On my way to the shops to buy the most mundane of groceries, I encountered a woman walking backward down the street. I immediately assumed it was a temporary measure on her part: she had dropped something and was returning to get it, or maybe she was dragging something heavy. But she just kept coming. Her head was twisted back over her right shoulder, with a look of glee and pride on her face. She took each step with deliberation, but with an attempt to inject speed. I began to worry about her. She walked smoothly enough, but she was an old woman. There was a stiffness to her gait. She needed to be careful ‘at her age’; any tumble backwards could cause serious damage to her brittle bones.