Domestication

The gray wolf was the first animal and only large carnivore to be domesticated by humans. The origin of the domestic dog has been controversial, and subject to numerous studies, with genetic data and paleontological evidence contradicting each other on the date and location of the first domestication event. Proposed centers of dog origins from genetic data have included the Middle East and East Asia 32,000 years ago, though this is inconsistent with the paleontological record, as the oldest dog remains in those areas are no older than 13,000 years. Much older remains were discovered in Europe and Russia, with one specimen discovered in Goyet, Belgium having been estimated to be 31,700 years old, and another found in the Altai Mountains being dated to be 33,000 years old.

Several studies on gray wolf and dog mitochondrial genomes in 2013-14 showed that modern dog genomes don't match those of extant gray wolf populations, and likely arose from a now extinct lineage of prehistoric gray wolves in Europe, with any similarity with modern wolf populations reflecting historical admixture rather than recent divergence. The genetic data is consistent with the paleontological record, which shows that the oldest dog remains in Europe are 18,800 to 32,100 years old. The domestication event may have begun during the Last Glacial Maximum, prior to the Neolithic Revolution, when hunter-gatherers actively hunted Pleistocene megafauna. The morphology and DNA of the Goyet and Altai specimens didn't match those of modern dogs, thus indicating that they were the result of separate, ultimately aborted domestication episodes. Further studies indicate that prehistoric Eurasian gray wolves underwent a threefoldpopulation bottleneck approximately 15,000-20,000 years ago, thus indicating that these gray wolves had substantially more genetic diversity for selection to act on than what is observed in modern wolf populations.

Although the genetic divergence between gray wolves and dogs is only 1.8%, as opposed to over 4% between gray wolves, Ethiopian wolves and coyotes, there are a number of diagnostic features to distinguish the two. The tympanic bullae are large, convex and almost spherical in gray wolves, while the bullae of dogs are smaller, compressed and slightly crumpled. The teeth of gray wolves are also proportionately larger than those of dogs; the premolars and molars of wolves are much less crowded, and have more complex cusp patterns. Dogs lack a functioning pre-caudal gland, and most enter estrus twice yearly, unlike gray wolves which only do so once a year.