Re: Best petri dish
"Occams razor says DNA spontaneously emerged here."
Logic says that if it emerged here, it probably also emerged in many other places. It also suggests that it (and it's building blocks) has probably been transferred from place to place by various events over the years. We will never know the actual details, but there is much to be learned from trying to understand them anyway.
 Note: No "spontaneously". Crawl first, then walk, then run.