You missed the point Jim. Given odds of say 1,000,000 to 1 against the chance organisation of a few simple, stable molecules into one larger molecule capable of replication, then the probability of that event happening at least once in 4,000,000,000 years is to all intents and purposes equal to 1. My last sentence was a paraphrase to a well-known recent title on the topic of the quantum universe.
But my reference to nucleic acid should also be explained. Why nucleic acid, when its first appearance was freeform, unbound by a cell membrane. The answer there lies in that as soon as one replicating machine had arisen, the mutational and evolutionary process had begun. In order to compete against ever more sophisticate versions of the same genus, the most successful nucleic acids created a protective shield around themselves, the cell membrane, thus making it more difficult for competing nucleic chains to absorb them into their own processes. Life was well and truly on its way. From there, the evolution of creatures using the highly sophisticated molecule haemoglobin was also, I'm afraid to say Jim - again given the time available - a certainty.