re: my previous post - I realize that 1/5 is for "potentially habitable" ... but I was thinking too far ahead. What I was trying to get at is what factor would

re: my previous post - I realize that 1/5 is for "potentially habitable" ... but I was thinking too far ahead. What I was trying to get at is what factor would we then need to multiply it (ie., this 1/5th) with to make intelligent life a mathematical/chemical/biological certainty - as we know it here on earth, for example. Was what happened on earth - us - a unique fluke - would intelligent life still come about if reran the whole thing 1000 times, even here on earth, where it was almost an after-thought? Are there other pathways - sliding doors - that would still have brought about intelligent life here on earth? What if we didn't have a magnetic field or if there was no Ozone? - that was another thing I left out before. We may be a fluke - the end result of a set of rare and unrepeatable circumstances?