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

Reviewing published concepts on the chemical interactions between small molecules implicated in the origin of life suggests that their chemical properties have included not only those that might have been suitable for metabolic pathways. Some of the immanent "excessive" potencies of molecules make them able to form covalent adducts with proteins and nucleic acids. The accumulation of macromolecules damaged in this way could decrease the viability of protocells 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 passing 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. Therefore, aging had not resulted from the biological evolution but rather has been 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 energy benefits of aerobic metabolism have 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 the role of oxygen in aging not limited to being the source of reactive oxygen species. Oxygen had been indispensable for the advent of both accumulators of chemical damage and ability to recognize it. In a sense, it was not a problem for nature 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 only be mental.