While stereo sensing for sound and light is common, there has been no clear evidence of an olfactory analogue. Now, Kenneth Catania of Vanderbilt University has made studies of the blind eastern American (or common) mole. Not only blind but with poor hearing and a bad sense of touch, the animal can head straight to food after a quick sniff. Plugging either nostril makes the animal veer in the direction of the open one and putting tubes in their nostrils and crossing them makes the moles go left when they should go right and vice versa – something that would not happen if they were just moving towards a stronger scent with no left-right discrimination.

Because the moles dig for their food, they may need this faculty to avoid wasting large amounts of energy in moving soil unnecessarily. It remains to be seen if other animals share this skill and to what degree.