According to the traditional explanations ("old paradigm"), aging is due to the progressive accumulation of heterogeneous damages that are insufficiently contrasted by natural selection. An opposite interpretation ("new paradigm") sees aging as selectively advantageous in terms of supra-individual natural selection, and this implies the indispensable existence of genetically controlled specific mechanisms that determine it. The aim of this work is to expound synthetically the progressive alterations that mark the aging by showing how these changes are clearly defined and regulated by genes. The possibility of such a description, based on sound evidence, is an essential element for the plausibility of the new paradigm, and a fundamental argument against the tenability of the old paradigm.