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The rate of living theory postulates that the faster an organism's metabolism, the shorter its lifespan. First proposed by Max Rubner in 1908, the theory was based on his observation that smaller animals had faster metabolisms and shorter lifespans compared to larger animals with slower metabolisms. [ 1 ]
The two theories; non-adaptive, and adaptive, are used to explain the evolution of senescence, which is the decline in reproduction with age. [8] The non-adaptive theory assumes that the evolutionary deterioration of human age occurs as a result of accumulation of deleterious mutations in the germline. [8]
Rate of living theory of aging; Reproductive exhaustion theory of aging; Reproductive-cell cycle theory; S. Selectivity theory (aging) Socioemotional selectivity theory;
Ageing (or aging in American English) is the process of becoming older until Death.The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal.
According to this theory, life span development has multiple trajectories (positive, negative, stable) and causes (biological, psychological, social, and cultural). Individual variation is a hallmark of this theory – not all individuals develop and age at the same rate and in the same manner. [15] Bronfenbrenner's ecological theory
The rate-of-living theory of aging states that senescence occurs because individuals accumulate damage to cells and tissues during cell division. This theory is not supported because its postulates that aging rate should be correlated with metabolic rate [13] and organisms cannot evolve longer lifespans [14] [15] were not supported in trials.
The immunological theory of aging suggests that the immune system weakens as an organism ages. This makes the organism unable to fight infections and less able to destroy old and neoplastic cells. This leads to aging and will eventually lead to death. This theory of aging was developed by Roy Walford in 1969.
The disputed late-life mortality deceleration law states that death rates stop increasing exponentially at advanced ages and level off to the late-life mortality plateau. A consequence of this deceleration is that there would be no fixed upper limit to human longevity — no fixed number which separates possible and impossible values of lifespan.