Don't expect a definitive answer any time soon. Part of the problem for scientists in dealing with this question is their need to replicate the results of their experiments over and over — and the "primordial soup" that is assumed to have started it all is likely to be difficult, if not impossible, to recreate. Instead, scientists may end up finding a far-off planet with similar conditions to that of earth and observe what happens there. As you can imagine, that will be a long, long way time in the future.