Dog noses are extremely complex and allow them to “see” the world, find mates and food, and avoid predators. The nose has two nostrils divided by a septum. Humans smell and breathe through the same airways. When dogs inhale, however, a fold of tissue inside their nostril creates two distinct zones: one for the air directed to the lungs and the other for the smell. The latter flows into the olfactory zone, rich in receptors that detect the smell. If humans have around 6 million of these receptors, dogs have up to 300 million. A person can recognize a scent in a closed room, a dog can identify it in an area the size of a stadium. Dogs sniff in “stereo” mode, each nostril functioning independently of the other. In this way the dog can also understand where the smell comes from. When we exhale, the air comes out the way it came in, while when dogs exhale, the air comes out from the sides.