AAll living beings will die sooner or later. But some of us take a little longer to say goodbye, especially some non-human and ocean-dwelling members of the animal kingdom. Many of these creatures continue to celebrate birthdays even after their 200th birthday, while others rarely suffer from the diseases of aging that tend to accumulate in humans: cancer cells, brain degeneration, heart disease. Scientists have been studying the long-lived creatures for decades to unravel their mysteries, hoping that they can use what they find to extend human life. Here are some of the longest-living creatures on Earth, what we know about how they do it, and whether there are any potential uses for humans.
Bowhead whales
Weighing in at more than 170,000 pounds, these endangered deep-sea giants can live up to 200 years. For a long time, scientists did not understand why, but just this week a group of researchers announced that studying their cells revealed a cold-activated protein that is a powerful DNA repair agent. DNA damage and mutations that accumulate during cell division are considered a major driver of aging and age-related diseases, so it makes sense that having a powerful DNA doctor in the house will do wonders for a person's ability to work for decades. The protein that repairs bowhead whale DNA is called CIRPB, and it is activated in cold conditions. When the team increased the levels of CIRBP in human cells, they found that the cells were also better at repairing breaks in their DNA. “The most interesting finding is that there is room for improvement,” study co-author Vera Gorbunova, a biologist at the University of Rochester in New York. said Nature. “We can improve the repair of our DNA.”
Naked mole rats
Pink, hairless and almost blind, these rodents, native to East Africa, have a fetal appearance that can make them appear completely defenseless. But creatures that lead their lives primarily underground can live up to 30 years. Of course, this is much shorter than the human lifespan, but very long for a rodent or any creature their size: most wild rodents live 6 years or less. Naked mole rats are also mostly immunity to cancer. Recently, a group of Chinese scientists discovered that the naked mole rat, like the bowhead whale, has a powerful protein in its sleeve that repairs DNA. Differences in this protein, called cGAS, allow rodents to more effectively repair damaged sections of DNA. The human and mouse versions of the cGAS protein only interfere with the repair process. Scientists also marked that these creatures eat a diet of tubers and roots, rich in anti-inflammatory and antioxidant compounds and very low in calories. The anti-aging effects of calorie restriction have been proven. confirmed in many species, from nematodes to mice and monkeys, but scientists still grade what impact does it have on human life expectancy?
Ocean quahogs
Bivalves—clams, oysters, and mussels—come from one of the oldest lineages of animals on the planet. These shell-like creatures are especially useful for aging research because many species have visible growth rings on their shells, allowing scientists to easily determine their age, and because the lifespan of mollusks varies widely. Some of the nearly 10,000 species in this group live no more than a year, while others live for hundreds of years. Take for example the ocean quahog, scientifically known as Arctic Icelandicwhich may take more than 500 years to say goodbye to the planet: one individual quahog was found to have lived to the ripe old age of 507 years. Scientists found that these quaogs have proteins that resist molecular damage, such as unfolding and sticking together, in response to acute environmental stressors, and that this is a key difference from short-lived bivalves. Proteins, of course, play a key role in repairing and removing damaged parts of cells. This creature's exceptional lifespan is especially remarkable given its body size: for most animals, a small body size means a shorter time on the planet. (In addition to being a miracle of longevity, ocean quahogs are also useful for climate science, since scientists can analyze their shells to determine how warm or salty the seas were hundreds of years ago.)
Greenland sharks
Known for their slow metabolism, deep-sea habitat, torpedo-shaped body and tiny eyes, these sharks are the longest-living vertebrates on Earth: they typically live for at least 250 years and can even live more than 500 years before they die. To determine their age, scientists relied on radiocarbon dating shark eye lenses. Greenland sharks do not reach sexual maturity until they are 150 years old, but some studies show that they give birth to hundreds of young at a time. These sharks grow very slowly, less than 1 centimeter per year, and maintain a cruising speed of less than 3 feet per second. One theory suggests that they slow metabolism may explain their extreme longevity, but genetic analysis also found that, like many other long-lived species, Greenland sharks are exceptionally good at repairing damaged DNA, especially breaks that occur in both strands of the double helix. (Can you sense a pattern here?)
Immortal jellyfish
Turritopsis dohrnii was discovered in the 1880s in the Mediterranean Sea, although it swims in seas around the globe.. What makes this tiny bell-shaped creature (smaller than a paper clip) unusual is not only that it can survive harsh conditions such as starvation, injury, low oxygen levels, and fluctuations in salinity and temperature. When faced with an impending threat, it can revert to its earliest stage of development – a polyp – within a period of 24 to 36 hours. When the grim reaper comes for him, he hits the reset button, starting from scratch. The reborn polyp eventually develops and releases an adult jellyfish genetically identical to the one that was injured. Theoretically, this little jellyfish could live forever – that's why it was nicknamed immortal jellyfish— although most end up falling prey to predators, disease, or other dangers. Scientists have discovered that, like other long-lived creatures, the immortal jellyfish has powerful DNA repair abilities.
Glass sponges
But Guinness Book of Records for old age goes to a species of sponge known as Skolimastra JubiniAntarctic hexactinellid or glass sponge. Glass sponges have skeletons made of silica and form beautiful patterns like fiberglass or lace. Scientists estimate that one 3-foot-tall specimen found in the Ross Sea was 23,000 years old, although historical sea level fluctuations suggest such a sponge could not have survived longer than 15,000 years. One of the secrets to the success of this species appears to be its extremely slow growth rate, about 2 centimeters per year. This will allow more resources to be devoted to maintenance and repair rather than to reproduction and growth, and will reduce the opportunity for damage to accumulate from cell division. Their deep-sea habitat is also very stable, with consistently low temperatures and little disturbance, and their glass exoskeleton makes them unpalatable to most predators.
Whether people can learn these longevity tips from the world's longest-living inhabitants is still an open research question. But maybe people could start at the tip of the glass sponge and just slow down a little.
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Main image: National Oceanic and Atmospheric Administration (NOAA) / Wikimedia Commons.
