Odds of intelligent life occuring?

[The Grand Nudger]

Half a billion years doesn't seem like much to me.  From the formation of earth to the emergence of intelligent life there was only 1b.  Half of that is the time it took for life to arise in the first place. It's our strange views on intelligence and "a long time"(and what either means) that leads people to conclusions of arduous rarity.

Since then, enough time has elapsed for life to have evolved intelligence 8 times over, just on this..relatively young, rock.  No more than 20m years after the big bang the oldest rocks would have had the potential for habitability.  On those rocks, enough time has elapsed since then for life to have evolved intelligence 29 times over.

Taking a more dim view, as intelligent life being ourselves and ourselves alone - then enough time has elapsed since the big bang for life like ours to have evolved at least three times over. In all of that time it's had no shortage of candidate rocks. Using the figure I leveraged earlier, of 40 billion potentially habitable planets - that gives us very nearly three potential startups for life ever single year just to fill the time averaged out.

I'd say that something which at least -could- have happened three times every year since the big bang is hardly a rarity. It would be something which at least -could- have reached terminus (life like ours) once every four months past 4.5b years. I suppose it's just a matter of perspective. So far, we've found life exactly where we expect to find it. 1 for 1....and we're starting to suspect that life may be able to exceed those boundaries...the tolerance is likely to go up, not down. The numbers will become more amenable to life (and they're already pretty damned amenable).