Yes, You Humans Can Smell Danger Too

Good news for human readers: Even you can learn to smell danger. The BBC reports on research at Northwestern University that exposed 12 volunteers to two "grassy smells." Initially, none of the volunteers could tell the difference between the two odors. Then some were given a clue, in the form of a mild electric shock, administered while they were smelling one of the odors. From that moment on, the shocked volunteers had no trouble identifying the odor that had been associated with pain. Geezer is still pondering how this information can be put to good use.
Read more about the sweet smell of danger at the BBC.