So RNA is a watershed, because from the bricks of life to RNA, chemistry was solely in charge. Once RNA appeared, or whatever first molecule was capable of being replicated, once replication was introduced, you had automatically variation, competition and selection. So natural selection, with RNA selection, came in. From then on life was chemistry plus selection. Now, the chemistry is a very deterministic kind of... of phenomenon and process. Chemical processes are always the same if the conditions are the same. They are reproducible. They are deterministic, which means that life must have started the way it started, the conditions being what they were. And quite a number of investigators now believe that life probably arose in volcanic surroundings, maybe in the deep sea hydro thermal vents that have been discovered, also in the last thirty years. And I like that idea, because among the singularities that I find in the development of life, two I find that particularly impressive to me. One is the use of the pyrophosphate bond for energy transfer. ATP, GTP, CTP, UTP are involved in virtually all energy transactions in all living organisms, and remarkably, ATP, GTP, CTP and UTP are the molecules from which RNA are made... is made. It's quite remarkable. So that is really one of the key molecules in the origin of life, and what ATP, GTP, CTP and UTP have in common is pyrophosphate bonds. And there is evidence that in the history of life, those molecules may have been preceded by inorganic pyrophosphate. Inorganic pyrophosphate may have been the very first conveyor of energy in this process. Now you find pyrophosphates only in a volcanic environment. You need heat... very high heat to condense phosphate molecules into pyrophosphates or polyphosphates, metaphosphates... those are all products of heat. So the environment that would produce pyrophosphates needed for this is almost certainly volcanic.