[Why and how do we age? - a single answer to the two questions.]

The chemical properties of compounds involved in metabolic processes, even the core ones, such as glycolysis and Krebs cycle, are not limited to what is realized via enzymatic reactions, because the properties include the abilities to form spontaneousely covalent bonds with other compounds, incuding those incorporated in macromolecules. The effects of the gene that codes for an enzyme, which catalizes the formation of a metabolite, which features such extra properties, may be regarded as antagonistically pleiotropic. The effects that are realized via the product of the reaction catalysed by the enzyme coded by a gene are required for current viability. The effects that are mediated by the spontaneous formation of covalent bonds between the same product and slowly renewable macromolecules will be increasingly deleterious with increasing time of their accumulation provided by the positive effects. Thus, the antagonistically pleiotripic effects are not late-acting, as it is commonly believed, but rather they are cumulative. Since these effects are inseparable from metabolism, they may be labeled "parametabolic". The driving force produced by these effects is sufficient for aging to take place in any system that exists due to metabolic processes therein and proliferate due to information stored by components featuring much slower turnover compared with that of metabolites. Thus, we age because of the chemical properties of our constituents and do it so as it is determined by these properies realized within conditions of our bodies. Aging is neither a direct product of evolution (such as a program that determines the span of life), nor a byproduct (a delayed payment for current advantages). Aging results from limitations that the immanent physicochemical properties of metabolites impose on the capabilities and outcomes of evolution by natural selection, and this is what distinguishes aging from the tear and wear of inanimate objects.