[Aging: Some theories, genetic, epigenetic and environmental considerations].

In this review several characteristics of the aging process are described and some theories that try to explain it are briefly mentioned. Although none of them fully explains this phenomenon, they can interact between each other in a complex way, out of which cellular senescence is the common outcome. Molecular changes take place on both genetic and epigenetic levels, and several studies have associated senescence with changes in the epigenetic-mediated chromatin condensation, while others consider that free radicals represent a useful mechanism to explain aging and age-related disorders that, along with the alteration of mitochondrial homeostasis, promote the aging process through the accumulation of damage along time.