I have been reading various articles on the web about self-replicating molecules created artificially. Apparently under controlled conditions these molecules can exist and replicate for a time. The hypothesis is that they were precursors to life.
It is also my understanding that there is an inverse relationship between complexity and probability; i.e., the more complex a system is, the less probable its existence and vice versa.
My question: Are self-replicating molecules commonly found in nature, or do they only exist under controlled laboratory conditions? I would guess they are very common given the fact they are less complex than life.