![]() The lengthening of life expectancy is mainly due to the elimination of most infectious diseases occurring in youth, better hygiene, and the adoption of antibiotics and vaccines.īefore examining the hypothesized biological factors at the basis of the aging process, it is crucial to underline that aging is not a disease. While the human life span has substantially remained unchanged for the past 100,000 years at ~125 years, life expectancy has sensibly increased (~27 years during the last century), especially in Western Countries ( Hayflick 2000b). Differently, life span is the maximum number of years that a human can live. Life expectancy is defined as the average total number of years that a human expects to live. The immediate consequence of the extended life expectancy is represented by the increasing number of older people in developed countries, an artefact of human civilization ( Hayflick 1998, 2000a). In other words, the advancing knowledge of hygiene and biomedicine has led us to discover the aging process, something that was teleologically not intended for us to be experienced ( Hayflick 2000b). ![]() The observation that most of the animals living in a natural environment rarely becomes senescent (because dying earlier for predation, disease, starvation, or drought) ( Holliday 2006) suggests that aging is a phenomenon unique to the human species ( Hayflick 2000b). The present review provides an overlook of the most commonly accepted theories of aging, providing current evidence of those interventions aimed at modifying the aging process.Īging is commonly defined as the accumulation of diverse deleterious changes occurring in cells and tissues with advancing age that are responsible for the increased risk of disease and death ( Harman 2003). Nevertheless, several studies on animal models have shown that aging rates and life expectancy can be modified. To date, no convincing evidence showing the administration of existing “anti-aging” remedies can slow aging or increase longevity in humans is available. Therefore, the different theories of aging should not be considered as mutually exclusive, but complementary of others in the explanation of some or all the features of the normal aging process. In this context, the search for a single cause of aging has recently been replaced by the view of aging as an extremely complex, multifactorial process. However, a global view of them is needed when debating of a process which is still obscure in some of its aspects. The major theories of aging are all specific of a particular cause of aging, providing useful and important insights for the understanding of age-related physiological changes. Aging is commonly defined as the accumulation of diverse deleterious changes occurring in cells and tissues with advancing age that are responsible for the increased risk of disease and death. ![]()
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