Ageing is the most universal human experience and the least understood. Every one of us, barring accident or disease, will undergo it: skin wrinkling, muscles weakening, memory fraying, and the rising risk of cancer, heart disease, diabetes and dementia. Yet ageing is not programmed like development; no gene says grow old at sixty. Instead, modern biology sees ageing as the accumulation of damage and the gradual failure of maintenance, a dozen interlocking processes that erode the body’s systems over decades. The exciting news is that these processes, called the hallmarks of ageing, are increasingly understood, and in laboratory animals, interventions targeting them extend healthy lifespan dramatically. We cannot stop ageing yet, but for the first time in history, we can see its machinery clearly enough to imagine slowing it.

The hallmarks of ageing

In 2013, researchers proposed nine hallmarks of ageing, expanded to twelve in 2023, that together explain growing old. Genomic instability: DNA accumulates mutations from radiation, chemicals and copying errors faster than repair systems can fix them. Telomere attrition: the protective caps on chromosome ends shorten with each cell division, eventually triggering cellular retirement. Epigenetic alterations: the chemical marks controlling which genes are on or off drift with time, scrambling cellular identity. Loss of proteostasis: the machinery that folds proteins correctly falters, allowing toxic aggregates like those in Alzheimer’s. Deregulated nutrient sensing: the metabolic pathways that balance growth and repair, including insulin and mTOR signalling, become miscalibrated. Mitochondrial dysfunction: the cell’s power plants accumulate damage and leak destructive free radicals. Cellular senescence: damaged cells enter a zombie-like state, refusing to die while secreting inflammatory signals that harm neighbours. Stem cell exhaustion, altered intercellular communication, chronic inflammation, disabled macroautophagy and gut dysbiosis complete the list. Ageing is not one clock but a committee of them, which is why no single pill will stop it.

What actually extends life

The interventions that extend lifespan in animals are remarkably consistent. Caloric restriction, eating substantially less without malnutrition, extends life in organisms from yeast to monkeys, apparently by activating repair pathways; whether humans can or should do this is debated, but milder fasting regimes show metabolic benefits. Exercise is the closest thing to a proven anti-ageing drug in humans: regular aerobic and resistance training slows muscle loss, protects the brain, improves metabolism and is associated with years of extra healthy life. Rapamycin, metformin and newer senolytics, drugs that clear senescent zombie cells, extend healthspan in mice, and human trials are underway. The most dramatic results come from reprogramming: briefly activating the Yamanaka factors that revert adult cells to stem-cell-like states has rejuvenated tissues and extended life in mice, though the cancer risk makes human application distant. Genetics matters too: centenarians cluster in families, and variants in genes like FOXO3A are associated with exceptional longevity. But genes load the dice; lifestyle rolls them, which is why even the best longevity science keeps returning to unglamorous advice.

Why we age at all: evolution’s perspective

Evolutionary biology asks a deeper question: why did natural selection not build bodies that last forever? The answer is that selection cares about reproduction, not longevity. The disposable soma theory holds that organisms have limited energy, and investing in perfect maintenance means less for reproduction; since most wild animals die young from predators or starvation anyway, selection favours reproduction over repair. Antagonistic pleiotropy adds that genes beneficial early in life can be harmful late: the same growth pathways that build a strong young body may drive cancer and ageing later, and selection, which acts most strongly on the young, keeps them anyway. This explains why ageing varies so wildly: mice, heavily predated, invest little in maintenance and live two years; bowhead whales and Greenland sharks, facing few predators, invest heavily and live two centuries. Humans, with our long childhoods and grandmother-powered families, evolved unusual longevity for primates. Ageing, in this view, is not a design flaw but the price of a reproductive strategy that worked.

• The 2023 update lists twelve hallmarks of ageing, from DNA damage to chronic inflammation.
• Caloric restriction extends lifespan in species from yeast to monkeys.
• Senolytics, drugs that clear senescent cells, extend healthy lifespan in mice.
• Greenland sharks can live nearly 400 years, the longest-lived vertebrates known.
• Exercise remains the most proven anti-ageing intervention available to humans.

How long could we live?

The maximum human lifespan, about 122 years set by Jeanne Calment, has barely budged in a century despite soaring average life expectancy, suggesting a biological ceiling around 120 to 150 years. Some researchers argue the ceiling is soft: if ageing’s hallmarks can be therapeutically targeted in combination, healthy life could extend well beyond current limits. Others caution that evolution built redundancy into ageing precisely because single-point interventions fail, and that the history of anti-ageing claims, from monkey-gland transplants to resveratrol hype, counsels humility. India’s demographic reality adds urgency of a different kind: the country is ageing fast, with the over-60 population projected to reach 340 million by 2050, making healthy ageing, not maximum lifespan, the pressing goal. The realistic promise of longevity science is not immortality but compression of morbidity: more years of vigour, fewer of frailty. That goal, unlike eternal youth, is already partially achievable, and its prescription is familiar: move, eat plants, sleep, connect, and avoid tobacco.

FAQs

Do anti-ageing supplements work? Most lack rigorous human evidence; some, like high-dose antioxidants, have even shown harm. No supplement is proven to slow ageing in humans.

Will humans achieve immortality? There is no scientific basis for expecting it; the realistic goal is extending healthy years, not eliminating death.

Why do women live longer than men? Partly biology, oestrogen protects hearts, two X chromosomes provide genetic backup, and partly behaviour, with men historically smoking more and taking more risks.

Ageing is damage outpacing repair, shaped by evolution’s indifference to old age. Understanding its hallmarks will not make us immortal, but it may give us more good years, which is the only kind worth wanting.

Compiled by the Khabar 24h Editorial Desk from publicly available sources.