Psychology Today, Mary Bates
Dogs are born sniffers. Humans have roughly five million olfactory cells in their noses. It sounds impressive, until you compare it to the 200 million cells in a typical dog’s nose. Canines’ sense of smell is generally 10,000-100,000 times superior to that of humans. Much more of their brains are devoted to processing smell, and they also possess more genes that code for olfactory ability and many more olfactory neurons than humans.
People have known about and taken advantage of dogs’ sense of smell for centuries, even breeding some dogs to be scent hounds used in tracking and hunting. In recent years, dogs have been trained to sniff out explosives, drugs, bodies and other scents.