrounding environment.

“Initially, we estimated its age to be slightly over 400 years. But after a more meticulous examination of its growth lines and comparisons with other shells, we realized it was actually 507 years old,” Butler revealed. It’s possible that even older specimens exist, especially in the colder waters around Iceland, where they tend to grow more slowly and live exceedingly longer. Is there a maximum age limit? “It’s astounding that they can survive for such an extended period,” Butler noted, embodying the enthusiasm of a true mathematician.

The longevity of the quahog seems to stem from its mitochondria—the tiny structures within our cells that convert food into energy. This applies to all eukaryotes, from yew trees and beetles to jellyfish and rabbits.

“Strong mitochondria, which Arctica islandica possesses, are vital for healthy aging across various model species,” comments Enrique Rodriguez, who studies mitochondria at University College London.

The mitochondria of quahogs exhibit enhanced resilience. Their membranes are sturdier than those of other species. These membranes house a protein apparatus that handles electrons and protons to produce ATP, the body’s universal energy currency. The quahog’s mitochondria are larger and more organized, making them even more durable. “Their proteins possess greater molecular weights and intricate structures,” Rodriguez adds. “They are interconnected more efficiently.”

This specialized structure allows the quahog to mitigate mitochondrial damage. It carefully orchestrates the countless protons and electrons that traverse these membranes every second. When electrons leak, they can generate reactive oxygen species (ROS), such as hydrogen peroxide, causing cellular harm. Rodriguez likens this process to cars stuck in traffic: in regular mitochondria, a red light up front triggers a back-up, resulting in exhaust emissions that harm the environment. Yet in quahog mitochondria, protein complexes (the traffic lights) facilitate smoother flow, resulting in diminished exhaust.

However, robust membranes are just part of what allows quahogs to enjoy lengthy lifespans. They also excel in eliminating the ROS they produce. Using Rodriguez’s analogy, this equates to cleaning a car’s exhaust.

Rodriguez compared the antioxidant abilities of the quahog to several of its short-lived relatives and found it had a notably superior capacity to eliminate ROS—3-14 times more effective. This finding aligns with the Mitochondrial Oxidative Stress Theory of Aging, also seen in the extraordinary lifespans of other species like naked mole rats, which can live up to 40 years—over six times longer than rodents of comparable size.

Pierre Blier, a researcher focused on animal metabolism and aquaculture genetics at the University of Quebec, raises quahogs in labs to investigate longevity mechanisms. He adds that the ocean quahog showcases a remarkable capacity to buffer oxidants. “Their mitochondria are incredibly durable and resistant to ROS,” he states, supporting the MOSTA theory.

While this provides insights into how these creatures achieve such extended lifespans, it also raises questions about the “why.” In other words, what evolutionary pressures contributed to the development of such robust mitochondria?

A possible explanation lies in the low levels of oxygen in the environments where these clams thrive. “Naked mole rats can remain confined in their burrows for about a week without needing gills for oxygen,” Rodriguez observes. Mitochondria have adapted to endure low oxygen conditions (known as anoxia) for extended periods, subsequently requiring robustness to handle sudden oxygen influxes and the correlative spike in oxidative stress. This similar adaptability is evident in naked mole rats, as their subterranean habitats often have diminished oxygen levels. Rodriguez notes a like pattern in their mitochondrial resilience under both oxygen deprivation and subsequent reoxygenation stress, suggesting that selection pressure related to low oxygen could lead to increased longevity almost inadvertently.

The pressing question is whether we can bolster our own mitochondria. Back in 2005, a team at the University of California, Irvine, created transgenic mice with enhanced production of the “scavenging” antioxidant enzyme catalase in their mitochondria, extending their lifespans by around five months—a notable increase considering their average lifespan of two years. Although gene editing in human mitochondria is now feasible, we still lack a comprehensive understanding of how to safely extend lifespan, prompting the necessity for alternative methods.

Regular exercise is known to improve mitochondrial function. Interestingly, Tibetan Sherpas, who dwell at high altitudes, exhibit distinct mitochondrial characteristics compared to lowland dwellers. A 2017 study examining indigenous lowlanders and Sherpas attempting to climb Mount Everest Base Camp, situated roughly 5,300 meters above sea level, found that Sherpas demonstrated superior oxygen utilization and greater defenses against oxidative stress—attributed to their stronger mitochondria, with genetic foundations for these traits.

Blier argues that Arctica islandica offers valuable insights into longevity. “To enhance your lifespan, focus on your mitochondria: engage in regular exercise, maintain a balanced diet, and incorporate cold showers… Cold showers seem to invoke mitochondrial quality control mechanisms.”

If it works for quahogs…