Aging is complex process characterized by numerous changes that take place at different levels of the biological hierarchy. It is presented as an ontogenic issue, the process of growing old and or the sum of all changes, physiological, genetic, molecular, that occur with the passage of time, from fertilization to death. The heterogenecity of the aging phenotype among individuals of the same species and differences in longevity among species underline the contribution of both genetic and environmental factors in shaping the life span. Aging is associated with a tissue degeneration phenotype marked by a loss of tissue regenerative capacity. Ageing is considered to weaken the body’s ability to respond to stress. The age-associated changes in the ability of tissues to replace lost or damaged cells is partly the cause of many age-related diseases such as Alzheimer’s disease (AD), cardiovascular disease, type II diabetes, and sarcopenia. Long time stress promotes the aging process, which is detrimental for all mammals well being.