The dog (Canis Familiaris) is generally believed to be man's oldest companion and was first domesticated around 15,000 years ago. A descendant of the wolf (Canis Lupus), the dog has since evolved into hundreds of breeds, varying enormously in size, shape and appearance. This knol provides an overview of the dog's evolution, geographical development and its early relationship with human society.
From Wolf To Dog: Evolution
Geneticists have traced the ancestry of the dog back to the period around 40-50 million years ago when modern carnivores emerged from two “superfamilies”, known as canoidea and feloidea.
The Canoidea clan evolved into a wide range of species, from canines like the dog, jackal and Arctic fox to such diverse mammals as the skunk, giant panda and the walrus.
The most recent DNA studies have confirmed that the domestic dog (Canis lupus familiaris) evolved from the wolf (Canis lupus). Scientists are divided on when this happened, however. Some argue it occurred 100,000 years ago, others that it was a far more recent development, closer to 15,000 years ago.
Most are agreed, however, that the dog almost certainly evolved in the far East, probably in China. Geneticists think the dog is closest in its make-up to the Chinese wolf. Ancient Chinese breeds, today represented by dogs like the Lhasa Apso and the Shih Tzu are regarded as the closest relatives of these prototype canines.
The basic construction of the dog’s skeleton is the same, regardless of whether it is a Labrador Retriever, a Boxer or a Yorkshire Terrier.
There is strong evidence that the dog became domesticated within human society some 15,000 years ago. A grave in Ein Mallaha in Israel dating back 12,000 years to 10,000 BC contained the skeleton of a woman, cradling a puppy.
The earliest archaeological evidence of dogs in Europe was found in Star Carr in Yorkshire. The dog bones found there date back to beyond 7,000 BC.
The widespread belief is that wolves evolved into dogs when our ancient ancestors recruited canines into human society to take advantage of its superior abilities, in particular its acute sense of smell and ability to travel and navigate long distances. Some, however, argue the change happened while wolves were living as man’s neighbours rather than his domestic companion. According to their theory, wolves would never have had the right temperament to live with humans but some were bold enough to start living off the scraps of food ancient villagers discarded. The wolves that were confident enough to live in close proximity to humans like this, thrived, evolving so as to be more and more compatible with their new neighbours. Those wolves that were wary of the strangers, however, grew apart, remaining essentially the same creature that we see in the wild today.
East to West: How Dogs Spread
Dogs - of some kind - are found on all but one of the earth’s continents, Antarctica.
According to one study, all 701 modern dog breeds evolved from ten, super breeds that emerged from the far East. These ten “progenitor” breeds were bred selectively to fulfil specific tasks. Sight hounds, specialists in coursing game and ancestors of the modern greyhound and Afghan hounds, emerged in Mesopotamia around 4,000 to 5,000 BC. Scent hounds, forefathers of the bloodhound, foxhound and daschund, appeared around 3,000 BC. Working and guard dogs probably emerged in Tibet around 3000 BC paving the way for descendants such as the Rotweiler, the St Bernard's, the bulldog and the Boxer. Some toy and companion breeds, the ancestors of breeds like the poodle and the pug, emerged at around the same time. For reasons that haven’t yet been explained fully, they came from Malta.
American breeds of dogs are descended from European not American wolves. Scientists think that when Europeans crossed the Bering Straits to colonize the Americas, 10,000 to 15,000 years ago, dogs were by their sides. These first settlers seem to have discouraged the breeding of native American dogs.
Old Pals: Dogs & Ancient Society
The Ancient Egyptians revered dogs. When a pet dog died of natural causes every occupant of its home shaved their bodies, including their heads.
n ancient Greece dogs were regarded as geniuses. Plato, no less, called his dog “a lover of learning” and “a beast worthy of wonder” while Socrates once made an impassioned speech arguing that his pet was “a true philosopher”.
The Greek historian Thucydides, on the other hand, believed dogs had the power to detect earthquakes. He described how, days before a cataclysmic earthquake flattened the city of Helice, dogs - along with rats, snakes and weasels - abandoned the place in their droves. Thucydides was convinced the dogs knew what was coming and had run for their lives.
The Romans produced the first ‘Beware of the Dog’ signs. Notices warning ‘cave canem’ were found in Rome and Pompeii. The signs were intended to protect the dogs rather than the citizens, however. Historians think they were designed to warn people against stepping on the small Italian greyhounds that were popular at the time. 
The Romans were the first to utilise the dog's high intelligence by using them as guide dogs. On the wall of a house buried in ash during the famous eruption of Vesuvius at Pompeii is a depiction of a blind man with a staff being led by a small dog, dating from 74BC.
You could call them bosom buddies.
Dogs were so successfully integrated into human society in south America that human mothers often acted as wet nurses for orphaned puppies. They provided milk for the first four weeks until weaning began.
Wild dingos are actually descendants of domestic dogs.
Researchers think their ancestors arrived in Australia on trading boats with their human owners around 4,000 BC.
At this point they were probably sources of food, which is why some of them escaped into the outback where they evolved into wild dingos.
By contrast, the Polynesian dog, or kuri, arrived in New Zealand with the Maori when they settled there. They happily settled down to domestic life on the islands, even though the Maori regarded kuri as a delicacy and ate them on a regular basis.