Dogs belong to the mammalian family Canidae. Members of this carnivorous group comprise domestic dogs, wolves, wild dogs, coyotes, dingoes, foxes, and jackals. Canis lupus familiaris (also referred to as Canis familiaris) is the species name given to all breeds of domestic dogs. The exact origin of domestic dogs has been a controversial topic, but the preponderance of genetic and fossil evidence points to a close relationship to the wolf (Canis lupus). The earliest evidence of ancient dogs has come from fossils excavated from the Goyet cave in Belgium, the site of Předmostí in the Czech Republic, and the Altai Mountains in Siberia. Some of these fossil remains are more than 36,000 years old. See also: Breeding (animal); Carnivora; Carnivoran evolution; Dogs; Domestication (anthropology); Fossil; Mammalia

Dogs were the first animals to be domesticated by humans. Various locations, including China, the Middle East, and North Africa, have been proposed as early sites for canine domestication. However, recent investigations have identified Europe as the earliest center for the domestication of dogs, which occurred approximately 18,800 to 32,100 years ago. Using a combination of zooarcheology (the study of animal remains from archeological sites) and paleogenomics (the study of the genomes of ancient organisms), researchers extracted mitochondrial DNA (mtDNA) from a number of fossil dogs and wolves. The analysis of this genetic material provided investigators with the opportunity to identify the ancient maternal lineages of these animals because the DNA from mitochondria (cytoplasmic organelles that generate cellular energy) is inherited strictly from the mother (maternally inherited). Then, by comparing the mtDNA sequences from a variety of prehistoric dogs and wolves to those of modern-day counterparts, investigators concluded that the oldest domesticated dogs were those located in Europe. The analyses also revealed that the ancestor of modern-day domestic dogs was a variety of ancient wolf that later went extinct. See also: Ancient DNA; Deoxyribonucleic acid (DNA); DNA and animal domestication; DNA sequencing; Genetics; Genomics; Mitochondria; Phylogeny; Zooarcheology

The initial process of the domestication of dogs by humans may not have been a premeditated action. The earliest forms of domestication likely originated when wolves and European hunter-gatherers began a loose association. In this scenario, wild wolves might have aided humans during the pulling down and killing of large prey. Alternatively, the animals might have scavenged carcasses that were left at or near areas of human habitation, bringing the animals into contact with humans. In these cases, more-socialized animals were more apt to receive food rewards. Over time, the ties between the two groups grew stronger, ultimately leading to a relationship in which the humans and early domesticated dogs interacted and bonded more closely. See also: Agricultural science (animal); Ethology; Social mammals