Wear-and-Tear theory, the body naturally wears out due to exposure to environmental stress and exhaustion. This explains why air pollution has a detrimental effect on our bodies but not why exercise improves the function of our hearts/lungs.
Purely genetics, every species has a maximum life span (ours being about 122 years). For us, genes affect all aspects of aging (from staying in the womb to eventual hair loss). This explains syndromes like Hutchinson-Gilford syndrome, where aging is increased drastically, and explains people like Jeanne Calment, who had the DR1 allele that allowed her to live up to 122 years. Another gene that increases longevity is ApoE2, which is found in a minority of men who have lived 70+ years. GWAS (Genetic-wide research) has found multiple genes that increase the risk of diseases, explaining why certain ethnicities are more susceptible to certain diseases. Although seemingly convincing, focusing on genes ignores the nurture aspect of our development. The metabolic syndrome is a group of syndromes that take place that increases the chances of attaining various health conditions.
Cellular aging - Focusing on the impact that stress/toxins have on cells. Senescence occurs when an organism can no longer repair cellular errors. This is first apparent on the skin and beneath the skin (leading to cancer). The Hayflick limit indicates that the maximum number of cell divisions that can occur is 50 - afterward, the life span ceases. A telomere, the tip of each chromosome, decreases in size as aging goes on. The telomere ends when the Hayflick limit is reached.
Ageism - Acts of prejudice where one is secluded because of their age. The obvious harms that come out of this are underestimating the elderly's independence, acts of behavior are applied to older people, and old people may focus on the losses in their life due to this prejudice. When it comes to sleep, elders insist on unsatisfactory sleep levels when prescribing to an ageist view on sleep (that they must not be in bed all the time compared to younger adults). When it comes to exercise, elder adults may not exercise because of the ageist view that elders need to relax. When it comes to communications, talking and speaking with elders is good - but elder-speaking isn't (a condescending way of talking to the elderly).
