The oldest dogs'skeletons ever found are approximately 30,000 years old, and therefore lived after Cro-Magnon (Homo sapiens sapiens) was already walking the earth. These ancient remains have always been found near human skeletons; this is why they were given the name Canis familiaris (- 10,000 years). It only seems logical that domestic dogs are descended from early wild Canids. Other possible ancestors include the wolf (Canis lupus), the jackal (Canis aurus), and the coyote (Canis patrans).
In addition, the oldest dog remains have been found in China, where it is believed jackals and coyotes never lived. It was also in China that the first authenticated association (dating to 150,000 years ago) between man and a small wolf variety (Canis lupus variabilis) took place. The coexistence of these two species during a period prior to their evolution, seems to corroborate the theory that the wolf is the ancestor of the domestic dog.
This hypothesis was recently reinforced following several discoveries, including the finding that some Nordic breeds are directly descended from the wolf. In addition, studies that compared the mitochondrial DNA of these species revealed similarity greater than 99.8% between the dog and the wolf, compared to only 96% between the dog and the coyote. Moreover, more than forty-five wolf sub-species have been classified; the diversity of the wolf species could explain the diversity of dog breeds. Finally, body and vocal languages are very similar and commonly understood between the two species.
Similarities between the Dog and The Wolf: A Difficult Analysis
The similarities between dogs and wolves make it difficult for paleozoologists to accurately determine whether remains are that of a wolf or a dog when remains are incomplete or the archeological context suggests that cohabitation is unlikely. Only a few minor, and highly unreliable, differences existed between primitive dogs and their ancestors. These included the length of the nose bridge, the angle of the stop, and the distance between the carnassial tooth and the upper tubercles.
In addition, there were certainly fewer Canids than the animals that they preyed upon, and therefore, it is less likely that Canid remains will be uncovered. These difficulties and the possibility of dog-wolf hybridization explain why many links are missing in the chain of events that led to the development of modern dog. Perhaps one day we will discover the link between Canis lupus variabilis and Canis familiaris, and the battle of the theories will come to an end.
It is worth noting that the diffusionist theory, which suggests primitive dogs adapted to their new environs as humans migrated, does not exclude the evolutionist theory, which states that dog varieties came from different areas where the wolf was domesticated.
Battle of the Theories
Numerous (conflicting) theories have been formed based on comparisons of skeletal and dental structures of wolves, jackals, and coyotes. Each, in turn, is credited as being the ancestor of the modern dog. Some experts even hypothesize that various breeds as different as the Chow Chow or the Grayhound may be descended from different species of the Canis genus.
In 1968, Fiennes suggested that four distinct sub-species of wolf-the European Wolf, the Chinese Wolf, the Indian Wolf and the North American Wolf-gave rise to the four main groups of modern-day dogs.
Others hold that crosses between the individual species resulted in the development of the canine species. They base their arguments on the fact that wolf/coyote, wolf/jackal, or even jackal/coyote matings can produce fertile hybrids, each with thirty-nine chromosome pairs. This hybrid theory is now thought to be invalid given the ecological barriers that separated the various species at the time that domestic dogs appeared, which would have made it impossible for coyotes and jackals in particular to mate.
Wolves were present throughout the world, but given the differences in size and behavior compared to the jackal and the coyote, it seems highly improbable that interspecies mating took place. This, of course, refutes one of many theories that argue that the hybridization of the jackal (Canis aureus) and the Grey Wolf (Canis lupus) gave rise to the modern dog.
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