I am watching a short and paunchy man in his seventies waddle down the street. Swaying from side to side, he is walking at the slowest pace possible. Hardly lifting his feet off the ground, he puts one leg in front of the other just in time not to fall on his face. If he walked even a tad more slowly, he would tumble any which way. It is nothing but inertia that keeps him moving forward. In terms of energy employed, he is close to the absolute minimum required for locomotion. A perfect gait, in short. When I try to mimic him while no-one is looking, I realize that I am too tall and skinny for the feat. When it comes to waddling, his paunch is a definite plus, for it is pulling him forward. And so are his stunted legs, which are ideal for waddling. For a brief moment, I am overcome by a sentiment very like envy.