In Yaksh Prasn episode of Mahabharat, thirsty Yudhisthir was asked by a Yaksh 125 questions. Only by answering them can he drink water from the pond, and also save his brothers. Yudhisthir goes on to answer all of them successfully. In one of the questions Yaksh asked him what he considers as the most amazing thing about humans? To that Yudhisthir replied that, “Although people see death happening every day, they live as if they themselves will never die.”
We tend to think of death as something that happens to others, because if we were to constantly think about our own mortality, we would go mad. Genes that make you worry constantly about death will be eliminated from the gene pool. Different cultures invented different ideas, including soul and rebirth, to make us believe that we are immortal. Even scientists are working to achieve the miracle of immortality.
And yet, we do believe that death is inevitable. If nothing else kills us, entropy will, by causing us to age. Interestingly, we seem to be one of the only species that frequently dies of old age. The only others are those in captivity, including our pets. The rest are either eaten by predators, killed in a fight, or succumb to disease, starvation, or accidents. That is the price of freedom.
Nobel laureate Venki Ramakrishnan’s book, Why We Die, offers a fresh perspective on death and immortality.
Our cells die every day, civilizations die every few centuries, stars die every few million years, and eventually, our universe will die as well.
According to Venki Ramakrishnan, “What we really mean when we say we die is that we stop functioning as a coherent whole. The collection of cells that forms our tissues and organs all communicate with one another to make us the sentient individuals we are. When they no longer work together as a unit, we die.”
Venki goes on to write, “The germ-line that propagates our gene (information on how to create another cell or an entirely new organism, even after the original carrier of that information has died) are immortal…The death of an animal or a human is really the death of a vessel.”
Scientists, and philosophers, are still confused about the exact time when we die. We have no idea how many people we have burnt or buried when they were still alive. Nails were put in the coffins to ensure that the dead don’t rise, but it was often seen that the coffins had scratches and nail mark, showing that the person thought dead, was actually alive when buried. Hence, in Germany, a priest suggested safety coffins. It had a rope attached to a bell. In case the persons was alive once buried, he or she could ring the bell for others to come for rescue. Hence the proverb, saved by the bell.
Science and technology has ensured that such horrible cases are not repeated. But it’s not perfect yet. Wikipedia tries to define death as the termination of the biological functions that sustain a living organism. But what biological function? There was a time when a person was considered dead when the heart stopped. Then technology like CPR brought them back to life. Now it considered in most places that the loss of brain function is sign of death. Technology is catching up with that too. This confusion means that there can be different rules in different places about what it means to be dead. This Schrödingerish confusion ensures that a person can be alive at one place and dead at others.
Death happens primarily due to the accumulation of molecular and cellular damage over time, a process known as aging. The accumulation of these damages is often caused by the very same genes that were beneficial in our youth.
Aging has not been eliminated by evolution because, throughout most of human history, people rarely lived past thirty due to accidents, disease, predators, or violence, meaning that natural selection acted mainly on traits that enhanced survival and reproduction in early life. Harmful genetic mutations that only affect individuals later in life, after reproduction, were not strongly selected against and thus accumulated over generations (Medawar’s mutation accumulation theory). George Williams’ antagonistic pleiotropy theory further explains that some genes have benefits early in life—such as promoting growth or fertility—but cause harm in old age, increasing the risk of diseases like cancer or dementia. Similarly, Kirkwood’s disposable soma hypothesis suggests that organisms must allocate limited resources between reproduction and bodily maintenance, prioritizing reproductive success over long-term repair. As a result, evolutionary trade-offs mean that traits increasing lifespan often reduce fertility, with those having fewer children tending to live longer.
Are we programmed to die? Not quite.
Organisms like hydra, immortal jellyfish, some flatworms and even lobsters can regenerate, rejuvenate, become young again, or repair DNA damage, and potentially live forever. They are biologically immortal. Though they eventually die of accidents, exhaustion or ending up in our seafood platter, they don’t die of old age. They are biologically immortal.
The quest for immortality has driven human civilization for centuries. We have improved our lifespan from around 40 years to almost a century, largely due to modern sanitation, vaccines, antibiotics, blood transfusions, the sterilization of water and food by chlorination and pasteurization, and artificial fertilizers. The inclusion of fertilizers may surprise you, but prior to the ready availability of food—which has brought about its own problems of obesity, diabetes, and cardiovascular diseases—humans were constantly struggling to get enough to eat.
Research has also shown that sleep, reduced stress, moderate exercise, and caloric restriction can slow down aging, in addition to genetic factors beyond our control. Drugs like rapamycin that inhibit nutrient-sensing pathways (TOR pathway) and mimic caloric restriction show promise in extending a healthy lifespan.
We have managed to increase our lifespan by improving our health. But can we reset our ageing clock?
We have reset the clocks once before, when we were born.
Since mothers are already born with all the eggs they will ever carry (we are, in fact, born in our grandmother’s womb), the egg that eventually develops into her child is as old as the mother herself. So why isn’t a child born to a 40‑year‑old mother twenty years older than a child born to a 20‑year‑old mother?
When a child is born, the aging clock resets to zero because eggs and sperm are very special cells called germ cells. These cells can give rise to any type of cell, from liver to heart to bone. They not only accumulate fewer mutations with age but also possess the ability to repair DNA damage that could otherwise make them “old.” Even then, some defects do accumulate. Nature eliminates the damaged cells, allowing only the healthy ones to fertilize. Even after fertilization, spontaneous abortions can occur to prevent fatal genetic errors from passing on.
That’s not all. When sperm fertilizes the egg, both parents’ genetic material is reprogrammed, erasing old chemical “aging marks” and setting new ones. This effectively “resets” the biological clock for the newborn, ensuring the embryo starts life fresh. The sperm race ensures that only the fittest sperm reach the egg, and on top of that, the egg releases chemical signals to guide and favor certain sperm.
While some risks, such as genetic defects, do increase with maternal age, the fundamental process ensures that all children begin life with similar biological starting points, regardless of the mother’s age.
Scientists are now exploring how to reset the aging clock of adult cells to zero, which could open the door to human immortality. All they need to do is replicate what germ cells can do, but within the far more complex setup of a multicellular organism. There are already biologically immortal animals that show no signs of aging. Perhaps someday, humans won’t either
While some progress toward increasing lifespan and health has been made, immortality is still a distant goal. However, tech billionaires seem to be in a rush.
Tech leaders such as Elon Musk, Jeff Bezos, and Mark Zuckerberg are attracted to anti-aging research, funding projects out of a desire to extend youth. When they were young, they sought wealth; now that they are wealthy, they seek youth. Only Bill Gates recognizes the importance of addressing healthcare inequities over chasing immortality. Most tech billionaires see aging as a problem to be hacked with rapid technological innovation and are heavily funding biotech research targeting cellular and molecular aging mechanisms.
The complexity of aging biology means fast breakthroughs like those in tech are unlikely, despite billionaire optimism and investment. The book cautions against hype and false promises in anti-aging, distinguishing legitimate research from speculation and fantasy.
Scientific understanding of aging pathways holds the potential for new therapies to delay aging and age-related diseases. But efforts to extend life face biological, technical, ethical, and societal challenges. For example, increasing lifespan could worsen inequality because advanced life-extension treatments might be available only to the wealthy, greatly increasing disparities in lifespan and healthspan between rich and poor populations.
This book explores numerous biological breakthroughs and scientific research, detailing the critical role proteins play in controlling life and, ultimately, death. It’s a must-read for anyone interested in the science behind aging and mortality.
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