Human beings have always resisted the idea that ageing and death are unavoidable. Civilisations created stories about fountains of youth, elixirs of life, resurrection and immortality. Egyptian pharaohs were mummified and buried with possessions believed to be needed in the afterlife, although this reflected religious beliefs about spiritual continuity rather than a scientific plan to regenerate their bodies. Modern science fiction transformed the same ancient longing into suspended animation, imagining astronauts sleeping for centuries before awakening unchanged at distant destinations.
Until recently, however, restoring youth to an old body belonged almost entirely to mythology. Medicine could treat individual diseases, exercise could preserve strength and nutrition could reduce health risks, but nothing could instruct an aged cell to become biologically younger. Research into cellular reprogramming has made that possibility scientifically conceivable, although it remains far from being proven in human beings.
The sequencing of the human genome and advances in molecular biology have allowed scientists to study how genes behave as organisms grow older. Contrary to some popular explanations, ageing is not controlled by a single gene containing a predetermined expiration date. DNA can accumulate mutations and other forms of damage, while mitochondria malfunction, proteins lose their proper form, stem cells become exhausted and senescent cells accumulate.
Another important process is epigenetic change. Epigenetic markers act like instructions telling cells which genes to activate or silence. The underlying DNA sequence may remain substantially the same, but cells can become less effective at reading and executing those instructions. Patterns of DNA methylation change predictably enough with age that researchers use them to construct “epigenetic clocks”.
Scientists have also observed a remarkable rejuvenation process during reproduction. Although an egg and sperm come from adults, a resulting embryo does not begin life at the biological age of its parents. During early development, many age-associated epigenetic markers are reset. The crucial question is whether part of that resetting process can be activated later in life without erasing a cell’s identity or causing cancer.
In 2006, Shinya Yamanaka discovered that four genes — Oct4, Sox2, Klf4 and c-Myc — could return mature cells to a state resembling embryonic stem cells. These became known as the Yamanaka factors. The discovery earned him the 2012 Nobel Prize, but applying all four factors inside a living organism can be dangerous. Excessive reprogramming may cause cells to lose their identities or form tumours.
Researchers subsequently explored “partial reprogramming”: turning back some biological markers of ageing while allowing cells to remain, for example, functioning skin, muscle or nerve cells.
In a landmark 2020 Nature study, researchers associated with David Sinclair’s Harvard laboratory used three factors — Oct4, Sox2 and Klf4, collectively called OSK — on retinal ganglion cells in mice. The treatment restored more youthful patterns of gene expression, promoted nerve regeneration and improved vision in aged mice and mouse models of glaucoma. The experiment supported the possibility that old mammalian cells retain recoverable information about their younger state.
Other researchers have reported encouraging results involving muscle, skin and organs in animals. Yet rejuvenating cells in a mouse, or even improving a particular tissue in a primate, is not equivalent to reversing the age of an entire human being. Animal findings frequently fail when translated to humans, and the dangers of gene therapy and uncontrolled cell growth remain serious.
The field crossed an important threshold in 2026. The US Food and Drug Administration cleared Life Biosciences to begin a Phase 1 trial of ER-100, an experimental epigenetic-reprogramming therapy for optic neuropathies, including open-angle glaucoma and non-arteritic anterior ischaemic optic neuropathy.
This should be described precisely. It is not a trial proving that human ageing can be reversed, nor is it intended to make participants generally younger. It is an early-stage trial designed primarily to evaluate safety and tolerability in a small number of patients, while also observing whether visual function improves.
The eye is a logical starting point because treatment can be delivered locally and monitored closely. A harmful reaction may be easier to contain than it would be after attempting to reprogram the liver, brain or entire body. Even if the therapy restores some vision, years of larger trials would be needed before scientists could establish its effectiveness and understand its long-term cancer risks.
Still, successful rejuvenation of a human tissue would represent a historic medical advance. It could open a route towards treating diseases once considered irreversible rather than immediately producing ageless human beings.
The economic implications could be immense because ageing contributes simultaneously to cancer, cardiovascular disease, dementia, diabetes, frailty and many other conditions. A therapy that delayed several diseases together could generate more value than treating each one separately after it appeared.
A 2021 study co-written by economists Andrew Scott and Martin Ellison and geneticist David Sinclair estimated that slowing ageing sufficiently to add one year to American life expectancy would be worth approximately $38 trillion; a 10-year gain was valued at $367 trillion. These figures represent an estimated aggregate social willingness to pay, including the value assigned to healthier and longer lives.
A later international study estimated that a one-year improvement in healthy longevity could produce an annual welfare benefit equivalent to roughly 4 to 5 per cent of GDP. The benefit would come through healthier workers, longer productive careers, reduced disability, lower demand for expensive late-life care and the intrinsic value people place on living well for longer.
Pakistan offers a different but equally important case. Its population reached approximately 255 million in 2025, life expectancy was about 68 years and nominal GDP was approximately $407 billion. Only 3.55 per cent of the population was 65 or older in the 2023 census, while nearly 56 per cent was of working age.
Applying the international estimate mechanically, a one-year improvement in healthy longevity might carry an annual welfare value equivalent to approximately $16 billion to $20 billion — 4 to 5 per cent of Pakistan’s present GDP.
The potential is enormous for the least-developed and developing countries. These countries could retain experienced doctors, teachers, engineers, farmers and entrepreneurs for longer. Families might spend less on chronic illness, while healthier older adults could remain independent instead of requiring full-time care. Reduced disability could also increase household savings and national productivity.
Longer lives would also affect employment, pensions, inheritance, housing and population growth. If retirement ages remained unchanged, the fiscal burden could rise. If careers became longer without creating new jobs, younger workers could face blocked advancement. Women might experience new social pressures concerning fertility and caregiving. Religious scholars, ethicists, physicians and legislators would need to consider whether rejuvenation is simply medical treatment or something requiring a new ethical framework.
However, while developed countries are already in this crucial race, developing countries should not wait for the technology to arrive. They should strengthen biotechnology research, establish gene-therapy regulations, train geneticists and bioethicists, and develop policies ensuring that successful treatments are not permanently restricted to the wealthy. Public investment must continue prioritising vaccines, sanitation, nutrition and primary care even while preparing for advanced medicine.
Humanity is not yet approaching immortality. It may, however, be approaching the ability to repair particular tissues by restoring some of their youthful biological instructions. If that achievement expands safely from the eyes to other organs, it could transform medicine and economics.
The greatest challenge will not only be making a longer, healthier life possible — but ensuring that its benefits belong to humanity rather than to a privileged minority.
