Ageing and longevity

This page is reference information compiled from the cited sources. It is not medical advice. For any decision about health, diagnosis or care, consult a qualified professional.

What it is

Ageing, or aging in American English, is the process of becoming older. The term refers mainly to humans, many other animals, and fungi. For example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In a broader sense, ageing can refer to single cells within an organism which have ceased dividing, or to the population of a species. In humans, ageing represents the accumulation of changes in a human being over time and can encompass physical, psychological, and social changes. Reaction time may slow with age, while memories and general knowledge typically increase. Current ageing theories are assigned to the damage concept, whereby accumulation of damage such as DNA oxidation may cause biological systems to fail, or to the programmed ageing concept, whereby internal processes such as epigenetic maintenance may inherently cause ageing. Programmed ageing should not be confused with programmed cell death, called apoptosis.

Key facts

Age-related changes can vary in different bodily systems and among individuals, a heterogeneity referred to as mosaic ageing. Of roughly 150,000 people who die each day across the globe, about two-thirds die from age-related causes. In industrialized nations, the proportion is higher, reaching 90 percent. Teenagers tend to lose the young child's ability to hear high-frequency sounds above 20 kHz. Wrinkles develop mainly due to photoageing, particularly affecting sun-exposed areas such as the face. After age 35, female fertility falls rapidly. Most people experience presbyopia by age 45 to 50. By age 55, hair tends to grey. Pattern hair loss by the age of 55 affects about 30 to 50 percent of males and a quarter of females. Menopause typically occurs between 44 and 58 years of age. In the 60 to 64 age cohort, the incidence of osteoarthritis rises to 53 percent, but only 20 percent report disabling osteoarthritis at this age. Almost half of people older than 75 have hearing loss, called presbycusis, inhibiting spoken communication. Many vertebrates such as fish, birds and amphibians do not develop presbycusis in old age, as they can regenerate cochlear sensory cells, while mammals including humans have genetically lost this ability. By age 80, more than half of all Americans either have a cataract or have had cataract surgery. Frailty, a syndrome of decreased strength, physical activity, physical performance and energy, affects 25 percent of those over 85. Atherosclerosis is classified as an ageing disease and leads to cardiovascular disease, which globally is the most common cause of death. The maximum human lifespan is suggested to be around 115 years. The oldest reliably recorded human was Jeanne Calment, who died in 1997 at 122 years of age. Dementia becomes more common with age, affecting about 3 percent of people between ages 65 and 74, 19 percent of those between 75 and 84, and nearly half of those over 85. Normal human cells die after about 50 cell divisions in laboratory culture, known as the Hayflick limit.

When to seek professional help

The source mentions treatment for cataracts and prevention for glaucoma. It states that a cataract occurs when the lens of the eye becomes cloudy, making vision blurry. It states that cataracts can be treated through surgery. It states that cataracts eventually cause blindness if untreated. It states that glaucoma is caused by damage to the optic nerve, causing vision loss. It states that glaucoma usually develops over time, but some forms have a sudden onset. It states that there are a few procedures for glaucoma, but there is no cure or fix for the damage once it has occurred. It states that prevention is the best measure in the case of glaucoma.

Source: Ageing (CC BY-SA 4.0 (Wikipedia)), retrieved 2026-10-14.