We already know that many senses work in stereo — for instance, visual information from our two eyes creates depth perception, and ear placement helps us identify the the source of sounds. A new study published in Nature Communications unveils evidence from researchers at Vanderbilt University that blind moles can smell in stereo. Previous studies have suggested that both humans and rats have the ability to locate smells using differing sensory information from both nostrils, but none have conclusively proven the phenomena.
No eyes, no nose, no food
Neurobiologist Kenneth Catania placed blind, eastern American moles in a chamber with 15 food wells arranged in a half-circle. The moles had to sniff their way to a piece of earthworm located in one of the wells. However, when researchers blocked a mole's right nostril, the animal veered to the left of its intended destination; the mole erred too far to the right when its left nostril was blocked. While an impaired sense of smell didn't stop the moles from locating the earthworm, it did significantly impact their performance. As you can see in this video (direct download), the closer the moles get to the smell's source, the farther they drift in the wrong direction.
Finally, researchers used tubes to completely switch the inputs from the moles' left and right nostrils. When placed in a chamber with an earthworm, the moles were completely baffled, shuffling around the entire chamber and only occasionally stumbling upon the specimen. While it isn't conclusive proof that moles and other animals can smell in stereo, the new study provides solid new support for the theory.