Your Dog and You
Overview
The dog (Canis lupus familiaris) is a domestic subspecies of the wolf, a mammal of the Canidae family of the order Carnivora. The term encompasses both feral and pet variants. It is also sometimes used to describe wild canids of other subspecies or species.
Over time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights at the withers range from just a few inches (such as the Chihuahua) to roughly three feet (such as the Irish Wolfhound); colors vary from white through grays (usually called blue) to black, and browns from light (tan) to dark ("red" or "chocolate") in a tremendous variation of patterns; and coats can be anything from very short to several centimeters long, from coarse hair to something akin to wool, straight or curly, or smooth.
Origins
What a cute little puppy I am, and sad. Sooooo sad.
Some research appears to show that dogs were domesticated from wolves as recently as 15,000 years ago, or perhaps as early as 100,000 years ago based upon recent genetic, fossil and DNA evidence. Other research suggests that dogs have only been domesticated for a much shorter amount of time and were domesticated from populations of wild dogs, which had previously diverged from wolves.
New evidence suggests that dogs were first domesticated in East Asia, possibly China, and the first peoples to enter North America took dogs with them from Asia. Genetic research has identified 14 ancient dog breeds, with the oldest being the Chow Chow, Shar Pei, Akita Inu, Shiba Inu and Basenji. Because many of the 14 breeds are associated with China and Japan, the theory that the dog originated in Asia seems to be likely.
As humans migrated around the planet a variety of dog forms migrated with them. The agricultural revolution and subsequent urban revolution led to an increase in the dog population and a demand for specialization. These circumstances would provide the opportunity for selective breeding to create specialized working dogs and pets.
Human relationships
Dogs, like humans, are highly social animals and this similarity in their overall behavioral pattern accounts for their trainability, playfulness, and ability to fit into human households and social situations. This similarity has earned dogs a unique position in the realm of interspecies relationships.
The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human idea of love and friendship, leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs. Dogs fill a variety of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as companions.
Dogs have lived with and worked with humans in so many roles that their loyalty has earned them the unique sobriquet "man's best friend". However, some cultures consider dogs to be unclean. In some parts of the world, dogs are raised as livestock to produce dog meat for human consumption. In many places, consumption of dog meat is discouraged by social convention or cultural taboo.
Intelligence
If I'm so smart, why am I the one carrying the stick?
Among dog lovers, dogs are generally valued for their intelligence, and both anecdotal evidence and scientific research suggest that dogs have a reasonably high intelligence. This intelligence is expressed differently with different breeds and individuals, however. For example, Border Collies are noted for their ability to learn commands, while other breeds may not be so motivated towards obedience, but instead show their cleverness in devising ways to steal food or escape from a yard. Being highly adaptable animals themselves, dogs have learned to do a great number of very eclectic jobs as humans have required over the generations. Dogs are employed in various roles across the globe, proving invaluable assets in areas such as search-and-rescue; law enforcement (including attack dogs, sniffer dogs and tracking dogs); guards for livestock, people or property; herding; Arctic exploration sled-pullers; guiding the blind and acting as a pair of ears for the deaf; assisting with hunting, and a great many other roles which they may be trained to assume. Dogs are descended from wolves, and are also pack animals, making them easier than other animals to train because dogs' instincts are to obey. Most dogs rarely have to deal with complex tasks and are unlikely to learn relatively complicated activities (such as opening doors) unaided. Some dogs (such as guide dogs for the visually impaired) are specially trained to recognize and avoid dangerous situations.
Physical characteristics
Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the wolves. Dogs are predators and scavengers, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Although selective breeding has changed the appearance of many breeds, all dogs retain basic traits from their distant ancestors. Like many other predatory mammals, the dog has powerful muscles, fused wristbones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing. Compared to the bone structure of the human foot, dogs technically walk on their toes.
Sight
Dogs were thought to be dichromats and thus, by human standards, color blind. It is now known that dogs can't see the color red very well.
Different breeds of dogs have different eye shapes and dimensions, and they also have different retina configurations. Dogs with long noses have a "visual streak" which runs across the width of the retina and gives them a very wide field of excellent vision, while those with short noses have an "area centralis" -- a central patch with up to three times the density of nerve endings as the visual streak -- giving them detailed sight much more like a human's.
Some breeds, particularly the best sighthounds, have a field of vision up to 270° (compared to 180° for humans), although broad-headed breeds with short noses have a much narrower field of vision, as low as 180°.
Hearing
Dogs detect sounds as low as the 16 to 20Hz frequency range (compared to 20 to 70 Hz for humans) and above 45 kHz (compared to 13 to 20 kHz for humans), and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate and raise or lower a dog's ear. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. Those with more natural ear shapes, like those of wild canids like the fox, generally hear better than those with the floppier ears of many domesticated species.
Smell
Psst. Hey little girl...want a puppy?
Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. What information a dog actually detects when he is scenting is not perfectly understood; although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing, an air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period. The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and the dog must be motivated to continue this hard work for a long period of time.
References
- McGourty, Christine (2002-11-22). Origin of dogs traced. BBC News. Retrieved on 2006 November 29.
- Vila, C. et al. (1997).
- [Robert K.]; Carles Vila, Peter Savolainen, Jesus E. Maldonado, Isabel R. Amorim, John E. Rice, Rodney L. Honeycutt, Keith A. Crandall, Joakim Lundeberg (1997-01-30; accepted 1997-04-14). "Multiple and ancient origins of the domestic dog" (pdf). Science 276: 1687-1689. Retrieved on 2006-12-09.
- Savolainen, Peter; Ya-ping Zhang, Jing Luo, Joakim Lundeberg, and Thomas Leitner (2002-11-22). "Genetic Evidence for an East Asian Origin of Domestic Dogs". Science 298 (5598): 1610 - 1613. DOI:10.1126/science.1073906.
- The Story of Old Drum. Cedarcroft Farm Bed & Breakfast - Warrensburg, MO. Retrieved on 2006 November 29.