
The dog (Canis familiaris) is a domesticated descendant of the gray wolf. Known as the domestic dog, it was bred from an extinct group of wolves during the Late Pleistocene by hunter-gatherers. Dogs were the first animals domesticated by humans, over 14,000 years ago, before farming began. Because of their long relationship with humans, dogs can thrive on a starch-rich diet that wouldn’t work for other canids.
Dogs have been bred for specific behaviors, senses, and physical traits. Dog breeds come in many shapes, sizes, and colors. They have the same number of bones as humans (except for the tail), strong jaws with about 42 teeth, and well-developed senses of smell, hearing, and sight. Dogs see less clearly than humans but have a much better sense of smell and a large olfactory cortex.
Dogs help humans in many ways, including hunting, herding, pulling loads, providing protection, offering companionship, assisting in therapy, helping people with disabilities, and supporting police and military work.
Dogs communicate through eye contact, facial expressions, sounds, body language, and scents. They mark their territories by urinating, especially when they enter new areas. Over time, dogs have adapted to human behavior and can understand and communicate with people. This connection has led to the idea that dogs are “man’s best friend,” which is often studied.
The global dog population is estimated to be between 700 million and 1 billion, found all around the world. Dogs are the most popular pet in the United States, living in 34-40% of households. Developed countries have about 20% of the world’s dog population, while around 75% of dogs are in developing countries, often as feral or community dogs.