> The percentage of population right and left handed can be estimated by
> counting the percentage of staircases in castles spiralling clockwise
> and counterclockwise, for similar reasons.  That's the ultimate defense
> spinoff, because the goal was to maximize the probability that the
> defender could cause the attacker to spin off the stairs.

I think swordfights on spiral staircases were far more common in movies
than in castles.  Cute pun, though.