Dogs experience the world mainly through smell, and their sense of smell is far stronger than ours. They are especially drawn to areas like the crotch or armpits because those parts of the body produce stronger scent signals. Through those scents, a dog can pick up clues about a person’s identity, mood, health, and even physical changes.
This behavior comes from canine social instinct. Dogs use scent to learn about each other, and because they see humans as part of their social world, they often treat people the same way. That is why they may become even more interested when someone is stressed, sick, pregnant, or otherwise giving off a different scent than usual.
