It would be possible to replace our organs as they damage or age, almost as if we were machines in a workshop? New heart, new liver, new lungs … and so on. The idea, to which Russian President Putin some time ago said he was very interested, sounds fascinating, but also a little disturbing: if it were enough to change the pieces, why shouldn’t we live forever? Still, science is clear: our body does not work as an engine in which it is enough to replace a broken piece. Behind the promise of “technical immortality” are hidden insurmountable walls: the biology of our body, the decline of the immune system, the limits placed by the evolution, the risk of tumors and the fragility of the brain remind us that a human body is not a car to repair. For these reasons, biological immortality remains out of our reach. Transplants, drugs, even the most daring experiments do not erase the limits imprinted in our biology. This does not mean surrendering: today we live longer and better than any past generation. The real challenge is not to become eternal, but stretch the years of healthreduce chronic diseases and make old age for a dignified and rich time.
Why are there no immortal organisms? The theories that explain why we age
The concept of immortality has always fascinated humanity, but biology teaches us that aging is an almost inevitable part of life. This raises a fundamental question: why has nature never selected immortal organisms?
The answer could come from two theories that have made school. In the 1950s George C. Williams developed the theory of antagonistic pleiotoropia: genes that in youth bring advantages, such as more fertility or strength, can become a burden of age, contributing to aging. It is the paradox of a gene that “wins” soon, but “loses” on the long term.
Twenty years later, Tom Kirkwood proposed the Body theory (Soma) USA without: the energy of an organism is limited, and nature has invested it above all in the reproductionnot in the infinite maintenance of the body. In other words, for evolution it counted that the genes passed to the next generationnot that the individual lived forever.
Why does the human body age old? The 12 sections of aging
Our body has control and regeneration systems that can cope with mutations, small and large cell damage, but these do not work infinity. In 2023 a group of scientists updated the distinctive features of aging, also known as “Hallmarks of Aging“, That is, that theoretical framework that scientists use to describe the fundamental mechanisms that cause aging. To date, they are identified Twelve processes which together consume the body. Here are what are:
- Genomic instability: DNA accumulates errors and damage, making cells less reliable.
- Shortening of telomers: The ends of our chromosomes, the telomers act like “hoods” that protect our genetic material, but shorten to every cell division, until the cell can no longer replicate.
- Epigenetic alterations: The “commands” that light and turn off the expression of the genes alter, so the cells lose part of their identity.
- Loss of Protestsi: The proteins bend badly or accumulate without being disposed of, in this way, the cellular functions.
- Mitochondrial dysfunction: The energy plants of our cells, the mitochondria, produce less energy and more harmful slag.
- Cellular Senescence: The damaged cells stop dividing or go apoptosis (programmed death), but remain active, releasing harmful and chronic inflammatory signals.
- EXHAUSTING OF HEARTS: The stem cells, i.e. immature cells capable of specializing in any other cell type, a bit as if they were the “spare parts” of the body, are reduced, and therefore the tissues pay more slowly.
- Altered intercellular communication: The cells no longer exchange clear messages and the signals become confused.
- Disregulation of the sensing of nutrients: The internal sensors that regulate metabolism and growth work badly, promoting disorders such as diabetes and obesity.
- Chronic inflammation (inflamm-aging): A weak but continuous inflammatory alarm wears out organs and fabrics.
- Decline of the immune system (immunossenscence): The production of new immune defenses decreases and are also less effective, so the body responds worse for viruses and infections.
- Alterations of the microbiota and tissue barriers: The balance of the intestinal flora and the skin breaks, making the body more vulnerable to external pathogens.
Let’s see some of these processes in detail.
We accumulate genetic mutations
During life, our DNA accumulates a series of mutationspontaneous or derived from environmental factors that can alter the information contained in our genetic material. A study, published on Nature In 2022, he analyzed 208 intestinal cryptic, small tube -shaped glands located in the intestinal mucosa, of 16 different species: surprising result, the man accumulates about 47 cell mutations every yearthe mouse almost 800. Yet, at the end of life, both come to a similar total: about 3000 cell mutations. More mutations, it means one greater probability of having unfavorable mutations Which could lead to developing pathologies: for example, it means a wide probability of developing cancer or cancer.
Most fragile immune defenses and growing inflammation
With the age, our internal army is frayed. The thyme – the “training school” of T lymphocytes – begins to reduce itself after puberty and, in old age, its activity is almost off. Result: few new recruits and increasingly weak defenses.
In parallel, the body continually produces inflammatory molecules such as IL-6. It is the phenomenon ofInflamm-aging: an inflammation chronicsilent but exhausting, which prepares the soil for cardiovascular diseases, tumors and Alzheimer’s.
The brain is an organ that does not change
Thanks to an ingenious method based on carbon-14, the group of Jonas Frisén al Karolinska Institute has shown that the human hippocampus produces about 700 new neurons per year. A minimum figure: if the hippocampus manages to regenerate a little, the cerebral cortex, on the other hand, does not do it almost for anything. For this reason it can be said that the neurons you were at twenty are, largely, the same ones who accompany you up to the eighties. And this is where the deepest limit emerges: We cannot “replace” the brain as we do with other organsbecause the cells that keep memory, memories and consciousness remain with us for life. It ages the body, but also ages our identity, in the sense that the biological structures that support it are known. Not only that. Toyama laboratory experiments published on Cell In 2013, they showed that Some brain proteins remain intact for decades. They are not recycled, but accumulate oxidative damage who stiffen them, as rusty gears that no one replaces.
Cellular Senescence: a double -edged protection mechanism
The more a cell is divided, the more you risk making mistakes. This was demonstrated by a 2017 study on different fabrics: tumors are much more frequent in rapid replacement organs, such as the colon or lungs, compared to the brain. To defend itself, the body uses the cellular senescence: a sort of emergency brake which blocks the proliferation of cells. It works as a barrier against cancer, but there is a price to pay. Senescent cells, even if they no longer divide, remain active And they release toxic substances that damage the surrounding fabrics.
Transplants are a partial victory
Transplants are an extraordinary conquest, but have precise limits. According to the international register ofInternational Society for Heart and Lung Transplantation (ISHLT, International Association for Westeen and Lungs transplants), which collects beyond 108,000 heart transplants From 1992 to 2018, survival at a year today is around the85–90%. At five years, conditional survival remains high, with values higher than the85% in Europe and North America. A chronic complication – the vasculopathy of graft – still remains the main cause of long -term failure.
And even if science experiences new roads, such as xenotrapriants from genetically modified pigs, The results are still at the beginning. In a 2022 study, two pork kidneys were transplanted to patients in brain death and worked for 54 hoursproducing urine and maintaining good filtration without signs of immediate rejection. A technical success, of course, but still very far from the idea of a “life” spare.
Is there a maximum age limit?
An analysis published in Nature in 2016 suggests that the maximum duration of human life is around 115 years. Other scientists, studying 3836 Italians overweight, noted that after the 105 years The risk of death stabilizes around the 50% per year. In other words: at that age, every year it is like launching a coin. There is no insurmountable wall, but the probability play against.
