How does it impact the probability of extraterrestrial life? I mean, after 4 billion years of relative peace, Earth still had only single-celled organisms. And it would have stayed that way, if not for this particular mutation. So it is not just how many planets can support life. First, it will need to continuously keep supporting life for billions of years before any form of intelligent life can emerge. THEN it has to wait till such a pathbreaking mutation occurs, which might take a random amount of time. I am starting to gravitate towards the lower bound of what the Drake equation estimates to be the number of planets with intelligent life. (= we are probably alone in the universe)