Chemistry of the Joint Origin and Evolution of Life, Death, and Aging

Reviewing the published insights concerning chemical interactions between small molecules implicated in the origin of life suggests that their chemical properties included not only those that may be suitable for metabolic pathways. Some of the immanent “excessive” potencies of the molecules make them able to form covalent adducts to proteins and nucleic acids. The accumulation of macromolecules damaged in this way could decrease protocells viability with increasing age. Thus, aging (senescence) could emerge concomitantly with life as its chemical heritage. Moreover, the exponential increase in mortality with age (the Gompertz law) could emerge when the kinetics of molecular disintegration according to the Arrhenius equation (disintegration rate depends exponentially on varying temperature at a constant activation barrier) was inherited by the kinetics of protocells dying out in their populations, the role of the independent variable having passed from temperature, which was virtually constant on the Calvin scale, to viability. The cooperation of these two chemical heritages was enough to eliminate effectively old living objects and to make any evolved program of aging needless. Thus, aging did not result from the biological evolution but rather was and still is its independent factor. All this was possible without oxygen, which could only modify rather than form de novo the primary chemical driving force of aging. With all that, the energetic benefits of aerobic metabolism provided for the advent of multicellular organisms, in particular those featuring massive extracellular matter and unrenewable cell populations, including those comprising the brain. Their functions are incompatible with complete renewal. This makes oxygen’s role in aging not limited to being the source of the reactive oxygen species. Oxygen was indispensable for the advent of both the accumulators of chemical damage and the ability to recognize it. In a sense, for nature it was not a problem to develop aging in the course of evolution towards humans for whom being aware of aging is a problem. Its satisfactory solution cannot be chemical, physical, pharmacological or otherwise technical. It can be only mental.