The Evolution of Destruction

Varied and many are the factors that occasion damage to our genomes. Included are oxygen radicals that are highly reactive. They are a by-product of essential biochemical pathways that include cellular respiration. This raises a question. Were the enzymes required to repair genomic damage already present at the time cellular respiration functions evolved? If so why is that presumed and if not then how would genomes have been protected from oxygen radicals?

Evolution of necessary biochemical pathways would have produced agents damaging to the integrity of an organism's genome. This involves a case where apparently reproductive fitness would be lessened by the introduction of an essential function. Accounting for the evolutionary sequential order of different cellular functions is a fascinating enterprise that demands no shortage of resourcefullness and imagination.