The wide range of domestic dogs originated from domesticated gray wolves about 15,000 years ago. Remains of domesticated dogs have been found in Siberia and Belgium from about 33,000 years ago, but none of those early breeds seem to have survived the last Ice Age.
Dogs were probably first tamed by early hunter-gatherer people. There are two main types: hunters and guards. By selecting and training over thousands of years, dogs today can perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship, and, more recently, aiding handicapped individuals. In some cultures dogs are also food animals - bred for their meat to be eaten by humans, however this practice has certain health hazards and is not widespread.
Most of the many breeds of dogs available today have been bred over the last few hundred years. This has been achieved by artificially selecting for particular inate behaviors or appearances appropriate for specific functional roles. In general, the more erect the ears, the more likely they are to be hunters. Floppy ears often indicates a puppy-like, gentle playful animal. However this is not always so, since dogs, like all animals are affected by their training and the situation as they see it.
Through this selective breeding, the dog has developed into hundreds of varied breeds, and shows more behavioral and morphological variation than any other land animal. Some of the popular breeds are listed below.
Smallest dogs edit
The smallest known adult dog was a Yorkshire Terrier, that stood only 6.3 centimeters (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head-and-body, and weighed only 113 grams (4.0 oz). This was developed to hunt vermin, but now is mostly used as a family pet.
Largest dogs edit
The largest known dog was an English Mastiff which weighed 155.6 kilograms (343 lb) and was 250 cm (98 in) from the snout to the tail. The tallest dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder. These dogs were bred as guards - they are gentle and playful - they raise the alarm early by barking as an invitation to play. However they are also powerful, loyal and territorial, and may attack if provoked by strangers.