Beach Walk II

Discovery: If you walk on your toes, your footprints look like paw prints, so heels developed as we became upright walkers.  I thought that'd be good for a mystery and I wondered if anyone else had ever thought of it before, and if so how many?  And wouldn't it be cool if you could get together all the people throughout time and place who had the very same thought as you?  Like a big (or small) convention.  But what'd you talk about?   "Yeah, I've thought that, too."