One of the most interesting, after the ant experiments and the safe cracking, parts of Richard Feynman’s book Surely You’re Joking Mr. Feynman! was his experiments with smell. While he was out of the room he would have a group of people pick a book from a shelf, handle it briefly then replace it on the shelf. He would then come back into the room and identify which books were handled and by which person. He said it was surprisingly easy.

Feynman’s experiments are entirely consistent with these which extend human smell to tracking.