Dogs nibble on humans primarily for several reasons related to affection, communication, and natural behavior. They may nibble to show love and bond with their owners, similar to social grooming in dogs. Nibbling can also be a playful way for dogs to explore their world, especially puppies during their teething phase. Additionally, dogs might nibble to get attention, to soothe themselves when anxious or stressed, or as a form of communication to express needs or invite play. Some breeds have historical instincts for using their mouths more, so nibbling might also be a breed-related behavior. In most cases, gentle nibbling is a sign of comfort, affection, or seeking interaction rather than aggression.