Human activity can leave telltale marks on its surroundings. These marks, in turn, can provide clues about the nature of the activity that created them or about the setting itself. See, for example, "Statistical Wear" and "An Irresistible Edge."
Recently, I started paying attention to wear caused by finger contact in the vicinity of elevator buttons. Shown below is a set of buttons for a hotel elevator. What can you tell about the setting just from the scuff marks?
The wear pattern suggests that this particular set of buttons is most likely located on the lobby floor; many more people have pressed (or tried to press and missed) the "up" button than the "down" button. The curious tail toward the right indicates that people tended to come from the right, presumably making contact with the brass plate prematurely.
Indeed, these buttons are on the lobby floor of a hotel in Toronto, and the only entrance to this bank of elevators is from the right, with no exit to the left.
You'll see similar wear marks in the example below, from a hotel in Austin, though the distribution isn't quite as strikingly asymmetric.
Wear marks appear in all sorts of settings. Foot traffic can be responsible for some of the more striking examples, particularly when the marks appear on stone, as seen in the photo below of a stone staircase in Wells Cathedral in Great Britain.
What can you say about the traffic patterns that these worn steps reveal?
Photos by I. Peterson