Two-thirds of daily deaths track age-related causes
Of roughly 150,000 people who die each day worldwide, about 100,000 die from ageing-linked disease. Reaction time may slow, yet vocabulary often holds; leading theories still split between accumulating cellular damage and built-in biological programs.
Ageing is the process of becoming older—mainly discussed for humans, many animals, and fungi—while some bacteria, perennial plants, and simple animals can look potentially immortal under the right conditions. In people it piles physical, psychological, and social change: reaction time may lag even as memories and general knowledge grow. Of about 150,000 global deaths each day, roughly two-thirds—around 100,000—are attributed to age-related causes, and in industrialized countries the share can reach about 90 percent. Jeanne Calment, who died in 1997 at 122, remains the oldest reliably recorded human; maximum lifespan is often suggested near 115 years.
Biology still argues over mechanism. Damage theories stress accumulating insults such as DNA oxidation; programmed theories stress internal schedules like epigenetic maintenance, distinct from apoptosis. Sexual reproduction in eukaryotes, emerging with fungal and animal lineages about a billion years ago, made disposable parents more thinkable, though findings in bacteria such as E. coli complicate tidy immortality stories. Normal human cells in culture stop after about fifty divisions—the Hayflick limit, named for Leonard Hayflick’s 1961 work—while HeLa cancer lines and certain germ cells behave as if they can keep going.
The body shows mosaic ageing: systems fade on different clocks. High-frequency hearing above 20 kHz often slips in the teens; wrinkles lean on photoageing; female fertility falls fast after 35; most people meet presbyopia by 45–50 as the lens hardens. Pattern hair loss by 55 hits roughly 30–50 percent of men and a quarter of women; menopause typically lands between 44 and 58; osteoarthritis incidence rises to 53 percent in the 60–64 cohort, though only about 20 percent report disabling disease then. Nearly half of people over 75 have hearing loss that hinders speech; by 80 more than half of Americans have a cataract or cataract surgery. Dementia climbs from about 3 percent at ages 65–74 to nearly half past 85. Across species, extreme longevity—from bristlecone pines over 5,000 years to Greenland sharks near 400—shows how genetically flexible ageing rates can be.
Source: Ageing
