|Subspecies||C. l. familiaris (Domesticated dog)|
Dogs are one of the most well-known domesticated species, with archaeological and historical records showing that they have lived in a mutually beneficial relationship with humans for thousands of years.
Offspring are called pups (or puppies) until around a year old. The collective noun for a group of offspring is a litter.
Research has shown that it is probable that the first settlers of the Americas brought dogs of some sort with them. The case in Australia is not so clear. The dingo was not found in Tasmania, evidence that it was introduced to Australia after Tasmania became an island after the last Ice Age. It was introduced to Australia either in a subsequent wave of immigration or by Asian visitors.
Dogs (scientific name Canis lupus familiaris) are a subspecies of wolves, divided into a multitude of different breeds all in principle capable of interbreeding (though in some cases, physical relations between representatives of two breeds are unlikely or problematic - Chihuahuas and Great Danes, for example).
Fossils of canine skulls smaller than those of wolves have been found with human artifacts, with dates based on evolutionary assumptions estimated to between 130,000 and 190,000 years ago. whilst DNA evidence has been used to suggest that dogs diverged from wolves between 100,000 and 135,000 years ago.  Secular archeology has placed the earliest known domestication at potentially 12,000 BC-10,000 BC and with certainty at 7,000 BC. 
Dogs are also viewed as being the single most genetically diverse species on Earth - largely thanks to human-imposed selective breeding, the vast array of dog breeds surpasses any other creature on the planet. Due to selective breeding by man, however, many breeds of dog have significant genetic disorders. These include hip dysplasia (common with German Shepherds), and respiratory problems caused by shortening of the face, as seen with Boxer dogs and the Bulldog's lip. To overcome the prevalence of genetic disorders rendered common by inbreeding, many breeders regularly practice outcrossing, or introducing new material into a breed line via mating with other kinds of dog. This restores vigor to a breed and can decrease the likelihood of genetic disorders manifesting.
Despite being colloquially known as "man's best friend", every 40 seconds, someone in the United States seeks medical help for a dog bite, with approximately 800,000 such bites per year requiring medical attention. Due to the high cost of dog bite liability claims, some insurance companies have blacklisted certain breeds and refuse to provide homeowners insurance to those who own these dog breeds. 
Dogs are used for many purposes:
- Being a companion for the old or lonely
- Guarding property and livestock
- Herding sheep and cattle
- Tracking by scent, carrying messages, and mountain and water rescue
- Pursuing, flushing and retrieving game, and killing vermin
- Providing assistance to people with disabilities
- Military and police duties including guarding, tracking, interrogation, and attacking. In World War II, the Soviet Union attempted to train dogs to place explosive charges under German tanks
- To detect cadavers, explosives, or illegal drugs (German Shepherds are commonly trained to do so by police)
- As a beast of burden, or for drawing sledges, sleighs, and dogcarts
- As a performing animal. Circus dogs have been trained to dance, ride bicycles, speak, and walk the tightrope
- For fighting, now illegal in most places, e.g. everywhere in USA
- As food. Dog is still considered a delicacy in China, Korea and parts of Africa today
Today most dogs in western countries are kept for companionship only. Stray and feral dogs cause many problems, spreading diseases such as rabies, and attacking people and livestock. Muslims see dogs as unclean, and often kill dogs found as pets .
- Kingsley, Danny, Humans live a dog's life
- Vila, Carles; Carles Vila, Peter Savolainen, Jesus E. Maldonado, Isabel R. Amorim, John E. Rice, Rodney L. Honeycutt, Keith A. Crandall, Joakim Lundeberg, Wayne, Robert F. (1997-01-30; accepted 1997-04-14). Multiple and ancient origins of the domestic dog, Science 276: 1687-1689. Retrieved on 2006-12-09.
- Scott, John Paul (1965), Dog behavior: The genetic basis, University of Chicago Press. ISBN 0-226-74338-1.