Dog (Canis lupus familiaris) is a domesticated descendant of extinct Pleistocene wolves and closely related to foxes and jackals. As the most popular companion animal, dogs live with humans in a wide range of roles—as hunting partners, guardians, and objects of scorn or adoration. Dogs are also known for their deep and unwavering loyalty, leading many owners to consider them full-fledged family members.
There are approximately 69 million households in the United States with a dog, making dogs one of the most common domestic animals. While many people own dogs for practical reasons, such as protection or exercise, others find them more of a companion, and the love between a dog and its owner is often compared to that between a human and their spouse or partner.
Despite their ferocious appearance, dogs are actually very social creatures and get along well with other animals and humans. As pack animals by nature, they are also open to integrating members of other species into their groups and exhibit selfless acts of compassion, such as adopting orphaned kittens or saving other injured animals or children from harm. Their olfactory senses are particularly powerful, and they can smell something from a very long distance after smelling it once.
A dog’s tail can be held at different heights to communicate its emotional state. When the tail is at a lower height, it signals that the dog is relaxed. When it is raised vertically, it indicates aggression. The shape of the tail also carries meaning: A sickle-shaped tail signals that the dog is playful, while a corkscrew-shaped tail indicates dominance and power.