Life on Earth has evolved from the chemical world, so nothing of chemistry has disappeared in biology even though of might become unapparent being obscured or counteracted by some other chemistry according to the biological design. Living bodies incorporate molecules involved in biological functions with all their potencies, not only those implicated in the respective functions. The useful properties are exploited by enzymatic catalysis. The excessive properties have manifestations that accompany the enzymatic processes and may be not only irrelevant but even overtly adverse. The accumulation of damage caused by these multiple parametabolic processes results in the reduction of vitality generally known as aging. Another chemical legacy is the exponential dependency of mortality rate on age, which emerged because, in the multimolecular prebiotic aggregates, the role of the main variable in the Arrhenius equation for their decomposition shifted from temperature to activation barrier, which was compromised by the parametabolic processes. This resulted in the shift of the effect of the ever-acting parametabolic damage, as it is manifested in changes in mortality, to later ages. Numerical modelling shows that, in this case, the evolutionary acquisition of new functions that increase resistance to the causes of death may be associated with increased rate of functional decline and reduced cohort lifespan yet increased investment of resources into progeny and thus increased overall fitness, favoured by natural selection.