The most plausible explanation for the origin of life on Earth is that physical processes created organic molecules, such as amino acids, and some combination randomly assembled that could make copies of itself. This may have been somewhat akin to the way crystals form as the result of probability and their own chemical characteristics. From there, these ‘replicators’ became more diverse and capable, ultimately branching out into the entirety of life observed on our planet today. Richard Dawkins may have expressed these ideas best, in the opening section of The Selfish Gene:
Was there to be any end to the gradual improvement in the techniques and artifices used by the replicators to ensure their own continuation in the world? There would be plenty of time for their improvement. What weird engines of self-preservation would the millennia bring forth? Four thousand million years on, what was to be the fate of the ancient replicators? They did not die out, for they are the past masters of the survival arts. But do not look for them floating loose in the sea; they gave up that cavalier freedom long ago. Now they swarm in huge colonies, safe inside gigantic lumbering robots, sealed off from the outside world, communicating with it by tortuous indirect routes, manipulating it by remote control. They are in you and me; they created us, body and mind; and their preservation is the ultimate rational for our existence. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines.
If this explanation is basically correct, we should expect there to be a lot of life in the universe. There are millions of billions of galaxies out there, comprised of a phenomenal number of stars. We have already observed planets around some, including small rocky planets like the Earth and planets with orbits compatible with liquid water on their surfaces. The Kepler Mission may discover hundreds more. The Drake Equation expresses this idea mathematically, while the Fermi Paradox considers why extraterrestrial civilizations, which we might expect to be common, have not yet been found.
Finding other forms of life would certainly both answer and raise scientific questions (such as how different forms of life can be.) Would actually observing direct evidence of life (probably microbes) elsewhere have any effect on human perspectives or behaviour? It might for religious people who believe life on Earth to have been uniquely created, but that isn’t a terribly interesting consequence to me. Would it have any ethical, political, or moral ramifications for those who already believe that life essentially arose by accident? Would intelligent life have any effect above and beyond that of observing microbes, even if such life was too far away to ever really engage or communicate with? The question may not be such an abstract one. As described well in one chapter of Oliver Morton’s book on photosynthesis, there are several ways through which we might be able to identify unmistakeable signs of life at great distance.
Perversely, life elsewhere might actually somewhat diminish our perception of how important it is to preserve and protect life on Earth. Right now, as far as we know, we are the sole such example in the universe. Finding others might lend even more strength to the psychological pressures that make us favour immediate interests rather than long-term survival. On the other hand, it might help reinforce the point that we are here by accident and that nothing about the nature of the universe is ‘on our side’ when it comes to survival. Such a realization might prompt some serious thinking of what it will mean to endure in a universe that will endure long beyond the comparatively comfortable circumstances in which we emerged as a species.