Aging represents a physiological and per se non-pathological and multifactorial process involving a set of key genes and mechanisms being triggered by different endogenous and exogenous factors. Since aging is a major risk factor in connection with a variety of human disorders, it is increasingly becoming a central topic in biochemical and medical research. The plethora of theories on aging - some of which have been discussed for decades - are neither isolated nor contradictory but instead can be connected in a network of pathways and processes at the cellular and molecular levels....