YOU’RE designed to die: eventually the cells that make you — that multiply and grow into organs and limbs — will sustain damage, grow old and inactive and fail. This is an oversimplification, of course, as various theories about why we age and eventually die range from gene theory, which posits that your lifespan is determined by genetic inheritance, to endocrine theory, which points to hormonal fluctuations as the main cause of aging, and so on. Nevertheless, the undeniable fact is that we start dying as soon as we’re born.
Can we slow down or reverse this process? Is it conceivable that human lifespans can be extended to well over a century, even indefinitely? Increasingly, signs are pointing towards the answer being ‘yes’. Earlier this month, researchers proved that it is possible to halt the decay of tissues after death and even restore partial function to dead organs by “persuading cells not to die”. They stopped the hearts of anaesthetised pigs for 60 minutes — essentially inducing death — and then managed to restart circulation using technology they dub OrganEx and six hours later found that some of the damage caused by cardiac arrest, such as organ swelling and blood vessel collapse, had been reduced or corrected. A few years back, the same team had managed to revive the disembodied brains of pigs four hours after the animals had been slaughtered, challenging the idea that brain death is final. While this research is still in early stages, it can certainly lead to massive advancements in organ transplantation and revival, dramatically boosting longevity in humans.
Meanwhile the Japanese are targeting zombies, or rather zombies’ cells to be accurate. These are aged and decrepit cells in your body that have grown so old that they have stopped multiplying, but haven’t died either. And so, like zombies, they just hang around the body eventually causing damage to nearby healthy cells and exacerbating the aging process and leading to age-related illnesses. But their days may be numbered, as a team of scientists from Japan’s Juntendo University have developed a ‘vaccine’ that can eliminate these zombie cells. It works by enabling the body to create antibodies that then attach to these zombie cells, which are then removed by your body’s white blood cells. When tested on mice it removed the aged cells which then led to a shrinking of areas affected by age-related diseases.
Alternatively, if killing old and damaged cells doesn’t sound appealing, perhaps a way could be found to prevent or repair cell damage to begin with? Researchers at Israel’s Hebrew University claim to have discovered a group of molecules that can repair the damaged parts of cells that break down over time, essentially repairing cellular aging. They hope to turn this into a pill that can be taken as a preventative measure, preventing your cells from breaking down in the first place.
Can we slow down or reverse the aging process?
Others are taking a more cold-blooded approach by looking not at the way the human body works, but examining reptiles and amphibians like crocodiles, salamanders and turtles (the oldest living land animal in the world is a 190-year-old tortoise) who have extremely slow aging rates. Opinions are divided as to why that is, with some pointing towards the low metabolisms of these cold-blooded species, who are in fact able to slow their body processes, while others feel that their longevity is due to the natural protections, such as scaly armour or shells, that nature has afforded them. While this may not exactly be a viable solution for humans, given we are already apex predators, it is possible that some of our fellow warm-blooded mammals have something to offer: hibernation.
Biologists studying yellow-bellied marmots found that these animals “are able to virtually halt the aging process during the seven to eight months they spend hibernating”, burning only a single gram of fat a day by effectively shutting down their metabolism. Could humans hibernate? The answer to that question may be locked in our DNA, as bone samples from an extinct branch of humanity, dubbed the Sima de los Huesos hominins, suggests that they spent the winter much like bears do, in a state of prolonged inactivity. Certainly, cracking this code would be a prerequisite for long-haul space travel by humans.
But in the end, we may just have to hail the hydra. This tiny freshwater polyp is effectively immortal, as scientists were shocked to discover and, unlike other multicellular creatures, shows no sign of deteriorating with age. Its secret is that much of its body is composed of stem cells which are capable of constant division and can be moulded into any kind of cell, thus providing indefinite regeneration. Over the past 200 years, global life expectancy has increased from 30 to over 72 years. At current rates of progress, we may see average human lifespans of over a century fairly soon. Whether that’s a good thing is another question entirely.
The writer is a journalist.
Published in Dawn, August 15th, 2022