Dogs smell 10,000 to 100,000 times more clearly than humans because the animals are estimated to have 50 times more olfactory receptors in their noses than humans do, and the area of the brain that deciphers smells is 40 times larger in dogs than in humans. Rather than scents being inhaled in and out with the air that is breathed, like in humans, dogs’ olfactory receptors are able to recognize differences in the air molecules and filter the scents. Dogs also exhale air through slits in their noses so it is separated from newly inhaled air, unlike humans, who inhale and exhale air and its accompanying scents through the same passageways, so the air going in and out is mixed together.
More about animals’ sense of smell:
- Bears are the land animals with the strongest sense of smell and have been reported to be able to find food sources 18 miles (28.97 km) away.
- It is thought that a dog could detect the scent of a single teaspoon (4.93 mL) of sugar in two Olympic-size pools' worth of water.
- The male silk moth is considered the best insect smeller and might be able to smell a single particle of a female’s pheromones — the chemicals that attract mates — at a distance of 6 miles (9.66 km).