As we know, ~3 billion years ago there was a moment of 'genesis' on earth where life sprouted from non-life. We also know that the conditions on earth at the time were what we would consider "hostile" to most forms of life. What I wonder is, considering that earth is now a place that is much more supportive of life, why do we not see more 'geneses' all of the time? Assuming that the process of non-life to life isn't a stupefyingly improbable event, should this event not be occurring in ponds, lakes, oceans and caves around the world right now? Why is it that only one 'tree of life' has emerged on this planet and not many competing trees?
To me, one plausible explanation is that in the transition from non-life to life, the organism must go through many evolutionary stages to have an encoding system as complex as DNA - and perhaps no other tree of life is able to emerge and evolve as they would be competing for resources against all of the current organisms which dominate every nook and cranny on earth. Would be very interesting to hear some thoughts on this. Thanks

life is thought to have independently evolved in different forms very many times.

I can see no reason why such processes as you describe are not occurring at present. To note however that the difference between then and now is that when it first occurred there was nothing else to compete with that new life forms and thus life would have spread rapidly as the local environmental conditions allowed. In marked contrast if that occurred now any new "life" would be competing with the current occupants of whatever niche it arises, making it very difficult to detect or measure.

One could theoretically imagine an event with some form of different life that was so superior and better able to survive that it would out-compete the current species and thus might become evident - that would however be an incredibly rare event (if at all) since current species have evolved over millions of years to be well (if not ideally) suited to the envinmental niche they occupy.

An article here that may be of interest

http://www.theguardian.com/science/2009 … ee-of-life