The dog was the first species and the only large carnivore to have been domesticated. Over the past 200 years, dogs have undergone rapid phenotypic change and were formed into today’s modern dog breeds due to artificial selection imposed by humans. These breeds can vary in size and weight from a 1 lb teacup poodle to a 200 lb giant mastiff. The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores.
Some breeds demonstrate outstanding skills in herding, retrieving, scent detection, and guarding, which demonstrates the functional and behavioral diversity of dogs.
There have been major advances in understanding the genes that gave rise to the phenotypic traits of dogs.
The first dogs were certainly wolflike, however the phenotypic changes that coincided with the dog–wolf genetic divergence are not known.
In 1914, on the eve of the First World War, two human skeletons were discovered during basalt quarrying at Oberkassel, Bonn in Germany.
With them were found a right mandible of a “wolf” and other animal bones. After the end of the First World War, in 1919 a full study was made of these remains. The mandible was recorded as “Canis lupus, the wolf” and some of the other animal bones were assigned to it. The remains were then stored and forgotten for fifty years. In the late 1970s there was renewed interest in the Oberkassel remains and the mandible was re-examined and reclassified as belonging to a domesticated dog. The mitochondrial DNA sequence of the mandible was matched to Canis lupus familiaris – dog and confirms that the Oberkassel dog is a direct ancestor of today’s dogs. The bodies were dated to 14,223 YBP. This implies that in Western Europe there were morphologically and genetically “modern” dogs in existence around 14,500 years ago.
Later studies assigned more of the other animal bones to the dog until most of a skeleton could be assembled. The humans were a man aged 40 years and a woman aged 25 years. All three skeletal remains were found covered with large 20 cm thick basalt blocks and were sprayed with red hematite powder. The consensus is that a dog was buried along with two humans. A tooth belonging to a smaller and older dog was also identified but it had not been sprayed with red powder. The cause of the death of the two humans is not known. A pathology study of the dog remains suggests that it had died young after suffering from canine distemper between ages 19 and 23 weeks. The dog could not have survived during this period without intensive human care. During this period the dog was of no utilitarian use to humans, and suggests the existence of emotional or symbolic ties between these humans and this dog. In conclusion, near the end of the Late Pleistocene at least some humans regarded dogs not just materialistically, but had developed emotional and caring bonds for their dogs. – Thanks to Wiki